Self-Shielding Experiments with Gaseous and Solid B-10

The relative reactivity worth of several B¹⁰F₃ gaseous coupons has been determined at pressures up to 4.2 atmospheres. These worth values are compared with equivalent B¹⁰ loading as B₄C dispersed (100 mesh or less) in stainless steel. Gaseous boron is more than five times as effective as the dispersed boron due to particle self-shielding. Bulk self-shielding becomes important only at high concentrations. The gaseous coupons are also compared with two alloy coupons (normal B¹⁰ and enriched B¹⁰).