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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.
Hiroki Sono, Hiroshi Yanagisawa, Akio Ohno, Takuji Kojima, Noboru Soramasu
Nuclear Science and Engineering | Volume 139 | Number 2 | October 2001 | Pages 209-220
Technical Paper | doi.org/10.13182/NSE01-A2232
Articles are hosted by Taylor and Francis Online.
To evaluate neutron and gamma-ray absorbed doses in human bodies at criticality accidents, two kinds of tissue-equivalent dosimeters, a polymer-alanine dosimeter and a thermoluminescent dosimeter (TLD) made of 7Li211B4O7, were applied to dosimetry experiments with ~10% enriched uranyl nitrate solution at the Transient Experiment Critical Facility (TRACY) in the Japan Atomic Energy Research Institute. For the experiments, five transient operations were conducted to simulate criticality accidents by varying the conditions of reactivity addition. Very high doses from both neutrons and gamma rays were successfully measured in the range of 1.5 to 1600 Gy by using polymer-alanine dosimeters. The gamma-ray doses were able to be determined in the range of 1 to 900 Gy by using 7Li211B4O7 TLDs. In addition, it is confirmed that the doses are proportional to integrated power during transient operations although the conditions of reactivity addition are different. Since the sensitivity of 7Li211B4O7 to gamma rays is almost the same as that of alanine, the neutron doses are easily evaluated without any complicated correction by subtracting the gamma-ray doses obtained by the 7Li211B4O7 TLDs from the sum of neutron and gamma-ray doses by the polymer-alanine dosimeters. As a result of computational analyses by the MCNP4B code, it is also found that calculated doses agree with measured ones within 95% confidence intervals and the MCNP4B is applicable to the evaluation of neutron and gamma-ray absorbed doses during the transient.
