Experimental studies of UO2-H2O uniform lattices

An experimental technique to evaluate models for lattice calculation by measuring what is known as micro parameters is presented. It is shown that a generalized four-factor formula expressed in terms of the microparameters could successfully evaluate sources of discrepancy between measurement and calculation in regard to gross quantities, such as critical mass and multiplication factor. Lattices studied are of U02, enriched in 235U to 2.5 and 1.5w/o, with water-to-fuel volume ratio ranging from 0.43 to 3.5. Detailed description is given on the measurement of the microparameters in epithermal and fast energy regions. Analysis of the results has been made mostly with the JUPITER (modified MUFT)-THERMOS-SUNRISE (diffusion) code system. A new experimental approach for directly measuring the non-leakage probability is also presented. The multiplication factor obtained by this method is compared with that derived from the microparameters. The resulting good consistency supports the validity of both of these experimental techniques.