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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.
Mohamed Sawan, Robert W. Conn
Nuclear Science and Engineering | Volume 54 | Number 2 | June 1974 | Pages 127-142
Technical Paper | doi.org/10.13182/NSE74-A23401
Articles are hosted by Taylor and Francis Online.
Methods for the analysis of neutron pulses slowing down in heavy media are presented. The Green’s function coupling method is reviewed and the application of a prompt-jump approximation to pulses slowing down in heavy media is discussed. In this paper, these methods are applied in particular to the analysis of the lead slowing down time spectrometer (LSDTS) and the application of this device to nondestructive fissile material assay (NDA). The effects of pulse width, spectrometer size, higher order spatial modes, and lead cross-section data on the calibration curve (t versus 1/√E, the dieaway curve N(t) versus t, and the time-dependent spectrum of the LSDTS are reported. For NDA, the assay of fresh light-water reactor (LWR), plutonium recycle, and fast reactor fuel pins, as well as spent LWR fuel pins, is studied. The effects of self shielding and pulse width on the discrimination capability of the LSDTS are assessed. Two energy ranges (27.6 to 43.6 eV and 10.3 to 16.3 eV) are proposed for the assay of mixed-oxide fuel where discrimination between 235U and 239Pu is required. An error analysis of NDA with lead spectrometers that includes the calibration surfaces which occur in the assay of mixed-oxide fuel pins is given.
