OECD Database Projects: these projects promote the international exchange of experience regarding incidents in and damage to nuclear power plant components which could trigger accidents. For this purpose, subject-specific databases are built up into which damaging incidents and events are entered by the participating OECD states. The data then undergoes statistical evaluation for the purpose of obtaining indications as to the causes of such damage or incidents. Pooling on an international basis is necessary for this purpose because the relevant events and incidences of damage in nuclear power plants are infrequent. ENSI took part in the following projects in 2009:
- OECD OPDE – Piping Failure Data Exchange Project: this database contains information from findings of damage on pipes in nuclear power plants that are risk-relevant and classified for safety purposes, which have led to fluctuations in wall thicknesses, fissures, leaks or fractures. The international working group for this project has completed the status report for the 2002–2008 project period, which it published in November 2009. Collecting cases of damage to pipes in nuclear power plants was continued in 2009. Three of the four Swiss nuclear power plant operators have entered into active participation in the project. The newly entered datasets from Swiss nuclear power plants relate to damage that did not have major effects on safe plant operation and which could be rectified during maintenance.
- OECD SCAP – Stress Corrosion Cracking and Cable Ageing Project: this database is used to collect and evaluate cases of damage in nuclear power plants that are attributable to stress corrosion cracking of vessels, tanks and pipes, or which occur due to the ageing of electrical cables. Switzerland has taken part in the SCAP sub-project on stress corrosion cracking since 2009. An extensive knowledge database on this subject was set up in 2009. Important reference cases of damage were identified among the large number of database entries collected for the different types of stress corrosion cracking findings. The current level of knowledge regarding the main mechanisms of stress corrosion cracking was summarised in a report drawn up by international experts.
- OECD ICDE – International Common Cause Failure Data Exchange: this database covers events in which failures of the same sort have occurred on at least two (safety-relevant) components due to common causes – so-called “Common Cause Failure (CCF)” events. With the entries made in 2009, the database contains about 1500 datasets on potential or effective CCF events for ten different types of component. In addition, coding guidelines and analytical reports for various components were updated, drafted or completed. Various additional functions were added to the database application in order to facilitate the management and evaluation of the datasets.
- OECD FIRE – Fire Incident Record Exchange: the objective of this project, launched in 2003, is to survey and analyse data on fire events in nuclear power plants as a contribution towards a better understanding of the causes, propagation and effects of fires. In addition, there should be ongoing optimisation of fire prevention and improvement of the phenomenological and statistical basis for probabilistic safety analyses (PSA) of nuclear power plants. As planned, data on additional fire events were gathered in 2009, dating back as far as 1990 where possible. Moreover, the first detailed analyses were carried out with the help of the database. A report was compiled to document the second phase of the project.
- OECD Compsis – Exchange of Operating Experience Concerning Computer-based Systems Important to Safety: the Compsis project entails the collection of operating experience with computer-based systems, and with digital control systems in particular. This can provide information about the causes and failure types in events involving computer-based systems, and about the reciprocal influences between hardware and software. In 2009, the main goal was to continue recording and processing data. A first analysis gives indications as to which types of failures and activities in the life-cycle of computer-based systems call for special attention. In addition, quality management regulations on criteria for reports and publications were revised.