Transient analysis for lead-bismuth-cooled accelerator-driven system proposed by JAEA

Sugawara, Takanori  ; Nishihara, Kenji  ; Tsujimoto, Kazufumi 

It is supposed that an Accelerator-Driven System (ADS) is safer than conventional critical reactors since the ADS is driven by the external neutron source in the subcritical state. In this study, the transient analyses for the lead-bismuth cooled ADS proposed by JAEA were performed by using the SIMMER-III and RELAP5/mod3.2 codes to investigate the possibility of the core damage. Three accidents; the protected loss of heat sink, the protected overcooling and the unprotected blockage accident were calculated as the typical ADS accidents. Through these calculations, it was confirmed that all calculation results except the protected loss of heat sink satisfied the no-damage criteria. In the protected loss of heat sink, the cladding tube temperature reached at its melting temperature after 18-21 hours although the calculation condition was very conservative. It is required to design a safety system of the ADS to decrease the frequencies of the accidents and to ease the accidents.