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Members are devoted to applying nuclear science and engineering technologies involving isotopes, radiation applications, and associated equipment in scientific research, development, and industrial processes. Their interests lie primarily in education, industrial uses, biology, medicine, and health physics. Division committees include Analytical Applications of Isotopes and Radiation, Biology and Medicine, Radiation Applications, Radiation Sources and Detection, and Thermal Power Sources.
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Las Vegas, NV|Mandalay Bay Resort and Casino
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College students help develop waste-measuring device at Hanford
A partnership between Washington River Protection Solutions (WRPS) and Washington State University has resulted in the development of a device to measure radioactive and chemical tank waste at the Hanford Site. WRPS is the contractor at Hanford for the Department of Energy’s Office of Environmental Management.
John F. Carew, Kai Hu
Nuclear Science and Engineering | Volume 152 | Number 3 | March 2006 | Pages 256-273
Technical Paper | doi.org/10.13182/NSE06-A2580
Articles are hosted by Taylor and Francis Online.
The changes in the energy dependence of the neutron removal cross section at the vessel inner wall water/steel interface produce a substantial shift in the neutron spectrum as the fluence propagates into the pressure vessel. To account for this spectral shift, Regulatory Guide 1.99, Revision 2 requires that the fluence used in determining the reference temperature for nil-ductility transition RTNDT be extrapolated from the pressure vessel inner surface using the displacements per atom (dpa).The strong azimuthal and axial variation of the fluence at the vessel inner wall results in a substantial redistribution of the fluence as it propagates through the vessel due to transverse neutron leakage (i.e., perpendicular to the radial direction through the vessel). This transverse leakage tends to increase the dpa radial attenuation in regions of high fluence and reduce the attenuation in regions of low fluence.A series of pressure vessel fluence calculations has been carried out to determine the effect of (a) the transverse neutron leakage and (b) the plant-specific reactor design configuration on the radial attenuation of the dpa through the vessel. The calculations were performed for four operating pressurized water reactors and were carried out using the methods described in U.S. Nuclear Regulatory Commission Regulatory Guide 1.190. The calculations were performed with the DORT discrete ordinates transport code using ENDF/B-VI neutron transport and dpa cross sections.The transverse leakage is found to introduce a substantial variation of the dpa attenuation rate over the inner surface of the vessel. In the belt-line region opposite the core, the transverse leakage results in an ~6 to 14% azimuthal variation and an ~3 to 11% axial variation in the dpa at a 15-cm depth into the vessel, depending on the plant configuration.In order to simplify the determination of RTNDT in probabilistic fracture mechanics analyses, conservative belt-line and reflector region dpa attenuation rates have been determined. Plant-specific analytic expressions for the radial dependence of the dpa through the vessel have also been determined.