H. WERDINE, R. NICHOLS, F. PERRAMON Department of Nuclear Safety and Security, International Atomic Energy Agency, Vienna
Email: h.werdine@iaea.org
1. RATIONALE/BACKGROUND
It has been 25 years since the Three Mile Island accident in the United States of America and 18 years since the Chernobyl accident in the former USSR. These two major events had far reaching effects on national and inter-national cooperation in sharing lessons learned from operating experience. As a result of Three Mile Island, the nuclear industry of the USA pooled its expertise by creating the Institute for Nuclear Power Operations (INPO). This initiative was supported by several other nations that had nuclear industries.
Later, as a result of the Chernobyl accident, the IAEA increased its emphasis on operational safety by establishing the Department of Nuclear Safety and the world’s nuclear industry created the World Association of Nuclear Operators (WANO), a truly international utility organization to promote technical cooperation and sharing of lessons learned and good practices. INPO and WANO were created by the nuclear utilities and have worked seriously throughout the years, focusing on human factors and organizational issues.
Fundamental roles in this endeavour have also been conducted by the IAEA and the OECD Nuclear Energy Agency (OECD/NEA) and other international organizations.
Since these two events, no further major accidents have taken place.
However, several significant incidents have occurred, including some in very mature national nuclear programmes. These incidents have caused significant economic losses in addition to a consequent decline in the related public confidence and acceptance of a future reliance on nuclear power.
It is often assumed that the lessons learned from Three Mile Island and Chernobyl have been adequately understood and incorporated into the day-to-day routine of operating a nuclear power plant. In summary, one of the major lessons from the Three Mile Island accident was that human factors could overcome the design safety systems and lead to an accident. The major lesson
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of Chernobyl was that organizational factors with a lack of adequate technical knowledge and safety culture could also lead to a significant accident.
Hence, two important common root causes were identified: inadequacies in human performance and organizational factors.
The IAEA publication INSAG-15, Key Practical Issues in Strengthening Safety Culture, issued in 2002, states that:
Most incidents and accidents in the nuclear industry have occurred because someone has failed to take the relevant precautions or has failed to consider or question, in a conservative way, decisions that they have made, or the steps which were taken to implement them.
Since the two major events mentioned above, and with the increasing attention of the nuclear industry in developing and enhancing operational safety assessment programmes, the number of significant events has been reduced and the operating plant performance indicators have been steadily improved.
With the reduction in opportunity to learn from significant events, more management consideration and increased attention is necessary to the learning opportunities to be gained from events of lower significance, often referred to as minor events, near miss events and low level events. Although a lot has been written on this topic, there has been little defined regulatory guidance or requirements in this area. Also, within the industry there is still some confusion in understanding the importance and need of such an assessment process.
There is a tendency to react to events that have occurred, and little importance or commitment is evident in attempting to proactively manage the future by identifying issues or likely issues before they develop.
The use of a proactive approach becomes more and more important as the rate of technological and business change increases through our naturally conservative industry. Since the two major events highlighted above, there have been radical technological changes, especially in electronics and information technology. There have also been radical changes in the business environment, with reductions in staffing levels and reliance on outside expertise becoming prevalent. Some of these changes have already been factors in recent events, as will be highlighted later.
Throughout the world, the performance of nuclear power plants continues to improve in the majority of areas, including reliability and safety, and improved operating plant performance indicators throughout the nuclear industry demonstrate this. These facts are commendable; however, there is a need to consolidate this performance in the face of the current trend of deregu-lation and competition in the electricity market, factors that are outside the direct control of the management of the nuclear utilities.
TOPICAL ISSUE 2
121 If the reduction in the number of reportable events is analysed, it could be deduced that sometimes the plants that are operating with almost no events deserve greater attention. There could be a misconception in analysing and ranking the performance of these plants by using only this group of indicators.
With the apparent pressure of demonstrating an improved business performance, sometimes significant events are classified as being only reportable inside the plant or utility and reluctantly only few may be sent to the international community to be included in international databanks. Sometimes outside pressure has to be applied to encourage plants to report so that others can also benefit from the lessons learned.
With the focus on reporting only significant events, opportunities to consistently and routinely identify and analyse minor events, including near misses and low level events, may be missed in some organizations due to non-existent internal plant policy or mandatory regulatory requirements to analyse and review trends.
To be proactive in the management of safety, opportunities have to be taken to identify trends of deteriorating performance before events can occur.
Indicators based on significant events show encouraging trends and are, therefore, considered very positive. However, they can hide one very important aspect since the level of the threshold for reporting of events remains at the same position. The majority of possible lessons learned, i.e. the minor events and near misses lie below this threshold, populating an area of augmented proportion of required awareness and assessment. Considering the number of operating nuclear power plants around the globe, hundreds of thousands of such events — considered very minor — occur every year. Some nuclear power plants do not have a comprehensive approach to assess such events. INSAG-15 highlights the need for developing a reporting culture:
Failures and near misses are considered as lessons learned which can be used to avoid more serious events. All employees need to be encouraged to report even minor concerns — in a good reporting culture, it is accepted that it is the failure to report any issue that may adversely affect safety.
Significant benefits could be obtained in strengthening and enhancing the management of safety and reliability if this information is identified and adequately utilized. This involves the less important events not individually reported to the regulator or to the industry and the low level events and near misses. They should be reported at least in-house, introduced into the operating experience programme and analysed collectively to identify trends. The lessons learned from this in-house collective analysis should then be shared within the nuclear industry to alert the operating organizations from antecedents, precursors and pitfalls.
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The information given in Fig. 1 is very well known and is shown to demonstrate its validity and usability. The numbers could vary here and there by some amount, but the most important message should not be overlooked or disregarded: there is a significant number of minor events that, if not identified, analysed and trended, lie dormant, waiting for different circumstances or failed barriers to recur as incidents or accidents.
Similarly, the operating experience programmes in place are only using a very small part of the available experience accumulated over the years by the nuclear industry. Mainly, they are only focusing on event information. It is now considered timely to also attempt to identify the good events; the embedded lessons learned in this amount of good experience that has driven so many plants to successful and safe operation. By proactively identifying the attributes of these successful events and sharing them within nuclear installations, it will be possible to contribute further to improve the organization’s processes leading to higher levels of safety and reliability.
2. PRESENT STATUS 2.1. Current situation
Several of the nuclear power plants visited by the Operational Safety Review Teams (OSARTs) of the IAEA did not have an adequate process in
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