IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making
A PSA and Safety Monitor Application
Lecturer
Lesson IV 3_11.7
City , Country
XX - XX Month, Year

– Temelin PSA Project carried out in 93-96 with NUS
– Scope: Level 1 & 2, Shutdown, External events
– Support to plant staff in analyzing day-to-day decision issues related to the areas like:
•
Operating and maintenance strategies based on risk minimization
•
Outage risk management
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Assessment of modifications
•
Tech Specs issues (AOTs, STIs, LCOs)
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IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making

– All Temelin PSA models update for current plant status
– Conversion of updated PSA models to SM models
(internal events, shutdown, Level 2)
– Software update for 3.0 version enabling:
•
Dual Unit interactions
•
Faster solution engine
•
Maintenance Rule
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IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making

– on-line risk monitoring (real, hypothetical)
– restoration advice from safety viewpoint
– important operable components
– calculating risk for scheduled configurations
– limiting recommended configuration time
These are useful features, but Safety Monitor databases could provide also other interesting information
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IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making

Provides access to some of this information for any selected point in the operating history:
• equipment restoration advice
• combinations most contributing to risk
• system/trains inoperability indication
• probabilities of containment failure modes and
STCs
This application runs in MS Access 97 environment
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IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making

to view operable components most important for plant safety in current configuration to view out-of-service components whose restoration reduces risk most significantly
IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making
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?
 So, it is not possible to find out the most contributing components in any time point on risk profile (e.g. to find out reasons for high risk in the past)
 When optimizing schedules, risk peaks cannot be easily removed without knowing the highest contributors
?
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IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making

allows:
 to calculate the most contributing components for any time point of a risk profile
 to calculate component out of service combinations contributing mostly to the risk
 to indicate direct or
„hidden“ train/system inoperability caused by the system dependencies
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IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making

In this window, the user can enter a date and time of point to be analyzed (manually or by rightclick to a desired point of the risk profile) ...
... and press
„Analysis“
IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making
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• is loaded to database used for hypothetical calculations,
• calculated by Safety Monitor,
• and the most contributing components are listed by Safety Monitor...
Restoration of one individual
... however reduction down to the acceptable
...
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IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making

As can be seen, for certain configurations, restoration of a single component made on Safety
Monitor restoration advice does not reduce risk to the required level.
This is solved by other Risk Panel function:
„Combinations“ - calculating the risk most contributing combinations of components
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IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making

IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making
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provides another function:
„Accident Progression“ - calculating probability of containment failure mode, in case that core damage occurs, on basis of PSA Level 2
This function can be also used for any time point in operating risk profile provided that Level 2 model is available
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IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making

IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making
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is
that indicates availability of user defined plant systems depending on components out of service
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IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making

and red color indicates that a system or a division is inoperable
Green color indicates that a
Orange color
Clicking on red, orange indicates that more or yellow item shows reasons of inoperability than one division of a system is inoperable system is operable
Yellow color indicates that one division of a system is inoperable
IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making
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This screen shows portion of the Safety Monitor fault tree...
... from „top“ event at system/division level...
Clicking at a gate develops corresponding branch of the fault tree.
... to basic event(s) at component level.
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IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making

...and so on...
IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making
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• adding items
• moving items
• removing items
..and System Panel recalculates the fault tree to show new system inoperability
IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making
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– indicates date/time in status bar when moving mouse over the risk profile
– allows easy selection of risk profile interval
– shows normal/logarithmic scale of risk profile
– lists configuration in points of risk profile where
CDF exceeds user specified limit
– prints graphs of CDF, releases, cumulative risk, probabilities of containment failure
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IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making

Enter begin and end date manually ...
Print graph and reports
... or drag mouse over risk profile
IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making
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IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making
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IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making
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IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making
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IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making
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IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making
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Risk Panel does not replace Safety Monitor but provides additional useful functions:
• comprehensive, easy analysis of past configurations for any point in operating history
• system inoperability information
• Level 2 basic information
• printouts of graphs and reports for archiving, presentations or reports
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IAEA Training Course on Safety Assessment of NPPs to Assist Decision Making