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Substitution measurements on 28-fuel-rod critical clusters in D/sub 2/O and their analysis by the second-order perturbation method

Journal Article · · Nucl. Sci. Eng.; (United States)
OSTI ID:5024043
Material bucklings have been determined as functions of /sup 235/U enrichment in UO/sub 2/ (0.7, 1.2, and 1.5 wt % /sup 235/U), PuO/sub 2/ enrichment in PuO/sub 2/-UO/sub 2/ (0.54 and 0.87 wt % PuO/sub 2/), fissile content of plutonium (91 and 75% Pu-fissile), lattice pitch (V/sub mod//V/sub fuel/: 7.4 and 9.9), and coolant void fraction. The reference loading of 1.2 wt % /sup 235/U-enriched UO/sub 2/ clusters was progressively replaced by the test clusters. Buckling differences resulting from the substitutions were analyzed by the new second-order (iterative) perturbation method, on the assumption that neutron diffusion is isotropic and that no difference in diffusion coefficients exists between the two lattices. This analysis takes into account the effect of distortion in radial neutron flux distribution in the substituted core without any iterative correction procedure that is usually adopted in the first-order perturbation method. Also, it is not necessary in the case of the present analysis to introduce any usual intermediate region for taking into account the effect of spectrum mismatch between two lattices. The material buckling differences between the test and reference lattices, which are in the range of -10.2 to 9.1 m/sup -2/, were determined within 3% of uncertainty.
Research Organization:
Power Reactor and Nuclear Fuel Development Corp., Ibaraki, Japan
OSTI ID:
5024043
Journal Information:
Nucl. Sci. Eng.; (United States), Journal Name: Nucl. Sci. Eng.; (United States) Vol. 65:3; ISSN NSENA
Country of Publication:
United States
Language:
English