Thermal Hydraulic Performances Analysis of Cr-Coated Zircaloy Clad During Station Blackout Accident

摘要

A special MELCOR1.8.6 UDGC developed by Idaho National Laboratory is used to evaluate the performance of Cr-Coated Zircaloy by comparing with uncoated Zircaloy and FeCrAl coated cladding. Our focus is primarily estimating oxidation kinetics and the assumed failure criterion depending on the cladding conditions. After simulation and comparison, we come to conclusion that the presence of the coating material can significantly reduce the initial rate of hydrogen generation and delays the time when generation rate becomes significant (almost 2 hours). This decrease in the rate of oxidation and delay in timing can provide additional coping time for compensatory actions. Failure criterion of the coated cladding material, such as melting temperature, will not affect the hydrogen initial time significantly since majority of hydrogen can also be produced from stainless-steel and steam reaction.