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DOE issues new NEPA rule and procedures—and accelerates DOME reactor testing
Meeting a deadline set in President Trump’s May 23 executive order “Reforming Nuclear Reactor Testing at the Department of Energy,” the DOE on June 30 updated information on its National Environmental Policy Act (NEPA) rulemaking and implementation procedures and published on its website an interim final rule that rescinds existing regulations alongside new implementing procedures.
Masayuki Nakagawa, Hideaki Inoue
Nuclear Science and Engineering | Volume 83 | Number 2 | February 1983 | Pages 214-228
Technical Paper | doi.org/10.13182/NSE83-A18215
Articles are hosted by Taylor and Francis Online.
The double heterogeneity effect due to the fuel pin and the subassembly is estimated for neutronics parameters of a prototype fast power reactor. Both of the heterogeneity effects caused by the flux fine structure and the resonance shielding are taken into account. The model of the hexagonal unit subassembly consists of the smeared fuel, the wrapper tube, and the outer sodium regions, where the average cross sections of the smeared fuel region are obtained by a unit pin cell calculation in cylindrical geometry. It is shown that the equivalent smeared model agrees well with the refined cluster model. A formula to define the background cross section of the fuel isotopes is derived based on the rational approximation, and its accuracy is examined. This formula can take into account the contribution from the wrapper tube to the background cross sections of each ring of fuel pin array. The heterogeneity effect of the whole reactor model is calculated based on two-dimensional diffusion theory and perturbation theory. The double heterogeneity effect is found to be 0.5%Δk for keff, the positive sodium-void worth is reduced by 26%, and the negative Doppler reactivity increases by 7% for a prototype fast breeder reactor. These results are considerably larger than the estimates made by earlier workers. These effects are significant from the viewpoint of target accuracy goals in fast power reactor design.