|Plutonium and Uranium Reprocessing
n Reprocessing is a method for recovering unused portions of uranium and plutonium from used nuclear fuel and recycling it for use in new reactor fuel. Reprocessing is not an alternative to geologic disposal of nuclear fuel after it is used in a reactor, but a fuel-cycle technology that complements ultimate disposal.
n Recycling the uranium and plutonium contained within a metric ton of used fuel provides as much energy as at least 100,000 barrels of oil.
n About 75,000 metric tons of used nuclear fuel have been reprocessed worldwide during the past four decades.
n France, Japan and the United Kingdom reprocess used nuclear fuel utilizing technology originally developed in the United States.
n The U.S. government and American industry have years of experience with fuel reprocessing and the development of related technology. The United States does not reprocess used fuel, but did so in the past.
n Until the mid-1970s, U.S. energy policy called for the use of separated plutonium from reprocessing as a commercial nuclear fuel source.
However, concerns about the potential for plutonium to be diverted and converted to weapons material, which could lead to the proliferation of nations with nuclear weapons, resulted in a 1977 presidential ban on reprocessing used nuclear fuel in this country. Although the ban was subsequently lifted, the high cost of reprocessing and regulatory considerations continue to drive decisions not to reprocess in the United States.
The composition of uranium changes when it is used as fuel in a nuclear reactor. During nuclear fission, uranium-235 atoms are split—creating heat that is used to produce steam to generate electricity. The fission process also produces many other elements, including plutonium, other heavy metals and radioactive byproducts (called “fission products”). Certain isotopes of uranium and plutonium are “fissile” elements—i.e., they will sustain a nuclear chain reaction—and can be reused as nuclear fuel. When nuclear power plants are refueled—typically every 18 to 24 months—the used fuel that is removed contains uranium that was not consumed (96 percent), plutonium that was created (1 percent), and several fission products that are considered waste (3 percent). Reprocessing is a procedure for recovering that uranium and plutonium for use in new fuel.
A reprocessing plant is a chemical processing facility. Used nuclear fuel is delivered to the plant, pulverized and dissolved in nitric acid. Inside the reprocessing plant, the liquid is separated into three streams:
§ uranium (generally in the form of uranyl nitrate)
§ plutonium (generally in the form of plutonium nitrate)
§ highly radioactive fission products.
After this processing, the liquid uranium and plutonium are converted into solid uranium oxide and plutonium oxide.
Worldwide, about 75,000 metric tons of used fuel have been reprocessed during the past 40 years. The uranium recovered from that fuel is manufactured into new fuel or stored for later use. The recovered plutonium is either stored in facilities monitored by the International Atomic Energy Agency or combined with uranium and manufactured into mixed oxide (MOX) fuel, a blend of uranium and plutonium.
The remaining highly radio-active, liquid fission products (called high-level nuclear waste) are mixed with other materials and turned into a durable, solid glass-like material, then placed in metal canisters for storage pending final disposal. That final disposal will most likely be in an underground, engineered repository.
Different countries take different reprocessing approaches, depending on several factors. France, Japan and the United Kingdom reprocess used fuel as a service to nuclear utilities in these and other countries, which retain ownership of the fuel and all its constituents at all times.
Canada, Sweden and the United States do not reprocess. These nations plan to build centralized disposal facilities for storage and direct disposal of used nuclear fuel. The United States is developing a federal repository at Yucca Mountain, Nev., for underground disposal. The project was approved by Congress in 2002 and is in the NRC licensing phase.
Until the mid-1970s, the United States had planned to use separated plutonium, generated by reprocessing, as a commercial fuel source. But in May 1974, India detonated a nuclear device made from plutonium separated at its reprocessing facility, prompting the United States to revise its policy on reprocessing to reflect proliferation threats it perceived to be the result of separated plutonium.
In a 1976 policy statement, President Gerald Ford declared, “The avoidance of proliferation must take precedence over economic interests.” He also stated that U.S. domestic policies must be changed to defer “the commercialization of chemical reprocessing of nuclear fuel which results in the separation of plutonium.”
In 1977, President Jimmy Carter deferred indefinitely commercial reprocessing of plutonium produced in commercial U.S. nuclear plants, citing concerns about the consequences of proliferation.
President Ronald Reagan lifted that ban in 1981, but the development of reprocessing facilities was no longer considered economically viable in the United States.
President Bill Clinton issued his own policy statement on reprocessing in 1993: “The United States does not encourage the civil use of plutonium and, accordingly, does not itself engage in plutonium reprocessing for either nuclear power or nuclear explosive purposes. The United States, however, will maintain its existing commitments regarding the use of plutonium in civil nuclear programs in Western Europe and Japan.”
In spite of its earlier declaration of opposition to commercial reprocessing, beginning in 1995, the Clinton administration and the Russians embarked on a joint program to safely and effectively dispose of plutonium from surplus nuclear weapons by converting it into MOX fuel for use in nuclear power plants. The conversion of weapons material into commercial reactor fuel is to take place at the Department of Energy’s Savannah River Site in South Carolina.
Converting plutonium has now become the primary means to avert the “clear and present danger” presented by the potential diversion of surplus weapons plutonium, thus helping the United States achieve its nuclear nonproliferation objectives.
The U.S. government and American industry have decades of experience with reprocessing. The “Purex” reprocessing technology—used by the British, French and Japanese to reprocess used fuel from commercial reactors—was developed in the United States for nuclear weapons production.
The U.S. government used the Purex technology to reprocess used fuel from government-owned nuclear reactors in Hanford, Wash., and at Savannah River. The government’s reprocessing sites produced weapons-grade plutonium used in nuclear warheads.
When President Carter instituted the ban on reprocessing, he also launched a major diplomatic initiative—the International Nuclear Fuel Cycle Evaluation—to persuade other industrialized countries to follow America’s lead and ban the procedure. The initiative met with little success.
Until that time, several U.S. companies had actively developed reprocessing capacity:
§ General Electric built a large reprocessing facility in Morris, Ill. The plant, which never operated, now stores used nuclear fuel.
§ Nuclear Fuel Services, while a subsidiary of Getty Oil, built and operated a small reprocessing facility in West Valley, N.Y. The high cost of meeting new regulations in the mid-1970s forced the company to close the plant. The Department of Energy is now decontaminating and decommissioning the site.
§ Allied General Nuclear Services, an Allied Chemical and General Atomics joint venture, invested more than $500 million dollars in a new reprocessing plant in Barnwell, S.C. The Carter administration’s reprocessing ban—coupled with costly new regulatory requirements—ensured that it, too, never operated.
§ The development of U.S. regulations for reprocessing facilities was halted by President Carter.
Despite President Reagan’s 1981 reversal of the ban, such unilateral changes in government policy dampened industry willingness to invest the billions of dollars needed to complete reprocessing facilities. The economics of reprocessing also changed: Globally, the supply of natural uranium was plentiful, resulting in prices that were far lower than the cost of reprocessing.
Before making the large capital investment required to build a reprocessing plant, companies and countries must weigh a number of considerations, such as the economic value of uranium and plutonium recovered during reprocessing, the future market price of natural uranium, and policy considerations like the cost, availability and security of other sources of energy. Other factors include the management of low-level radioactive and transuranic wastes requiring a repository and other values, such as an emphasis on recycling natural resources.
In 1994, the Organization for Economic Cooperation and Development issued a study that concluded total life-cycle costs are virtually the same for reprocessing and eventual disposal or direct disposal of used fuel. Today, fuel economics and other policy issues drive reprocessing decisions.
Countries that recycle nuclear fuel do so mainly to retrieve the energy value that remains after the fuel is discharged from a reactor after one fuel cycle. Recycling the uranium and plutonium contained within a metric ton of used fuel provides as much energy as at least 100,000 barrels of oil.
Other benefits include a reduction in the hazardous life of some of the remaining high-level radioactive waste and the conversion of much of the plutonium. However, reprocessing operations produce additional low-level radioactive and transuranic wastes.
From a natural resources perspective, some countries value the reprocessing technique because it extends the supply of uranium reserves and minimizes the environmental
impacts of uranium mining. However, there are limits. After five or six reprocessing cycles, the remaining plutonium can no longer be reused.
France, for example, relies on nuclear power plants for more than 75 percent of its electricity supply, rather than turning to imported energy sources. France also views the plutonium and uranium remaining in used fuel as valuable resources. And, because recycled plutonium is degraded or eliminated when used in a reactor, France sees reprocessing as one step in the process of eliminating plutonium and reducing proliferation risks.
France has reprocessed more than 10,000 metric tons of used reactor fuel. It has two reprocessing plants—UP2 and UP3 in La Hague—that together can reprocess 1,600 metric tons of used fuel per year.
Japan also is developing a reprocessing industry, largely because the move advances its goal of greater energy independence. Like France, Japan has a high reliance on nuclear power, providing 34 percent of its electricity.
In support of its long-term program to increase its nuclear capacity, Japan is building a new reprocessing plant at Rokkasho-mura to handle 800 metric tons per year, which will supplement the 90-metric-ton annual capacity at the Tokai-mura plant. Reprocessing used fuel gives Japan a greater measure of energy security.
In the United Kingdom, where nuclear power provides nearly one-quarter of the electricity supply, the reprocessing decision is left to the electric utilities. During the past 40 years, the United Kingdom has reused more than 15,000 metric tons of uranium recovered through reprocessing to power its domestic nuclear reactors. The Thorp reprocessing plant in Sellafield can reprocess 900 metric tons of fuel per year. Reprocessing allows Britain to realize the full value of its nuclear fuel.
Unlike France, Japan and the United Kingdom, the United States does not reprocess nuclear fuel. It relies on a plentiful supply of relatively low-cost uranium to fuel its nuclear reactors as part of a diverse mix of energy sources, including abundant reserves of natural gas and coal for electricity production. In an emission-free, reliable and affordable manner, nuclear power meets 20 percent of U.S. electricity needs.