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NRC proposes changes to its rules on nuclear materials
In response to Executive Order 14300, “Ordering the Reform of the Nuclear Regulatory Commission,” the NRC is proposing sweeping changes to its rules governing the use of nuclear materials that are widely used in industry, medicine, and research. The changes would amend NRC regulations for the licensing of nuclear byproduct material, some source material, and some special nuclear material.
As published in the May 18 Federal Register, the NRC is seeking public comment on this proposed rule and draft interim guidance until July 2.
E. C. Miller, J. K. Mattingly, S. D. Clarke, C. J. Solomon, B. Dennis, A. Meldrum, S. A. Pozzi
Nuclear Science and Engineering | Volume 176 | Number 2 | February 2014 | Pages 167-185
Technical Paper | doi.org/10.13182/NSE12-53
Articles are hosted by Taylor and Francis Online.
Simulations of neutron multiplicity measurements of a highly multiplicative plutonium sphere measured with a moderated array of 3He proportional counters have consistently overpredicted the mean and variance of the measured multiplicity distribution. In contrast, identical experiments using a 252Cf source have been accurately simulated. This paper outlines a sensitivity analysis of several key parameters that could account for the overprediction in the simulation of the plutonium sphere. Parameters that were analyzed include source-detector distance, detector dead time, variations in density and volume of the plutonium, and the value of for v̅ 239Pu-induced fission. Of these parameters, the only factor that accounted for the overprediction within reasonable bounds was a change in the value of the 239Pu v̅. The sensitivity analysis showed that a small change (1.14% reduction) in the value of v̅ dramatically improved the simulated results.
