Characterization of salt deposit layer growth and prediction of cladding temperature of heated rod bundles under long-term seawater injection and pool boiling conditions

摘要

Seawater has been recognized as an alternative water source in severe accident countermeasures even before the TEPCO Fukushima Dai-ichi NPS accident. In this article, influences of deposit layers of salt precipitates on the early core degradation were investigated. A heated part of a fuel bundle was regarded as a major deposit site and numerical models for predicting growing geometry of deposit layers and resultant temperature responses of cladding were developed. These models have been validated based on precipitation tests employing 5 x 5 short length mockup bundles submerged in solutions of simple seawater and a mixture of seawater and boric acid.