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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.
Delgersaikhan Tuya, Hiroki Takezawa, Toru Obara
Nuclear Science and Engineering | Volume 188 | Number 1 | October 2017 | Pages 33-42
Technical Paper | doi.org/10.1080/00295639.2017.1337383
Articles are hosted by Taylor and Francis Online.
An approach to multiregion supercritical transient analysis based on the integral kinetic model (IKM) and Monte Carlo method is further developed with new features. The IKM describes the region-dependent fission rate during the transient in a system of arbitrary geometry using a secondary fission probability density function, which takes the explicit neutron transport time between successive fissions across the regions into account. The new features of the improved approach include treatment of the multiregion transient using repeated multidimensional linear interpolation between pre-obtained kinetic functions (i.e., secondary probability density function), a new method for calculating the kinetic functions using the continuous-energy Monte Carlo code MVP2.0, and utilization of kinetic functions directly in the IKM without the fitting function that introduces a fitting error. The improved approach is verified by applying it to the supercritical transient in simple Godiva systems of different region combinations without feedback. In addition, we attempt to validate the improved approach by applying it to the supercritical transient in a simplified Godiva system with thermal expansion feedback and compare the obtained and experimental results. The verification results indicate the improved approach works well with different combinations of regions while the validation results show promising agreement with the experimental results. This study is part of an ongoing research activity on the development of Multi-region Integral Kinetic (MIK) code for general space- and time-dependent kinetic analyses.
