Method for Qualification of Non-Safety Grade Electric Equipment in Nuclear Power Generating Stations

Abstract

This report is written as a part of a master thesis project where safety requirements for Swedish nuclear power plants, such as the regulations issued by the Swedish Radiation Authority (SSM) and other standards, are used to develop a limited and customized qualification for non-safety grade electric equipment. The qualification is general, but the focus in this report will be on protective devices in the internal electric grid of the power plant and the generator supply line. The electric grid and the equipment of a Swedish BWR has been used as a basis for the qualification. The report also details the incident at Forsmark 1 2006 as a part of the background behind the purpose of such a qualification. The qualification is also demonstrated on an example; a protective relay used to detect overvoltages on the generator busbar. The protective relay did not meet all the requirements of the qualification, mostly due to the difficulty of finding detailed documentation as the requirements for documenting non-safety grade equipment are not stringent as for safety grade. Keywords: qualification, protective relay, nuclear power Please note that this is the public version of the master thesis report and that certain information has been omitted. For access to the full version, contact Westinghouse Electric Sweden AB, Västerås.