The temperature coefficient of reactivity at the plant operating temperature was --1.92 DELTA K/ DELTA T x 10/sup -//sup 4/, as obtained from the curve of the temperature coefficient plotted as a function of the temperature. (B.O.G.)

An investigation was conducted to determine the feasibility of using an NaK free-convection-cooled shaft freeze seal on the SRE main sodium pumps. The use of sodium in this application instead of tetralin eliminates the carburization hazard present should the seal coolant-(tetralin) leak into the sodium system. Results and recommendations are included. (J.R.D.)

The reactivity accounting and calculating techniques currently used in operational physics work are almost entirely based upon the flux squared weighting theorem. This theorem has some very serious limitations as the flattening of the reactors is increased. As a consequence many of the calculating techniques and results are theoretically unsound. Unexplainable discrepancies from pile to pile, and in reactivity data compared to original startup data and lattice physics measurements have been noted in the past. This report describes a method of reactivity evaluation based upon a one-group diffusion theory and a multi-region cylindrical geometry approximation. Results are presented which indicate that the methods outlined provide satisfactory accuracy. It is recommended that the methods outlined be adopted for routine reactivity evaluations as soon as the necessary machine computations have been made and standard procedures have been developed. Specific recommendations and results will be published as supplements to this report as soon as data are available.