Development and Implementation of New Accident Tolerant Instruments Against Severe Accident Conditions - Enhancing Reliability of Measurements During Severe Accidents -
Based on the lessons learned from the Fukushima Daiichi Accident, new regulatory requirements request enhancement of reliability for instrumentation and monitoring systems in severe accident management. Particularly it is essential for in-situ instrumentation, located in a containment vessel, to have function to withstand harsh environmental conditions during a severe accident. Therefore, Mitsubishi Heavy Industries, Ltd. designed and developed new accident-tolerant sensors such as pressure, water level and hydrogen monitoring system and a hydrogen igniter to withstand severe accident environmental conditions of high-temperature, high-pressure steam atmospheres with chemical spray and high radiation exposure through qualification testing. These new accident-tolerant sensors were installed and have been in operation in domestic PWRs.
