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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.
C. R. Gould, A. I. Hawari, E. I. Sharapov
Nuclear Science and Engineering | Volume 165 | Number 2 | June 2010 | Pages 200-209
Technical Paper | doi.org/10.13182/NSE09-48
Articles are hosted by Taylor and Francis Online.
We revisit the determination by Bowman et al. of unusual neutron transport characteristics for a newly fabricated form of graphite [Nucl. Sci. Eng., 159, 182 (2008); Nucl. Sci. Eng., 161, 68 (2009)]. From MCNP modeling and consideration of data from other experiments, we determine revised values for the neutron transport parameters of this graphite. Our reanalysis gives a coherent scattering cross section coh ˜ 4 b at 50 meV, a small-angle neutron scattering cross section sans ˜ 11 to 13 b at 1 meV, and an effective capture cross section a = 5.8 ± 0.5 mb. Scaled to a graphite reference density of 1.60 g/cm3 , we find a diffusion coefficient [overbar D] = 0.94 ± 0.03 cm and a diffusion length L = 47.7 ± 3.7 cm. Apart from the somewhat larger values of a and [overbar D], these are not untypical parameters for graphite. Based on our investigation, the recent experiments and analysis of Bowman et al. do not give evidence for different transport properties for this newly fabricated graphite.
