Abstract
The United States maintains huge stockpiles of plutonium and highly enriched uranium (HEU) for weapons use—far larger than needed for any conceivable military contingency. After disposing of the plutonium it has designated as excess to military requirements, the United States will retain enough for some 10,000 nuclear weapons. After disposing of HEU it has deemed excess, the United States will have enough for 10,000 to 16,000 nuclear weapons. Though still grossly oversized, the US nuclear arsenal has dropped to somewhat fewer than 5,000 weapons, including those in reserve. The United States should declare all fissile material above the amount needed for 5,000 weapons as excess to military needs and dispose of it expeditiously. To reduce the risk that terrorists could steal and use US plutonium to make a nuclear weapon, the United States should directly dispose of excess plutonium rather than using it to fuel reactors.
Keywords
On July 28, 2012, three antinuclear protestors—an 82-year-old nun and two middle-aged men—used bolt cutters to slip through fences and enter the protected area surrounding the Highly Enriched Uranium Materials Facility, the highest-security area of the Y-12 National Security Complex in Oak Ridge, Tennessee. Although their intrusion set off several alarms, the three were in the secured area long enough to put up banners and paint slogans on the outside of the building before being apprehended by Y-12 security forces. While they did not enter the building, their ability to reach it could have had serious consequences if they had been terrorists.
After investigating the incident, the Energy Department inspector general found that multiple security measures, including video cameras, were not active at the time of the break-in, and that security personnel did not respond to several warning systems that did function—partly because of many past false alarms. One press report cited up to 200 false alarms per day, many triggered by squirrels and other small wildlife (Priest, 2012). Another cited 800 false alarms in just the four days leading up to the break-in (Munger, 2013). The investigation also found that personnel inside the facility did not react to the noise the protestors made while using hammers to hang banners outside, because maintenance workers had often arrived without advance notice (Energy Department, 2012b).
The Y-12 incident highlights the importance of improved security at US facilities that store fissile materials that can be used to make nuclear weapons—plutonium and highly enriched uranium. But there are other concrete steps the United States needs to take to reduce the threat of nuclear terrorism, as we discuss in a report we and several others co-authored for the Union of Concerned Scientists (Gronlund et al., 2013).
With the Cold War more than two decades in the past, one of the greatest nuclear threats to the United States now comes from the possibility that some fissile materials from its own huge stockpiles could be stolen and used by terrorist groups to make a nuclear weapon.
Since launching its nuclear weapons program during World War II, the United States has produced or acquired more than 110 metric tons of plutonium for military purposes. While some of this has been consumed in nuclear tests or discarded as waste, the US inventory today exceeds 95 metric tons. 1
A simple implosion nuclear weapon requires some six kilograms of plutonium; a sophisticated design might use as little as two kilograms.
While operating its nuclear weapons programs, the United States produced or acquired highly enriched uranium (HEU) containing about 850 metric tons of uranium 235. Some of this has been consumed as reactor fuel and in nuclear tests, transferred to foreign countries, or down-blended—mixed with natural or depleted uranium—to make low-enriched uranium (LEU) fuel for reactors. As of the end of 2012, the International Panel on Fissile Materials estimates that the US HEU stockpile was 595 metric tons (IPFM, 2013).
Highly enriched uranium presents a greater security risk than plutonium because it can be used to make a simple gun-type weapon, rather than the more difficult implosion design required for a plutonium-based weapon. A gun-type weapon can be made with about 50 kilograms of weapons-grade HEU; an implosion-type weapon would require about 20 kilograms.
The United States has already pledged to dispose of some of this material, which could help reduce the threat of nuclear terrorism. But current plans leave too much of the fissile material untouched.
Even after disposing of the plutonium designated as excess to military requirements, the United States will retain enough for some 10,000 nuclear weapons—many more than are needed for the current or future arsenal. Similarly, after disposing of HEU it has designated as excess, the United States will retain enough for 10,000 to 16,000 nuclear weapons—again, many more than it needs.
An administration pledge to dispose of more of this material would be a way for President Obama to move forward on his stated commitment to the eventual elimination of nuclear weapons. It would also reduce the opportunity for nuclear terrorism, if the United States then moves toward disposing of excess fissile material in a way that minimizes security risks and consolidates remaining stores of fissile materials at fewer, more secure sites.
A massive plutonium stockpile
Sites with plutonium, as of September 2009, in metric tons
Pantex is authorized to store up to 20,000 pits and had about 14,000 as of June 2007 (PantexInfo, 2007). Publicly announced rates for dismantling nuclear weapons suggest that the Defense Department added at least another 1,000 pits by the end of 2009 (Defense Department, 2010). A Los Alamos magazine noted in 2012 that pit storage at Pantex is nearing capacity, but whether that means it has nearly 20,000 pits or that existing capacity is less than 20,000 pits is unclear (Dillingham, 2012). 2
In 2007, the National Nuclear Security Administration (NNSA) decided to consolidate as much excess non-pit plutonium as possible—including material then at the Hanford Site in Washington state, at the Los Alamos National Laboratory, and at the Lawrence Livermore National Laboratory—at the Savannah River Site by the end of 2010 (Energy Department, 2007). As of September 2009, Savannah River stored 12 metric tons, of which 8.8 tons was weapons-grade material excess to military needs, but these amounts have likely increased since then.
In September 2012, the NNSA announced it had removed all “significant” amounts of plutonium from Livermore, leaving it with less than 500 grams for research (NNSA, 2012a). 3 Postponement of construction of the Chemistry and Metallurgy Research Replacement–Nuclear Facility at Los Alamos means that more work on characterizing plutonium will occur at Livermore. Shipments of Category III amounts of plutonium from Los Alamos to Livermore for such work are scheduled to begin in 2015 (Dillingham, 2012; Stark, 2013).
Los Alamos stored four metric tons of plutonium as of September 2009. The United States has declared 1.2 metric tons of that to be excess and has likely moved that amount to Savannah River. The remaining 2.8 metric tons—enough for more than 1,000 pits—is available to produce new pits for nuclear warheads.
Workers at Hanford produced military plutonium for many years, and 6.6 metric tons in spent nuclear fuel remained as of 2009. It is considered a low security risk, because the spent fuel is radioactive and in large and heavy fuel assemblies, making theft difficult.
Idaho National Laboratory, which conducts research on nuclear reactors and fuels, stored 4.6 metric tons of plutonium—most as fresh reactor fuel. While this fuel is not highly radioactive, the plutonium is again embedded in large and heavy assemblies, so stealing it would be difficult.
Savannah River, Hanford, Idaho, Los Alamos, and Oak Ridge National Laboratories also stored material that has been contaminated with plutonium. The Nevada National Security Site (formerly the Nevada Test Site) also stored a small amount of plutonium in waste, with unknown amounts left underground after hundreds of explosive tests.
As of 2009, some 4.8 metric tons of plutonium in waste form had been disposed of at the Waste Isolation Pilot Plant (WIPP) in New Mexico. Based in a dry rock salt bed, WIPP is a permanent repository for transuranic waste, which includes contaminated clothing, tools, rags, debris, residues, and other disposable items. The amount of plutonium mixed with the waste is small enough that it does not pose a security risk.
While the NNSA has removed all smaller quantities of plutonium from Livermore, outside experts believe that the agency will send pits or primaries to the laboratory for periodic testing at its Hardened Engineering Test Building (Tri-Valley CAREs, 2012). This facility heats, cools, drops, and shakes components “to duplicate as nearly as possible the likely environments for a weapon during its lifetime, known as its stockpile-to-target sequence” (Sefcik, 2001: 9). These experts expect the NNSA to grant Livermore an exemption to handle large amounts of plutonium on an as-needed basis. However, the site is no longer set up to handle such quantities. According to the NNSA, Livermore “may require special security accommodations on a periodic basis to support stockpile stewardship” (NNSA, 2013: 5–12).
Given the security risks of this plutonium, it would make more sense to move the equipment in that building to a location that already handles larger amounts of plutonium and will continue to do so over the longer term. Pantex would be the most sensible location, because technicians there disassemble weapons for surveillance and testing.
Plutonium at Los Alamos
The proposed—and now delayed—Chemistry and Metallurgy Research Replacement-Nuclear Facility (CMRR-NF) at Los Alamos includes a vault for long-term storage of up to six metric tons of nuclear material. In the environmental assessment conducted for the facility, the only argument made for such a vault is that the existing Chemistry and Metallurgy Research Facility has one. This is not a compelling argument. The same assessment noted that the existing vault was downgraded because of safety concerns and contains only smaller quantities of plutonium or other radioactive materials (NNSA, 2003).
Most of the plutonium at Los Alamos is stored at its Plutonium Facility. Now that the nuclear facility is delayed, the NNSA is seeking to free up space at the Plutonium Facility to allow the production of more pits. The vault there is relatively full, but waste will be processed and shipped to WIPP. If more space is needed, the “NNSA can stage plutonium for future program use in the Device Assembly Facility in Nevada,” according to the agency’s fiscal 2013 budget request (Energy Department, 2012a: 185). The Device Assembly Facility was built to assemble the nuclear weapons tested underground at the Nevada Test Site. The facility was not completed until after 1992, when the United States began a moratorium on such tests. It is built to be highly secure and is underused, relatively new, and isolated from population centers.
A 1996 Energy Department study identified the facility as one of several that could store plutonium pits—in this case, 8,000 (Energy Department, 1996). The plutonium at Los Alamos is in powdered form and easily inhaled, so it poses a greater health risk than plutonium pits (NNSA, 2011b). Diverting powder is also easier than stealing an entire pit. The NNSA may therefore need to modify the facility to allow it to store powdered plutonium safely and securely. More important, moving plutonium from Los Alamos to Nevada would undermine the goal of consolidating it and introduce new security risks, because the Nevada Site does not now store significant quantities of plutonium.
Another approach to free up space at the Los Alamos Plutonium Facility, if necessary, is to ship some material to the Savannah River Site, which already stores a large amount of non-pit plutonium. The proposed vault that would be built along with the Nuclear Facility at Los Alamos is unnecessary.
The better way to dispose of excess plutonium
In 2009, the US inventory of plutonium not in waste was 95.4 metric tons (NNSA, 2012b). The United States has designated 57.1 metric tons of this material as excess to military needs, leaving 38.3 metric tons of plutonium for weapons purposes (International Atomic Energy Agency, 2012). 4 US primaries contain less than four kilograms of plutonium, so this material is enough for some 10,000 US weapons—many more than needed for the current or future arsenal.
The current arsenal includes roughly 2,150 nuclear weapons deployed on aircraft and land-based and submarine-based missiles. The United States has an additional estimated 2,500 weapons in reserve storage, for a total arsenal of about 4,650 (Kristensen and Norris, 2013). Thus, it should declare an additional 18.3 metric tons as excess to military needs. This would leave 20 metric tons for military purposes—enough for 5,000 weapons.
However, disposing of this plutonium will only reduce the terrorism risk if disposal is done right.
The federal government has considered two methods for disposing of excess plutonium. The first entails immobilizing it (in metal or oxide form) with highly radioactive waste in rods made of glass or ceramic material. These rods would be heavy, large, and so radioactive that theft would be very difficult. They would be disposed of in a permanent underground repository for nuclear waste, once one is built. Alternatively, the plutonium could be placed in very deep boreholes or possibly disposed of at WIPP.
The second method entails converting suitable plutonium into an oxidized form, and then mixing it with low-enriched uranium oxide. This process produces mixed oxide, or MOX, which could be made into fuel rods for use in commercial nuclear reactors. (US commercial reactors use uranium oxide as fuel. As it burns, some is converted into plutonium, so all operating reactors already have plutonium in their cores.) After use, the spent fuel would also be disposed of in a geological repository.
Although it contains plutonium and other fissionable material that could be used to make a nuclear weapon, spent fuel from commercial power plants is not attractive to terrorists because the material is in large, heavy fuel rods that remain too radioactive for direct handling for decades. Moving the rods requires heavy machinery, and extracting weapons-usable amounts of plutonium requires a major, industrial-sized program. These barriers motivated the “spent fuel standard” for plutonium disposal: The National Academy of Sciences recommended that excess plutonium from defense uses be rendered as inaccessible and unattractive as the growing stockpile in civilian spent fuel (NAS, 1994).
Both immobilization and the MOX option meet the spent-fuel standard. However, the MOX approach presents far greater security risks. Fresh MOX fuel does not contain the highly radioactive components that make spent fuel dangerous and difficult to handle. Moreover, a straightforward chemical process can be used to separate the plutonium of MOX from the uranium. The manufacture, transport, and storage of MOX fuel at reactor sites would therefore increase the risk of nuclear terrorism.
Even worse, the theft of enough plutonium to build one or more nuclear weapons from a MOX fabrication facility could go undetected for several years. Such a facility would handle plutonium in solution or powder form, so measuring the exact amount in the facility would be impossible. For a facility with an annual throughput of several metric tons of plutonium, the measurement uncertainty would range from several kilograms to tens of kilograms. At a Japanese fuel production facility in the 1990s, the amount of plutonium not accounted for grew to 70 kilograms over five years. The theft of tens of kilograms—enough for several weapons—could have gone undetected for years. To finally account for this missing plutonium, the plant operator had to shut down the entire facility.
Yet to cut costs and make MOX more palatable for utilities that operate nuclear power plants, the NNSA has encouraged the Nuclear Regulatory Commission (NRC) to reduce safeguards and security requirements for mixed-oxide fuel, which would otherwise need to be protected like plutonium. The NRC has already weakened security requirements for storing MOX fuel at reactor sites and is considering across-the-board security rollbacks that would also reduce security requirements during transportation of MOX and at the MOX plant. Weakening security undermines a chief goal of plutonium disposition: reducing the likelihood of theft.
In 2000, the United States and Russia each agreed to dispose of 34 metric tons of plutonium excess to military needs, using either or both the immobilization and mixed-oxide approaches. Delays, disagreements, and program changes have meant that the nations have since made no progress toward that goal.
At the time, the United States planned to use both disposal methods, while Russia was intent on the MOX option. Shortly after the initial agreement, Russian officials argued that because immobilization would not change the isotopic composition of the plutonium, it would not meet the spent-fuel standard. Russia threatened to withdraw from the agreement if the United States pursued immobilization. Meanwhile, the United States grew increasingly concerned about the cost of the dual-track approach. Although the Energy Department had concluded that immobilization would be less expensive than the mixed-oxide option, the Bush administration ended the immobilization program in 2002 and focused solely on MOX (NNSA, 2002).
The US–Russia agreement, updated in 2010, now specifies that both countries will use the MOX method. 5 The United States also plans to use it to dispose of all other excess plutonium that is in a form suitable to be made into MOX. All excess plutonium that is unsuitable for conversion to MOX—roughly two metric tons—would be shipped to WIPP in southeastern New Mexico (NNSA, 2012a).
The United States is building a mixed-oxide fuel-fabrication facility at the Savannah River Site; it is grossly over budget and behind schedule. The initial 2003 estimate was that construction would cost $1.6 billion and be completed by 2007. The fiscal 2014 NNSA budget request puts the construction cost at $7.7 billion and startup is now expected to slip to 2019, according to the Government Accountability Office (2013). The plant’s expected annual operating costs have also risen by nearly a half-billion dollars per year. The cost to build and operate the MOX facility long enough to dispose of 34 tons of plutonium is estimated to be $18 billion (Clements et al., 2013).
Because of these cost increases and delays, the Obama administration has decided to slow down construction of the facility and consider alternatives to MOX. In its fiscal 2014 budget request, the NNSA asked for $320 million for building the mixed-oxide facility—significantly less than in previous years. Out-year funding for construction has been zeroed out. However, despite frustration in Congress, the project has influential supporters in key committees who are attempting to increase funding to allow construction to continue. It makes no sense to continue building this facility while the Energy Department considers other options.
If the Obama administration decides to continue the mixed-oxide fuel approach, the Energy Department needs to find utilities willing to burn it. Duke Energy signed a contract to use the fuel, but allowed it to lapse in 2008. No other partners have emerged, though the Tennessee Valley Authority is reportedly studying the possibility.
Because disposing of excess plutonium by converting it to mixed-oxide fuel poses greater security risks than immobilization, the United States should cancel the mixed-oxide fuel program and refocus on immobilization. That would require renegotiating the 2010 plutonium agreement, but Russia would likely be willing to do so, given that the United States recently agreed to change the original agreement to accommodate Russia’s desires.
Although $3 billion has already been invested in the MOX program, immobilizing excess plutonium may be less costly in the end. It may also be possible to convert the partially completed MOX facility for use in immobilization. Temporary storage of excess plutonium at Savannah River and Pantex is a secure and safe option, if the United States decides to restart the immobilization program.
An enormous stock of highly enriched uranium
Because it is part of a nuclear weapon’s secondary stage, highly enriched uranium is a crucial component of all modern US thermonuclear arms. It is also used as fuel in the nuclear reactors that power US submarines and aircraft carriers. HEU is used in some US research reactors as well, but the number is declining, as their operators are replacing HEU with fuel made of LEU, which cannot be used directly in weapons.
HEU presents a greater security risk than plutonium because it can be used to make a simple gun-type weapon, whereas a plutonium-based weapon requires a more sophisticated implosion design. In a gun-type weapon, conventional propellant such as smokeless powder or gunpowder slams together two subcritical pieces of HEU. Such a weapon can be made with about 50 kilograms of weapons-grade HEU; an implosion-type weapon would require about 20 kilograms of weapons-grade highly enriched uranium. HEU also is far less radioactive than plutonium, making it easier to handle and more difficult to detect.
While operating its nuclear weapons programs, the United States produced or acquired HEU containing about 850 metric tons of uranium 235. Some of this has been consumed as reactor fuel and in nuclear tests, transferred to foreign countries, or down-blended to make LEU fuel for reactors. In September 2004, the date of the most recent official information, the US inventory contained 687 metric tons of HEU and 547 metric tons of uranium 235 (Energy Department, 2006). As of the end of 2012, the International Panel on Fissile Materials (2013) estimates that the US HEU stockpile was 595 metric tons. It continues to shrink as more highly enriched uranium is down-blended to LEU.
Sites storing HEU, as of September 2004, in metric tons
Other HEU, most in the form of spent nuclear reactor fuel, is stored at the Savannah River Site and the Idaho National Laboratory. Spent naval nuclear fuel is also shipped to Idaho for long-term storage or disposal. This HEU is in heavy, highly radioactive spent fuel rods that present an inherent barrier to theft.
As of 2004, almost 20 metric tons of highly enriched uranium was stored at several other sites, including the three weapons laboratories, the Oak Ridge and Brookhaven national laboratories, and the Hanford Site. Some of this material has since been consolidated at Y-12, including all significant amounts of HEU previously stored at Livermore. Finally, Nuclear Fuel Services, a Babcock & Wilcox subsidiary in Erwin, Tennessee, manufactures HEU naval reactor fuel and stores some of it before transporting it to the Navy. The use of HEU for naval reactors also increases the threat of nuclear terrorism, and the Navy should convert its reactors to use LEU fuel, as do French naval reactors.
The main repository for weapons-related HEU is a new facility at Y-12, the Highly Enriched Uranium Materials Facility. This high-security facility, which replaced several aging structures at Y-12 and across the country, stores highly enriched uranium from throughout the nation’s nuclear complex. Often touted as the Fort Knox of HEU, the facility is made of reinforced concrete and designed to withstand various kinds of disasters, including flooding, earthquakes, lightning strikes, tornadoes, and aircraft impact (Energy Department, 2013). Construction was begun in 2004 and completed in 2008 at a cost of $550 million. The facility began operating in 2010 and is planned to have a lifetime of 50 years.
The transfer of HEU from several other locations at Y-12 to the new facility was completed in August 2011, and about 68 percent of Y-12’s HEU is now stored there (NNSA, 2011c). The other 32 percent is in use elsewhere at the site to supply near-term needs. Shipments of HEU from other sites will go directly to the facility.
The NNSA also plans to build the Uranium Processing Facility at Y-12, to further consolidate facilities that handle significant amounts of HEU. According to the agency, that facility will allow a 90 percent reduction—from 150 to 15 acres—in the site’s “protected area,” which requires the highest level of security (Babcock & Wilcox Technical Services Y-12, 2011).
The 2004 US inventory of fissile materials listed 18.7 metric tons of HEU stored in the L Area Complex at Savannah River (Energy Department, 2006; Savannah River Nuclear Solutions, 2011). This HEU is in multiple forms, including spent nuclear fuel from foreign and domestic research reactors.
Disposing of excess HEU
In 1994, the United States declared 174 metric tons of highly enriched uranium to be excess to military needs. Of this, 18 metric tons were in the form of waste, and the remaining 156 metric tons were to be down-blended to LEU and used to make reactor fuel.
In 2005, the United States withdrew another 200 metric tons of HEU from use in nuclear weapons, setting aside 160 metric tons of that for use in naval nuclear reactors. 6 The NNSA anticipates that 32 of the 160 metric tons will be unsuitable for naval fuel and will instead be down-blended (NNSA, 2011a). 7 Another 20 metric tons of HEU was reserved for space and research reactors, and the remaining 20 metric tons will be down-blended (Energy Department, 2005). Of the 374 metric tons of HEU that the United States has declared excess to nuclear weapons, it expects to down-blend 208 metric tons.
Nine metric tons of HEU from spent fuel from US and foreign research reactors is also slated to be down-blended. Thus, the Energy Department’s Fissile Materials Disposition Program aims to down-blend a total of 217 metric tons of HEU by 2050 (GAO, 2011). After this down-blending is complete, the United States will retain about 260 metric tons of HEU (containing 230 metric tons of U-235, for an average enrichment level of 88 percent) in weapons and for weapons purposes, and another 130 tons of weapons-grade HEU for naval reactor fuel (IPFM, 2010).
US nuclear weapons contain roughly 15 kilograms of weapons-grade HEU in their secondaries, and some weapons also contain about 10 kilograms of highly enriched uranium in the primary. If each weapon contains 15 to 25 kilograms of HEU enriched to 95 percent U-235, the 260 metric tons of highly enriched uranium is enough for 10,000 to 16,000 weapons—which is two to three times the size of the current arsenal. The United States should declare an additional 135 metric tons of HEU excess to weapons use—leaving 125 metric tons, enough for at least 5,000 weapons.
As of the end of 2012, 134 metric tons of surplus HEU had been down-blended, and another 7 metric tons had been delivered to commercial facilities for near-term down-blending (IPFM, 2013). Meeting the Energy Department’s disposal goal would require down-blending another 80 metric tons by 2050, or just 2 metric tons per year—much lower than previous rates of up to 20 metric tons per year.
NNSA officials acknowledge that the 2050 target date for disposal is an arbitrary placeholder, and that down-blending could be completed earlier. The reason for choosing a date so far in the future, according to the agency, is that the actual rate of down-blending depends on when the HEU—some of which will come from dismantled retired weapons—is received. All dismantling of weapons now occurs at the Pantex Plant, where this operation competes for space and personnel with life extension programs. As a result, weapons are dismantled at a lower rate than in the past, and that slowdown also means a slowdown in disposing of HEU (GAO, 2011).
Clearly, the United States could and should speed up the down-blending of excess highly enriched uranium. It should also declare more of the country’s HEU stock as excess to military need, dispose of it expeditiously, and consolidate any remaining large stocks of HEU at the Y-12 facility as soon as possible.
Declare. Dismantle. Dispose.
The danger of terrorists acquiring nuclear materials in the United States will exist as long as there is a nuclear weapons program and highly enriched uranium is used for naval and research reactor fuel. The United States can, however, take several steps to reduce this risk now. It should consolidate the fissile material in secure storage and minimize its handling and transportation. To this end, the NNSA should not reintroduce significant amounts of plutonium to the Lawrence Livermore National Laboratory. It should consolidate plutonium and highly enriched uranium not used for military purposes at the nation’s most secure storage sites—the Savannah River Site and Y-12, respectively. But the 2012 break-in to the most highly secured area of Y-12 was a disturbing indication that even these storage facilities need to be made more secure.
The huge stocks of plutonium and highly enriched uranium that the United States maintains for weapons are far more than it needs for any conceivable contingency. These materials were produced at a time when the United States built a nuclear arsenal of tens of thousands of warheads and faced a Soviet Union that did likewise. The US security environment has fundamentally changed since this time, and although the US nuclear arsenal is still grossly oversized, it has dropped to somewhat fewer than 5,000 weapons, including those in reserve. The United States should declare all material above the amount needed for 5,000 weapons as excess to military needs and dispose of it expeditiously. This would entail declaring excess an additional 18.3 metric tons of plutonium and 135 metric tons of HEU.
By declaring more fissile material excess, the United States will also demonstrate its commitment to following through on President Obama’s pledge to lay the groundwork for the eventual elimination of nuclear weapons.
But declaring material excess is just the first step in making sure terrorists do not steal it and use it to make a nuclear weapon. The United States has been slow to dispose of the HEU it has already declared excess and has not yet begun to dispose of its excess plutonium. Even more worrisome is the current plan to use mixed-oxide fuel as the method for disposing of plutonium—a choice that could actually increase the risk of nuclear terrorism. A far better approach is to immobilize the plutonium with nuclear waste and dispose of it in a repository—or possibly to dispose of it directly in a borehole or WIPP—thereby enhancing US and international security.
Footnotes
Funding
This research was made possible through the support of the Colombe Foundation, the William and Flora Hewlett Foundation, the Ploughshares Fund, the Prospect Hill Foundation, Telemachus: Foundation to Empower the Poor and End War, and members of the Union of Concerned Scientists.