Calculation of the international standard problem ISP-46 using the RELAP/SCDAP and melcor computer codes

The main objective of calculating the international standard problem ISP-46 was to assess the capabilities of computer codes to simulate phenomena which occur in pressurized-water reactors during a serious accident. The FPT1 experiment with melting of fuel, performed on the PHEBUS (France) facility in 1996, served as the basis for the problem. The results of calculations which specialists at the Experimental Design Office Gidropress performed using the MELSIM/MELCOR 1.8.4 and RELAP/SCDAPSIM/MOD 3.2 computer codes are presented. The results obtained are analyzed and compared. An assessment is made of the possibility of using these codes for design validation of VVER safety.