Breeding of 242mAm in a Fast Reactor

Abstract

There is growing interest in the use of 242mAm as a nuclear fuel. Since the thermal absorption cross section of 242mAm is very high (σa = 8950 b), the best way to obtain 242mAm is by the capture of fast or epithermal neutrons in 241Am. As a result, we have considered replacing the radial blanket of a fast reactor, which is usually depleted uranium, with 241AmO2.We chose a 714-MW(thermal) MONJU reactor, and we replaced some of the radial blanket and the outer core assemblies with 10 676 kg of 241AmO2 fuel. We calculated the reactor core by using the MCNP Monte Carlo code.The total amount of 242mAm becomes stabilized after 16 yr, but the enrichment does not. In our calculation, ~7.2% enrichment is obtained after 18 yr. Obtaining higher enrichments might indicate that 242mAm nuclear fuel can be used without further enrichment in many cases.The results presented in this paper are considered an upper limit scenario. In particular the target 241Am loading is not likely to be available soon, but 242mAm production from lesser amounts is easily scaled down proportional to the actual mass irradiated.