Analyses of physics specimens in fuel pins 1 and 2 irradiated in the Dounreay Prototype Fast Reactor

The United States and the United Kingdom have been engaged in a joint research program in which samples of fissile and fertile actinides have been incorporated into three separate fuel pins and irradiated in the Dounreay Prototype Fast Reactor in Scotland. The actinides in the second fuel pin were studied for fission-product decay, specifically to obtain absolute yields of {sup 137}Cs. Comparisons with calculated yields result in ratios of measured to calculated between 0.67 ({plus_minus}0.05) and 1.09 ({plus_minus}0.18). Plotting of experimental versus calculated values of {sup 137}Cs indicated that the assumed flux levels were some 5 to 20% overestimated. This flux level information will be useful in the forthcoming analysis of the last fuel pin, FP-4.