Fuel Behaviour During Simulated Reactivity Initiated Accidents in the NSRR Experiments and its Application

Abstract

This paper describes the major achievement of the research on LWR fuel behavior during reactivity-initiated accidents (RIAs) conducted in the Nuclear Safety Research Reactor (NSRR) at Japan Atomic Energy Research Institute (JAERI). The application of the results to the regulatory guideline and to the analysis of the Chernobyl accident are also presented.


The threshold enthalpy for fuel cladding failure and fuel fragmentation, effects of fuel rod design and cooling environments on the thresholds are discussed in relation to the fuel failure mechanisms. The philosophy in establishing the RIA guideline in Japan are introduced based on the present understanding of the RIA. The fuel behavior in the Chernobyl accident can well be understood based on the RIA data base from the NSRR experiments and other preceding experiments.