Can the Energy Department store 50 tons of weapons-grade plutonium for 10,000 years?

The nuclear age is undergoing a paradigm shift. During much of the latter half of the past century, the nuclear enterprise was ascendant; now, it has entered a period of decline and uncertain long-term custodianship. This reversal of fortune is especially apparent in the United States’ efforts to rid itself of its unwanted reserves of plutonium. It’s been more than 75 years since a blinding flash lit up the pre-dawn sky at Alamogordo in the Chihuahua Desert of New Mexico. On July 16, 1945, a single gram of the grapefruit-size sphere of plutonium at the center of the world’s first nuclear explosion released three times the destructive force of the largest conventional bomb used during World War II. [1]

Thereafter, the United States government built a grossly oversized nuclear arsenal and never envisioned having to stop building it. Between 1944 and 1994, the Energy Department and its predecessors produced 99.5 metric tons of plutonium for use in an estimated 70,000 nuclear weapons. (An additional 11 tons were produced or acquired for research and development purposes.)

The perverse logic of the nuclear arms race reached a point of ultimate absurdity during the early Reagan presidency, when it was asserted that the winner of a nuclear war would be the one with the most weapons left afterward. Now, 80 percent of the US nuclear arsenal has been discarded, and the United States is still struggling with the strategic mistake of producing so much fissile material to begin with. Currently,  a total of 61.2 tons of plutonium is declared excess to the needs of the US government, of which 53.4 tons is designated for nuclear weapons.

The Energy Department faces the daunting task of geologically disposing of this huge cache of weapons-grade plutonium, so it can never be used again, while ensuring that its does not threaten the environment over a time period longer than human civilization has existed. Achieving safe plutonium disposal will be a multifaceted challenge requiring both long-term commitments and large financial investments at a time when nuclear modernization programs are also competing for federal funding. But arms control and disarmament will not progress as they should unless the excess plutonium problem is solved.

The scope of the problem. Safely ridding the nation of one of the world’s largest excess stockpiles of weapons-grade plutonium will be no minor feat. At issue is the US Energy Department’s 2016 decision to dilute and dispose of, all told, about 48.2 metric tons of plutonium, including 26.2 tons of components, known as “pits,” from several thousand dismantled thermonuclear warheads and 22 metric tons in other forms. These massive quantities of plutonium are destined for the Energy Department’s Waste Isolation Pilot Plant (WIPP), the nation’s only geologic burial site for radiological waste, dug into a deep-underground salt formation near Carlsbad New Mexico. WIPP was opened in 1999, originally for disposal of equipment, clothing, and soil contaminated with dilute amounts of transuranic elements, mostly plutonium, somewhere in the nation’s nuclear weapons complex. If one gram of soil contains as little as 1.587 micrograms of plutonium, the Energy Department is required by federal standards to geologically isolate it from the environment for at least 10,000 years at WIPP.

The site is not without its problems. In 2014, a drum burst open deep underground, shooting contamination to the surface and leading to a three-year closure of the facility that cost about $2 billion.

During the Cold War, the Energy Department facilities involved in weapons productions recovered residual plutonium from production processes—for example, the lathe turnings produced when spherical plutonium bomb cores were shaped—when the cost of doing so was less than the cost of making new plutonium in production reactors. After the downsizing of its Cold War warhead stockpile, in 1998 the Energy Department reclassified residues from the Rocky Flats Plant— some 3.5 metric tons of weapons-grade plutonium, or enough to fuel some 900 weapons—as waste that should also be disposed of in the WIPP. In fact, as of September 2019, more than two thirds of 5.36 metric tons of plutonium 239 placed  in the repository originally had been set aside to make bombs. An additional 5.29 metric tons of this residual plutonium is awaiting disposal, and amount that is separate from and above what is generally considered as excess fissile material from the weapons stockpile.

The government has not publicized the formidable challenges of protecting thousands of workers and members of the public during the process necessary to geologically dispose of this enormous stockpile of nuclear explosives. To put it bluntly, if not done with extreme care, plutonium is a waste-disposal nightmare. The isotope used in American nuclear weapons, plutonium 239, has a specific activity (that is, an amount of radiation produced per unit of mass) that is about 200,000 times greater than uranium 238’s, and plutonium 239 has a radioactive half-life of 24,110 years. Alpha particle emissions from plutonium and other transuranic elements are considered to be about 20 times more carcinogenic than x-rays.

Particles of plutonium less than a few microns in diameter can penetrate deep in the lungs and lymph nodes and also be deposited, via the bloodstream, in the liver, on bone surfaces, and in other organs. If inhaled, extremely small amounts can lead to cancer.

Stringent procedures—many involving large number of workers with specialized skills—are required to ensure that even small amounts of plutonium are properly processed. That processing often must be done by hand, using gloveboxes, to prevent the creation of a critical mass that initiates a nuclear chain reaction and the resulting highly dangerous bursts of energy and radioactivity. While technologies have existed for years to process plutonium, they come out of the Cold War era when safety was secondary to production. Over the years, dozens of workers around the world have been killed or seriously over- exposed from criticality accidents. Various safeguards—including a security system that carefully accounts for all plutonium and protects against theft and diversion—add another costly dimension to handling this nuclear explosive.

Plutonium production ends, but problems continue. Years before the collapse of the Soviet Union, the growing cost of plutonium production led to its gradual cessation. By the 1980s, half of every dollar spent to make plutonium at the aged Energy Department nuclear complex went for its burgeoning waste-management and environmental-restoration problems. By 1988, production costs compelled Energy Secretary John Herrington to declare: “We’re awash with plutonium. We have more than we need.”

By 1992, the United States had stopped making new nuclear weapons as the industrial base for producing them began to collapse; about 80 percent of the Energy Department’s sprawling nuclear weapons production complex was shuttered a few years later. This left behind a legacy of radioactive waste and human suffering, one that is still unfolding. The Energy Department’s recent baseline cost estimates for waste management and environmental remediation are about $435 billion for the two main plutonium production facilities, the Hanford Reservation in Washington and the Savannah River Site in South Carolina. The single largest portion of the entire US government’s environmental liability in 2019, including the Defense Department, is due to plutonium production at these two sites. In terms of the human legacy,  22,459 sick workers at three major plutonium and fabrication sites have been granted more than $4.2 billion in compensation and medical care.

The US-Russia plutonium disposal disagreement. The end of the Cold War led to deep cuts in the US and Russian nuclear arsenals, and in 1993 President Clinton issued a directive declaring that the United States is “committed to eliminating, where possible, the accumulation of stockpiles of highly enriched uranium and plutonium.” In September 2000, the United States and Russia signed the Plutonium Management Disposition Agreement, under which 34 metric tons of plutonium from weapons would be blended with uranium and serve as mixed-oxide or MOX reactor fuel to produce electricity.

Construction on the Mixed Oxide Fuel Fabrication Plant at the Savannah River Site began in 2007, but  the United States abandoned the project because of delays and estimated cost overruns of $30 billion to $50 billion. After a “Red Team” expert review in 2015, the Energy Department decided to pursue a “dilute and dispose” option for storing plutonium, which, the team reported, would cost about half as much as the MOX project. Plutonium from weapons and other forms would be converted from metal to oxide, diluted with a secret adulterant, and then placed  a special container for shipment and disposal at WIPP.

In April of that year, Russian President Vladimir Putin took issue with the US decision, saying it “is not what we agreed on.” The dilute-and-dispose option for excess plutonium does not meet the same level of proliferation resistance as the 300-year radiation barrier provided by the “spent fuel standard”; within a few decades after emplacement, radiations levels could fall low enough to allow the plutonium to be recovered, in theory. But the salt formation at WIPP is expected to slowly collapse and seal off the drums of waste. Just the same, in October 2016 Putin suspended implementation of the plutonium disposition agreement “due to Washington’s unfriendly actions toward Russia.”

The dilute and dispose project. The Energy Department optimistically estimates that its dilution and disposal project will start up in 2027 and store 34 metric tons of weapons-grade plutonium by 2049, at a cost of $18 billion. That time estimate seems likely to be unrealistic; according to the Institute for Defense Analysis, “we could find no successful historical major project that both costs more than $700 million and achieved [Energy Department project startup] … in less than 16 years.”

The dilute and dispose project involves four facilities:

• The Pantex weapons assembly and disassembly plant near Amarillo, Texas, where thousands of pits and other forms of plutonium have to be prepared for safe and secure shipment to Los Alamos National Laboratory (LANL) in New Mexico. The majority of the plutonium at Pantex is stored in facilities at that were built in the 1940s. In 2010 and 2017, unexpected 2,000-year rains flooded a major plutonium storage area with several inches of water, which shut down the plant. It cost of hundreds of millions of dollars to deal with about 1,000 containers affected by the flooding.
• At the Los Alamos National Laboratory, pits will be converted from metal to an oxide that resembles a yellow-to-olive-green talcum-like powder, which is highly dispersible if it escapes from leaking glove boxes. The conversion process takes place at the PF-4 facility, a 69-year-old complex where the Energy Department has a major multibillion-dollar project underway to upgrade aged processes to produce new plutonium bomb triggers. In 2020, a panel of the National Academies of Science warned that “LANL may be a major bottleneck” impacting the plutonium disposal mission. The disposal and production projects could be on a collision course by the middle of this decade, when both are planned to scale up by 10 times.
• Once Los Alamos produces plutonium oxides, they will be sent to the Savannah River Site in South Carolina, where the plutonium will be diluted and mixed with a secret adulterant, sometimes via the use of mortars and pestles. About 166,000 specially designed drums will be filled with the dilute fissile material. This task is a tall order for the Savannah site, where the round-the-clock work is expected to scale up by 10 times in a facility that officially exceeded its design life years ago. The facility will be almost 100 years old by 2049 when the dilute and disposal project is expected to be completed.
• Once the drums are filled, commercial trucks are expected to transport them across the country, from South Carolina to New Mexico and WIPP, in more than 3,888 shipments.

As it plans to dispose of its excess plutonium, the Energy Department has, notably, paid little attention to inspections and verification by the International Atomic Energy Agency, a key element of the Nuclear Non-Proliferation Treaty. As noted by the report of an expert panel of the National Research Council, “IAEA monitoring and inspections are an important component of the [Plutonium Management and Disposition Agreement with Russia]  requirements, and they could also provide enhanced public and international confidence that the material is properly accounted for and emplaced in WIPP.”

Plutonium disposal beyond dilute and dispose. Over the past three years, WIPP and the nearby area have become ground zero for several storage and disposal plans for the bulk of civilian and military radioactive wastes. In addition to trans-uranic wastes set for WIPP and plutonium related to weapons production, the Energy Department seeks to dispose of six tons of fuel-grade plutonium from its research and development program, sludge from 15 of Hanford’s high-level radioactive waste tanks, trans-uranic waste generated from the production of new plutonium pits, and other radioactive waste.

Even after the Energy Department recently recalculated its excess plutonium and other radioactive wastes, resulting in a 30 percent reduction in the total volume to be sent to WIPP, the federal statutory limit set in the Land Withdrawal Act, which authorized the opening of WIPP, will be exceeded by these planned disposal efforts. Congress would have to amend the law to expand the volume, set for WIPP at 175,564 cubic feet, by as much as than 50 percent to accommodate all the waste. Moreover, it appears that new plutonium pit production is projected to generate huge amounts more waste.

Lurking in the shadows, 71 miles from the WIPP, sits an Energy Department effort to dispose of as much as 500,000 gallons of grouted wastes from Hanford’s high-level radioactive waste tanks at the Waste Control Specialists landfill in Andrews County Texas.

That firm is also seeking a license from the Nuclear Regulatory Commission to establish centralized interim storage of spent nuclear fuel from the nation’s power reactor fleet. So, too, is the Holtec Corporation with a proposed spent nuclear fuel storage site 16 miles from WIPP in Lea County, New Mexico.

If these interim storage efforts succeed, by mid-century up to 10,000 spent fuel cannisters containing nearly the entire US commercial spent nuclear fuel inventory will be transported across the country for storage near WIPP. They may sit there for more than 100 years. (See sidebar: “The long-term problem of “peaceful” plutonium.) If these plans are realized, WIPP and the nearby area will have become the recipients of an enormous, decades-long, radioactive-waste-transport funnel directing the bulk of the nation’s commercial and military radioactive detritus to New Mexico and far West Texas.

The need for a long-term commitment to plutonium disposal. The Energy Department faces the daunting and unprecedented task of geologically disposing of tens of tons of weapons-grade plutonium, so it can never be used again, while ensuring its toxic dangers do not threaten the environment over a time period longer than the existence of human civilization. Sustaining a full-time, 30-year effort to process and dispose of this vast amount of plutonium, at the same facilities that have been designated to produce new plutonium warheads for the US nuclear arsenal, inevitably will lead to an intense competition for space, funding, and skilled workers.

Geological disposal of separated weapons-usable plutonium should not be subordinated to resuming new weapons production and other planned disposal schemes. The safe geological disposal of this highly dangerous and toxic nuclear explosive requires a long-term commitment from the US government to build new, costly infrastructure and to provide the knowledge and skills needed for such a vast disposal effort to generations of workers, who deserve greater protection than currently allowed by a great deal of hands-on work. Such a commitment will put the country on the path of irreversibility—the rendering of excess weapons-grade plutonium unusable for weapons purposes, a key element of nuclear disarmament.

The cost of such a commitment will be enormous, but the cost of “kicking the can down the road” in terms of our environment and international security is incalculable.

Notes

[1] About 20 percent of the 6.4 kilograms of plutonium exploded at the “Trinity” test with an explosive yield of 21 kilotons. Thus, one gram yielded 16.4 tons of TNT. He largest bomb used during WWII was the British “Grand Slam” bomb which had a yield of 6.5 tons of TNT.