A SIMPLE METHOD OF DETERMINING THE EFFECT OF REACTOR TEMPERATURE ON CRITICALITY CONDITIONS
RAND CORP SANTA MONICA CA
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As part of a series of studies designed to simplify reactor analysis for use in engineering evaluations, an analysis is made of the effect of reactor temperature on criticality conditions, and simple relations are obtained for calculating these effects. The buckling and hence reactor size for criticality may be expressed as a function of the fission, capture, and scatter cross sections of the reactor materials averaged over the flux spectrum. If these parameter averages are known for one reactor temperature, then the simple relations derived in this study allow computation for other reactor temperatures. A substantial simplification of the analysis results from the assumption that the major part of the influence of reactor temperature comes from the changes in the cross sections and in the values of the flux distribution in the vicinity of thermal energy. Good agreement is obtained between the values computed from the equations and the values obtained from an 18-group machine calculation performed for a series of reactors covering a temperature range from 25 C to 1450 C.
- Fission Reactor Physics