The accuracy with which the breeding ratio of HRE-3 could be determined after a period of reactor operation was investigated. Inaccuracies in measurement of the core U/sup 233/ inventory and blanket U/sup 233/ and Pa/sup 233/ inventories appear to be the major sources of error. Appreciable errors could result from attempting to determine these inventories by sampling the reactor contents. For example, if generalized attack on stainless steel is at a rate of 1.0 mpy and if the associated film of corrosion products is 1% uranium, failure to account for this fuel in evaluation of the core inventory would cause an error of about 5% in the breeding ratio. (auth)

An analysis of the temperature structure in the CCR-2 fuel elements and coolant stream at the position where the maximum fuel element surface temperature exists is presented. Results were obtained by numerical methods on the IBM 704 digital computer. The effect of variation in channel size is shown, and a method of data correlation is suggested. Preliminary conclusions are presented as to the effect of temperature structure on the design and testing of gas cooled reactor fuel element configurations. In view of the rate at which gas cooled reactor work is proceeding results of the calculations are being published in their current incomplete form. The study is continuing in an effort to refine the calculations, and experimental data will eventually be available with which to verify the analytical conclusions. (auth)

Program F/sub 3/ provides an anslysts of a three group, one-dimensionni reactor in multi-region slab or cylindrical geometry. Input consists of a description of the geometry of the assembly, energy group constants defining the nuclear characteristics of each region, and control information specifying the type of calculation desired. The fission density and neutron flux, computed at each lattice point, are used to calculate the reactivity of the system. (auth)

The reduction in HRE-3 breeding ratio resulting from neutron absorptions in the core-inlet line was examined for spherical and cylindrical cores; it was found to be less than 0.5% if the pipe does not extend more than 1/4 the way from the top to the bottom of the core. The power density at the end of the pipe would be 57 kw/l if it extended 5 in. into the sphere. (auth)