Tritium production in a sphere of /sup 6/LiD irradiated by 14-MeV neutrons

Abstract

The specific production of tritium in samples of s LiH and 7 LiH embedded in a 600-mm-diam sphere of "LiD irradiated by a central source of 14-MeV neutrons has been determined by measuring the activity of the hydrogen evolved from the samples of each isotope at each of five different radii in the "LiD assembly. The entire process of decomposing the LiH, transferring the evolved gas into counters, and determining the decay rate was standardized by processing LiH samples irradiated by thermal neutrons for which the *Li(n,a) cross section is well known. The specific production of tritium in °LiH and 7 LiH (embedded samples) and the activation of radiochemical detector foils of "Sc, "Y, M Zr, "Tm, l91 Ir 373 1M Ir."", ""Au, a ' B U, and aM U placed at various positions in the «LiD sphere have been calculated and compared with the experimental data. Oneand three-dimensional Monte Carlo and S n neutron-transport calculations were performed. The most reliable (three-dimensional Monte Carlo) calculation is in reasonable agreement with both the tritium-production and the radiochemical-activation data, The existing discrepancies between calculation and experiment appear largely attributable to uncertainties in some tritium-production and radiochemical-activation cross sections.

Evaluated Iridium, Yttrium, and Thulium Cross Sections and Integral Validation Against Critical Assembly and Bethe Sphere Measurements

“…Here, for simplicity, we refer to both types of experiment as "Bethe spheres", Bethe providing the better name recognition! Results from these 1970s experiments, together with results from simulations, have been published previously in internal Los Alamos reports [10][11][12][13][14][15][16][17] and in a journal publication [18]. The experiments involved a 30-cm Lithium-6 Deuteride (LiD) sphere surrounding a target chamber where deuterons impinged on a tritium target creating 3.8x10 15 14 MeV source neutrons at the center [19].…”