Subproject proposal for
Research Area 2 " Systems Performance,
Monitoring and Diagnostics"
Subproject Full Title:
Harmonisation of Probabilistic Risk Assessment Use for Risk-Informed
In-Service Inspection Applications
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 (PSA) have achieved a
sufficient level of credibility to be used as an important tool in decision making
process. The development of PSA technique was mostly driven by demands from
nuclear power industry to estimate and manage nuclear risk.
The proposed project deals with investigation of requirements for PSA studies and
their output to be used in development of risk-informed in-service inspection (RI-ISI)
program at nuclear power plants. 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, cost and personnel radiation exposure, and at the same time
reducing or maintaining the same level of plant risk. Thus, the method identifies highrisk areas neglected by previous or current practice.
Currently, the development of RI-ISI at a European level is much 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 RIISI. 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 initial purpose of PSA was to estimate a risk level of the plant. The development
of plant models and computational tools was targeted to achieve this purpose.
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However, later it appeared that PSA is 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 PSA applications is to use risk topography to define
in-service inspection programs, which alternatively to deterministic-based ISI
programs would focus on high risk locations, instead of inspecting all components
equally. The ISI programs, based on risk approach are named as risk-informed ISI
programs (RI-ISI).
In fact, the application of PSA results to produce RI-ISI program is not
straightforward. Due to earlier mentioned initial PSA purpose and other modelling
limitations, PSA 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 PSA and RI-ISI.
Project description:
The project is aimed to research PSA applicability to be used in RI-ISI. This would
include development of certain requirements for PSAs quality and level of detail in
order to be used in RI-ISI; “best practice” interface between PSA and RI-ISI, possible
acceptance criteria and others.
The potential project deliverables could cover the following important areas for PSA
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 PSA to be applied;
- Uncertainty transfer from PSA to RI-ISI;
- Impact of PSA 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.
The potential project partners are from within the ENIQ group (for the ISI part), from
within the IAEA PSA Quality Working Group and JRC's contacts from Member
States & Accession Countries (for the PSA part), as well as from NRWG (for both ISI
and PSA).
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