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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.
O. K. Harling, K. J. Riley, T. H. Newton, B. A. Wilson, J. A. Bernard, L-W. Hu, E. J. Fonteneau, P. T. Menadier, S. J. Ali, B. Sutharshan, G. E. Kohse, Y. Ostrovsky, P. W. Stahle, P. J. Binns, W. S. Kiger III, P. M. Busse
Nuclear Science and Engineering | Volume 140 | Number 3 | March 2002 | Pages 223-240
Technical Paper | doi.org/10.13182/NSE02-A2258
Articles are hosted by Taylor and Francis Online.
A new type of epithermal neutron irradiation facility for use in neutron capture therapy has been designed, constructed, and put into operation at the Massachusetts Institute of Technology Research Reactor (MITR). A fission converter, using plate-type fuel and driven by the MITR, is used as the source of neutrons. After partial moderation and filtration of the fission neutrons, a high-intensity forward directed beam is available with epithermal neutron flux [approximately equal to]1010 n/cm2s, 1 eV E 10 keV, at the entrance to the medical irradiation room, and epithermal neutron flux = 3 to 5 × 109 n/cm2s at the end of the patient collimator. This is currently the highest-intensity epithermal neutron beam. Furthermore, the system is designed and licensed to operate at three times higher power and flux should this be desired. Beam contamination from unwanted fast neutrons and gamma rays in the aluminum, polytetrafluoroethylene, cadmium and lead-filtered beam is negligible with a specific fast neutron and gamma dose, D,fn/epi [less than or approximately equal] 2 × 10-13 Gy cm2/nepi. With a currently approved neutron capture compound, boronophenylalanine, the therapeutically advantageous depth of penetration is >9 cm for a unilateral beam placement. Single fraction irradiations to tolerance can be completed in 5 to 10 min. An irradiation control system based on beam monitors and redundant, high-reliability programmable logic controllers is used to control the three beam shutters and to ensure that the prescribed neutron fluence is accurately delivered to the patient. A patient collimator with variable beam sizes facilitates patient irradiations in any desired orientation. A shielded medical room with a large window provides direct viewing of the patient, as well as remote viewing by television. Rapid access through a shielded and automatically operated door is provided. The D2O cooling system for the fuel has been conservatively designed with excess capacity and is fully instrumented to ensure detection and control of off-normal conditions. A wide range of possible abnormal events or accident scenarios has been analyzed to show that even in the worst cases, there should be no fission product release through fuel damage. This facility has been licensed to operate by the U.S. Nuclear Regulatory Commission, and initial operation commenced in June 2000.
