Abstract: A method for increasing the boron.sup.10 content of a neutron absorbing article, such as one in flat, flexible sheet shape, includes coating a surface of such article with a solidifiable liquid synthetic organic polymeric material, such as a phenol formaldehyde type resin, applying boron carbide particles to the polymeric material and solidifying the polymer, such as by curing to cross-linked permanently set form, so as to hold the neutron absorbing boron carbide particles in place thereon. In highly preferred embodiments of the invention the boron carbide particles applied will extend beyond the surface of the external material and will serve as anchoring means for applications of subsequent coatings and the plurality of coatings, usually after initial partial curing to solidify them and make them form-retaining, will be permanently cross-linked simultaneously.

Abstract: A neutron absorbing article, preferably in long, thin, flat form, suitable for but not necessarily limited to use in storage racks for spent nuclear fuel at locations between volumes of such stored fuel to absorb neutrons from said spent fuel and prevent uncontrolled nuclear reaction of the spent fuel material, is composed of finely divided boron carbide particles and a solid, irreversibly cured phenolic polymer forming a continuous matrix about the boron carbide particles, in such proportions that at least 6% of B.sup.10 from the boron carbide content is present therein.

Abstract: A neutron absorbing article, preferably in long, thin, flat form, suitable for but not necessarily limited to use in storage racks for spent nuclear fuel at locations between volumes of such stored fuel, to absorb neutrons from said spent fuel and prevent uncontrolled nuclear reaction of the spent fuel material, is composed of finely divided boron carbide particles and a solid, irreversibly cured phenolic polymer, forming a continuous matrix about the boron carbide particles, in such proportions that at least 6% of B.sup.10 from the boron carbide content is present therein.