A Detailed Reassessment of the Criticality Property of Pure241 Am

Abstract

We present results of new calculations of criticality of pure 241Am using several basic evaluated neutron-nuclear cross section databases. The re-assessment of the criticality property of 241Am presented in this paper is relevant to studies of criticality safety, nuclear waste incineration and non-proliferation. Our calculations start from the basic evaluated nuclear data files and use the NJOY-MCNP code system. This paper invalidates the earlier conclusion and belief in a section of the national and international literature that the minor actinide241 Am is better than 235U or 239Pu as a nuclear fuel. Further our calculated critical mass is larger by 28% than the 197kg reported in 1997 by Nojiri and Fukasaku who used the SCALE-4.3 system using the same ENDF/B-IV data, showing that there is large discrepancy due to the use of different computational codes and/or QA in nuclear data processing. Our calculated value of critical mass using JENDL-3.2 is 75kg. This result is essentially in agreement with Nojiri and Fukasaku who used the same JENDL-3.2 data and the then available version of the NJOY-MCNP systems.