Working Group on Integrity of Components and Structures (IAGE)
Risk-Informed Piping Integrity Management
Hotel Tryp Atocha
Calle Atocha 63
28012 Madrid, Spain
2-4 June, 2008
Deadline for Abstracts extended to March 21, 2008
The objective of this workshop is to examine the results of the OECD/NEA and European Commission Joint Research Centre (JRC) co-ordinated risk-informed in-service inspection methodologies benchmark (RISMET). Workshop participants will also discuss the results and applications of the OECD Piping Failure Data Exchange (OPDE) Joint Project along with other related activities in NEA member countries.
Workshop participants will explore the application of risk-informed piping integrity management, their regulatory, utility and industry aspects, as well as related R&D activities in NEA member countries. As a result, workshop participants should understand the differences and discrepancies between approaches in different countries and be able to propose methods to address these differences.
Background
Risk-informed in-service inspection (RI-ISI) methodologies have been developed in several countries, although so far the only widely applied methods are those developed by the Westinghouse Owners Group (WOG)/
American Society of Mechanical Engineers
(ASME) and by the Electric Power Research Institute (EPRI) in the USA. Some attempts have been made to compare the different RI-ISI methodologies. There have not been any direct comparisons of several RI-ISI methodologies applied to an identical scope of components (system, class, etc.). Recommendations and support for benchmarking various RI-ISI approaches have been given by several international bodies.
The NEA Committee on the Safety of Nuclear Installations (CSNI) and its
Working Group on Integrity of Components and Structures (IAGE) considered that there was a need to clearly understand how the different RI-ISI methodologies affect reactor safety and whether they lead to significantly different results, as well as how the operating experience could be used to estimate failure probabilities. In parallel, the European Network for Inspection and Qualification (ENIQ), through the JRC, was also working in this field. As a result, the possibility for co-operation between the two organisations has been discussed.
In consequence, the OECD/NEA CSNI supported the proposal from the IAGE to conduct a benchmark study as a joint NEA/EC-JRC initiative. By benchmarking the different methodologies it would be possible to identify what impact they might have on reactor safety and whether or not they lead to significantly different results. The benchmarking exercise could also help identify those phases in the methodologies currently in use with the greatest potential to affect the outcome, thereby suggesting areas for further improvement.
The RISMET benchmark is a unique comparative study of various approaches to set up an ISI programme. As a result, the knowledge of different approaches and their impact on plant safety are likely to be improved. At the same time, the use of risk-informed ISI will be promoted.
The NEA established in 2002 the OECD Piping Failure Data Exchange (OPDE) Joint Project to produce an international database on the piping service experience of commercial nuclear power plants. The aim of the OPDE project is to collect pipe failure data. This data includes service-induced wall thinning, part through-wall cracks, pinhole leaks, leaks, and rupture/severance (e.g. events involving large leak rates up to and beyond the make-up capacity of engineered safety systems). The part through-wall events include degradation in excess of permitted pipe wall thinning or crack depth. The OPDE project also collects information on pipe degradation that could have generic implications regarding the reliability of in-service inspection.
The OPDE database is used to produce the following analyses: trend analysis, including ageing analysis; statistical analyses to determine pipe failure rates and rupture frequencies for use in risk-informed activities (e.g., loss-of-coolant accident frequency assessment, internal flooding initiating frequency assessment, high-energy-line break frequency assessment, RI-ISI change-risk assessment); source of data parameters as an input to probabilistic fracture mechanics codes; degradation mechanism analysis (DMA) in RI-ISI programme development; development of defences against recurring (e.g., systematic) pipe failures); and exchange service data in order to pinpoint potential generic implications of a specific, significant pipe failure.
The OPDE project is therefore improving the quality of piping degradation experience data and thus making it more useful in predicting piping failures. The RISMET and OPDE projects contribute to improving the management of piping inspections.
|
