The Carborundum Company

Kennecott Corporation

Robert G Naum

Carl H McMurtry

Dean P Owens

Michael T Hortman

Paul F Forsyth

George I Dooher

A composite, neutron absorbing, coated article, normally flat and thin and of comparatively light weight, suitable for installation in storage racks for spent nuclear fuel and for other neutron absorbing applications, includes a backing member, preferably of flexible material such as woven fiberglass cloth, a synthetic organic polymeric coating or a plurality of such coatings on the backing member, preferably of cured phenolic resin, such as phenol formaldehyde or trimethylolphenol formaldehyde and boron carbide particles held to the backing member by the cured coating or a plurality of such coatings. Also described is a method for the manufacture of the neutron absorbing coated article and the use of such an article. In a preferred method the backing member is first coated on both sides thereof with a filling coating of thermosettable liquid phenolic resin, which is then partially cured to solid state, one side of the backing member is then coated with a mixture of thermosettable liquid resin and finely divided boron carbide particles and the resin is partially cured to solid state, the other side is coated with a similar mixture, larger boron carbide particles are applied to it and the resin is partially cured to solid state, such side of the article is coated with thermosettable liquid phenolic resin, the resin is partially cured to solid state and such resin, including previously applied partially cured resins, is cured to final cross-linked and permanently set form.

Method for manufacture of neutron absorbing article

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. In another aspect of the invention the plurality of flat neutron absorbing articles may be joined together by contacting surfaces thereof with such a coating material, preferably containing boron carbide particles, and curing it.

Method for increasing boron.sup.10 contents of neutron absorbing articles

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. The described structures possess a multiplicity of desirable properties for the use mentioned, including withstanding thermal cycling from repeated spent fuel insertions and removals, withstanding radiation from said spent nuclear fuel over long periods of time without losing desirable neutron absorbing and physical properties, being sufficiently chemically inert to water so as to retain neutron absorbing properties if brought into contact with it, not being galvanically corroding and being sufficiently flexible so as to withstand operational basis earthquake and safe shutdown earthquake seismic events without loss of neutron absorbing capability and other desirable properties when installed in storage racks for spent nuclear fuel. In preferred embodiments of the invention the phenolic polymer is a phenol formaldehyde type polymer, such as a trimethylol phenol formaldehyde type polymer, the boron carbide contains at least 12% of B.sup.10, the plate contains from 8.0 to 11.5% thereof, the plate density is 1.6 to 2.1 g./cc. and the proportions of boron carbide (which may be accompanied by limited amounts of certain impurities) and phenol formaldehyde type polymer (preferably free of halogens, mercury, lead and sulfur) are from 20 to 35% of the former and 65 to 80% of the latter. The invention also relates to a plurality of such neutron absorbing articles in a storage rack for spent nuclear fuel and to a method for the manufacture of the articles. In the manufacturing method a portion of the phenol formaldehyde type resin, in liquid state, is mixed with the boron carbide particles, compacted and cured, after which the cured article is impregnated with additional phenol formaldehyde type resin, which is then cured to make the final product.

Method for manufacturing neutron absorbing article

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. The described articles withstand thermal cycling from repeated spent fuel insertions and removals, withstand radiation from said spent nuclear fuel over long periods of time without losing desirable neutron absorbing and physical properties, are sufficiently chemically inert to water so as to retain neutron absorbing properties if brought into contact with it, are not galvanically corrodible and are sufficiently flexible so as to withstand operational basis earthquake and safe shutdown earthquake seismic events, without loss of neutron absorbing capability and other desirable properties, when installed in storage racks for spent nuclear fuel. The disclosure also relates to a plurality of such neutron absorbing articles in a storage rack for spent nuclear fuel and to a method for the manufacture of the articles.

Neutron absorbing article and method for manufacture of such article

A composite, neutron absorbing, coated article, suitable for installation in storage racks for spent nuclear fuel and for other neutron absorbing applications, includes a backing member, preferably of flexible material such as woven fiberglass cloth, a synthetic organic polymeric coating or a plurality of such coatings on the backing member, preferably of cured phenolic resin, such as phenol formaldehyde or trimethylolphenol formaldehyde and boron carbide particles held to the backing member by the cured coating or a plurality of such coatings. Also within the invention is a method for the manufacture of the neutron absorbing coated article and the use of such an article. In a preferred method the backing member is first coated on both sides thereof with a filling coating of thermosettable liquid phenolic resin, which is then partially cured to solid state, one side of the backing member is then coated with a mixture of thermosettable liquid resin and finely divided boron carbide particles and the resin is partially cured to solid state, the other side is coated with a similar mixture, larger boron carbide particles are applied to it and the resin is partially cured to solid state, such side of the article is coated with thermosettable liquid phenolic resin, the resin is partially cured to solid state and such resin, including previously applied partially cured resins, is cured to final cross-linked and permanently set form.

Neutron absorbing article and method for manufacture thereof

A neutron absorbing article, preferably in flat plate form and suitable for use in a storage rack for spent nuclear fuel, includes boron carbide particles, diluent particles and a solid, irreversibly cured phenolic polymer cured to a continuous matrix binding the boron carbide and diluent particles. The total content of boron carbide and diluent particles is a major proportion of the article and the content of cured phenolic polymer present is a minor proportion. By regulation of the ratio of boron carbide particles to diluent particles, normally within the range of 1:9 and 9:1 and preferably within the range of 1:5 to 5:1, the neutron absorbing activity of the product may be controlled, which facilitates the manufacture of articles of particular absorbing activities best suitable for specific applications.

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Lewiston, NY, United States of America

Robert G Naum