Design report: SCDAP/RELAP5 reflood oxidation model [report]

E.W. Coryell, S.A. Chavez, K.L. Davis, M.H. Mortensen
1992 unpublished
Current SCDAP/RELAP5 oxidation models have proven to underpredict oxidation, and therefore hydrogen production, when modeling reflo_d during in-pile tests. As an example, while OECD LOFT Experiment LP-FP-2 shows significant increases in temperature and pressure during reflood due to increased oxidation, only minimal additional oxidation is currently predicted with SCDAP/RELAP5. Since SCDAP/RELAP5 predicts a steam rich environment during reflood, the parameter limiting oxidation must be the
more » ... on must be the availability of zircaloy. Two phenomena, not currently modeled, may provide the necessary unoxidized zircaloy during reflood: (1) localized steam starvation prior to reflood, caused by debris blockage or hydregen generation, or (2) shattering of oxidized cladding during reflood. The objective of this design report is to develop new models to accurately predict zircaloy cladding oxidation during the temperature transients prior to and during reflood. Evidence compiled from postirrzdiation examination (PIE) of fuel bundles subjected to severe accident conditions from several in-pile tests is used to identify mechanisms for additional cladding oxidation during reflood and to develop specific criteria to determine when these mechanisms are applicable. FIN No. A6889 --SCDAP/RELAP5/MOD3 Maintenance ! ¢ Table of Contents
doi:10.2172/10115541 fatcat:v5g4a6j6vvcd7btmvir6ikqbmu