A Study on the Optimal Cooling Time of Actinide Feedstock for Use in Transuranic Mixed Oxide Fuels in CANDU Reactors

Abstract

Transuranic actinides from spent fuel can be burned in current reactors as a mixed oxide (MOX) with natural uranium, reducing spent fuel radiation and heat loads. Detailed reactor physics analysis of transuranic MOX in CANDU (TRUMOX-CANDU) showed significant actinide conversion while maintaining operational performance. The different cooling times of spent fuel feedstock affect the MOX fuel actinide composition, which: i) alters the neutronics of the resulting TRUMOX fuel, ii) affects actinide conversion, and iii) determines end of cycle composition, dictating spent fuel radiation and heat loads. These effects are examined to find a balance between in-core performance, actinide conversion and end of cycle spent fuel properties. TRUMOX fuel compositions, dictated by the cooling time of the actinide feedstock, are evaluated with WIMS-AECL CANDU lattice cell calculations. In-core neutronics, actinide conversion ratio, and end of cycle fuel composition are examined to estimate an optimal cooling time for the actinide feedstock before use in TRUMOX fuel.