Improving the NPP safety against loss of off-site power accident by extending the house load operation period

Safe operation of nuclear power plants (NPP) is highly dependent on the continuous supplying of alternating current via the external grid. The more reliable the external grid is, the safer the NPP operates. The loss of offsite power (LOOP) event occurs when all power supplies from external grid are suddenly lost. LOOP as an initiating event, contributes more than 26 percent to the core damage frequency (CDF) of GEN-II NPPs, which can have a major negative impact on a NPP safety. The objective of this paper is aimed towards the improvement of NPP safety against LOOP accident. In order to ameliorate the value of CDF due to LOOP, a novel technique is proposed. By extending the period of house load operation, the NPP will be able to stay at power during temporary external grid issues. By utilization of probabilistic safety assessment method, it is realized that the implementation of proposed technique decreases the CDF significantly, which indicates a remarkable improvement of NPP safety against LOOP.