The IAEA/NEA Incident Reporting System
Using Operational Experience to Improve Safety

WHAT IS IRS?

Through IRS, information is collected from around the world on unusual events in nuclear power plants (NPPs) that may be important for safety or accident prevention and actions. The information is then assessed, analysed and fed back to operators to prevent similar occurrences at other plants. The ultimate objective is reducing the frequency and severity of safety significant unusual events at NPPs.

IRS is also concerned with identifying what are called "precursors." These are events of apparently low safety significance, which, if not properly attended to, have the potential to escalate into more serious incidents. Through its study of widely based experience, IRS helps to accelerate identification of these precursors.

IRS reflects a systematic approach to the feedback of lessons learned from operating experience, which is a key element of the "defence in depth" approach used in the nuclear power industry.

WHAT ARE THE BENEFITS?

The IRS increases awareness of actual and potential problems. It draws attention to those incidents, which, if not dealt with in a timely fashion, could escalate to more serious events through subsequent failures of equipment or human response. This heightened awareness has resulted in numerous improvements to plants, procedures and training in many nuclear power plants and reduced danger from unusual events.

Part of the IRS database contains "individual event reports" which include a detailed description and analysis of the event's causes that may be relevant to other plants. The analysis may lead to action by plant management or by regulatory authorities. Another IRS resource are topical studies resulting from events of particular interest. These studies have emphasized the importance of human actions, common mode failures or fires, shutdown and low power operation modes of the plants and the need for vigilance during plant improvements and modifications.

Most countries participating in the IRS are well aware of the benefits of exchanging information related to the root causes and lessons learned from incidents at nuclear power plants. Feedback on how to adequately treat, or avoid, these possible precursors is of paramount importance to operational safety. For example, abnormal pipe thinning in short piping bends that is not identified in time could eventually lead to a pipe break which, in turn, could result in an accident. The identification of such precursors can help to warn of an imminent problem.

Another use of IRS is application of system data in the design of the next generation of nuclear power plants. Experience with backfitting presently operating nuclear power plants has demonstrated that design modifications arising from IRS reports can have a significant impact on NPP safety.

HOW DOES IRS WORK?

Event reports

Each participating member country designates a national IRS co-ordinator. An event report is submitted to IRS when the event is considered by the national co-ordinator to be of international interest. Only events of safety significance are reported.

When information is considered time sensitive, a short preliminary report is distributed within one month of the event. In all cases a main report is produced (usually within three months) and in some cases a follow-up report is distributed.

The main report contains basic information include the title and date of the event, characteristics of the plant, and an abstract. It also includes a narrative description of the event, a safety assessment (what were its direct causes, consequences, and implications), root causes and corrective actions, lessons learned and a coded watchlist containing the essenial information that can be easily searchable and retrievable. Very often a written description of the event is supported by graphics (diagrams of affected parts of the plant, etc.).

When an event or group of events points to the existence of a generic problem (eg. pilot operated valves), a national co-ordinator may produce what is known as a "generic report".

Dissemination

Each IRS report becomes part of the IRS database and is communicated to all participants in the system without delay. The national co-ordinators disseminate the information to appropriate governmental and non-governmental organizations, including nuclear power plants, for professional use. The routine receipt and distribution of reports on incidents form the basis for in-depth studies on implications and remedies, and assist in identifying issues common to certain types or all nuclear power plants.

The incident reports included in the IRS are selected because they hold particular interest for the international nuclear community - whether due to important lessons that can be learned from them, new aspects of safety being discovered, or hitherto unsuspected interrelationships between events.

Topical studies

Topical studies constitute a major component of the IRS activity. They are intended to release the latent benefit from the IRS data by in-depth evaluations. Identification of topical or generic issues begins with national assessments which are then studied in depth by experts at the international level. National nuclear event reporting systems share lessons among regulators, operators en manufacturers

National nuclear event reporting systems share lessons among regulators, operators and manufacturers.

Annual meetings

National co-ordinators meet each year to review the information received and the operation of the system in general. The committee of national co-ordinators selects for further analysis topics and reports of those events which it considers to be of particular safety interest to the international community. Conclusions of the committee are distributed to participating countries. Moreover, a joint IAEA/NEA meeting to exchange information on unusual events is held annually. These meetings serve to strengthen the mechanisms for the exchange of experience in the assessment of incidents and in improvements made to reduce the probability of similar events.

Restricted distribution

IRS reports are intended for restricted distribution because the system is designed to be of value mainly to technical people working in the nuclear power field. The information reported is not for general distribution. This restriction encourages openness within the nuclear community and disclosure of detail on incidents. However, steps are constantly being taken to ensure and improve visibility and transparency of the IRS activity.

There is also an event reporting system operated by WANO (World Association of Nuclear Operators). This is an e-mail system run by and for the utilities who own and operate the power stations and has similar but not identical reporting criteria to IRS, which is an intergovernmental system operated by IAEA/NEA in collaboration with the national regulatory bodies of each country. As one would expect there is some overlap between the two systems, with some events appearing in both.

WHAT HAS BEEN ACHIEVED?

Virtually every country with a nuclear power programme participates in the IRS. There are now over 2400 event reports on the system, with new ones added at about the rate of 100 per year. The reports are now being made available in a user-friendly full-text database, with a powerful search engine allowing full-text searching. The capacity for inputting, storing and treating written, numerical and graphical information is increasing reporting and analytical capabilities and making IRS more effective in the improvement of nuclear safety.

Over the years, the IRS has expanded from a vehicle for information exchange to also being the source and starting point for in-depth discussions, generic studies, and meetings for the exchange of valuable information related to operating experience.

Recent products from IRS include:
• A published review of corrective actions taken at nuclear plants. (Compendium of actions taken in response to events reported to the IRS).

• Recent topical studies include: events during shut down and low power operation; events arising from modifications and upgrades improve safety; implications of the Barsebäck blocked strainer incident; ageing effects on components; fire protection and turbine hall fires; man-machine interactions; steam generator for performance; motor operated valves.