The NEA Computer-based Systems Important to Safety (COMPSIS) Project

Software-based systems are currently being used and retrofitted in operating nuclear power plants worldwide. The failure modes of both hardware and software in these systems are to some extent different from the analogue instrumentation and control (I&C) systems. At present, there is no established international database where the failure modes of computerised systems are collected. The general aim of the Computer-based Systems Important to Safety (COMPSIS) project is to exchange information on computer-based system reliability in a structured way. The high-level objective is to contribute to the improvement of safety management and to the quality of software risk analysis for software-based equipment. Software and hardware faults in safety-critical systems are typically rare events and, consequently, most countries do not experience enough faults to allow meaningful syntheses. Combined information from several countries, however, is expected to yield sufficient data to help draw conclusions. The main objectives of the COMPSIS project are to:

  1. define a format and collect software and hardware fault experience in computer-based safetycritical NPP systems (hereafter called "COMPSIS events") in a structured, quality-assured and consistent database;
  2. collect and analyse COMPSIS events over a long period so as to better understand such events, their causes and their prevention;
  3. generate insights into the root causes of and contributors to COMPSIS events, which can then be used to derive approaches or mechanisms for their prevention or for mitigating their consequences;
  4. establish a mechanism for an efficient feedback of experience gained in connection with COMPSIS events, including the development of defences against their occurrence, such as diagnostics, tests and inspections;
  5. record event attributes and dominant contributors so that a basis for national risk analysis of computerised systems is established.

Work during the first phase of the project (2005-2007) concentrated on the development of the COMPSIS data collection guidelines, quality assurance and data exchange interface. Data collected during first and second phase is about 80 Licensee Event Report (LER) events covering the period from the early 1990s to 2010.

Further to the December 2011 CSNI request about the future of the COMPSIS project, the Secretariat informed CSNI in June 2012 that the ICDE Project is willing to integrate computer failures as a new component that will allow for the preservation of the COMPSIS data and for qualitative analysis of these failures without additional cost.

Participating countries

Finland, Germany, Hungary, Korea, Sweden, Switzerland and the United States. In addition, the Atomic Energy Council of Chinese Taipei has confirmed its participation.

Project period

January 2005 to December 2011


EUR 100 000 per year.

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Last updated: 14 October 2013