Identification of important phenomena through the PIRT process for development of sodium fire analysis codes

Aoyagi, Mitsuhiro ; Uchibori, Akihiro ; Kikuchi, Shin  ; Takata, Takashi  ; Ohno, Shuji  ; Ohshima, Hiroyuki

JAEA has developed sodium fire analysis codes to evaluate the consequences of sodium fire events. This paper describes a PIRT (Phenomena Identification and Ranking Table) process for such events. Because a sodium fire event involves complex phenomena, the FOMs are specified through a factor analysis. Associated phenomena in a sodium fire event are identified through both element- and sequence-based phenomena analyses. The importance of each phenomenon is evaluated by considering the sequence-based analysis of associated phenomena related to the FOMs. Then, a ranking table is established. An assessment matrix of important phenomena and experiments is completed to confirm the sufficiency of experimental data for the validation of the models in the sodium fire analysis codes. Additional assessments are discussed specifically for the aerosol module and the CFD module in three-dimensional codes from a perspective of careful validation.