FUSION REACTOR BLANKET EXPERIMENT.
Technical rept. (Doctoral thesis),
MASSACHUSETTS INST OF TECH CAMBRIDGE RESEARCH LAB OF ELECTRONICS
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The behavior of 1-14 Mev neutrons was measured in cylinders, 46 cm in diameter and 38 cm thick, to evaluate previous theoretical calculations on neutron economy and tritium production in proposed fusion reactor blankets. The cylinders were constructed from 0.5-inch graphite slabs and 1-inch layers of solid lithium-beryllium fluoride salt encased in aluminum pans. The neutron spectrum was measured with a series of threshold detectors U-238n, f, P-31n, p, Fe-56n, p, I-127n, 2n, and F-19n, 2n. The spectra in the graphite assemblies are characterized by a sharp peak near 14 Mev, with a smaller, broader peak at 3 Mev. Farther from the source, the 14-Mev peak is attenuated more than the 3-Mev peak. Adding 3-cm Mo to the base of the assembly shifts the 3-Mev peak to lower energies and increases its size at the expense of the 14Mev peak, because of the Mo-92n,2n reaction. Addition of the lithium-beryllium fluoride has no effect, because of the similarity in the scattering properties of the salt and the graphite. The removal of neutrons through the Li-6n, t reaction was not observed, because of the small size of the assembly and the low 1-3 isotopic content of Li-6 in the salt. Preliminary measurements indicate the feasibility of directly measuring the tritium produced in the assemblies by the Li-6n, t and Li-7n, tn reactions. Author