Monitoring system for monitoring the state of nuclear reactor core.

摘要

The nuclear reactor container of a boiling water reactor has a dry well (5) and a pressure suppression chamber (6). The level of radioactivity in the cooling water (7) filling the pressure suppression chamber in the event of accident, is measured by a liquid radiation monitor (24). An iodine monitor (13) measures the level of radioactivity of iodine in the space above the surface of cooling water in the pressure suppression chamber (6), while a noble gas monitor (18) measures the level of radioactivity of noble gas in the same space. Outputs from the liquid radiation monitor (24), the iodine monitor (13) and the noble gas monitor (18) are delivered to an accident judging device (28) which makes a judgement as to occurrence of perforation of fuel rods and melt down of fuel rods in the event of a Loss Of Coolant Accident (LOCA), the result of which is displayed at a display device (29).