It is aimed to provide a method for decontaminating radiocontaminated grains, the method improving a decontamination degree of radioactive .sup.134Cs and .sup.137Cs. The method for decontaminating radiocontaminated grains includes: a pre-treatment step of mixing radiocontaminated grains and a sodium phosphate-based dispersant; and a decontamination step of mixing the radiocontaminated grains processed by the pre-treatment step and paper sludge-derived sintered carbonized porous grains so as to incorporate radioactive .sup.134Cs and .sup.137Cs of the radiocontaminated grains in the sintered carbonized porous grains.

A supported membrane is provided comprising an inorganic, solid porous filtration membrane supported by an inorganic, solid porous support, said supported membrane comprising nanoparticles of a metal coordination polymer with CN ligands comprising M.sup.n+ cations, where M is a transition metal and n is 2 or 3; and Alk.sup.+.sub.y[M(CN).sub.m].sup.x? anions where Alk is an alkaline metal, y is 0, 1 or 2, M is a transition metal, x is 3 or 4, and m is 6 or 8; said M.sup.n+ cations of the coordination polymer being bound through an organometallic or coordination bond to an organic group of an organic graft chemically attached to the surface of the filtration membrane, inside the pores of the filtration membrane, and optionally inside the pores of the support. The supported membrane may be used in a process for separating at least one metal cation and solid particles from a liquid medium containing the same.

A composition to immobilize nuclear containing waste containing at least one radioactive element or alloy of uranium, graphite, magnesium, and aluminum is disclosed. The composition comprises at least one mineral phase forming element or compound for reacting with the at least one radioactive element or alloy. The composition further comprises at least one glass-forming element or compound to form a glass phase that will incorporate waste radioisotopes and impurities that do not react with the mineral phase forming element or compound. A method of using the disclosed composition to immobilize the nuclear containing waste into a solid wasteform is also disclosed.

Nuclear waste, such as, but not limited to, spent nuclear fuel (SNF) assemblies or portions thereof, are placed within diecast molds, and then gravity fed molding occurs within those loaded diecast molds and around the SNF assemblies (or portions thereof) that are located within those diecast molds, using molten alloy(s) for filling the diecast molds, to form solid metal ingots (castings) upon sufficient cooling of the newly formed ingots. The molten alloy(s) may contain a copper alloy. The molten alloy(s) may also contain neutron absorbers. Each such formed ingot may entirely encapsulate a SNF assembly (or a portion thereof) within the resolidified alloy(s). The ingots may be placed into waste capsules. The ingots and/or the waste capsules may be landed in deeply located horizontal wellbores. The deeply located horizontal wellbores may be at least partially located within deeply located geologic formations.

Nuclear waste, such as, but not limited to, spent nuclear fuel (SNF) assemblies (or portions thereof), are placed within diecast molds, and then gravity fed molding occurs within those loaded diecast molds and around and in the emplaced SNF assemblies (or portions thereof) that are located within those diecast molds, using molten alloy(s) for filling the diecast molds, to form solid metal castings upon sufficient cooling after the gravity fed operations. The molten alloy(s) may contain a copper alloy. The molten alloy(s) may also contain neutron absorbers. After the casting is formed, the casting is not separated from its diecast mold, as the diecasting mold and it's casting now form an integral unit. The integral units may be converted into waste capsules. The waste capsules may be landed in deeply located horizontal wellbores. The deeply located horizontal wellbores may be at least partially located within deeply located geologic formations.