POTENTIAL STRESS ON CLADDING IMPOSED BY THE MATRIX SWELLING FROM ALPHA DECAY IN HIGH BURNUP SPENT NUCLEAR FUEL

摘要

Studies using literature data were conducted on potential swelling of the spent nuclear fuel (SNF) matrix due to alpha decays. Swelling of the matrix may impose stress on cladding during long-term storage of SNF. The literature data were obtained for UO_2 having undergone accelerated irradiation conditions. The representation of the simulated accelerated tests for the SNF is discussed. The stress on cladding, and its potential implications in terms of long-term degradation, would depend on SNF matrix swelling, gap size, crack pattern and crack interlocking, and friction of the SNF matrix and cladding. Assessments and reviews are made for the observed SNF matrix swelling, stress generated on cladding, and gap size. Applying this information, the stress on cladding due to alpha decays is semi-quantitatively assessed using stress analysis induced by thermal expansion.