Deterministic integral codes, such as MELCOR and ASTEC, have been developed to predict and characterize severe accident progression in nuclear power plants. Due to the complexity and the mutual interaction of the several physical phenomena occurring in severe accident scenarios, the validation of these codes is fundamental. Moreover, considering the limited experimental database in prototypical conditions, sensitivity analysis and the quantification of code uncertainties should be carried out. The present paper describes the assessment of a MELCOR v2.2 input deck of the QUENCH test facility, located at KIT, and the QUENCH-06 test is selected for code validation. Such experiment aimed at evaluating the effect of the injection of 40 g/s of water on the hydrogen production and the degradation of a pre-oxide rod bundle. Having as reference the past QUENCH analyses available on public technical literature and experimental data, the authors developed the input deck exploiting several configurations and code features. The nodalization provides a fine representation of the test bundle active region and a detailed definition of the boundary conditions and of thermal insulation system. The validation has been performed evaluating the accuracy of the code by comparing, both qualitatively and quantitatively, the MELCOR results for some relevant parameters (such as hydrogen generation, maximum cladding temperature and oxide scale of the rods) against the experimental data. The results shows that MELCOR can reproduce the experimental data of hydrogen production and cladding oxide thickness in the instrumented bundle positions. In addition, the study includes a sensitivity analysis to test the behavior of different Zircaloy (Zry)-Steam oxidation correlations in the temperature range 1100K - 2200K. Cathcart-Pawel correlation provides the best agreement with the experimental data of zircaloy surface temperature from 1100K to 1800K, while for higher temperatures (i.e., above 1900K) the empiric Volchek correlation is the closest to the experimental data. Finally, an uncertainty analysis has been carried out to evaluate the dispersion of the figures of merit involved in the simulated phenomenology.
Simulation of QUENCH-06 Experiment by MELCOR v2.2 with Uncertainty Analysis
Bersano, A.;Mascari, F.
2023-01-01
Abstract
Deterministic integral codes, such as MELCOR and ASTEC, have been developed to predict and characterize severe accident progression in nuclear power plants. Due to the complexity and the mutual interaction of the several physical phenomena occurring in severe accident scenarios, the validation of these codes is fundamental. Moreover, considering the limited experimental database in prototypical conditions, sensitivity analysis and the quantification of code uncertainties should be carried out. The present paper describes the assessment of a MELCOR v2.2 input deck of the QUENCH test facility, located at KIT, and the QUENCH-06 test is selected for code validation. Such experiment aimed at evaluating the effect of the injection of 40 g/s of water on the hydrogen production and the degradation of a pre-oxide rod bundle. Having as reference the past QUENCH analyses available on public technical literature and experimental data, the authors developed the input deck exploiting several configurations and code features. The nodalization provides a fine representation of the test bundle active region and a detailed definition of the boundary conditions and of thermal insulation system. The validation has been performed evaluating the accuracy of the code by comparing, both qualitatively and quantitatively, the MELCOR results for some relevant parameters (such as hydrogen generation, maximum cladding temperature and oxide scale of the rods) against the experimental data. The results shows that MELCOR can reproduce the experimental data of hydrogen production and cladding oxide thickness in the instrumented bundle positions. In addition, the study includes a sensitivity analysis to test the behavior of different Zircaloy (Zry)-Steam oxidation correlations in the temperature range 1100K - 2200K. Cathcart-Pawel correlation provides the best agreement with the experimental data of zircaloy surface temperature from 1100K to 1800K, while for higher temperatures (i.e., above 1900K) the empiric Volchek correlation is the closest to the experimental data. Finally, an uncertainty analysis has been carried out to evaluate the dispersion of the figures of merit involved in the simulated phenomenology.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
