Analysis of Fuel-Cladding Chemical Interaction at High Burnup

摘要

The HEDL fuel-cladding chemical interaction (FCCI) wastage correlation has been revised to incorporate additional data from the HEDL P-23 high temperature test series at peak fuel pin burnups of approximately 90.0 MWd/kgM. The previous HEDL correlation was developed from a data base of fuel pins with peak burnups of approximately 50.0 MWd/kgM. Therefore, in order to predict the amount of cladding thickness loss to be expected at current anticipated fuel pin lifetimes in the range of 90 to 100 MWd/kgM a major extrapolation of the actual irradiation experience was necessary. To provide the needed data for the extension of the correlation to high burnups the irradiation of the HEDL P-23A subassembly in EBR-II was extended to a peak fuel pin burnup of approximately 90.0 MWd/kgM. An advanced matrix type reaction was observed in the high burnup fuel pin. The character and extent of the interaction made it possible to estimate the location of the original cladding inner surface to determine cladding thickness loss due to FCCI by measuring the depth of penetration. Therefore, it was necessary to measure total cladding thickness for the high burnup pin. In order to place the entire data set on the same basis, cladding thickness was also measured for the lower burnup pins. Cladding thickness was measured on 225X photographs of the polished cladding at 16 equally spaced locations on the circumference of each sample. From these measurements an average cladding thickness was calculated. (ERA citation 03:052585)