Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : July 26, 2021 - July 27, 2021
Progress of severe accidents (SAs) has been previously evaluated by transferring analytical results between multiple analysis codes. In this study, a new analysis code, SPECTRA was developed for integrated analysis of in- and ex-vessel phenomena during SAs. SPECTRA consists of in- and ex-vessel modules which have a thermal hydraulics (TH) module as a base part. The in-vessel TH module computes complicated multi-dimensional behavior of liquid sodium and gas by using the multi-fluid model considering compressibility. Relocation of a molten core is computed by the dissipative particle dynamics method. A lumped mass model was employed for computation of ex-vessel multi-component gas flow including aerosols. The fully implicit scheme was applied to both the TH modules to enable computation with a large time step width. Analytical models for sodium fire, sodium-concrete interaction, and debris-concrete interaction were integrated into the ex-vessel module. The in- and ex-vessel modules were coupled by exchanging the amount of leaked sodium and debris at every time step. Basic capability of SPECTRA was demonstrated through analysis of a loss of reactor level event.
