Impact of Environment on Severe Accident Monitoring Systems

Abstract

A severe accident in a nuclear power plant (NPP) can have significant consequences. Mitigating them is a major task of the severe accident management (SAM) program based on the SAM guideline (SAMG). On-line monitoring of certain critical plant parameters during and after a severe accident is extremely important for effective execution of a SAM program. The instruments and devices used in monitoring systems can be adversely affected by the extremely harsh environment induced by the severe accident. The temperature, pressure, humidity and radiation levels can significantly exceed the design basis assumptions of the plant. The electronic components of the monitoring system devices can become particularly susceptible to the high levels of radiation. Therefore, it is important to assess such extreme environmental conditions so that the monitoring system can be properly designed and protected. In this paper, environment conditions in NPPs under severe accidents, and the effects of such environments on the monitoring system devices are reviewed.