RISKCURVES version information
1
Table of Contents
Version 11 release history
2
Version 10 release history
11
Version 9 release history
22
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Version 11 release history
Version 11 release history
RISKCURVES 11.5.2 (March 2022) Version Info
This release only contains changes relevant for users with a university edition license.
· Resolved an issue where loading a university edition project could cause errors depending on the
computer configuration.
RISKCURVES 11.5.1 (December 2021) Version Info
· Several stability improvements for handling large projects.
· User interface: Log messages: A transport equipment could provide a misleading log message, which
was warning that the equipment was skipped from calculation whereas all results were available. This
warning message is no longer showing.
· Consequence Risk calculation: When performing a consequence risk calculation to obtain risk for an
overpressure threshold level, combined LoC scenario's now correctly adapt the location of the
overpressure contours using the potential offset of a vapour cloud explosion. In some cases this
overpressure risk calculation could be using the BLEVE blast or Gas blast offset, which would result in a
wrong offset of the contour. This adaptation might provide significant larger overpressure consequence
risk contours for vapour cloud explosion phenomenon in combined LoC scenario's.
RISKCURVES 11.5.0 (November 2021) Version Info
· User Interface: Project file opening: Opening a project file by double-clicking could trigger errors as a
result of the recently introduced asynchronous method of loading and activating the user interface. This
potential problem, occurring on very fast PC's, has been fixed.
· User Interface: Multi language support: The EFFECTS user interface can now also be switched to
Spanish (see Edit-Options,Language). The translations (Chinese and Spanish) in the chemical editor
have been extended with translated names of chemical properties.
· User interface: Calculate from here: When using the option to just calculate one specific node of the
project tree, the project file will no longer be backed up before calculation. This improves responsiveness
of the program when working with large projects, but should be used with caution. When the user has
made considerable changes to the project, it is advised to use the "Calculate" button, which will create a
full back-up of the project before initiating the calculation.
· User interface: Loading older version projects: When loading projects from earlier editions (version 9 or
10), recently introduced or modified parameters will also be automatically adjusted to defaults.
· Flammable cloud dispersion scenarios: The determination of flammable mass and flammable volume of a
cloud, requiring a volumetric integration of concentrations, has been converted into a multi-threaded
calculation, speeding up these specific calculations (both dense gas and neutral gas flammable cloud).
The graph of the flammable cloud volume vs time has been corrected, the volume will now always reduce
to exactly zero after the LFL cloud has passed. This change will not affect any risk result.
· Combined LoC G2 scenarios: The "release within 10 minutes" scenario no longer accepts modelling a
pipeline connected to a vessel. This release mode, intended to represent a high impact non
instantaneous scenario, should model a large release directly from a vessel, applying the associated
hole in the vessel.
· Combined LoC G3 scenario: When using the "fixed flow rate" method in a G3 (leak) calculation,
reloading the project could trigger an "Out of date" warning, requiring to recalculate this scenario. This
inconstancy has been fixed.
· Liquid LoC and PLG LoC with rainout: The pool evaporation model for boiling (cryogenic) pools from water
has been adapted. When using the boiling pool from water while using a confined water surface, the
model would assume there was ice formation, and switch to another heat transfer regime. This behaviour
might occur only at small scale (like experimental) releases and is now abandoned. The model will now
show similar heat transfer behaviour as with unconfined (free spreading) boiling pool from water.
Furthermore, both the "confined boiling from water" and "instantaneous boiling from water" situations will
now also fulfil minimum pool thickness requirements and no longer lead to an infinitely thin pool layer
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Version 11 release history
thickness. This modification may lead to significant lower evaporation rates and longer durations for
confined or instantaneous Propane or LNG on water situations.
· Gas and BLEVE fireball scenario: The heat radiation side-view graph has been improved, and will show
contour dimensions that can differ from the top view shown on the map, which is reporting at a specified
height Zd. This adaptation does affect any risk result.
· Toxic dispersion scenarios: A potential issue with a "frozen" calculation while searching for an extremely
high dosage or very low concentration (toxicity indoors) has been fixed. Furthermore, a "grid spacing
error" that might occur when dealing with negligible releases (never reaching lethal levels) has been
solved.
RISKCURVES 11.4.2 (August 2021) Version Info
· User interface: meteo distribution: Resolved an issue where the meteo distribution graph was no longer
visible.
· Export wizard: In large projects a situation could occur where the “Export consequences as CSV” and
“Export contour dimensions” wizards would crash. This has been solved.
· Toxic dispersion models: For very small releases an issue could occur presenting the contours. This
issue has been identified and resolved.
RISKCURVES 11.4.1 (July 2021) Version Info
· User interface: multiple language support: The Chinese translations have been improved.
· Reading old formats: The conversion of old style “damage definition” scenario’s as used in version 9 and
10.0 has been enabled.
RISKCURVES 11.4.0 (July 2021) Version Info
· User interface: multiple language support: The RISKCURVES user interface can now be completely
switched to Chinese language. Other languages will be made available in the near future by providing
additional language packs.
· User interface: shifted release location on copy: Some users experienced an annoying shift of the
release location when performing a “copy to clipboard” of the map view. This issue has been fixed in
version 11.4.
· User interface: responsiveness while loading and saving. When loading and saving large projects the
application could appear to be “frozen”. This no longer happens and additionally loading- and saving
times have been greatly reduced.
· Vulnerability: Toxic exposure indoors: The calculation of indoor toxicity can now potentially include a
limited exposure duration. This requires an additional “Vulnerability setting” input “Use exposure duration
limited indoors toxicity (Yes/No)”, which is only needed when activating the indoor toxicity calculation.
In previous versions, we would simply assume that the indoors location would be the escape location,
implying that people would continuously be there. This previous method (=selecting “No”) would mean
that if a concentration would build up inside, it would also decrease slowly after the cloud passed,
potentially still leading to substantial lethality indoors due to long lasting concentration exposure. By
selecting “Yes” the inside concentration time graph, which is determining the accumulated dosage, will
also be limited to the user defined exposure duration (default 1800 sec). This situation would represent
total evacuation of the population after exposure duration. This choice obviously has an important
influence on the inside lethality result.
· Toxic dispersion scenarios: The toxic dose dispersion scenario (Neutral and Dense gas) will now also
report indoors toxicity contours, when indoor toxic calculation is activated in vulnerability settings.
Furthermore, the cut-off distance of a toxic calculation will no longer be influenced by a potential “user
defined dosage”, which could previously lead to a different calculation domain and thus calculation
accuracy.
· Pool fire scenario: When applying very short duration continuous release scenario’s, where pool
spreading is not finished when the release stops, the pool fire would switch to instantaneous mode. In
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Version 11 release history
those situations, the pool area would be set to the defined max. pool area. The improved model will now
also check for minimum pool thickness and potentially apply a smaller pool size if the amount of liquid
cannot cover this max. area.
· Unified LoC scenario: This combined LoC scenario, capable of modelling gas, liquid and two phase
releases, could still ask for an input pressure, while the user actually selected “fixed flowrate” requiring a
calculation of this associated pressure. These unnecessary inputs are no longer required.
· Consequence risk using AEGL3 scenario duration: This specific toxic concentration threshold risk
requires calculation of a threshold level based on scenario results (its duration). In case of instantaneous
LoC scenario’s, the procedure will now potentially apply pool evaporation source duration if this
determines the source duration.
· Analysis point reporting: The reporting of risk ranking of consequence risk is now independent of
individual risk ranking. In previous version the risk ranking report of consequence risk could be
incomplete (no % contribution) if individual risk at the coordinate was zero.
· Storage format: The project files are considerably smaller but are not backward compatible. Therefore
projects saved with version 11.4 cannot be read with previous versions.
RISKCURVES 11.3.0 (January 2021) Version Info
· NEW: Imported calculations: Based on feedback from users we have extended the functionality of
RISKCURVES with the possibility to import previous calculation results and aggregate this into a
combined risk result (cumulating both Individual Risk, Consequence Risk and Societal Risk results).
This is specifically intended to avoid huge and calculation intensive projects with hundreds of scenarios,
and allows to split full site studies into separate unit studies, providing the possibility to combine them
later into a full and complete site study. The imported calculation is shown as a separate branch in the
project tree and can be combined with any other part of a project by creating a selection in a “cumulation
set”. See the user manual and instruction videos for more information on this new and very convenient
feature.
· Combined LoC scenarios for two phase releases: These models are now capable of dealing with pure
vapour outflows from top vent PLG releases.
· Heavy gas and Neutral gas explosive mass scenarios: Apart from footprint area and mass in the
flammable cloud the models now also report volume of the flammable cloud (also versus time).
· Jet fire scenario: When using the jet fire model with pure Hydrogen, the model will now apply a reduced
Surface Emissive Power, which reflects the low radiation flux of this material.
· Importing issues solved: Reading in a version 10.1.4 combined LoC scenario in version 11 could trigger
an unexpected error. This issue has been solved. As of version 11.2 the “Outcome” phenomenon
“BLEVE fireball” will now correctly be translated into “Gas or BLEVE fireball”.
RISKCURVES 11.2.2 (January 2021) Version Info
· Toxic consequence footprint definition scenario: This scenario type now allows to be included in a
concentration threshold consequence risk calculation. The risk calculation will use contour dimensions
based on a log-linear interpolation of provided concentration levels.
· Scenario graphs: The Individual risk per wind direction result would create an axis scaling error in case a
zero result (no risk) was obtained. This error has been fixed.
· Combined LoC scenario’s using pool evaporation: When applying an atmospheric pressure that leads to
a lower boiling point, the boiling point will be adapted accordingly. Furthermore, heat transfer from
subsoil will be based on real pool temperature, which can be potentially lower than Normal Boiling Point
for boiling liquids.
· Neutral gas toxic dose or explosive mass scenario: In case the source type is an “Evaporating pool
release”, the dispersion results will now start at the pool centre, avoiding concentration discontinuities
that occurred within the distance range of the pool radius.
· Heavy gas toxic dose or explosive mass scenario The cloud sideview for instantaneous releases could
present misleading and wrong contours, especially in case of rising behaviour. This sideview presentation
has been fixed, although we still advise against the use of this model for lighter than air situations.
Gexcon Netherlands B.V.
Princenhofpark 18
3972NG Driebergen-Rijsenburg
The Netherlands
Visiting address:
Princenhofpark 18
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Version 11 release history
· Combined Unified LoC scenario: If the user selects “fixed flowrate” in a G3 continuous leakage scenario,
the vessel dimensions are not relevant, and will no longer be presented after some change of process
conditions.
RISKCURVES 11.2.1 (November 2020) Version Info
The substantial modifications in version 11.2.0 unfortunately also introduced some potential issues, which
justified a subsequent minor release:
· Project file read problem: In some occasions, users have experienced project file read errors, not
allowing them to open an existing project in version 11.2.0. This appeared to be the result of having
duplicate user defined chemicals stored in multiple user databases. This has been fixed, but in general,
we advise not to make file copies of user databases (.tci files) and have both of them attached (edit>options->chemical databases list): they will both contain the same chemicals, leading to ambivalence
which properties from which database are used.
· Upgrade routine: Because a neutral gas dispersion scenario introduced a new input parameter “type of
continuous source” (Jet release / Pool evaporation / User defined window) old projects imported will now
always force this choice to “User defined window”, enabling all corresponding inputs.
· Dense gas toxic dose scenario: Version 11.2.0 introduced a problem in case an additional “user defined
dose” contour was selected. This issue has been fixed.
· Combined LoC Gas G3 scenario: This calculation could incorrectly flag a gas as a PLG when using the
“fixed flowrate” method, because input pressure is unavailable and atmospheric pressure was assumed.
This problem has been solved.
· Combined LoC Liquefied Gas scenario’s: In case the ambient pressure is lower than standard
atmospheric condition, the temperature of a created pool is now adjusted to the ambient pressure boiling
point instead of its “Normal” boiling point. This avoids the phase detection mechanism flagging this liquid
as a gas in the pool evaporation calculation.
RISKCURVES 11.2.0 (November 2020) Version Info
· Risk calculation: The huge improvement achieved with version 11.2 is that RISKCURVES now actually
performs a multithreaded calculation. This implies that, depending on the capabilities of your PC (a larger
number of “cores” in your CPU gives more speed), a substantial reduction of calculation times can be
expected.
· Gas fireball scenario: a completely new “Gas Fireball” scenario has been added. This scenario replaces
the previous “Flash fire (Instantaneous release)” scenario, but is different from the BLEVE fireball, which
is only intended for two phase (evaporating liquid) fireball situation. The previous flash fire model, merely
calculating the required diameter of an Upper Flammability Limit (UFL) concentration hemisphere, could
underestimate the fireball and heat radiation effects of direct ignition events of instantaneous gas
releases. The new scenario also includes prediction of overpressure effects (Gas blast) upon sudden
depressurisation. A full model theory background document can be obtained from our download site.
· BLEVE and Gas fireball scenario: The fireball scenario’s now also present heat radiation and lethality
grids, allowing to read out results at a specific coordinate using the map crosshair tool.
· Consequence risk calculation: The consequence risk calculation for “circular” events, such as fireballs
and local explosion events has been improved. The BLEVE and gas fireball will also provide overpressure
risks if “include overpressure effects” is selected.
· Combined LoC scenarios: After reconsideration of potential event trees it was concluded that
instantaneous releases of both gasses and PLG’s could always lead to “blast” phenomenon, due to the
rapid depressurisation wave. This Gas or BLEVE blast phenomenon is even relevant in case of nonflammable substances and is now specifically included (see ‘outcome’ selection) in the corresponding
combined model scenario’s.
· Combined LoC scenarios: The “chance direct ignition” and “chance delayed ignition” inputs should never
sum up to more than 1. This total probability of ignition is now automatically limited to one. Users should
be aware that previous versions did not check this, potentially leading to overestimation of risks.
· Combined LoC scenario, instantaneous gas (G1): In case of an instantaneous gas release, a modified
instantaneous gas release model is implemented. This model replaces the previous “expansion to UFL
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Version 11 release history
hemisphere” procedure and is applied if there is no direct ignition. Because mixing with air to UFL level is
no longer included, the end temperature can be substantially lower, now leading to a “heavy gas”
situation after the associated expansion cooling. Therefore, following dispersion model results may be
affected by this modification.
· Neutral gas dispersion scenario: Because users were often having questions about the required
application of the “Gas Turbulent Free Jet” model, this model has now been integrated within the neutral
dispersion models. This also allowed to improve the connection of a “turbulent free jet” phenomenon to
the dispersion phase and avoided the observed sensitivity for the jet “threshold concentration”. The
integrated dispersion models now contain a choice “type of continuous source” which can be
“evaporating pool release” (requiring pool area), “jet release” (requiring outflow parameters including angle
in XZ plane) or “User defined window” (requiring initial source dimensions). In case of a jet release the
model will run an internal “turbulent jet” calculation, translating the concentration profile at the end of the
jet into corresponding offsets and starting conditions for passive dispersion. The background of this
integration is described in a technical document available on our download site.
· Toxic dispersion scenarios: The toxic dispersion calculation will now also report an “Indoor concentration
vs time graph”, in case indoor toxicity is based upon the ventilation rate. This allows to evaluate the
effect of a delayed build up and decay of concentration, potentially even leading to higher lethality.
· All models: mixture phase check warnings: Potential misjudgements in the identification of a mixture
phase have been fixed. As a result of the applied tolerance in the phase check procedure (see version
info 11.1.0), pure gaseous mixtures or pure liquid mixtures could incorrectly get identified as being a
PLG (Pressurised Liquefied Gas) at the provided temperature and pressure. Furthermore, typical liquid
models will now also accept mixtures in “Multiphase Liquid-Solid” situations, as long as the pool
temperature is above the mixtures combined melting point.
· Mass–Volume calculator tool: The mass volume calculator no longer creates an error message “property
not all available” when evaluating mixtures.
· Flammable cloud and fire models: The test for required chemical properties like LFL,UFL and heat of
combustion could fail for flammable mixtures if one of the components was a non-flammable substance
(like Water or Nitrogen). This issue has been solved.
· Dense gas scenario: A rare “double array spacing” error, which could occur in the dense gas models
while trying to generate a contour with low resolution and small release rate situations has been fixed.
· Sample mixtures: The sample mixture “winter grade Gasoline” has been adjusted to be a pure liquid at
expected ambient temperatures. The associated heat of combustion and burning rate haven’t been
changed, giving it an identical result in the pool fire model.
RISKCURVES 11.1.0 (June 2020) Version Info
· User interface: We have been aiming to simplify the user interface. This has been archived by both
grouping the parameters (input and result panels) and by hiding the previously only disabled inputs. This
resulted in an important change of the number of parameters shown, but also in the ordering of
parameters. We realise that this might need some adaptation to get used to this new layout, but we are
confident that this way of presenting provides a more structured and less overwhelming list of inputs and
results.
· User interface: When loading a previously calculated combined LoC scenario, the result reports will now
skip listing parameters of models that did not run and will also provide a sub-model input-output report.
This more intelligible report was previously only shown upon calculation of a combined LoC scenario.
· User interface: We have also reorganised and reviewed the number of log messages that could be
presented. The number of messages has been reduced, and as of this version, the yellow
warning message should really be considered as a reason to check the log message. Typical feedback
messages about resizing source dimensions or database range limitations are now provided as pure
informative messages, because these aspects do not influence the reliability of results. An explanation
of the most common warning messages has been added to the user manual.
· User interface: Scenario’s will always provide a warning if a requested contour level (concentration, heat
radiation, over pressure or lethality level as defined in “presentation settings”) is not reached and the
corresponding threshold contour cannot be drawn.
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Version 11 release history
· Societal Risk calculation: The FN curve for a transport scenario will now be presented using the correct
Y axis scaling. The introduction of the “bottom” minimum in version 11.0.7 needed a manual adjustment
for transport FN curves.
· Individual Risk calculation: A potential error message when trying to use a turbulent jet expansion zone
as flash fire footprint in case of a non-flammable (toxic) substance has been fixed.
· Explosion scenario’s: A potential adjustment of the reporting distance Xd in explosion models, which
was merely reported in the log, is now abandoned. Reporting of explosion overpressures at Xd is now
skipped IF this distance is out of range of the explosion calculation (irrelevant, because overpressure at
those distances is already below any damage level).
· Pool fire scenario: The unintended rotation of the heat radiation grid in case of a rectangular or polygonal
shaped pool has been fixed. This issue was introduced in version 11.0.7 when we started to show the
side view grid in the correct wind direction.
· Pool fire scenario: If the chemical database does not contain a pre-defined value for the burning mass
flux, the so-called Burgess relation will be used. This relation (YB equation 6.67) has been extended to
the official literature’s formulation, which is more accurate for non-PLG situations.
· Pool evaporation / pool fire phase check warnings: As a result of a more systematic phase check
procedure, some flashed liquids (rained out at their boiling point), would be flagged as being a gas. This
problem was caused by a substantial difference between the provided normal boiling point and the vapour
pressure relation in the database. This issue has been solved by increasing the tolerance between
atmospheric pressure and vapour pressure at pool temperature. If vapour pressure at provided normal
boiling point differs too much from one atmosphere, a warning will be provided.
· Liquefied gas scenario’s phase check warnings: Both instantaneous and continuous liquefied gas LoC
scenario’s now also accept situations above critical pressure. These were previously flagged as
“compressible liquid” requiring a liquid outflow, although flashing might occur in specific situations. The
phase check (see Mass/Volume calculator for result of a phase state at any temperature/pressure) now
distinguishes “Compressible Liquid” (temperature <= normal boiling point) and “Compressible
PLG” (temperature > normal boiling point)
· Combined Unified LoC scenario: In case of a two-phase bottom release situation, the potential jet fire
phenomena will now use the liquid outflow temperature instead of the vapour temperature after flashing,
avoiding phase check warnings. For unignited outflows below liquid level, the spray release model will
determine end-temperature (and potential rainout).
RISKCURVES 11.0.7 (February 2020) Version Info
· User interface: Saving of graphs data in spreadsheet format has been improved, now supporting the
latest version of MS-Excel.
· User interface: An error message occurring when showing the temperature dependent property graph in
the chemical editor has been fixed. Unfortunately, this error was introduced in the 11.0.6. release.
· User interface: The Mass Volume calculator tool now also shows substance specific vapour pressure,
boiling point and melting point information. Furthermore, it will now apply “Pressure” and “Temperature”
values as applied in the current active model and will disable access to liquid (or gas) mass / volume
fields if such a phase is not present. The phase detection mechanism itself has been improved, providing
better descriptions of multi-phase situations in case of mixtures.
· User interface: The names of the scenarios have been made more consistent, improving accessibility in
the menu. Several abbreviations or alternative names have been removed, now focussing on describing
the function of the models.
· User interface: All graphs now consistently apply the word “lethality” instead of “mortality” in graph titles
and descriptions.
· User interface: The default US pressure units have been changed to a properly functioning [psi] unit.
· User interface: The use of equipment locations which are very far from one another (>50km) will now
create a warning because these situations would create very big risk calculation domains, leading to
reduced grid accuracy.
· User interface: Removing a scenario or equipment from a calculation set project tree will now always
trigger “out of date” warning (changed after calculation).
· Societal Risk calculation: FN curve frequency values below 10-16 will now also be properly stored as
non-zero data points. Furthermore a “bottom” minimum frequency for the FN curve can be defined in
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Visiting address:
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Version 11 release history
“presentation settings”. This new parameter allows evaluation of exceeding maximum number of fatalities
at very low frequencies. The default minimum FN curve frequency remains 10-10/yr. Furthermore, the unit
for the horizontal N (number of fatalities) axis can no longer be changed.
· Societal Risk Maps: The description of these maps in the help file and user manual have been expanded
to provide a better understanding of this risk presentation method.
· Dense gas dispersion flammable cloud scenario: A potential error message, triggered when applying the
model for “lighter than air” situations has been fixed. The scenario now gives a proper warning in the log
window when dense gas model is applied for “lighter than air” situations. Although this model predicts a
rising behaviour, we discourage the use of this model for these situations, especially for Hydrogen where
concentration predictions should be considered untrustworthy.
· Neutral gas dispersion scenarios: When connected to a Turbulent Free Jet (TFJ) model, the sideview
contours will now also be combined with the TFJ expansion zone, illustrating the initial offset (X and Z) of
the contours created by the jet.
· Fire scenarios: The heat radiation sideview graph would trigger an error when attempting to change units.
This issue has been solved.
· Pool fire scenario: When applying a rectangular or polygon shaped pool fire the side-view grid (shown in
the map view) will now also be rotated according to the applied wind direction.
· Rupture of vessels explosion scenario: The chemical properties check, introduced in 11.0.6 would
always require “heat of combustion” for the chemical being available. This property-check has been
adapted, now only checking for chemical info applied in the selected cause of vessel rupture.
· Toxic dispersion scenarios: When applying these models with a toxic mixture, the chemical properties
check could warn that toxic Probits are not available, if mixture toxicity was not yet evaluated in the
chemical editor. This behaviour has been improved.
· Combined LoC Release in 10 min scenarios: The phase detection, applied in the “release within 10 min”
combined models, has been improved. The absence of an initial pressure input could give a misleading
Liquid/PLG/Gas phase warning.
· Combined Unified LoC scenario: The switch to a “long pipeline” model whenever the pipeline length was
more than 10 km has been removed. This situation would subsequently assume a blocked pipeline
which is totally different from the intended “release from a vessel” scenario.
· Combined Unified LoC scenario: In case of a pure vapour vent from a PLG vessel (leak above liquid level)
the model will also apply a turbulent jet expansion zone.
RISKCURVES 11.0.6 (February 2020) Version Info
· User interface: The export of equipment locations as a shape file has been enabled.
· User interface: The test for graphic display capabilities using a unique Windows 10 call has been
modified. Although Windows 10 is the only officially supported system, this now allows RISKCURVES to
run in older Windows 7 or Windows 8 operating systems.
· User interface: The maximum distance to requested contour levels, as entered in presentation settings,
is now also shown in the scenario report for all weather-classes. To see the contours and obtain full
contour dimensions, a specific weather-class should be selected.
· User interface: Closing the program while an “empty field” error message is shown has been enabled.
Furthermore, exit warnings for changed project contents have been improved, now tracking changed
descriptions and comments.
· User interface: The representation of the wind-rose distribution graph of a meteorological definition has
been improved, now always using an isometric scaling.
· All scenario types: Before calculating a consequence model, a check has been added on availability of
required chemical properties for the specific consequence model calculation. If a specific property of the
substance is not available in the database (e.g. vapour pressure data for a BLEVE calculation), the
calculation will now stop and provide a specific “missing property” error message, avoiding unclear
internal errors.
· Dispersion model scenarios: The potential X offset applied in the dispersion models is now also
incorporated in the sideview contours and concentration versus distance graphs
· Combined Liquefied gas scenarios: The accuracy of the model has been improved by using chemical
properties, temperature and pressure in the applied “Schmidt number”. The applied Schmidt number is
explicitly reported and based on diffusivity calculated according to the “Fuller” relation.
Gexcon Netherlands B.V.
Princenhofpark 18
3972NG Driebergen-Rijsenburg
The Netherlands
Visiting address:
Princenhofpark 18
3972NG Driebergen-Rijsenburg
The Netherlands
helpdesk.effects@gexcon.com
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RISKCURVES version information
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Version 11 release history
· Combined Liquefied gas scenarios: A bug when using “hole in pipe” in a situation with pipeline length <
0.1m (therefore forcing pure Bernoulli outflow) would apply the pipeline area instead of the hole area. This
issue has been fixed.
RISKCURVES 11.0.5 (January 2020) Version Info
· User interface: When applying tile server background maps, users can now define the corresponding
coordinate system applied by the tile server URL. To increase loading speed, it is advised to also use
this coordinate projection system in presentation settings.
· User interface: The tile server address of the “OpenStreetMap” tile server has been changed to comply
with legal usage conditions.
· Unified LoC scenario: A version 11.0.4 modification in the pool evaporation model would require
subsurface roughness to be entered while substance is in gas phase. This input field is now properly
disabled for pure gas situations.
RISKCURVES 11.0.4 (December 2019) Version Info
· Setup / Installation: A dedicated legacy version of the software is available to run the software with
original black dongles provided until end 2018. Note that a network license system can only be run with
the new red Gexcon dongle type.
· User interface: The unintended change of a combo-box by using the mouse-wheel when hoovering over
an inactive input panel has been blocked.
· Pool fire scenario: When using the two-zone model in combination with Methanol, the soot definition
value for pool sizes 20m < D < 50m was undefined. This missing value has been added.
· Liquefied gas LoC G1/G2 scenario: The fixed flowrate calculation, using a predefined flowrate in
situations requiring pressures higher than saturation pressure would still report flashing (vapour fraction).
This has been corrected into a pure liquid phase outflow.
· Liquid or Liquefied gas LoC scenarios: The pool evaporation from water now also uses the subsurface
roughness parameter defining minimum pool thickness. Added subsurface categories are “Quiet water”
for 5 mm and “Rippling water” applying 20 mm minimum pool thickness.
RISKCURVES 11 Release notes (version 11.0.3 November 2019)
(version 11.0.0 to 11.0.2 have been internal release versions)
Prerequisites to run version 11:
· Windows 10 64-bit: RISKCURVES 11 has been changed into a native 64-bit windows application, which
requires a 64-bit Windows 10 operating system on your PC. This enables the software to use all
installed memory of the PC. The software will no longer run on Windows 32-bit or Windows 7 operating
systems. To check whether your version of Windows is 64-bit, look under Control Panel\System and
Security\System, or ask your system administrator.
· USB protection key: RISKCURVES 11 has a new licensing system that might require a different type of
USB protection key. The black version 10 protection key will require the “Legacy” version 11 to run.
When using the new red USB dongle, the software can now also use network licensing, potentially
available for multiple users. Furthermore, a single license can be “Soft locked” to a single PC not
requiring a USB hardware dongle. Details about the licensing possibilities and activation procedure are
provided in a dedicated “License Information” document.
Important changes in this version:
· Installation: the installer is now an MSI-based installation, allowing easier roll-out and integration into
company in-house application catalogues.
· User interface: The program is built with the latest version of the GIS-mapping and graphical tools,
leading to slightly altered “expert” dialogs in the graph- and map result pages.
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Version 11 release history
· User interface: the layer ordering in the legend of the map display panel has changed: the layer at the
top is now actually displayed at the top of the legend. This means that the background map is now at
the bottom of the legend list. Reordering of legend layers, if required, can be performed with a long <left
mouse> click on a layer, followed by a drag action.
· User interface: the graph panel now offers a “colour-line” tool, drawing a horizontal line at any level,
helping to check for exceeding specific levels or thresholds. The graphs properties setting allow changing
the colour, level or orientation
· User interface: the application now supports high-DPI screens, providing sharp and crisp screens on any
resolution, adjusting seamlessly to user display zoom settings.
In the risk calculation method, some enhancements have been applied:
· A scenario not leading to any lethality (therefore no individual or societal risk) might still have nonneglectable consequence risk result. This is now treated separately, avoiding scenarios getting skipped
from a consequence risk calculation (low concentration, heat radiation of pressure levels) whenever there
is no lethal effect.
· The reporting of societal risk ranking at user specified number of victims has been improved. These
results will now also be shown after reloading a project.
· The use of toxic consequence risk calculation no longer fails if the scenario does not contain any
chemical information (such as toxic lethality footprint scenario)
· The environment parameters have been expanded with specific day- or night description.
· The LFL footprint of a Turbulent Free Jet expansion zone can also be used as 100% lethality zone, even
in case flammable cloud dispersion model was not required anymore.
Apart from these generic adaptations, various specific consequence modelling changes have
been applied in version 11.
· Fire models: all fire models (pool fire, jet fire and fire ball) now also present heat radiation sideview
contours, at the requested levels in “presentation settings”. These sideview contours are shown as a
graph but based on a sideview grid-distribution, which can also be illustrated in the (2D) maps view. Note
that it can be confusing that this sideview grid on the 2D map is shown in the x-y plane but actually
represents the z-plane, visualised in the current wind-direction. To illustrate the location of the sideview
contours and grid, a sideview transect axis has been added to the map.
· Pool fire model: the pool fire model supports the use of heat radiation “shielding” at the bottom of the
flame. This is a situation occurring if a pool is enclosed by a bund or dyke, which is higher than the pool
itself. Also fires inside a tank where liquid level is far below the tank wall can now be modelled using this
“shielding”.
· Pool fire model: the pool fire types “confined” and “unconfined fixed-feed” have been renamed in
“instantaneous” and “semi-continuous”. A semi-continuous pool fire can now be elevated (at height).
· Pool fire model: in case of large pool fires (Dpool > 50m), the two-zone pool-fire model now uses
extrapolated soot fraction behaviour.
· BLEVE fireball model: the BLEVE fireball model now includes an initial height of the tank, potentially
leading to a fireball at a higher elevation. This was added to be able to model a truck on a bridge above
ground level (such as the Bologna accident).
· Combined model scenarios: the neutral gas dispersion model will adapt the initial source height to the
pool diameter, when preceded by a pool-evaporation source rate. When connected to a Turbulent Free
Jet (TFJ) model, the cloud concentration footprint will now be combined with the TFJ expansion zone, in
situations where the concentration contour is not detached from the source. This can lead to slightly
larger LFL clouds, which no longer have an offset from the release location.
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Version 11 release history
Version 10 release history
RISKCURVES 10.3.0 (April 2019) Version Info
· Licensing: Version 10.3 is completely identical to version 10.2 but supports a new type of USB license
key. When using the new red USB dongle, the software can now also use network licensing, potentially
available for multiple users. Furthermore, a single license can be “Soft locked” to a single PC not
requiring a USB hardware dongle. Details about the licensing possibilities and activation procedure are
provided in a dedicated “License Information” document.
RISKCURVES 10.2.0 (January 2019) Version Info
· User interface: The main screen has been adapted with the logo of GEXCON, where we are now
continuing the support and development of the safety software.
· Database editor: The link button to the ICSC website has been fixed. The layout of this site (containing
useful chemical specific properties) had been changed, requiring to adapt the URL to jump to.
· Vessel Rupture scenario: The initial velocity of fragments has been reverted to the original formula,
because it depends on the total mass of the vessel.
· Population grid: The minimum allowed cell grid size has been reduced to 1 m, allowing to have more
accurate societal risk calculations in case of short distance effects (< 10 m). However, because this
highly influences calculation time and memory usage, it is strongly advised to keep using the 10 m as a
minimum setting. ONLY use smaller values IF the total population area is very limited and lethality
distances are < 10 m.
RISKCURVES 10.1.9 (October 2018) Version Info
· Reporting of models: The report of dimensions of presented contours has been re-introduced. These
dimensions are shown after selection of a specific weather-class within a model-set and show the level
values as defined in “presentation settings” .
· Consequence risk: The calculation of a toxic consequence risk was skipped in case a scenario did not
provide any lethality, because such a scenario was considered “irrelevant”. Because lower concentration
may still occur for non-lethal scenario’s, this relevance criteria is now based on the specified threshold
levels, potentially leading to larger consequence risks for toxic levels.
· Liquefied gas Spray modelling in combined LOC scenario: The “Aminal” method for spray release
modelling has been adapted with some Yellow book relations (using the Aminal based flash/spray
fraction) allowing to get a more realistic diameter of the expanded jet.
RISKCURVES 10.1.8 (September 2018) Version Info
· Vulnerability settings: When using “Singapore Block mode” the choice to apply this step-based lethality
footprint (by default 3, 10, 50 and 100% lethality levels) has been expanded with a choice for “On-site
fatality risk method” and “Off-site fatality risk method”. This insures fulfilling the official Singapore QRA
guidelines, which for thermal radiation require to apply 4 kW/m2 as 3% fatality limit in case of “off-site
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Version 10 release history
fatality risk”. The previous versions would actually use a 3% lethality based on a heat dose calculation,
this method is now only applied in case of “On-site fatality risk”. Applying the “Off site fatality risk
method” will expand the lethality footprint of a fire event up to the 4kW/m2 distance.
When loading older projects, users who have been applying the “Singapore Block mode” will need to adjust
their choice (previously Yes: apply block mode) and specify to use either “Yes, On-site fatality” or “Yes,
Off-site fatality” risk method.
· Bleve fireball scenario: When including overpressures due to a BLEVE phenomenon, the Bleve blast
model would apply initial storage condition as starting condition. In case of a hot Bleve however, the
overpressures should be based on temperatures and pressures at failing conditions. This has been
corrected, leading to a higher pressure impact zone for a hot Bleve situation.
· Vessel Rupture scenario: An index typo mismatch was discovered in formula’s 7.15 and 7.18 of the
Yellow book. When calculating initial velocity of fragments, the mass M applied in these formula’s should
be fragment mass instead of vessel mass Mv. This error was also implemented in the model and has
been fixed, but because fragment lethality damage is not included, this will not lead to any changed risk
results in RISKCURVES.
RISKCURVES 10.1.7 (September 2018) Version Info
· Presentation settings: The concentration level choices now include flammable concentration levels,
allowing to illustrate various flammability limit contours by dispersion models.
RISKCURVES 10.1.6 (September 2018) Version Info
· Dispersion scenario’s: Flammable cloud dispersion models (dense gas, neutral gas) will also report
flammable contours if the associated explosive mass is neglectable. Furthermore the names of the
associated contours are more consistent with concentration level names listed in presentation settings.
· Overpressure damage: fixed an issue with a non-realistic Lethality-distance curve when using Singapore
block mode. This issue could result in misleading non-existing 50% lethality distance contour for an
explosion scenario but did not affect the individual risk (lethality) calculation itself.
RISKCURVES 10.1.5 (August 2018) Version Info
· Dispersion scenario: All dispersion models (dense gas, neutral gas) used in scenario’s now provide a
real “side view” for all requested concentrations levels selected in presentation settings. Setting the Yand X-axis unit to the same [m] unit will force an isometric visualisation providing a realistic side view of
the plume.
· Pool fire scenario: The model for confined (instantaneous) pool fires will now check for maximum pool
area, using liquid volume and minimum pool thickness.
· Consequence risk calculation: The calculation procedure for consequence risks has been adapted to
avoid overestimated risks of wide footprints in strongly predominant wind directions.
· Flash fire consequence risk: The calculation procedure has been adapted for use in combined models.
The previous version could fail to include the maximum flammable clouds that were calculated by a
combined model, which includes multiple dispersion models.
· Explosion footprint definitions: The input “offset overpressure effects” is now disabled if flammable cloud
dimensions have been defined, avoiding misinterpretation of this value as centre of the cloud (it was
intended as offset from centre of the cloud). These scenarios will now always put the overpressure
phenomena at the centre of the defined flammable cloud. The input “offset for explosion centre” is only
provided IF the user only includes overpressure and no flammable cloud phenomena (dimensions set at
zero).
RISKCURVES 10.1.4 (November 2017) Version Info
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Version 10 release history
The 10.1.4 update contains an important bugfix for a deviation from the Singapore QRA guidelines. This
issue may affect heat radiation contours calculated with the option “Use Singapore Blockmode lethality
levels”. The bugfix is mainly intended for Singapore users, although the increased grid resolution in fire
models or transport equipment may also be beneficial to other users.
· Pool fire scenario: When applying “Singapore Blockmode lethality levels”, the reported lethality contours
were based on a lethality calculation using the pool fire duration as exposure duration. This appears not
to be intended with the description in the Singapore QRA guidelines. The exposure duration has now
been maximised to the prescribed 30 seconds. This change may dramatically reduce the distance to
3%, 10% and 50% lethality contours.
· Pool fire and Jet fire scenarios: The resolution of the calculated heat radiation and lethality grid has been
increased. This will lead to more smooth heat radiation and lethality contours. Note that the contours
can be enhanced even further by using “medium” or “high” accuracy setting.
· Explosion lethality footprint: Applying the lethality footprint definition while the Singapore required
pressure-lethality relation was selected would lead to error message. The error message has been
eliminated but for Singapore style QRA, the use of the explosion lethality footprint should be abandoned.
Singapore users must be aware that the explosion lethality footprint will always be using the “Purple
book” pressure-lethality relation, only having total destruction (300 mbar) and glass fragments (100 mbar)
lethality levels. Therefore, it is strongly advised to these user to apply the explosion consequence
footprint, providing multiple pressure level distances. The explosion consequence footprint will also allow
the calculation of “Injury risk” and “Cumulative Escalation risk”, defined as consequence risk
calculations.
· Copying scenarios to EFFECTS: When copying a “Singapore blockmode” scenario to EFFECTS, the
resulting models would also apply these discrete 3%, 10% and 50% lethality levels. This behaviour has
been removed in EFFECTS because this method is not relevant for a consequence calculation
(EFFECTS release 10.1.4 ).
· Transport equipment: The risk grid cell size for transport equipment is now forced to the same cell-size
as any stationary equipment, avoiding inaccuracies with small routes. When utilising very long routes the
cell size will be increased to avoid huge grid dimensions.
· Population grids: an issue with importing of grids from external files, which was introduced in version
10.1, has been resolved. It appeared that the second (night) grid was not imported correctly by the
importer, leading to an empty night population.
· User Interface: Exporting background maps: When exporting a background map as pixel based image
format (JPG,TIF, PNG,BMP), without providing the required extension, the graph is now actually being
saved, in the default TIF format.
· User Interface: Changing axis boundaries: Adjustment of the X/Y axis boundaries in the graph expert
dialog would often cause an error message when retyping values. This behaviour has been fixed.
RISKCURVES 10.1.3 (November 2017) Version Info
· Combined LOC scenarios using Turbulent Free Jet : The reported density was based on pure material at
end conditions. This density is now corrected for the actual end concentration. This implies that the
reported mixture density will often lead to continuation with neutral dispersion due to dilution
phenomena.
· TNT explosion scenario: the TNT model now also reports Pressure-Impulse and Positive phase duration
versus distance graphs. As a result, the Pressure impulse damage probit relation can now also be
applied within a TNT based calculation. The TNT overpressure calculations are no longer based on
interpolation of discretised Yellow Book graphs, but are now using the Kingery-Bulmash correlations for
hemispheric explosions.
· Rupture of vessels scenario: the end point of the graphs is now based upon a 300 Pa end pressure, just
as other explosion models.
· Explosion results: all explosion models (Multi energy, TNT and rupture of vessels) now apply a
logarithmic x point distribution. This will ensure that readouts of higher pressure levels at shorter
distance are more accurate.
· Consequence risk toxic footprint A potential issue with AEGL-3 consequence risk and associated
concentration contours not showing up has been fixed.
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Version 10 release history
RISKCURVES 10.1.2 (October 2017) Version Info
· Risk ranking report: the risk ranking report for individual risk available at analysis point has been
extended with risk ranking report of all defined “consequence risks”.
· Footprint definitions: the pool- and jet-fire footprint definitions will now force the provided flame
dimensions as 100% lethality (in lethality footprints) or 100 kW/m2 (in consequence footprints) in the
contour dimensions table. This adapted procedure ensures awareness of the implications of providing a
flame dimension. This procedure also prepares the footprint definition for the fact that we intend to
remove flame dimensions as an input field in future versions. If the projected flame footprint is not to be
used as 100% lethality area, it is suggested to set flame dimensions to zero and provide 100% lethality
or 100 kW/m2 footprint at receiver height in the first table-row.
· Pool fire and Jet fire model scenario: will now also report flame footprint dimensions (as max distance,
min distance, distance to max width and max width).
· Combined models using gas outflow: The combined models using turbulent jet gas expansion now also
evaluate potential vapour cloud explosion within the expansion zone. These situation will now run a “Multi
Energy” explosion based on the explosive mass and cloud centre which is potentially reported by the
turbulent free jet.
· Unified LOC scenario: This scenario might use the “long pipeline” model to calculate outflow IF provided
pipeline length is larger than 1 km. These “long pipeline” models (Gas and two-phase) now support the
use of “double sided outflow” and a potential inlet flowrate, providing an outflow feed after pipe
decompression.
· Vessel rupture scenario: the input parameter “fraction of liberated energy…” has been removed because
it was only relevant for “BLEVE overpressure” calculations but forced to 4% according to the advised
Yellow book value inside this calculation.
· Chemical Database: the relevant predefined sample mixtures now include a value for the “burning mass
flux” which might be used in pool fire calculations. These values that were introduced in version 10.0.3
were missing in the 10.1 database. Furthermore, the AEGL values of Hydrogen Fluoride have been
adjusted because they were reported as being incorrect.
RISKCURVES 10.1.1 (July 2017) Version Info
· Toxic consequence definition: This footprint definition scenario now also presents concentration level
contours, as defined in presentation settings.
· Neutral gas Toxic dose: This scenario could give an “empty box” error in case the 1% lethality
concentration was never reached. This issue has been solved.
· Toxic dispersion scenarios: The toxic dispersion calculation allows to calculate a contour for a specific
user defined toxic dose level. This allows to illustrate dosage contours which are lower than the 1%
lethality dose, such as a dose equivalent for AEGL2-during 1800sec.
· Dispersion model scenarios: All dispersion scenarios now allow to use non-standardised roughness
length values. Previous version would always require to enter a roughness class type, which was
associated with a specific Z0 value. These types now include a “user defined” choice, allowing to enter a
specific roughness length Z0 value (expert parameter).
· Combined LOC scenarios: the choice for “Use representative step” now includes choices “maximum
flowrate”, and “Third 20% average (mean)”, where outflow duration and specific outflow conditions are
calculated accordingly.
· Explosions (overpressure) scenarios: The explosion overpressure calculation would use a lower cut-off
value of 3500 Pa, which disabled the possibility to draw overpressure contours for lower values. This cutoff has been reduced to 300 Pa, which is the minimum value to obtain any relevant damage.
RISKCURVES 10.1.0 (June 2017) Version Info
· User Interface: contour levels and thresholds are now centrally set in “Presentation settings”: they apply
to all available models within the project:
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Version 10 release history
· User interface: in “Reports” the dimensions of calculated contours will be reported as: maximum
distance, minimum distance (offset), maximum width and distance to the maximum width. Note that the
previously reported “contour length” corresponds to the new “maximum distance” minus “minimum
distance (offset)”.
· Consequence risk: Consequence risks are now visible as a separate and expandable branch in the
project-tree. Users can now define multiple level assessments, in which selected risks for exceeding
heat radiation, overpressure, toxic concentration levels and flammable cloud exposure are now
aggregated into one total consequence risk for all active selected levels.
· Damage definitions: have been renamed to “lethality footprint definitions”, whereas additional
“consequence footprint definitions” have been added. Consequence footprint definitions allow calculation
of both individual and consequence risks by defining distances to heat radiation, overpressure or
concentration thresholds.
· Damage definitions: both footprint definitions (lethality and consequences) are now defined using Max
distance, Min distance (offset), Distance to max width and Max width, allowing to define “egg shaped”
contours instead of perfect ellipses. Previous length/width/offset dimensions are translated when
importing whereas calculate contour dimensions from EFFECTS can be easily copied into these
definitions.
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Version 10 release history
· Vulnerability settings: for overpressure lethality, the translation to lethality can now also be a user
definable peak pressure-lethality relation.
· Vulnerability setting: lethality conversion can now be forced according to Singapore prescribed lethality
level blocks of 6.5%, 30% and 75%.
· Scenarios: The “rupture of vessels” model has been included as a potential explosion phenomena
scenario.
Apart from these changes some model specific changes have been applied
· Dense gas dispersion: a wide range of changes have been applied to the dense gas models. A special
document is available for more information. Summarised the changes are:
· Instantaneous releases are now modelled as an initial cylinder instead of a half-sphere, where users can
define the initial area. If this area is entered as zero (default), the model will assume a cylinder with
height equal to diameter. Because the initial column height determines the initial spreading forces, users
can now adapt the behaviour to the real world storage situation.
· Semi continuous releases now have an improved transition behaviour at the end of the outflow. Previous
inconsistent discontinuity behaviour has been removed.
· The initial concentration internally calculated in vol% is now translated into density based concentration
[mg/m3] using the actual vapour temperature.
· The model now reports a side view of the cloud as a graph (plume shape), illustrating the potential
vertical descending or rising behaviour. This is a qualitative representation: the plume axis is shown, as
well as the extend of the cloud (not configurable).
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Version 10 release history
· Fire models: when applying the choice “Include protection factor clothing” the model now also takes into
account that above a certain heat dose, clothing will be set on fire, leading to 100% lethality. This
“clothing burning distance” is reported.
RISKCURVES 10.0.6 (November 2016) Version Info
· Combined models Liquefied gas: When adding pool evaporation source to a spray release rate and using
neutral gas, the initial dimensions will now be calculated based upon 100vol% initial concentration. In
previous versions a pre-dilution could occur, leading to shorter effect distances.
· Combined model for instantaneous release of pure gas: The pressure input field can also be set for
substances below critical temperature. For sub-critical temperature substances, the pressure can be set
by selecting “actual pressure” instead of the suggested “vapour pressure”.
· Liquid release model: In case of an unknown liquid viscosity of a substance, the model would raise an
unhandled error. This situation is now handled properly.
· Jet fire model: A jet fire can now be modelled as a “grounded jet”. If the release height is set below zero,
a situation of a “jet fire inside a crater” is now assumed. Due to impingement effects, these jet fires do
not have any lift-off so they are now modelled as a typical “grounded jet” (fire frustum shape starting at
ground level).
· Risk calculation of societal risk maps: When using “temporary population polygons” , the calculation of
societal risk maps could raise an unhandled error due to coordinate projection inaccuracies. This issue
has been solved.
· A file exporter has been added, allowing to export user specified consequence data to a CSV file. See
the help file/user manual “Exporting consequence data” for more information about this functionality.
RISKCURVES 10.0.5 (June 2016) Version Info
· Combined models: Risk calculation: For a scenario with a substance which has both toxic AND
flammable phenomena, the toxic risk is expected to occur only IF the material is not burned. Therefore,
the probability of toxic exposure is now reduced with the chance of ignition. This correction will NOT be
applied if the user has chosen to evaluate toxics only (Outcome /phenomena = ”Toxic dispersion” only)
or no relevant fire phenomena occur. This adaptation, which is now according to various governmental
guidelines, will change toxic risk results IF combined models were used for toxic AND flammable
substances (Ammonia, Acrylonitrile). Note that some official guidelines explicitly state that Ammonia
should ONLY be evaluated for its toxic risk. In such cases, the user should choose outcome parameter
“Toxic dispersion” only.
· User interface: exporting risk grids: When saving calculated grids from the map view page, the resulting
exported file could end up mirrored on Y-axis. This issue has been fixed.
· User interface: exporting graphs: several fixes in the exporting of graph data.
· User interface: combined models input screen behaviour: For combined models the choice for an outflow
type “Fixed flowrate” would disable some vessel property input boxes. Unfortunately, these inputs were
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Version 10 release history
not re-enabled when changing back to “Leak from vessel” or “Release from vessel through pipe”. This
unintended behaviour has been fixed. Furthermore, the enabling of “vessel length/height” input box while
using a spherical vessel was avoided.
· User interface: The ruler has been extended with the functionality to measure an area and the length of a
path. This could be used to determine the area for pool evaporation for instance.
Select the ruler button in the maps view, and select the desired functionality. Reselect the option or
press ESC to end measuring.
· Mixtures: A calculation issue within the calculation of the burning mass flux for a mixture containing a
non-flammable component has been resolved.
· Various performance improvements in the loading of a project and adding models to a project.
RISKCURVES 10.0.4 (April 2016) Version Info
· User interface, Copy protection system: If the information from the copy protection dongle indicates that
the user has 30 days or less as a remaining license time, a warning will be displayed upon the start of
RISKCURVES.
· User interface, Projection systems: The default coordinate projection to use can now be set in
“Presentation settings defaults” (Menu “Edit..Options”). This allows the user to always start with a local
preferred system instead of the previous defaulted Pseudo Mercator system.
· Risk calculation: flammable cloud scenarios: The flammable cloud scenarios now allow the user to
specify the time of ignition. The previous RISKCURVES versions would always use the “free field
method”, assuming that a vapour cloud would ignite at the time where the area of the cloud is at its
maximum (at Tmac = Time maximum area cloud). The user can now also select either “Time of
maximum explosive mass” or any user definable time. Note that changing the ignition time from its
default Tmac will influence both societal and individual risk results.
· Risk calculation: consequence risks: The threshold values, provided in consequence risk settings, are
now forced as explosion overpressure threshold, third heat radiation threshold and toxic threshold
concentration in all relevant scenarios. As a result, these input fields are now longer shown at scenario
level. If a toxic concentration threshold risk contour is required, and the specified concentration
threshold (e.g. “IDLH concentration”) is not available in the database for a specific chemical used in a
scenario, an error message will be provided. This will indicate that the user has to add this threshold to
the chemical properties.
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Version 10 release history
· Dispersion scenario: A potential unlinking of the “threshold concentration” input fields in a dispersion
modelset has been repaired and avoided. This unintended unlinking could occur upon a changing a
chemical substance, because the list of available predefined concentration would be refilled, potentially
leading to a conflicting existing threshold concentration choice.
· Pool fire scenarios: The definition method for the burning mass flux of mixtures has been changed. This
important parameter for the pool fire calculation is either provided as a substance specific parameter in
the database, or if this value is not available, the Burgess formula will be used to calculate a burning
mass flux. In case of mixture’s the same method is now provided for subcomponents and the mixture
itself. The user can provide a mixture specific value, or it is calculated using ideal mixing rule using the
components specific burning mass fluxes, which are potentially also being calculated. Furthermore,
many predefined example mixtures now have their typical values provided in the database, according to
the original publication of Rew & Hulbert (see model documentation). If the database value is not
provided, feedback will be given on the calculated burning mass flux.
· BLEVE Fireball scenario: The burst pressure input value is now a simple mode input value, and always
visible. This has been adapted because this input determines the hot or cold BLEVE fireball distinction,
which should always be considered.
· Combined model Gas G2/G3 scenario: A potential error when applying the combined model with a fixed
flowrate has been eliminated. (This error was raised by the “Turbulent Free Jet” model, because fixed
flowrate is no valid choice for this model).
· Combined model Liquefied Gas G2/G3 scenario: the bottom discharge calculation in case of a pure
vapour outflow has been improved. The result of the bottom discharge (TPDIS) calculation for a pure
vapour outflow no closely resembles the result of the top vent situation. Furthermore, the rare occurrence
of an error message from the spray calculation “exit temperature lower than boiling temperature” while
the chemical is at saturated conditions has been avoided.
RISKCURVES 10.0.3 (February 2016) Version Info
· Societal Risk calculation: the societal risk calculation in case of a flammable cloud scenario has been
corrected. It appeared that the event tree “fraction with explosion phenomena” was not taken into
account correctly in societal risk calculations. This explosion fraction is now correctly handled as “the
fraction of the flammable cloud events where both a flash fire AND an explosion overpressure occur”. This
correction will NOT affect individual risk results, but it does influence SR results of flammable cloud
scenario’s .
· Consequence Risk calculation: the calculation method to obtain the toxic consequence risk of
exceeding a specific concentration threshold has been improved. Because toxic dispersion models now
also report the outer contour of the concentration threshold, this contour can now directly be used to
derive the toxic consequence risk, making the method faster and more accurate.
· Population definition: the area calculation of user drawn population polygons has been corrected for
projection system conversions. This will influence the population density conversion if non “WGS 84
Pseudo Mercator” systems were used. Note that the societal risk calculation will always be based on
the “total number of people” in the area. Therefore, this correction will only affect societal risk results IF
population has been defined by providing a population density for the polygon AND local projection
system were applied.
Consequence model improvements:
· Dispersion models: both the neutral gas and dense gas model now report an outer contour of the
concentration threshold (user input choice). This contour illustrates the maximum distance to the
specified threshold concentration. In flammable cloud scenarios the LFL concentration outer contour
will be shown. In toxic scenario’s, this concentration threshold will be set by the “Toxic Consequence
Risk” threshold choice.
· Toxic dispersion models: both neutral and dense gas now report a “Concentration versus time” graph at
reporting distance Xd. This graph clearly illustrates the relation between maximum concentration and
associated dose.
· Dispersion models: the step size refinement when searching for maximum concentration has been
improved, leading to a more accurate calculation and smoother graphs in the maximum region.
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Version 10 release history
· Neutral gas toxic model: the calculation of the dose of a continuous source was corrected. As of version
10.0, this dose was calculated using an incorrect toxic exposure duration.
· Dense gas dispersion: a rare non convergence iteration situation that would lead to closing of the
application has been fixed.
· Pool fire model: the calculation of the burning mass flux for mixtures has been corrected. For single
components, many common substances already had an experimental value provided in the database
(expressed as kg/s.m2). If this value was not available, the Burgess relation (equation 6.67 of the Yellow
book) will be used to estimate the burning mass flux. This procedure could be inconclusive for mixtures
and has been improved. Note that as soon as a “burning mass flux” value is (user) defined in the
chemical database, this value will overrule the Burgess relation.
RISKCURVES 10.0.2 (November 2015) Version Info
· BLEVE fireball scenario: the model now corrects temperatures for “hot” BLEVE situations. If the burst
pressure entered is higher than saturation pressure, this means that a “hot” BLEVE (tank heated up by
external fire) occurred, and the corresponding burst temperature will be calculated based on the failure
pressure. This implies that flash fraction and incorporated mass will be higher for a “hot” BLEVE.
· Cumulation set: The presentation of “Cumulation set” risk grids (both Individual Risk and Consequence
Risk grids) has been improved, solving a potential issue with different projection systems.
· The population import wizard now properly handles potential “empty” day/night grids when importing from
CSV format.
· The visualisation of the wind distribution in the “wind rose “ graph has been changed.
RISKCURVES 10.0.1 (August 2015) Version Info
· It is now possible to copy/paste linked models or a complete equipment from EFFECTS to
RISKCURVES. All RISKCURVES supported models will be inserted as separate scenarios / model sets.
· Changing the coordinate system when importing population as a shape is now enabled.
· Consequence Risk results are now removed prior to recalculating. This resolves an issue where the
results would still be available after setting the ‘Calculate Consequence Risk’ back to ‘no’.
RISKCURVES 10.0 (July 2015) Version Info
RISKCURVES 10 was revised in a number of fields.
1. First of all, RISKCURVES now utilizes a coordinate projection system. To be able to use this setting
on version 9 project files, loading a version 9 file will start with upgrade wizard, asking where this project
should be located, and what projection system to use.
2. Apart from background maps which can be loaded from files, background maps can be also streamed
from internet based tile servers.
3. The project file structure has been changed, its extension is now .RISX, and it also incorporates any
chemicals used within the calculation.
4. One of the biggest enhancements of RISKCURVES 10 and EFFECTS 10 is the ability to define and
work with chemical mixtures, including the support for multiple database files (user defined or
company specific databases). To be able to provide these features, the chemical editor layout has been
redesigned. Any “User-defined” chemicals that were defined in version 8 or 9 can be converted into the
new separate user database file.
5. A damage definition scenario can now also be using a block-mode lethality footprint, avoiding
interpolation between provided lethality distances.
Many consequence models (based on new EFFECTS 10 core models) have been improved or revised in
this version. Below is a list of the important enhancements included:
· Outflow models: The spray release model now also contains a new "Statistical spray" method, which is
applicable for CO2 as well (which is a solid/gas equilibrium). Instead of using one typical droplet size,
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Version 10 release history
this model uses a droplet size distribution, where rain-out fraction is highly dependent of these droplet
sizes and height of the release (falling height). The model can work with different number of samples,
influencing the calculation time and accuracy of the distribution. Compared to the original "Yellow book"
model, this model results in a higher approximation of the rainout fraction. The spray release model now
contains a selection box allowing to choose "Yellow book", "Aminal rule" or "Statistical spray method".
· The pool evaporation model will provide warnings when being applied with YAWS chemicals, because
the calculation of the Schmidt number uses critical volume which is highly unreliable when derived for
YAWS chemicals.
· Combined models outflow: All G3 "Leak" scenario now allows to use a "fixed flowrate" instead of a
calculated flowrate based on hole size and pressure. This option is available within Gas, Liquid, Liquefied
gas an Unified LOC combined models. When using this "fixed flowrate" selection, the model will
calculate a corresponding required exit pressure to obtain this flowrate. This exit pressure is often
required in many following calculations (like turbulent jet or spray release). This fixed flowrate can be
used in situations where release rate and hole size are given, such as a specific pumping rate.
· The BLEVE model was originally only used to calculate the fireball phenomenon, although a BLEVE
abbreviation itself refers to an explosion behaviour. The BLEVE fireball model can now also calculate
overpressure, which is based on "BLEVE blast" calculation method as published by van der Berg. (see
model references). The BLEVE blast calculation is also available as a separate explosion model.
· The BLEVE fireball model no longer uses a BLEVE mass as input, but asks for storage conditions like
vessel volume and temperature. Depending on these storage conditions a BLEVE mass incorporated
within the phenomenon will be calculated. This BLEVE mass is based on the generally accepted rule of
"3 times the adiabatic flash fraction". This is particularly important for (pressurized) LNG tanks, were
usage of the full vessel contents would lead to overestimation of the fireball phenomenon.
· All fire models will now report both heat radiation level contours and damage contours. Furthermore, a
heat radiation footprint can be presented for pool fire and jet fire.
· The pool fire model has been extended with a new "two zone pool fire" method, which is based on
original publication from Rew&Hulbert (see model references). Apart from this new calculation method,
separating the flame in a clear and a sooty part, the model will now calculate the view factor using a
"Discretised Radiation Method", which was already used for jet fires in version 9. Due to this extension
the pool fire can now have any shape: circular, rectangular, a rim or a user drawn polygon pool shape.
The specific burning rate, which was previously hard-coded for chemicals listed in the Yellow Book, is
now added as a chemical dependent property. The values that are listed here are taken from the more
recent Rew&Hulbert publication. If no data is provided, the Burgess relation is used to calculate the
burning rate.
· The Multi- Energy explosion model can now also use the GAME correlations ("Guidance on the
Application of Multi Energy", see model references) to estimate the blast strength. Instead of using a
fixed ME curve number, the max. overpressure will be calculated based congestion characteristics:
"Volume Blockage Ratio", average diameter of the obstacles, laminar burning velocity of the chemical
and flame path length. These substance dependent laminar burning velocities have been added to the
chemical database as a property.
· Chemical database: The threshold concentration level to be used for contour presentations can now be
taken from a list of available thresholds in the database. Many common chemicals will have values like
IDLH, AEGL and ERPG values listed.
· The "explosion dispersion" model have been renamed to "flammable cloud" and now also support
presentation of 50% LFL concentration contours.
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Version 10 release history
Version 9 release history
RISKCURVES 9.0.26 (March 2015) Version Info
· Riskcurves ProjectConverter, This converter that will translate version 7 project towards version 9, has
been adapted. It will now also translate old “Explosion scenario’s” into Explosion (Multi Energy)
scenario’s.
· Background maps: If the background map stored in a Riskcurves project would contain an error, the
project would fail to load. The handling of such a situation has been improved and a problematic
background map will simply be skipped upon load.
· Dense gas calculation: In some unreproducible situations the TNO_Densegas model, which is an
external executable, could come up with a strange error message “TNO_DenseGas.exe - No Disk”.
The TNO_Densegas program has been adapted to avoid any sensitivity for detached external drives.
RISKCURVES 9.0.25 (December 2014) Version Info
· Improved handling of Windows Regional settings.
· Spray release calculation: When using the “Aminal” method instead of the Yellow book method, the
reported liquid fraction was not corrected for rainout. The liquid fraction calculation for this situation has
been corrected.
RISKCURVES 9.0.24 (December 2014) Version Info
· Damage definition: The behaviour of the damage definition for pool and jet fire has been corrected, now
forcing the lethality footprint to include provided flame dimensions.
· Toxic dispersion models: The calculation of the indoor toxic dose could result in an error when
performing toxic calculation on locations without a relevant concentration profile. This potential error has
been solved, now resulting in zero indoor dose for those situations.
· Turbulent Free jet: The width of the concentration contour is now also reported when a full concentration
contour is being calculated (concentration threshold reached within expansion zone).
RISKCURVES 9.0.23 (October 2014) Version Info
· Individual Risk calculation: The usage of the choice “use Pressure probits for IR” would lead to incorrect
results for areas outside the total destruction level contour. The calculation procedure for IR for
overpressure using “pressure probits” has been improved, now accurately taking into account lethality
due to overpressure until the provided cut-off pressure limit.
· Outflow models for 10 minutes (fixed duration release): When applied for very small vessels, requiring
flow rates smaller than 1 kg/s the tolerance in finding the holesize would be taken too high which would
lead to inaccurate holesize calculation. This issue has been fixed.
· Poolfire model: When using very short outflow durations, the pool boundaries are not reached within the
outflow period. This could lead to the situation that a larger hole would lead to a smaller poolfire because
the timestep in calculating the poolradius was taken too big. This reported issue has been fixed in this
version.
RISKCURVES 9.0.22 (August 2014) Version Info
· Societal Risk calculation: The combination of using “temporary population polygons” without generating
“Societal Risk Maps” could lead to an internal error in the scenario calculation. This issue has been
solved.
· Overpressure probit for individual risk calculation.
Although the probit-based pressure damage relation is usually derived from glass fragments damage,
thus specific for inside damage, some countries require to apply this overpressure probit for individual
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Version 9 release history
risk calculation as well. This is now possible by adding a choice “Use probits for IR calculation” in the
vulnerability settings.
· Explosion damage definition.
The usage of a “probit based” lethality for overpressure is not supported in combination with an explosion
damage definition, because overpressure distance information is not available in this damage definition.
This combination will now result in a warning message because the calculated risk will only be based on
the “total destruction” and “flash fire” envelope lethality’s.
· Individual- and consequence grids.
The individual- and consequence risk grid, which is the base for the calculated contours, can now be
visualized. This grid is only shown in “expert mode”. The grid colours are derived from the defined level
colors, and by using the crosshair tool on the selected grid layer, it is now possible to derive the
corresponding risk value for any coordinate under the cursor.
· Consequence Risk Contours.
New functionality is added*) to calculate “Consequence Risk Contours”. These contours visualise the
probability of exceeding a specific consequence threshold level (which can be an overpressure, heat
radiation or toxic threshold). The specific levels of threshold (Pressure = overpressure level, Heat radiation
= radiation intensity or heat dose level, Toxic = dose or concentration level) are defined as a new entry
(“Consequence Risk Settings”) in the “Calculation Settings”.
*) This new functionality is only available for users with an active time-based license.
RISKCURVES 9.0.21 (May 2014) Version Info
Several internal model improvements have been applied in EFFECTS consequence models, which will also
affect RISKCURVES scenario calculations using these models:
· Latitude input: The combined models would disable the “Latitude” input field, if the solar heat radiation,
required for pool evaporation calculation, was manually added. Because this input is also required by the
Neutral gas dispersion model, this dispersion model would use a fixed default of 51 degrees (which is
the Dutch value). This behaviour is improved, and the dispersion model now uses the local environment
settings value.
· Pool fire model: When using the pool fire model with a semi-continuous release, the resulting pool
diameter is calculated based on an equilibrium between pool spreading due to the supply and the
burning rate occurring. When using longer duration of releases (hours), the time step for this calculation
would be taken too big, resulting in an overshoot and thus inaccurate pool diameter calculation. This
behaviour has been fixed.
· Unified LOC Combined models: The combination of the evaporation rate with a potential “air born” fraction
of the release would calculate the density based on pure vapour coming from the pool. For liquid
releases, this combination would result in a too high density, because the dilution above the pool was
not taken into account. In specific cases this would lead to the choice to use a “dense gas” dispersion
models whereas the dilution above the pool would already provide a “neutral” mixture. This behaviour did
not occur in the liquid LOC models, only in the unified LOC model, and for two phase releases, the
density would always result in “heavier than air” situation due to liquid droplets in the spray. The
calculation of the combined source density has been fixed, which may lead to slightly different results for
pure liquid situations in the unified LOC model.
· Liquefied gas combined models for instantaneous release: the potential occurrence of a BLEVE fireball
phenomenon was skipped if the material was toxic, to avoid a BLEVE fireball phenomenon being
calculated for a commonly used chemical like Ammonia. However, this would also eliminate a substance
like Ethylene Oxide from having a fireball phenomenon. This issue has been solved in this version, the
potential occurrence of a BLEVE fireball is now based on flammability limits criteria.
· Pool evaporation model: The so-called “Schmidt number” used in the main relation to determine the
evaporation flux, was calculated using thermal diffusivity, which was not according to the original theory
(formula 3.24 from Yellow Book, ref. Kawamura). This behaviour has been corrected, now using mass
diffusivity, calculated using the Fuller correlation (see model documentation). The calculated Schmidt
number, which is influenced by temperature, atmospheric pressure and typical air and chemical
properties, is now also listed in the results. Furthermore, the calculation of pool evaporation from water
for cryogenic liquids, released just below boiling point, will now be forced to a boiling situation. The LNG
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24
Version 9 release history
evaporation from water has been fitted to the Burgess experiments and the film boiling heat transfer rate
has been corrected. These modifications might result in small changes (generally < 3%) in the
calculated evaporation rates.
RISKCURVES 9.0.20 (Oct 2013) Version Info
· Windows 8.1: This updated version of EFFECTS and RISKCURVES is now supported under Windows
8.1. The previous driver for the copy protection dongle has Windows 8.1 compatibility issues. This
version includes the latest version of this driver, which fully supports Windows 8.1. Users who want to
move to Windows 8.1 must FIRST update the driver (by running our new setup) before updating their OS.
If you encounter problems uninstalling the old driver please contact the TNO helpdesk.
· Individual Risk calculation : The “explosion fraction” (the fraction of the events that have overpressure
effects) was not always correctly taken into account when calculating the individual risk of an VCE. This
behaviour is now fixed. Although many scenarios will have a situation where the footprint of the LEL
cloud will be bigger than a potential “total destruction contour” (by default the 0.3 bar overpressure circle
around the cloud centre), thus minimising the influence of overpressure damage, this fix may lead to
slightly smaller IR contours in specific situations.
· Poolfire, Jetfire and BLEVE models: The maximum Surface Emissive Power (SEP) of the flame surface
will always be limited to 400 kW/m2, to avoid unrealistic high radiation fluxes (e.g in case of high
“fraction of heat radiated” values).
· Jetfire model; the atmospheric transmissivity is now calculated using the minimum distance to the flame
surface instead of the average distance. This will result in slightly higher radiation values but is more
realistic since the closest parts of the flame will contribute the most to the received radiation.
· Combined models: when combining toxic dispersion results from an instantaneous source with a
continuous source, the distance to a toxic threshold was taken from the graph, even if the graph was cut
off at an end distance Xd before the threshold was reached. These distances are now correctly
presented, according to the contours drawn.
RISKCURVES 9.0.19 (Sept 2013) Version Info
· Cumulation set: The presentation of Societal Risk Maps for a combination which is based on multiple
calculation sets has been disabled. It appeared that the “cumulate” feature could be used to combine
results from different population definitions (with potentially different cell sizes or boundaries), leading to
an incorrect aggregated map. The aggregated FN curve will still be calculated and presented, but the
maps have been skipped for these situations.
· Population import wizard: The handling of so-called “multi-polygons” and “polygons with holes” has been
improved. The occurrence of these kind of complex shapes in a shape file could lead to an incorrect
population distribution.
· Import (Copy and Paste) from EFFECTS: A model that is copied from EFFECTS would be forced to use
environmental and weather conditions from the user defined environment settings and stability classes /
wind speeds. It appeared that the wind direction was not forced into the standard “to East” direction.
Since the resulting lethality footprint is used to calculate the risk, this rotated footprint could lead to
incorrectly calculated contours. This potential error has been fixed in this release.
· TNT model: The model now also accepts an explosion centre offset when the calculation is based on
TNT mass, enabling the possibility to use this calculation mode on vapour cloud explosions as well.
· Poolfire model: Some chemicals appeared to have a normal boiling point definition that deviated from the
exact temperature at which the vapour pressure is atmospheric pressure. For this reason, the phasecheck included in the poolfire model would conclude that the material is a vapour at its normal boiling
point and skip the calculation. This behaviour has been corrected, now using a tolerance on the
temperature, potentially providing a message that the pool temperature has been corrected.
· Neutral gas dispersion models: the minimum concentration averaging time allowed for (semi) continuous
releases, has been reduced from 20 seconds to 18.75 seconds, now exactly corresponding to a
minimum σy correction of 0.5 (YB par 4.5.3.4).
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Version 9 release history
RISKCURVES 9.0.18 (July 2013) Version Info
· Risk calculation: The calculation of societal risk when using temporary population polygons has been
improved. It appeared that some users defined multiple “temporary” population polygons (with a high
presence fraction of 365 days/year) to be able to correct for outside (unprotected) situations. This way of
utilizing temporary polygons was not foreseen, nor handled correctly, because the potential
simultaneous presence of multiple temporary polygons was not taken into account. The improved
calculation procedure now also evaluates all potential combinations of affected temporary population
areas (with the correctly derived probability of this combination happening). Please refer to the user
manual for some practical tips on usage of “temporary population”.
· Explosion damage definitions: Fixed an issue where an explosion damage definition with zero flash fire
dimension (only an overpressure definition) would result in a neglected scenario.
RISKCURVES 9.0.16 (July 2013) Version Info
· User interface: The “Map” presentation now offers the possibility to read out values of presented grids,
such as population grids or lethality grids. Use the “crosshair” button and activate a grid layer to present
coordinates and corresponding grid value at the cursor position.
· Risk calculation: A lethality cut-off value is now used to limit the distance used for risk calculations. The
parameter is provided in “Accuracy settings”: lowest significant lethality level, and has a default value of
1%. Individual Risk and Societal Risk results will hardly be affected, but SR risk area maps can now
potentially show a smaller affected area.
· Population: it is now possible to import population either from a grid (ESRI grid, CSV or RC7 Pop files) or
from shapes (SHP files). A “Population Import Wizard” has been added that will guide the user in
importing population from external files (see user manual). Some potential errors with importing ESRI
grids (issues with grids only containing “NoValue” values, or issues with non-consistent decimal
separators) have been fixed.
· Explosion scenarios: The TNO-Multi Energy consequence model and TNT consequence model have
been added as potential “Explosion” scenario’s. These scenario’s do not perform a dispersion calculation
but require an “explosive mass” to be provided as input.
· BLEVE scenarios: The “Dynamic BLEVE” and “Static BLEVE” model have been integrated in one
“BLEVE” model, with a choice for the modeling approach to use. This implies that combined models
(LoC scenarios) can now also be used with the “Static” BLEVE approach. Old projects using one
specific approach will still run, but new scenarios will be creating using the dual BLEVE model approach.
· Spray model: The “Spray Release” model now has the possibility to choose the “AMINAL approach” to
calculate spray fraction. The model documentation contains backgrounds of this alternative method.
· Turbulent Jet Model: The “Turbulent Free Jet” model, used to calculate the expansion phase of a high
pressure gas outflow, now also reports offsets (X and Z direction), required to correct the starting point of
the dispersion. This implies that a combined model using a gas outflow can potentially have a slightly
increased consequence distance.
· Explosive Dispersion Models: both neutral gas and dense gas now use the same “LEL concentration at
Tmac” parameter to illustrate results. This enables the possibility to compare results.
· Reporting: The new Internet Explorer 10 versions appeared to be able to create a “Floating Point Error”
when creating the report table. This issue has been solved.
RISKCURVES 9.0.15 (March 2013) Version Info
· Project loading: A version translation error in the combined LOC scenario G1 for liquids has been solved.
Due to a change in input parameters of the pool evaporation (in version 9.014) the dispersion source type
would get misinterpreted when loading an older project. This issue, leading to potential large effect
distances, has been fixed. Loading an older project containing a neutral dispersion scenario will now
require re-entering the “type of release” choice.
· User interface: Model results including contours for user specified threshold levels (heat radiation,
overpressure or percentage damage) will now always contain a legend description indicating the actual
level presented.
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26
Version 9 release history
· User Interface: The FN curve is now displayed as a “block” based graph. Previous versions would draw
connecting lines between calculated risk values (frequency + number of fatalities points). This would
suggest scenarios with frequencies in-between those points and lead to wrong “interpolated” readouts.
· Dongle driver: A new version of the copy protection dongle drivers has been included in the setup. This
driver version now also supports the MS Windows 8 ® operating system.
· Jet fire model: a jet fire that would touch the receiver height plane could create strange heat radiation
curves and contours because heat load calculations cannot be performed “inside” the flame. This has
been solved by forcing a 100% lethality inside the jet fire frustum. Furthermore, the calculation of the
‘maximum view factor” has been adapted, resulting in a more realistic view factor vs. distance graph.
RISKCURVES 9.0.14 (Feb 2013) Version Info
The 9.014 update contains important fixes and improvements affecting the behaviour of population
definitions:
· A potential error in combining multiple population grids and polygons has been fixed, this issue could
lead to “negative” population values in the resulting population grid.
· The occurrence of any negative value in a population grid definition will now create an error warning in the
log of the population definition.
· The display of the resulting grid from a population polygon has been improved. The usage of multiple
polygons will no longer result in a slow and erroneous display of multiple result grids.
· If a defined population polygon would be smaller than ONE grid cell the value presented in the report
could show a misleading high number of people per grid cell. This behaviour has been corrected.
RISKCURVES 9.0.13 (Feb 2013) Version Info
· Educational license: Changes to support “educational” licensing. Educational licenses will be offered at
special conditions to non-commercial educational institutes only.
· Fire model scenarios: The Static BLEVE, Dynamic BLEVE and Jet fire models now support the use of a
“height of the receiver” input parameter, allowing to provide heat radiation footprints and damage results
on various heights. Because this height is taken from “Vulnerability settings” and will probably be nonzero, recalculation of a project might provide slightly different results.
· Combined LOC scenario: When using the Unified LOC scenario, the situation of a hole which is above
the liquid level is now correctly treated as a vapour outflow, using the vapour release model to calculate
the release rate.
· Outflow models: The user defaults for contraction (discharge) coefficients and concentration averaging
time, entered in the “System Defaults” are now properly used inside the models. Previous version tend to
use hardcoded defaults, although discharge coefficients could be modified for every scenario. Toxic and
Flammable concentration averaging time are no longer hardcoded to 600 and 20 sec respectively but
taken from system defaults.
· Cumulation set: The use of a “cumulation set”, using selected scenarios from multiple calculation sets,
could provide wrong accumulated results, because identical scenarios were counted twice. This issue
has been fixed, and any associated analysis points will now provide correct scenario contributions.
· Transport scenarios: The moving of a scenario from “stationary” to “transport ” (or vice versa) using dragand-drop mouse action will now force a recalculation of the associated scenarios. Usage of this method
in previous version could lead to misleading results because it required a manual (forced) recalculation
for the associated scenarios. Note that the use of “Cut-and-Paste” worked did correctly and already
showed the moved scenarios in italics (as “needs recalculation”).
· Background maps: The copying of background maps in the project tree has been disabled because it did
not work properly. Additional background maps need to be added using the <right mouse> button: “add
background” choice.
RISKCURVES 9.0.12 (Dec 2012) Version Info
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Version 9 release history
· Importing a population grid: This update handles an issue when importing population distribution from an
ESRI grid file. Any “no data” value from the grid is now correctly interpreted as “zero” population.
· Accuracy settings: The provided “risk grid cell size” in is now also used to influence the societal risk
calculation. Increasing the value from its default 10 mtr will lower the memory footprint and increase
calculation speed. Please refer to the help file (<F1> help for this parameter) for more information on the
influence of this parameter.
· The saving and loading of a RISKCURVES project file is performed is smaller steps to avoid memory
issues when reading/writing equipment definitions containing large numbers of scenarios. The file format
is still upwards compatible.
· Vulnerability settings: The usage of pressure damage probits in a calculation has been corrected
because it created errors when determining the maximum %lethality distance.
· Multi Energy model: To be able to derive the maximum explosion damage distance, the end distance for
multi-energy overpressure / pressure impulse graphs has been increased to always include the lowest
(1% lethality or glass fragment damage) pressure levels. This may also influence results of dispersionexplosion ME effect model scenario’s when using pressure level threshold damage criteria, because this
scenario could have been using the overpressure graph cut-off distance.
RISKCURVES 9.0.11 (Dec 2012) Version Info
· Toxic dispersion models: This update fixes a very rare but annoying issue where a toxic dispersion
model has a very small toxic result (lethality vs distance is not zero) but no 1% contour can be found.
Due to this situation, the societal risk calculation would fail.
· The model log has been improved, and important messages about failing initial models (such as Gas
LOC model applied for a two phase substance) will now show up as in EFFECTS.
· The help file has been improved and now also provides more information about the location of user
settings and chemical database files.
RISKCURVES 9.0.10 (Nov 2012) Version Info
· Combined LOC scenarios: This update fixes a potential problem (introduced in vs 9.0.9) within the LOC
scenarios (combined models) where a toxic model inside the model chain would not be updated with a
modified chemical choice.
· The LOC Gas G1 (instantaneous) scenario will now always use the diameter of the expanded cloud as
the “width of the source (Y direction)”, thus avoiding required input for the scenario. Because this may
start the initial concentration at a lower value (UEL concentration for flammables) , this might have a
small influence on the maximum effect distance.
RISKCURVES 9.0.9 (Nov 2012) Version Info
· Memory usage: This update contains an important improvement with respect to memory usage during
the saving procedure of (very) large projects: it is now much faster and uses considerably less memory.
· The dense gas dispersion scenario would force a pool evaporation source to be set at the minimum of
normal boiling temperature and ambient temperature. As of this version, the temperature will now be
maximized to the normal boiling point and a warning will be provided if it is adjusted. (The release
temperature can thus still be sub-cooled or above ambient temperature.)
· Local cloud fire: The usage of a “local cloud fire damage definition” which was causing problems has
been improved.
· Combined LOC scenarios: Within combined models, the single selection of a “local cloud fire” outcome
now actually presents this single phenomena.
· In G3 Leak LOC scenarios, it is now possible to use a maximum duration of the outflow, to be able to
include the interference of a blocking system.
· Combined LOC G2 scenarios: The behavior of the “Vessel emptying time” as used in G2 scenarios
(release of full inventory within ## minutes) has been improved. This parameter appeared to be enabled in
G3 scenarios as well, where it is not used.
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Version 9 release history
· Loading previous versions: Whenever an older version project is loaded, RISKCURVES will now warn for
version conflicts and force “out of date” situation. This advises recalculation of the project because
incorporated calculation models and methods might have been changed.
Apart from the improvements mentioned above, some important user interface request have
been implemented:
· Consequence results for stationary equipment are now actually shown at the release location on the
map (instead of at a 0,0 coordinate without map) . For transport scenarios, the effects/consequences are
shown at the middle point of the route.
· A maximum effect distance contour is added to the results of a Modelset and Scenario. This will
illustrate the maximum 1% lethality limit distance around the release location. The percentage of
lethality to be shown can be set in “presentation settings”. When selecting a single weatherclass, the
corresponding contour for the selected class is illustrated.
· When using “temporary” population polygons, which are not cumulated within the total population grid
(they are incorporated separately because of the probability of presence), the shapes of the polygons are
now also shown on the map, using a color representing the density as compared to the grid cells.
· The coordinates of a route definition can now also be copied / pasted from other applications, such as a
spreadsheet table.
· An overview of Analysis Points is now included in Calculationset and Cumulationset reports.
· Pressing the ‘/’ key (numpad) on the project-tree performs a recursive collapse on the selected node,
allowing to quickly reduce the size of the tree view.
· Release locations can now also be shown at Analysis Point level.
· The legend should now be copied to the clipboard individually (right click on the legend) and is no longer
added to the clipboard export of the GIS(map) view.
RISKCURVES 9.0.8 (Sept 2012) Version Info
· This update contains a fix for a potential error within the combined models. It appeared that, whenever a
liquid chemical has been selected, the input field for “initial pressure in vessel” would get overwritten with
atmospheric pressure. Unfortunately this would “unlink” this field in specific weather-class models of a
modelset. When switching back to a two-phase or gaseous phase chemical, the pressure input fields
from weather-class specific models would now remain empty, creating an error upon calculation. The
occurrence of this issue has been solved, and a potential broken link (=empty pressure field for B3-D5
etc.) in existing modelsets will be repaired.
· The memory footprint for a RISKCURVES project has been reduced considerably, minimizing the
possibility of memory overflow errors with large projects.
RISKCURVES 9.0.7 (Sept 2012) Version Info
· Version 9.0.7 contains an important fix for memory overflow errors that could occur when using large
numbers of combined LOC models. The memory usage of RISKCURVES can still be large, especially
when using societal risk maps. When copying and pasting complete calculation sets, it is strongly
advised to save the combined project under a new name before calculation.
· The risk calculation procedure for situations calculated by a neutral gas dispersion model has been
improved. The consequences of flash fire contours are now treated exactly the same way as the nonelliptical contours calculated by dense gas models. This may have a small influence on calculated risk
values.
RISKCURVES 9.0.6 (Sept 2012) Version Info
Three important improvements that have been released in the latest EFFECTS version 9.0.10 (September
2012) have been incorporated within this RISKCURVES update:
· Two Phase Discharge model: The TPDIS model now also allows potential two phase outflow for
situations with a release from a hole in a pipe, where the hole size would be smaller than the pipe
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Version 9 release history
diameter. Previous version would assume a liquid outflow, which was maximized to the two phase
release from the full diameter.
· Pool fire model: the pool fire scenario now allows the height of the pool to be a non-zero value. This
implies that the pool fire can be elevated, even if the receiving plane is at 1.5 meter height.
· Pool evaporation model: Within the latest version 9.0.5. of the combined LOC models, the maximum
pool area, as used within the pool-evaporation model was also used as the limiting area for the pool fire
model. Unfortunately, if this value was empty, because the pool evaporation was using “spreading
without bunds”, the pool fire model would return an error. This behavior has been corrected.
RISKCURVES specific improvements:
· The parameter “height of the receiver” has been moved from “defaults” towards “Vulnerability” settings.
This has been changed because this “receiver height” value is actually forced inside toxic dispersion and
pool fire models and cannot not be adjusted inside the scenario itself. Because this introduces a new
parameter inside the input, previous projects will require to enter this value (the vulnerability settings
node will be illustrated in red due to a missing value).
· The switching of focus from a calculated “Calculation set” towards a “Model set” node of the project tree,
could trigger an “out of date” event, which would trigger required recalculation of this scenario. This
annoying behavior that was introduced in version 9.0.5. has been corrected.
· The form caption will now display a “star” added to the project name to indicate that the current project
contents have been modified compared to the project file.
· The calculate button will display “RECalculate” if the <Alt> key has been pressed, illustrating that a full
recalculation will be forced with this key combination.
RISKCURVES 9.0.5 (August 2012) Version Info
After the introduction of EFFECTS 9 in March 2012, several improvements have been applied in
consequence models that are used by specific scenario types. These improvements have just been
released in the latest EFFECTS version 9.0.9 (August 2012) and are now also incorporated within
RISKCURVES:
· Dense Gas Dispersion Toxic Dose scenario: When using a “Toxic Exposure Duration based on” choice
for “time limit of release” the exposure duration was not applied correctly. This would lead to an
unrealistic high lethality at longer distances because the release duration was not actually limited by the
exposure duration value provided by the user. This issue has been fixed.
· Toxic Dispersion scenario: Both the “Neutral Gas ” and the “Dense Gas” toxic models will now also
report the maximum concentration versus distance graphs as available in the Dispersion concentration
models.
· Pool fire scenario: when using the “Unconfined fixed feed” choice, no limit was applied for the maximum
pool area size. The pool area is being calculated as the equilibrium situation were the input feed rate
would be equal to the burning rate. Since this might lead to huge pool areas, and this “Unconfined pool”
mode is also applied in the G2/G3 combined models, the G2/G3 continuous release scenario could not
be applied for “bunded” pool fire situations. In the updated model, the pool fire area can have also have an
upper limit for “unconfined fixed feed” pool fire situations. In the combined LOC models, this pool area
upper limit is copied from the pool evaporation input value.
· Chemical database editor: The temperature dependent “vapour pressure” graph was not shown for some
specific chemicals (e.g. Gasoline from YAWS database). This behaviour has been corrected.
· Jet fire scenario: The heat radiation from the top plane of the torch was overestimated due to a
simplification in the viewfactor calculation. This calculation has been improved, leading to more realistic
(lower) heat radiation values for situations were the top plane is visible and very close to the receiver.
· Jet fire scenario: The third heat radiation contour could be presented at the wrong location. This
behaviour has been fixed.
· Long pipeline: The “Gas release from long pipeline (Wilson) model” (used in LOC scenarios for gas
releases from a pipeline longer than 1 km) had an issue when trying to run a “hole in pipe” calculation.
This calculation has been corrected.
· Two Phase Bottom Discharge: When using a “pipe connected to the vessel” mode of the Two Phase
Bottom Discharge model (used for two phase G2/G3 scenarios), the vapour outflow calculation would
use the pipeline diameter instead of the hole diameter. This behaviour has been corrected.
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Version 9 release history
· BLEVE models: The “Bleve (Static)”and “Dynamic Bleve” calculations will now adjust the maximum
distance for the graphs, if necessary, to obtain requested threshold values for effects or consequence
distances. A correction was applied in the dynamic model in the used atmospheric transmittance values.
· Toxic dispersion models: If a toxic model is run with a chemical that does not have toxic probits provided
in the database, the model will now give a more adequate warning.
RISKCURVES 9.0.4 (March 2012) Version Info
· User interface: The export of a map layer with multiple shapes has been improved. An equipment layer
with both stationary locations (points) and routes (lines) will now be exported properly.
· A “Probit Converter”, a tool to translate Toxic Probits to different concentration units has been added to
the main form (under menu “Tools”).
· The calculation of the viewfactor in the jetfire model has been improved, (it now uses a discretized
method, dividing the frustum cone into many small surface elements) leading to more consistent and a
less conservative heat radiation footprint.
· Poolfire scenario: The poolfire model has been simplified and now uses either confined pool or
unconfined fixed feed. The calculation of a source rate based on hole diameter / liquid height has been
removed because it would use the initial flowrate (instead of averaged flow). The parameters hole size,
discharge coefficient, liquid height etc. have been removed from the model.
· Poolfire scenario: The burning rate of the poolfire model can be determined by the chemical type (YB
table 6.5), where the selection was based on the name. Since chemicals can be copied using different
names, an alternative selection based on CAS number has been added. (For example: the burning rate
for Butane is used if chemical name is Butane, or if the chemical CAS number = 106-97-8).
· Project conversion: The conversion of Riskcurves 7 project which uses DIPPR chemicals has been fixed.
Note that the project converter requires a license dongle to be able to handle DIPPR chemicals.
RISKCURVES 9.0.3 (February 2012) Version Info
· The Roughness length (dispersion) and Subsoil Roughness (pool spreading) parameters were removed
from the environment parameters because they were not “pushed” into all scenario’s. These parameters
need to be (user) defined per scenario because they can change with the location of the equipment.
· The handling of DIPPR chemicals in “view / read only” mode (no copy protection dongle present) is
improved. The chemical field is now disabled when the license is not found, but the scenario itself
remains unchanged.
RISKCURVES 9.0.2 (February 2012) Version Info
As a result of feedback of early adapters, several improvements on the first release are implemented:
· The Jetfire (Chamberlain) model was calculating flame dimensions based on the initial source rate (at
t=0). As of version 9.02 the Jetfire model uses calculated averaged source rate for the torch dimensions,
which may also come from a “long-pipeline” model.
· The G2 (outflow within 10 minutes) combined scenarios now allow to use other outflow duration periods
(other than 10min). This “outflow duration” is added as an expert parameter. (The G2 model calculates
the corresponding hole size to obtain this outflow duration.)
· The Toxic dispersion models have the added possibility to define the method for applying a toxic
exposure duration: based upon time until sheltering, based upon time limit for passage of the cloud, or
based on a limit of the release duration.
· The logging of combined models is simplified, less relevant information messages (e.g. “submodel Toxic
did not run because substance not toxic”) have been removed.
· Calculation sets, Population and Scenario’s now have a “user comment” parameter, which can be used
to add some comment on the origin of frequencies, population or background of a QRA calculation.
· The meteorological probability editor now provides feedback on the validity of the figures that were
entered. Since the total of day-time and night-time situations should be both 100%, these “total day” and
“total night” numbers will be displayed in red if they are invalid.
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Version 9 release history
· Possible errors within the “meteo editor” when working with a “,” decimal separator have been fixed.
· The loading and usage of “user defined” chemicals has been improved.
· The applied length units in the map view scale bar have been improved.
· Possible errors in the “mass and volume calculator” with non-defined chemicals have been fixed.
RISKCURVES 9 Release notes (version 9.0.1 December 2011)
RISKCURVES 9 is the successor of version 7. A version number 8 was only released as a beta of this
redesigned RISKCURVES, as an internal development version based on the EFFECTS 8 code. This
RISKCURVES version 9 is built on the same engine as EFFECTS version 9. The approach of the QRA
has been completely redesigned and has a user interface that is similar to our EFFECTS product.
This implies that the way of working with RISKCURVES and defining scenarios has changed considerably.
For that reason we advise even experienced users to start with reading the "Quick Start Guide" which is
part of the manual.
Basic improvements in version 9
· The consequence modelling engine is now based on the EFFECTS version 9 code (see additions on
consequence modelling below).
· RISKCURVES now includes combined models, which will calculate the full chain of events and
phenomena that might occur for the specified chemical and release case.
· Since RISKCURVES is based upon the current EFFECTS code, it is now possible to paste EFFECTS
model calculations as a scenario into RISKCURVES.
· The Risk calculation engine only recalculates scenario’s if they have been changed since the last
calculation.
· A new geographic based visualisation method of Societal Risks has been added: Societal Risk Maps.
· RISKCURVES is now capable of comparing different calculations, or different subsets of the scenarios
which is useful to evaluate impact of changes in population, or changes scenario definitions.
· Instead of the laborious procedure of repeatedly making selections of scenarios, the program now
provides a “Cumulation set” to make predefined subsets of scenarios, possibly even from different
calculation sets.
· Copying and Pasting of scenario definitions, equipments, population definitions and even complete
Calculation sets is now supported.
· The definition of vulnerability settings has been extended, allowing the use of customised lethality
relations which can be adopted to local regulations.
· Discretisation methods for the risk calculation method have been optimised, resulting in a more accurate
calculation. RISKCURVES version 9 now uses a much higher resolution for storage of risk calculation
results. The individual risk contours are created form a grid with a fixed resolution, chosen in accuracy
settings. For transport scenario’s, risk calculations will use a fixed inter-accident distance, by default 50
mtr. The previous version used a fraction of the maximum distance. The population grid also uses a fixed
resolution, which can deviate from original supplied resolution.
· The meteorological definition now distinguishes a separate DAY and NIGHT distribution, furthermore a
“night time” scenario will also use “night time” environment definition (e.g no solar heat radiation, nighttime ambient temperature)
· Apart from the appreciated analysis functionality – in version 9 available as “analysis points” and “risk
ranking reports”, RISKCURVES now supports the use of “Risk Transects” illustrating the individual risk
along a user definable track.
· A population can now be combined from multiple grid areas and multiple area descriptions (“population
polygons”).
· Furthermore, population areas (polygons) can now be defined as “temporary population”, allowing to
include non-permanent presence into the societal risk calculation.
· The file format for storage has been changed. RISKCURVES now uses a XML based compressed file
format. Note that any background images added to the project, will be saved within the compressed file,
making it easy to transfer complete project contents.
· Project files of previous version 7 can be translated into the new file format by the provided
“RISKCURVES project convertor”. Note that this utility only translates the input, and not the results. Due
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Version 9 release history
to consequence model changes and modifications of the risk calculation method, results will always
differ slightly.
· RISKCURVES 9 is designed for Windows 7 operating system. It runs on Windows 7 64-bit as a 32 bit
application and has been thoroughly tested on 64 bit environment. An administrator account is required
during installation, but after installation RISKCURVES can run with restricted rights. RISKCURVES will
use the designated “User” storage location to extract project files.
Database related improvements
· The extended database is now based on DIPPR® 2010 and chemicals can have multiple functions for
multiple temperature ranges. This will potentially result in greater accuracy of the calculations and less
“out of temperature range” warnings during calculations.
· Since the DIPPR® 2010 is now always available, TNO advises to use this extended database for greater
reliability and accuracy of the calculations. The YAWS database is still available for backward
compatibility.
· The database file format has been changed. It is now SQL-based and contains DIPPR, YAWS and
USER defined records in a single table. Various calculations sessions of a model can now use
chemicals from different sources, providing the possibility to compare results for different chemical
property sources.
· The chemical database editor has been redesigned providing greater ease of use and now provides
graphs for all temperature dependent properties and a convenient search facility. The new editor can be
accessed directly from the toolbar and the chemical selection box.
· If the user of previous versions of EFFECTS has created user defined chemicals, these added records
can be imported with the supplied “Chemicals convertor”.
Model improvements (as compared to EFFECTS 8 models)
· Dispersion models Toxic: The toxic dispersion model is now capable to perform a calculation of dose
and lethality inside, based on a ventilation rate.
· Dispersion models Explosive: The explosive calculation can perform a explosive mass calculation based
on mass between Upper Explosive Limits and Lower Explosive limits. This is now a user choice: either
mass above LEL or mass between UEL and LEL.
· The jet fire model (Chamberlain) has been adapted for usage in case of two phase releases.
Furthermore, the heat radiation footprint calculation is added. To be able to supply this, the calculation of
the viewfactor is no longer based on a cylindrical shape but is now based on the real cone shape of the
jet flame.
· All fire models have possibilities to modify heat radiation damage probits. Previous versions had
hardcoded values based on the Dutch Green book. These Green book values are now used as defaults
but can be altered.
· The liquefied gas from long pipeline (Morrow) model now also reports representative vapour fraction.
Furthermore all two phase release models will now report “vapour fraction” instead of the confusing “Void
fraction” or “Quality of outflow” parameter names.
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