Nuclear Science and Engineering / Volume 35 / Number 3 / March 1969 / Pages 358-363
Technical Paper / dx.doi.org/10.13182/NSE69-A20014
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Exponential and critical approach experiments have been performed to determine material buddings and extrapolation distances for several hexagonal lattice arrays of 2.1 wt% 235U enriched uranium tubes in light water. Tubes of two sizes were measured—2.33-in. o.d., 1.77-in. i.d.; and 1.38-in. o.d., 0.63-in. i.d. The arrays included clean lattices of uranium tubes; uranium tubes containing lithium aluminate target rods; uranium tubes with adjacent neutron absorbing columns; and two mixed lattices of 0.95 and 2.1 wt% enriched tubes—one with the 0.95 and 2.1 wt% tubes evenly distributed in the lattice, and the other with the 0.95 and 2.1 wt% tubes arranged in alternate rings. These experiments supplement data obtained in 1965 for 1.002, 1.25, and 1.95 wt% enriched uranium tubes. Critical parameters for these lattices, calculated with the HAMMER code, agree reasonably well with the measured results.