Metal alloy and metal alloy storage product for storing fast neutron emitters

Abstract

A liquid reactant metal alloy includes at least one chemically active metal for reacting with non-radioactive material in a mixed waste stream being treated. The reactant alloy also includes at least one radiation absorbing metal. Radioactive isotopes in the waste stream, including any fast neutron emitting isotopes alloy with, or disperse in, the chemically active metal and the radiation absorbing metals are able to absorb a significant portion of the radioactive emissions associated with the isotopes. A transmutation target fraction is included for absorbing fast neutrons and a transmutation emission absorbing fraction is provided for absorbing emissions that result from the absorption of a fast neutron by the transmutation target fraction. Non-radioactive constituents in the waste material are broken down into harmless and useful constituents, leaving the alloyed radioactive isotopes in the liquid reactant alloy. The reactant alloy may then be cooled to form one or more ingots in which the radioactive isotopes are effectively isolated and surrounded by the radiation absorbing metals. These ingots comprise the storage products for the radioactive isotopes.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. patent application Ser. No. 10 / 059,808, filed Jan. 29, 2002, entitled “METAL ALLOY AND METAL ALLOY STORAGE PRODUCT FOR STORING RADIOACTIVE MATERIALS,” which is a continuation-in-part of U.S. patent application Ser. No. 09 / 334,985, filed Jun. 17, 1999, and entitled “REACTANT METAL ALLOY TREATMENT PROCESS FOR RADIOACTIVE WASTE (as amended),” (now U.S. Pat. No. 6,355,857) which was a continuation-in-part of U.S. patent application Ser. No. 09 / 096,617, filed Jun. 12, 1998, entitled “REACTANT METAL ALLOY TREATMENT PROCESS AND STORAGE PRODUCT FOR RADIOACTIVE WASTE,” and also U.S. patent application Ser. No. 09 / 274,583, filed Mar. 23, 1999, entitled “HIGH TEMPERATURE MOLTEN METAL REACTOR AND WASTE TREATMENT PROCESS” (now U.S. Pat. No. 6,195,382). The Applicant claims the benefit of U.S. patent application Ser. Nos. 10 / 059,808, 09 / 334,985, 09 / 096,617 and 09 / 274,583 under 35 U.S.C. § 120. The entire con...

AI Technical Summary

Benefits of technology

[0014] Regardless of the particular composition of the chemically reactive fraction according to the invention, the metal alloy including the chemically reactive fraction is heated to a liquid state for receiving the waste stream. It is typically desirable to use the lowest metal alloy temperature necessary to react any non-radioactive constituents in the waste stream and to efficiently melt or dissolve the radioactive material into the alloy. For mixed wastes that include organic constituents, a metal alloy temperature of at least 770 degrees Celsius is generally required to quickly break the organic molecules down into the desired materials. Higher temperatures may be desirable to better dissolve or melt heavier radioactive isotopes such as transuranic elements.

[0017] In order to produce a mechanically stable ingot for long-term storage, the amount of radiation absorbing metal in the metal alloy is maintained at a particular minimum ratio to the number of radioactive isotopes in the resulting alloy or as a function of the corresponding expected radioactive emissions in the volume of the resulting alloy. The preferred ratio comprises no less than approximately seven hundred and twenty-seven (727) atoms of radiation absorbing metal to the corresponding radioactive emission. This ratio produces an alloy in which radioactive emissions may be absorbed by the radiation absorbing metals without significantly degrading the mechanical integrity of the ingot.

[0019] One advantage of the treatment process according to the invention is that it combines the separation of radioactive waste from non-radioactive wastes with the chemical treatment of non-radioactive wastes. Also, the ingots which result from the process are very stable. There is very little chance for release of the alloyed or otherwise dispersed radioactive isotopes from the ingots. Furthermore, radioactive emissions from the ingots are reduced by the radiation absorbing metals which are distributed throughout the matrix of the alloy along with the radioactive isotopes. The radiation absorbing metals also serve to prevent the radioactive emissions from adversely affecting the other metals in the ingots and prevent significant mechanical degradation in the alloy material.

Problems solved by technology

These mixed wastes which include radioactive and non-radioactive materials have proven particularly difficult to treat.

Although, many non-radioactive wastes may be treated chemically and broken down into benign or less hazardous chemicals, radioactive constituents of the mixed waste stream cannot be manipulated to reduce or eliminate their radioactive emissions.

Storing radioactive waste poses several problems in itself.

However, radioactive emissions, particularly alpha radiation, can interact with the material of a container intended to store radioactive waste.

This interaction can cause the container to degrade relatively quickly, long before the radioactive waste itself has degraded.

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