An Auxiliary System to Monitor the Key Environmental Variables in Spent Fuel Pool at the Loss of Power Accident

摘要

If the spent fuel pool is at normal state, the 3 key environmental parameters (i.e., the water level, temperature and radiation level on the water surface) are within their ranges specified by technical specifications for the nuclear power plant. Otherwise, the 3 key parameters should deviate from their ranges of the technical specifications. It is possible to recognize if the emergency occurs in the spent fuel pool when the changes in the 3 key parameters are being monitored. This study is to suggest an auxiliary system to check if the emergency occurs in the spent fuel pool by monitoring the 3 key environmental parameters, water level, water temperature and radiation level on the water surface in the spent fuel pool at the same time. The auxiliary system could be operated using a low-voltage DC power against the long-lasting loss of AC power to the main monitoring system. This auxiliary system has a merit to crosscheck the 3 key parameters at the same time and minimize the possibility to misjudge the situation in the spent fuel pool. The auxiliary system is expected to enhance the instrumentation capability of the spent fuel pool.