A. Eriksson, C. Kirchsteiger, EC-JRC-IE-Petten
Subproject proposal for
Research Area 2 " Systems Performance,
Monitoring and Diagnostics"
Subproject Full Title:
Use of Methods from Probabilistic Risk Assessment for Risk-Informed
In-Service Inspection Applications (UPRA-RIISI)
Proposing organisation: EC-JRC-IE (Institute for Energy)
Contact person name: Arne Eriksson, Christian Kirchsteiger
Address: Westerduinweg 3, 1755 LE Petten, The Netherlands
Tel: +31.224.56.5383 / 5118
Fax: +31.224.56.5621 / 5641
Email: Arne.Eriksson@jrc.nl ; Christian.Kirchsteiger@jrc.nl
Background:
Risk assessment methodologies have been developed in Europe for several decades
since the early '70s. Based on extensive research and data collection activities, risk
assessment methods, mainly probabilistic risk assessment have achieved a sufficient
level of credibility to be used as an important tool in decision making process.
Originally, the development of risk assessment technique was mostly driven by
demands from nuclear power industry to estimate and manage nuclear risk. However,
recent industrial demands indicate that nuclear risk technologies could be successfully
transferred to non-nuclear, thermal power plants.
The initial purpose of probabilistic risk assessment techniques was to estimate a risk
level of the plant. The development of plant models and computational tools was
targeted to achieve this purpose. However, later it appeared that risk studies are also
capable to give useful insights to the plant operation and these results could be used in
many different plant operation management tasks. One area of risk applications is to
use risk topography to define in-service inspection programs, which alternatively to
deterministic-based ISI programs would focus, in a systematic way, on high risk
locations, rather than on risks assumed at design stage. . The ISI programs, based on
risk approach are named as risk-informed ISI programs (RI-ISI).In fact, the
application of risk study results to produce RI-ISI program is not straightforward. Due
to earlier mentioned initial risk assessment purpose and other modelling limitations,
risk study contains rather limited and generalized information about many passive
components (piping, tanks etc.). This creates a number of problems to develop a
rational interface between risk assessment and RI-ISI.
Project description:
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A. Eriksson, C. Kirchsteiger, EC-JRC-IE-Petten
This project aims at researching applicability of risk assessment techniques in the
development of RI-ISI methodologies. This includes development of certain
requirements for risk study quality and level of detail in order to be used in RI-ISI;
“best practice” interface between risk results and RI-ISI, possible acceptance criteria
and others, followed by benchmark pilot studies.
More specifically, the project is aiming at developing a generic procedure that is
applicable to power generation in general, taking over the large experience from
probabilistic risk assessment (PRA) in the nuclear sector to essentially probabilistic
Reliability-Availability-Maintainability (RAM) assessment for all type of power
plants, including non-nuclear ones. Ultimate goal is to cross-compare existing
approaches (simple performance indicators, FT/ET, Markov, Petri nets, Bayesian
belief networks etc.) and come up with recommendations together with an application
to a conventional power plant.
The project would also include investigation of requirements for probabilistic risk
studies and their output to be used in development of risk-informed in-service
inspection (RI-ISI) program in energy production systems. Risk-informed approach in
ISI programs was introduced in 90s and provides an effective risk management tool in
optimising the number of inspections and their locations. Its effectiveness is shown by
reducing inspection volume and cost, and at the same time reducing or maintaining
the same level of plant risk and availability. Thus, the method identifies high-risk
areas neglected by previous or current practice.
Currently, the development of RI-ISI at a European level in the nuclear and nonnuclear fields is mostly driven by networks like ENIQ and RIMAP. Regulators are at
the same time harmonising European regulatory aspects within NRWG (Nuclear
regulators Working Group). Both ENIQ and NRWG have identified a need for further
R&D on PSA for its application to RI-ISI. The proposed project will build strong
links with ENIQ, NRWG and other relevant European groups. This is guaranteed
through JRC-IE who is the operating agent of ENIQ and RIMAP and participates in
NRWG meeting. Further, JRC-IE is member of an IAEA Technical Working Group
on developing common PSA quality criteria for different types of application, one of
them being RI-ISI.
The available expertise from these research groups could be used in the project to
develop RI-ISI applications on the extended basis applicable to most power
generation industry.
The theoretical development is followed by 1-2 benchmark pilot studies.
Innovative aspect:
This research project is innovative because of its contribution to strengthening the link
between (probabilistic) PSA and (deterministic) ISI. This is especially relevant in the
overall context of the on-going strengthening of elements of risk informed regulation
for the energy sector. A strong demand in this direction has also been expressed by
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A. Eriksson, C. Kirchsteiger, EC-JRC-IE-Petten
the ENIQ Network members. To avoid academic exercises, 1-2 pilot studies in real
power plants (nuclear and/or non-nuclear) are foreseen.
The project deliverables represent
 a guidance report on the use of PSA for RI-ISI and corresponding requirements,
covering the following important areas for risk assessmnet use in RI-ISI:
- Estimation of passive components (to be treated by RI-ISI) failure frequencies,
as initiating events;
- Estimation of safety barriers, given failure of passive components;
- Consequences of risk to be applied;
- Uncertainty transfer from risk study to RI-ISI;
- Impact of risk study limitations to RI-ISI;
- RI-ISI acceptance criteria with respect to numerical risk estimates.
- Dissemination of results to relevant European and international groups like
ENIQ, NRWG, IAEA (PSA Quality Group), etc.
 1-2 pilot benchmark studies in nuclear and/or non-nuclear (thermal) power plants,
followed by a corresponding evaluation report.
 a kick-off seminar, an intermediate workshop and a final international conference
on discussing and presenting the progress achieved, together with IAEA, OECD
and ENIQ.
The project partners are
 the members of the technical working group "Risk" within the ENIQ Network and
from RIMAP (for the ISI part),
 the members of the IAEA PSA Quality Working Group and of
OECD/NEA/WGRisk and NRWG ((for the risk assessment part), and
 a utility / research institute from a Member State or Accession Country for the 1-2
benchmark pilot studies to be performed.
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