Center for Reactor Information

High-Level Radioactive Waste

J. H. Kittel
February 1997

Abstract

High-level radioactive waste, generated by both civilian and government activities, is temporarily stored while the federal government is proceeding with the Yucca Mountain Project, which is expected to enable final disposal of the waste in a mined geologic repository.

The technical operations required for treatment and disposal of high-level waste are well developed and have long been in practice.

No private U.S. industrial entity has been willing to construct and operate a reprocessing facility and assume the financial risk of possible future changes in governmental policies.

The treatment by electrometallurgical processes of spent nuclear fuels owned by the government is being developed at Argonne National Laboratory. Process benefits include economy, greatly reduced packaged waste volume and the production of a common waste type, regardless of starting fuel compositions and types. (See ref. 3.)

An alternative for final disposal of high-level wastes termed "actinide burning" (see ref. 7) converts actinides chemically separated from spent fuel to short-lived radionuclides or non-radioactive elements.

The United States has chosen to use a mined geologic repository in which canisters containing spent fuel or vitrified waste is placed in tunnels bored in the host rock. (See ref. 8.)

The 1987 amendments to the Nuclear Waste Policy Act limited site characterization studies to the Yucca Mountain Disposal Site for potential location of the high-level waste repository.

The ability of natural geologic barriers to isolate radioactive waste is demonstrated by the Oklo reactors. These were naturally occurring reactor systems that developed about two billion years ago in a rich uranium ore deposit in Gabon, Africa. Large quantities of plutonium and other radionuclides were produced during that time but have since moved only extremely short distances. (See ref. 11.)

I. Introduction

High-level radioactive waste has attracted much attention from government and the public. High radioactivity requires both shielding against unsafe exposure to radiation, and cooling to remove heat generated during radioactive decay. The technical operations required for this shielding and cooling, and treatment and disposal of high-level waste are well developed and have long been in practice, most notably in France.

Nevertheless, fears and perceived hazards related to radioactivity continue to raise strong concerns among the public and legislative bodies.

Congress has recognized the concerns regarding high-level waste and has directed that its management, including treatment, transport, storage, and disposal, shall be the responsibility of the federal government.

There are two principal forms of high-level radioactive waste--spent fuel and reprocessed waste.

Spent fuel is nuclear fuel that has been removed from a nuclear reactor after it has operated for a period of time and has then been replaced by fresh fuel. Spent fuel is composed of residual uranium along with plutonium and other radioactive elements including "fission products" and "actinides" that have been generated in the fuel during its operation in the reactor.

Reprocessed waste is composed of the fission products and actinides generated in spent fuel that have been chemically separated out of the fuel so that the residual uranium and plutonium can be reclaimed.

II. Management of Civilian Spent Fuel

The current difficulties in the United States regarding the storage and disposal of spent fuel generated in the private sector were never anticipated when utilities in the 1950s first constructed nuclear reactors to augment their electrical power generation.

Based on governmental policies in effect at that time, the utilities had assumed that, after a brief period of on-site storage, their spent fuel would be shipped to industrial facilities for reprocessing to remove the fission products and actinides generated in the fuel.

In 1977 the first large-scale reprocessing plant was effectively barred from going into commercial operation by the Ford and Carter administrations. Those administrations cited concerns that plutonium recovered during reprocessing could somehow be diverted for weapons or terrorist purposes.

The interdiction against commercial fuel reprocessing in the United States was removed in 1981 by the Reagan administration. Nevertheless, no private U.S. industrial entity has since been willing to construct and operate a reprocessing facility and assume the financial risk of possible future changes in governmental policies.

Congress enacted the Nuclear Waste Policy Act of 1982 and its 1987 amendments, which directed the Department of Energy to select a site for construction of a mined geologic high-level waste repository.

From the very beginning of commercial nuclear power generation in the United States, the nuclear utilities have been required to store their spent fuel at their plants in water-filled basins.

Because of the removal of the reprocessing option, several nuclear utilities no longer have adequate water pool storage capacity for their spent fuel.

They are therefore using dry storage in approved casks of older spent fuel which, because of radioactive decay, is less radioactive and generates less heat.

The comprehensive Nuclear Waste Policy Act of 1996 sought, among other things, to place more firmly on the federal government its responsibility for accepting civilian spent fuel. The Act required construction of an interim fuel storage facility no later than December 31, 1998 near Yucca Mountain in Nevada, the candidate site for a high-level waste repository. Although the legislation was passed by the Senate, it was not acted upon by the House.

III. Management of Government-Owned Spent Fuel

Significant quantities of spent fuel from Plutonium-production reactors and from foreign research reactors are also in the custody of the Department of Energy.

The treatment by electrometallurgical processes of spent nuclear fuels owned by the government is being developed at Argonne National Laboratory under the direction of the Department of Energy. This simple, compact technology shows promise for improving the economics for the disposition of certain spent fuels in custody of the Department of Energy. In addition to its economic advantages, electrometallurgical treatment of spent fuel provides the benefits of greatly reduced packaged waste volume and the production of a common waste type, regardless of starting fuel compositions and types. (See ref. 3.)

IV. High-Level Wastes from Reprocessing Spent Fuel

Almost all of the high-level wastes produced by reprocessing spent fuel are from defense programs and are in aqueous solution or slurry form to be solidified and immobilized in glass (vitrified).

V. Disposal Technology

The Department of Energy and agencies of other countries have evaluated several technical alternatives for final disposal of high-level wastes.

A more recently proposed alternative currently under study is termed "actinide burning". (See ref. 7.) This technology irradiates actinides chemically separated from spent fuel in nuclear reactors or accelerators to convert them to short-lived radionuclides or non-radioactive elements.

The United States has chosen to use a mined geologic repository as its disposal technology, in common with other developed countries.

Current U.S. plans call for horizontal emplacement of canisters containing spent fuel or vitrified waste in tunnels bored in the host rock of the repository. (See ref. 8.)

Several barriers, both engineered and natural, will be between the waste and the earth's surface to prevent transport by ground water.

VI. The Proposed Yucca Mountain Disposal Site

In the late 1970s the Department of Energy initially undertook characterization of various geologic formations for potential location of a high-level waste repository.

The 1987 amendments to the Nuclear Waste Policy Act limited the characterization studies to Yucca Mountain.

VII. Natural Analogs of Geologic Repositories

The ability of natural barriers to minimize corrosion of metals and glass for thousands of years and to isolate radioactive waste for billions of years is effectively demonstrated by natural analogs in several different geologic formations, including some which simulate conditions at Yucca Mountain. (See ref. 10.)

The most widely studied natural analogs of geologic repositories are the Oklo reactors...naturally occurring reactor systems that developed about two billion years ago in a rich uranium ore deposit in Gabon, Africa. Large quantities of plutonium and fission products were produced during this time and moved only extremely short distances. (See ref. 11.)

KW: Actinide burning, disposal, fuel cycle, Gabon Africa, limited migration of uranium and plutonium fission products for 2-billion years, Oklo nuclear reactors, reprocessing, spent fuel, Yucca Mountain.

For additional information, please contact CFRI, an independent organization of retirees with extensive nuclear experience.

References

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2. INFCE Summary Document, IAEA, 24 (1980).

3. J. J. Laidler, "Pyrochemical Processing of DOE Spent Nuclear Fuel", Proc. Topical Mtg. on DOE Spent Nuclear Fuel - Challenges and Initiatives, Salt Lake City, Dec. 13-16, 1994, Am. Nuc. Soc., La Grange Park, IL, pp. 188-195 (1994).

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6. E. E. Rice, et al, "Preliminary Risk Assessment for Nuclear Waste Disposal in Space", NASA CR 162028, 1 (1982).

7. A. Renard, et al, "Actinide Recycling for Reactor Waste Mass and Radioactivity Reduction", in Proc. Fifth Annual Int'l. Conf. on High-Level Radioactive Waste Management, Las Vegas, Nevada, May 22-26, 1994, Am. Nuc. Soc., La Grange Park, IL, pp. 1682-1686.

8. C. G. Whipple, "Can Nuclear Waste Be Stored Safely at Yucca Mountain?", Sci. Am., 72-79 (June 1996).

9. S. Fried et al, "Retention of Plutonium and Americium by Rock", Science, 196 , 1987-1089 (1977).

10. B. Miller and N. Chapman, "Postcards from the Past: Archeological and Industrial Analogs for Deep Repository Materials", RADWASTE Magazine, 2 No. 1, 32-42 (1995). (See also succeeding articles in series on natural analogs in 1995 RADWASTE Magazine).

11. G. A. Gowan, "Migration Paths for Oklo Reactor Products and Applications to the Problem of Geological Storage of Nuclear Wastes", Proc. Mtg. of Tech. Com. on Nat. Fission Reactors, IAEA, 693-699 (1977).