Assessment of criticality and burn up behavior of candu reactors with nuclear waste trans uranium fuel
Date
2012-04-23
Journal Title
Journal ISSN
Volume Title
Publisher
Progress in Nuclear Energy
Abstract
Large quantities of nuclear waste plutonium and minor actinides (MAs) have been accumulated in the
civilian light water reactors (LWRs) and CANDU reactors. These trans uranium (TRU) elements are all
fissionable, and thus can be considered as fissile fuel materials in form of mixed fuel with thorium or nat uranium in the latter. CANDU fuel compacts made of tristructural-isotropic (TRISO) type pellets would
withstand very high burn ups without fuel change.
As carbide fuels allow higher fissile material density than oxide fuels, following fuel compositions have
been selected for investigations: ① 90% nat-UC þ 10% TRUC, ② 70% nat-UC þ 30% TRUC and ③ 50% nat UC þ 50% TRUC. Higher TRUC charge leads to longer power plant operation periods without fuel change.
The behavior of the criticality kN and the burn up values of the reactor have been pursued by full power
operation for > w12 years. For these selected fuel compositions, the reactor criticality starts by
kN ¼ 1.4443, 1.4872 and 1.5238, where corresponding reactor operation times and burn up values have
been calculated as 2.8 years, 8 years and 12.5 years, and 62, 430 MW.D/MT, 176,000 and 280,000 MW.D/
MT, with fuel consumption rates of w16, 5.68 and 3.57 g/MW.D respectively. These high burn ups would
reduce the nuclear waste mass per unit energy output drastically. The study has show clearly that TRU in
form of TRISO fuel pellets will provide sufficient criticality as well as reasonable burn up for CANDU
reactors in order to justify their consideration as alternative fuel.
Description
Keywords
energy systems engineering