and illustrate some vulnerabilities of the plant electrical system to over voltage transients. It identified electrical equipment involved, failure modes, contributing factors, actual and potential consequences, and corrective actions. Initiating factors and associated root causes were also analysed. The analysis of International Operation Experience Feedback revealed number of events that involved disturbances in the plant electrical systems, and which may have features in common with the Forsmark-1 event. It underlines the importance of sharing lessons learned from design modifications made at another unit of similar design that if known, it could have identified susceptibility of emergency diesel generators to common mode failure before the event occurred. This paper also summarizes international projects that were initiated by Forsmark event, as well as important lessons that still can be learned from Forsmark event. This paper presents actions taken at nuclear power plants and regulatory authorities in different countries to prevent similar event to occur. K e y w o r d s: Forsmark event, nuclear power plant, disturbances in the plant electrical systems

No abstract

No abstract

Learning from operational experience and applying this knowledge promptly and intelligently is one of the ways to improve the safety of Nuclear Power Plant (NPP). Recent reviews of the effectiveness of Operational Experience Feedback (OEF) systems have pointed to the need for further improvement, with importance being placed on tailoring the information to the needs of the regulators. In 2007, at the request of a number of nuclear safety regulatory authorities in Europe, the Institute for Energy of the European Commission's Joint Research Centre (EC JRC) initiated a project on Nuclear Power Plant operational experience feedback, which adopts an integrated approach to the research needed to strengthen the European capabilities for assessment of NPP operational events and to promote the development of tools and mechanisms for the improved application of the lessons learned. Consequently, a so-called “European Clearinghouse” on NPP OEF was established, which includes scientific officers from the EC JRC, a number of European nuclear safety regulatory authorities and some of their Technical Support Organizations (TSOs). The paper discusses the activities implemented in 2008 within the framework of the European Clearinghouse on NPP OEF (hereinafter called the European NPP Clearinghouse) and provides an overview of the main conclusions drawn from the safety studies performed. Outlook of the activities carried out in 2009 are given.

No abstract