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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.
I. Pázsit, A. Jonsson
Nuclear Science and Engineering | Volume 167 | Number 1 | January 2011 | Pages 61-76
Technical Paper | doi.org/10.13182/NSE10-15
Articles are hosted by Taylor and Francis Online.
The dynamic space- and frequency-dependent response of a molten salt reactor (MSR) to stationary perturbations is investigated in a simple analytical model. The Green's function of the system is investigated in the general case of arbitrary fuel recirculation velocity and in the limiting case of infinite fuel velocity, which permits closed-form solutions in both the static and dynamic cases. It is found that the amplitude of the induced noise is generally higher and the domain of the point kinetic behavior valid up to higher frequencies than in a corresponding traditional system. This is due to the differing behavior of the delayed neutron precursors as compared to the traditional case. The MSR equations are not self-adjoint and the adjoint equation and adjoint function have to be constructed, which is also done here. Finally, the space-dependent neutron noise, induced by propagating perturbations of the absorption cross section, is calculated. A number of interesting properties that are relevant to full-size MSRs are found and interpreted. The results are consistent with those in traditional systems, but the domains of various behavior regimes (point kinetic, space dependent, etc.) are shifted to higher frequencies or system sizes.