科研之友
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摘要
The neutronic penalty and advantages are quantified for potential accident tolerant claddings in a CANDU-6 (Canada Deuterium Uranium) reactor. Ferritic-based alloy (FeCrAl and APMT), steel-based alloy (30455 and 310SS) and silicon carbide (SiC) claddings are compared with Zircaloy-II. High thermal capture in nickel-59 and iron-56 imply a neutronic penalty in iron and steel-based bundles. A minimum enrichment of 1.0% and 1.1% is required for ferritic and steel-based claddings, respectively, to achieve the CANDU-6 burnup average criticality. An average increase of 0.35% in reactivity is introduced when SiC is considered, while keeping a natural enrichment condition. Average thermal neutron absorption rate is found to be 203, 8 and 6 times higher in UO2 pellets than in silica, iron and steel-based claddings, respectively. A spectral hardening is observed in fuel, cladding and coolant for all enriched cells. Neutron flux is 30.5% higher at 0.0253 eV in SiC and Zr bundles. For FeCrAl, APMT, 304SS and 310SS, less (PU)-P-239 is produced during all fuel residence time and a minimum of 50% more Xe-135 poison is being produced at equilibrium. As well, a minimum of 60% more U-235 is left at end-of-life. For bundles cladded with SiC and Zr, 7.6% higher fission rates are found on the pellet periphery. Decreasing the cladding thickness by 200 mu m made it possible to satisfy the criticality requirements for all claddings with an enrichment below 1%. Moderator and coolant temperature coefficients are found higher in SiC and Zr bundles. At mid-burnup, the Doppler effect and the voiding effect are higher in FeCrAl, APMT, 304SS and 310SS cladded cells.
- 出版日期2018-3
