Abstract: An analysis of SM-1 Core II and SM-1A Core I zero power experiments was made by comparing these cores to each other and to AM-1 Core I on the basis of critical bank positions, bank calibrations and available chemical analyses of the fuel plate compositions. The effects of replacing boron absorbers by europium absorbers upon rod worth and stuck rod conditions were studied. Comparisons of measured and calculated power distributions were made. It was concluded that both SM-1 Core II and SM-1A Core I contain nearly identical B-10 loading of 17.79 grams, compared to the best estimate of 15.75 grams for SM-1 Core I. The available data indicates that all three cores possess similar nuclear characteristics.

Abstract: A zero power experiment on the SM-1 Core II included an element by element reactivity check of fuel elements and control rod absorber sections, and an estimate of burnable nuclear poison loading in stationary fuel elements. An approach to criticality was made by the inverse multiplication method, and critical rod bank position obtained as a function fuel loading up to full core loading. Minimum and maximum core reactivity measurements were obtained by selective loading of stationary fuel elements, and total excess K of the core was established. Power distribution measurements were taken in the regions of the core-reflector interface and the fuel-absorber interface in the control rod assemblies. The effectiveness of europium flux suppressors in the top of control rod fuel elements was determined, and power peaking was measured in stationary elements adjacent to control rod assembly water gaps. Survey measurements established the work of spiking clean, cold SM-1 cores with SM-2 elements and the work of water holes in the SM-1 Core. The reduced scope zero power experiment performed on SM-1A core I included an element by element uniformity check of stationary fuel elements, a core assembly test, comparison of Eu2O3 and B4C absorber sections, and development of …