IEC/IEEE International Standard--Nuclear facilities--Instrumentation important to safety--Spent fuel pool instrumentation

This IEC/IEEE standard sets out the requirements for instrumentation to monitor spent fuel pool water level and temperature in nuclear facilities as well as radiation monitoring in the vicinity of the pool. Prior to the accident at Fukushima Daiichi, spent fuel pool monitoring in nuclear power plants was provided mainly to enable operators to monitor pool temperature at a location near the top of the pool. It was also used to determine that the water level remained below the point where flooding of operational areas would be a concern and above the level assumed in safety analyses that evaluated the release of fission products from the pool in the event of a fuel handling accident. In general, robust spent fuel pools protect the fuel from physical damage and use highly reliable coolant systems that ensure continuous decay heat removal. Monitoring of the pool cooling system and drain taps at the bottom of the pool were considered sufficient to confirm pool cooling under operational states and design basis accidents. Because these are straightforward measurements, neither IEC SC 45A nor IEEE NPEC considered that a standard on this topic was necessary.