INTERIM REPORT ON THE USE OF SM-2 ELEMENTS IN SM-1, SM-1A AND PM-2A CORES

Interim results of analytical investigation of nuclear and thermal characteristics of SM-2 type fuel elements in SM-1, SM-lA, and PM-2Ae reactor cores are reported. Utilizing modified two-proup diffusion theory, predictions of power distribution and core and rod reactivity were performed. The calculations indicate that use of SM-2 fuel elemente in SM-1, SM-lA, and PM-2A is feasible from the nuclear standpoint. A steady state thermal analysis of each plant utilizing SM-2 elements was carried out. This analysis showed that the minimum departure from nuclear boiling ratios were considerably abovs the minimum value ftom the design criteria standpoint at both the operating and scram power levels. The investigation indicated that SM-2 elements can successfully be employed in SM-1, SM-lA, and PM-2A as replacement core elements. (auth

FLUX AND POWER DISTRIBUTIONS FOR THE SM-2 REFERENCE AND CRITICAL EXPERIMENT CORES

A detailed analysis was made of the power distributions in the SM-2 experimental core at 68 deg F and the SM-2 reference core at 510 deg F. This analysis supersedes the power distribution calculations presented in APAE No. 69. The calculated distributions for the experimental core were normalized to measured data wherever possible in order to obtain corrections factors for application to the reference core. The over-all power distributions were calculated by synthesis of one-dimensional axial calculations with twodimensional radial calculations. The variation of the power distribution with fuel burnup is also presented. In order to improve the agreement between measured and calculated axial power distributions, flux-weighting the nuclear parameters in the rods-in and rods-out regions was investigated. (auth