Before the RPV failure, the CNMT pressure was repeated to increase and decrease by the opening and closure of the PSRV. After the RPV failure, 0.26 MPa of pressure peak was observed due to the direct containment heating (DCH) by the HPME.
Accident sequence Time (s) Reactor trip 0 RCP trip 0 MFW trip 0 SG dryout 3,762 PSRV open 4,881 Core exposure 5,359 Oxidation start 8,991 Core dryout 9,990 Cladding melt 10,297 Initial melt relocation 10,441 First LP dryout 12,866 RPV failure 14,462 CNMT over-pressurization 60,100 Table 3: The statistics values of accident progress.
In addition, AFW, the safety depressurization system (SDS), containment spray, the passive autocatalytic recombiner (PAR), pressurizer safety relief valve (PSRV
), main steam safety valve (MSSV), and atmospheric dump valve (ADV) were also modelled to enable depressurization of the primary and secondary systems.