Experimental Studies for the VVER-440/213 Bubble Condenser System for Kola NPP at the Integral Test Facility BC V-213

In the frame of Tacis Project R2.01/99, which was running from 2003 to 2005, the bubble condenser system of Kola NPP (unit 3) was qualified at the integral test facility BC V-213. Three LB LOCA tests, two MSLB tests, and one SB LOCA test were performed. The appropriate test scenarios for BC V-213 test facility, modeling accidents in the Kola NPP unit 3, were determined with pretest calculations. Analysis of test results has shown that calculated initial conditions and test scenarios were properly reproduced in the tests. The detailed posttest analysis of the tests performed at BC V-213 test facility was aimed to validate the COCOSYS code for the calculation of thermohydraulic processes in the hermetic compartments and bubble condenser. After that the validated COCOSYS code was applied to NPP calculations for Kola NPP (unit 3). Results of Tacis R2.01/99 Project confirmed the bubble condenser functionality during large and small break LOCAs and MSLB accidents. Maximum loads were reached in the LB LOCA case. No condensation oscillations were observed

International Conference Nuclear Energy in Central Europe 2001 VAPEX CODE ANALYSIS OF FARO L-33 TEST

ABSTRACT The analysis of the FARO L-33 test has been carried out with the VAPEX code. The FARO L-33 test has been implemented to study premixing and quenching processes for large mass (100 kg) of corium. The specific features of the test are: high subcooling (124 K), low pressure (4 bar), presence of noncondensable gas (argon) and triggered vapor explosion when melt reached the bottom of the vessel. Special procedure, based on the Kelvin-Helmholtz approach and evaluation of steam film parameters, has been applied to estimate a size of melt droplets under melt jet fragmentation. Using of two different models of the jet fragmentation (which predicted both full fragmentation and non-full one) yielded practically the same results. No steam generation was revealed in the calculations. Level swelling, occurred in the test, is possibly due to hydrogen generation, which is not modeled in the code. Modeling of vapor explosion, taken place in the test, yielded reasonable comparison with the test data in the case of using of significant void fraction in the jet region. It can be interpreted as occurrence of hydrogen in this region. VAPEX analysis of the FARO L-33 test has shown reasonable agreement between experimental and calculated data, demonstrated capabilities of the VAPEX code to predict melt-coolant interaction phenomena taking place under severe accidents