A review of the equipment qualification testing sequence

Nuclear power plant digital instrumentation and control (I&C) systems have to consider the effects of electromagnetic interference, radiofrequency (EMI/RFI) and power surge for reliable system operation. However, the current requirement (IEEE Std. 323) related to equipment qualification does not include the EMI test requirement and the proper E.Q testing sequence including EMI/RFI and surge withstand testing. Until now there has been no requirement regarding the proper testing sequence and no definitive technical evidence to support any particular sequence on the equipment qualification. In order to find the most conservative and reasonable testing sequence, we compared and analyzed the results of the SMMP (Sub-cooled Margin Monitoring Panel) qualification test. The SMMP consists of analog and digital modules. We measured the output voltage of the analog and digital modules of the panel before and after a heat rise and EMI tests. The results show that output variation increases during and after the heat rise test in the analog modules but the increase is negligible in the digital modules. From our results, we conclude that the heat rise test affects the functioning of the electronic modules, although insignificantly, and the most conservative testing sequence occurs when the EMI/RFI and surge withstand tests are performed after the heat rise test