Models for the Configuration and Integrity of Partially Oxidized Fuel Rod Cladding at High Temperatures - Final Design Report

Technical Report · Mon Feb 01 00:00:00 EST 1999

DOI:https://doi.org/10.2172/911492· OSTI ID:911492

Siefken, Larry James

Models were designed to resolve deficiencies in the SCDAP/RELAP5/MOD3.2 calculations of the configuration and integrity of hot, partially oxidized cladding. The modeling was improved in five areas. First, the configuration defined for melted metallic cladding retained by an adjacent oxide layer was improved. Second, the empirical model to account for the effect on oxidation of intact cladding is not significantly reduced by the presence of a rather high concentration of relocated material. Third, models for the dissolution of the oxide layer by the metallic layer were implemented into the code. Fourth, a model was added to calculate the thermal stress applied to the oxide layer by the temperature gradient across the oxide layer and to compare this stress to the ultimate strength of the oxide layer. Fifth, a new rule based on theoretical and experimental results was established for identifying the regions of a fuel rod with oxidation of both the inside and outside surfaces of the cladding. The assessment of these models and their integration into SCDAP/RELAP5 showed that the calculated axial distribution in cladding oxidation and relocation are in significantly better agreement with experimental results than is currently the case. The modeling changes account for three aspects of behavior that were not previously calculated correctly. The implementation of these models eliminates to a significant extent the tendency of the SCDAP/RELAP5 code to overpredict the extent of oxidation of the upper part of fuel rods and to underpredict the extent of oxidation of the lower part of fuel rods and the part with a high concentration of relocated material.

• Research Organization: Idaho National Lab. (INL), Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: DE-AC07-99ID-13727
• OSTI ID: 911492
• Report Number(s): INEEL/EXT-99-00107; TRN: US0704590
• Country of Publication: United States
• Language: English

Related Subjects

22 - GENERAL STUDIES OF NUCLEAR REACTORS
CONFIGURATION
DESIGN
DISSOLUTION
DISTRIBUTION
FUEL RODS
IMPLEMENTATION
OXIDATION
OXIDES
SAFETY REPORTS
SIMULATION
TEMPERATURE GRADIENTS
ULTIMATE STRENGTH
dissolution
melted metallic cladding
oxide layer
oxidized cladding
post-irradiation examination (PIE)
relocated material
SCDAP/RELAP5/MOD3.2
steam
thermal stress