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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.
Peter M. Song, Mahmoud Z. Youssef, Mohamed A. Abdou
Nuclear Science and Engineering | Volume 113 | Number 4 | April 1993 | Pages 339-366
Technical Paper | doi.org/10.13182/NSE93-A15333
Articles are hosted by Taylor and Francis Online.
A new approach for treating the sensitivity and uncertainty in the secondary energy distribution (SED) and the secondary angular distribution (SAD) has been developed, and the existing two-dimensional sensitivity/uncertainty analysis code, FORSS, was expanded to incorporate the new approach. The calculational algorithm was applied to the 9Be(n,2n) cross section to study the effect of the current uncertainties in the SED and SAD of neutrons emitted from this reaction on the prediction accuracy of the tritium production rate from 6Li (T6) and 7Li (T7) in an engineering-oriented fusion integral experiment of the U.S. Department of Energy/Japan Atomic Energy Research Institute Collaborative Program on Fusion Neutronics in which beryllium was used as a neutron multiplier. In addition, the analysis was extended to include the uncertainties in the integrated smooth cross sections of beryllium and other materials that constituted the test assembly used in the experiment. This comprehensive two-dimensional cross-section sensitivity/uncertainty analysis aimed at identifying the sources of discrepancies between calculated and measured values for T6 and T7. Without considering the uncertainties in the SED and SAD of the 9Be(n,2n) cross section, the uncertainties in T6 are ∼2 to 3% in the Li2O breeding zone, whereas they are ∼10% when the uncertainties in the SED and SAD are included. The contribution from the uncertainties in the SAD was small (∼1%) compared with the contribution from the uncertainties in the SED. As for T7, the uncertainties in the Li2O zone with and without considering the SED and SAD results are 4 to 7 and 2 to 5.5%, respectively. The estimated uncertainties in T6 and T7 could partly cover the observed discrepancies between calculations and measurements, although other sources have been identified. Although the approach followed to complete the uncertainty analysis is not standard because of the absence of an existing file that contains the uncertainty information in the SED and SAD of the 9Be(n,2n) reaction, the results obtained by introducing approximations to these data clearly demonstrate the importance of accounting for the uncertainties in the SED and SAD when a complete cross-section sensitivity/uncertainty analysis is to be performed.
