Measurement and Analysis of Thermal Disadvantage Factor for UO<SUB>2</SUB>-H<SUB>2</SUB>O Lattices
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概要
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Dy-activation disadvantage factors for seven UO<SUB>2</SUB>-H<SUB>2</SUB>O lattices were measured and compared with the results calculated by AMOUYAL, THERMOS and GRAFA codes. The experimental value does not decrease monotonically with decrease of the volume ratio, and GRAFA gives results in good agreement with these experimental values. In order to further examine these results, one of the thermal neutron spectrum parameters, the Lu-Cu activation ratio, which also was measured in another experiment, was compared with the calculated results.<BR>Thermal neutron spectra of the individual regions in a lattice calculated by various current computations are softer than those determined by experiment. These differences are particularly large in the moderator regions.<BR>It is shown that the two dimensional multi-group collision probability model calculated by GRAFA gives results in good agreement with experimental values for the disadvantage factor, and that the cylindrical cell approximation with isotropic or reflecting boundary condition gives poor results in closely packed lattices.
- 一般社団法人 日本原子力学会の論文