NEUTRON FLUX AND Cd RATIO MEASUREMENTS IN THE HN-1 BEAM HOLE FOR THREE FUEL LOADINGS OF THE OAK RIDGE RESEARCH REACTOR

Neutron flux measurements were made in the Oak Ridge Research Reactor beam hole HN-l shield plug. at low reactor power (N/sub L/) with three fuel configurations. The purpose of these tests was to determine the most favorable fuel arrangement in the region of the experimental hole in order to permit minimization of exposure time of an in-pile slurry loop experiment using pure thoria. It was found that the perturbed thermal neutron flux decreased by factors of 2, each 1.4 in., at the forward end of the beam hole. Maximum and average fluxes observed for three fuel configurations were: high, 9.7 x l0/sup 13/ , 5.6 x 10/sup 13/; intermediate, 8.0 x 10/sup 13/, 4.7 x l0/sup 13/; and present operating, 7.4 x l0/sup 13/, 3.8 x 10/sup 13/. In the high and intermediate configurations fuel elements were located in the outer row of the lattice adjacent to the beam hole. Cadmium ratios were generally high (22 to 111) implying low available epi-cadmium flux under any of these configurations. (auth