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TODOROVA, Galina*; Nishi, Hiroshi*; Ishibashi, Junichi;
Journal of Nuclear Science and Technology, 41(12), p.1237 - 1244, 2004/12
Times Cited Count：3In order to reduce the ezisting energy-group collapsing effect in the few-group results for the effective multiplication factor; a new algorithm for condensation of the macroscopic transport XS has been proposed and verified. This work presents the definition of the new collapsing algorithm, the results from the verification tests and a short discussion from the viewpoint of the consistency of the algorithm with the specific finite-difference method of the code NSHEX. According ti the presented results, the new collapsing algorithm can be recommended for condensation of the transport XS from 70 into few enerfy-group structures.
Galina Todorova; Nishi, Hiroshi*; Ishibashi, Junichi
Saikuru Kiko Giho, (22), p.1 - 10, 2004/00
FBR MONJU Initial Critical Core (ICC) criticality problem has been solved by deterministic and Monte Carlo transport methods by the codes NSHEX and GMVP. The analysis has been carried out in different energy-groups approximations. As a result the effect of cross-section (XS) condensation from 70 into few energy-group structures by different collapsing methods has been evaluated. The 3D discrete-ordinate code NSHEX has been applied for wide range of core simulations-from whole core, considering the fissile, fertile and shielding regions to simplified models that simulate an increased neutron leakage. It has been found that there is room for improvement in the assessment of the neutron leakage in the few energy-group approximations. The good agreement between NSHEX and GMVP results, especially without XS collapsing, is pointed out as a conformation for the applicability of the code NSHEX in FBR 3D whole core calculations. Some practical conclusions have been extracted that are important
