DESIGN OF A FAST BREED/BURN REACTOR CORE USING THE DETERMINISTIC CODE KANEXT

摘要

Fast breeder reactors are an interesting type of nuclear systems, due to, given the correct design conditions, they can generate more fissile fuel than they consume; nevertheless, in order for that breed fuel to be usable, it must be extracted from spent fuel an reprocessed before being used in the fabrication of new fuel. On the other hand, in a Breed/Burn reactor (B&B), bred plutonium is burned "in situ", inside the core, just after being bred; this reduce costs and fuel proliferation by simplifying the fuel cycle. In this work, we present a B&B reactor design consisting of 210 active fuel assemblies plus 7 spaces for control rod assemblies. This core differs from most of the B&B reactors in its design that include a blanket zone in the center of the core; this is to take advantage of the population of fast and epithermal neutrons in the center of geometry, due to the fissions in adjacent zones. A satisfactory fuel reshuffling scheme was found in which the reactor operated for about 38 years, about 10 years more of what would have operated without any reshuffling scheme. Regarding the tool for the full core calculations, KANEXT code was used. Since this is a deterministic code, hardware needs were easy to satisfy and computational time was suitable for this kind of trial and error repetitive fuel reshuffling tests.