Managing Military Uranium and Plutonium in the United States and the Former Soviet Union: Current Security Challenges

THE CURRENT SECURITY CHALLENGES

Bunn, Matthew, and John P. Holdren. "Managing Military Uranium and Plutonium in the United States and the Former Soviet Union." Annual Review of Energy and the Environment 22 (1997): 403-486.

As noted above, the collapse of the Soviet Union and ongoing weapons dismantlement are creating new security challenges for the management of weapon-usable materials. The essential facts relating to these current challenges can be divided into two categories: the size of the current stockpiles of nuclear weapons, plutonium, and HEU, and how these are changing under the influence of current nuclear arms reductions; and the vulnerability of these stockpiles to potential theft.

Stockpiles, Rates of Change, and Arms Reductions

In connection with arms-control agreements and unilateral commitments entered into by the United States, the Soviet Union, and the successor states to the Soviet Union at the end of the Cold War and thereafter, substantial fractions of the US and Russian nuclear arsenals became surplus to perceived military needs and were slated for dismantlement. Tens of thousands of these weapons, containing hundreds of tons of fissile material, are being dismantled. Ensuring that nuclear arms reductions could not be readily reversed would require that both the United States and Russia declare a very large fraction of this material to be excess and make it available for civilian use or disposal, as opposed to holding it in reserve for possible reincorporation into weapons.

HEU does not occur in nature, and plutonium occurs in only microscopic quantities, but the stockpiles of these materials produced technologically over the last five decades now amount to many hundreds of tons11 (see Figure 1). One unclassified estimate suggests that as of the end of 1994 the global stockpile of plutonium (including military and civilian stockpiles and both separated plutonium and plutonium embedded in spent power-reactor fuel) was just short of 1200 tons, while the global stockpile of HEU was nearly 1800 tons (17).12

Figure 1: World Inventories of plutonium and HEU (central estimates for end 1994, in metric tons). Figures are rounded to nearest 10 tons; HEU figures represent tons of 90% enriched HEU equivalent.
(Source: 17)

By this estimate, the global stockpiles of military plutonium (incorporated in intact weapons, weapon components, inventories of metal and oxides, and in solutions, scrap, and residues) accounted for 250 tons of the total world plutonium stockpile, while military stockpiles of HEU (including all the categories just mentioned plus naval fuel) amounted to 1750 tons (leaving only 20 tons of HEU in civilian stockpiles). These estimates are acknowledged to be uncertain to +/- 25-30%, and different sources differ in their central estimates: Unclassified US government estimates, for example, suggest that the United States and Russia alone account for some 255 tons of military plutonium (85 for the United States and 170 for Russia).13 The other nuclear weapon states and the threshold states have far smaller quantities of military plutonium and HEU, with combined totals estimated at just under 13 tons and just under 53 tons, respectively.

Civilian inventories of separated and unseparated plutonium are estimated to have stood at over 900 tons as of the end of 1994, of which 122 tons was separated plutonium in storage. Nearly 40 tons of the remaining civilian plutonium was in the midst of various fuel-cycle processes (fabrication, irradiation, and reprocessing), while more than 750 tons of civilian plutonium remained in unreprocessed spent fuel, mostly in spent-fuel cooling pools or dry storage casks at reactor sites.

By the 1990s, production of HEU had almost ceased and production of plutonium for military purposes had slowed to less than two tons per year, but the rate of growth of the stocks of civilian plutonium embedded in spent fuel, produced as a byproduct of continuing nuclear power generation, was about 70 tons per year. In recent years, roughly 20 tons of this material has been separated from spent fuel by reprocessing each year, and to date, fabrication of this separated material into fresh reactor fuel has not kept pace (resulting in the large and growing stockpile of separated civilian plutonium in storage, mentioned above).

Stockpiles of nuclear weapons, by contrast, are declining. For roughly a decade, for the first time in the nuclear age, dismantlement of nuclear warheads worldwide has far out-paced new production. Publicly available estimates suggest that the US stockpile of intact nuclear weapons (including both strategic and tactical weapons and both active weapons and reserves) stood at approximately 23,500 by the late 1980s (45) and had declined by 1996 to approximately 14,000-15,000 weapons,14 as a result of nearly a decade of dismantlement proceeding as fast as the available facilities would safely allow. Dismantlement of US nuclear weapons has taken place at the Pantex facility in Texas, where these operations continue; a limited number of additional weapons were dismantled at Oak Ridge. The year-by-year figures for US warhead dismantlement are shown in Table 1.) Unless further arms reduction agreements are reached, dismantlement in the United States is reportedly planned to essentially end in 1999, leaving an estimated 10,000 warheads remaining in the stockpile. Under current plans, if START II is ratified, the warheads retired as a result reportedly will simply be shifted from active to reserve status, without being eliminated (46).

Table 1: U.S. warhead dismantlements, 1990-1999 a

a Source: (46).
b Projected as of time of data.

A similar pattern appears to be prevailing in Russia, though the United States has no transparency or verification measures in place to confirm this. Unclassified estimates suggest that the Soviet nuclear arsenal, now entirely inherited by Russia, has declined from a peak that may have been as high as 45,000 weapons in 1986 to perhaps 25,000 weapons as of 1996.15 US intelligence estimates of the Soviet nuclear stockpile are publicly described as being uncertain by +/- 5,000 warheads. Russian officials have indicated that, during the last decade, the Soviet Union and then Russia were dismantling weapons at a rate roughly comparable to the US rate, but these officials have not provided specific and consistent figures (47, pp. 31-32, 49-51). Nor have they indicated to what level they plan to reduce their stockpile.

What might these ongoing dismantlements mean in terms of the quantity of fissile material that may ultimately be surplus? One estimate based on unclassified sources suggests that the future US stockpile of 10,000 warheads will contain roughly 35 tons of plutonium and 225 tons of HEU (17). If this estimate is correct, nearly 50 tons of plutonium and over 290 tons of HEU will have been removed from nuclear weapons by the time currently planned dismantlement is complete, and the total stockpiles of US plutonium and HEU outside of weapons will be 65 tons and 420 tons, respectively. To date, the United States has declared that, of these amounts that will be outside of weapons, over 50 tons of plutonium and some 175 tons of HEU are excess to its military needs and has formally committed that this material will never again be used in nuclear weapons. (For a detailed and authoritative account of these figures, see 48). The remainder, under current plans, will stay in military reserves for possible reincorporation in the weapons stockpile or use as fuel for naval reactors.

Russia's stockpiles of plutonium, HEU, and nuclear weapons are all larger than those of the United States. If Russia also reduces its stockpile to 10,000 weapons, unclassified estimates suggest that Russia would then have 125-165 tons of plutonium outside of weapons (including 30 tons of civilian plutonium) and 825 tons of HEU outside of weapons.16 Russia has made no formal declaration of how much of this material it considers excess to its military needs, but it has (a) agreed to blend down 500 tons of HEU for sale to the United States (discussed in more detail below); (b) agreed in principle that none of the tens of tons of plutonium to be stored in a facility being built with US assistance (described below) will ever again be returned to weapons; and (c) made a formal statement that none of the material produced in its plutonium production reactors since October 1994 will ever be used in weapons.

Further progress in arms reduction could substantially increase the amount of excess fissile material. If further reductions were agreed on that required the United States and Russia to reduce their total stockpiles of nuclear warheads to, for example, 2000 warheads, and to reduce their stockpiles of military plutonium to the minimum required to support an arsenal of that size (perhaps with a 20% allowance for purposes of stockpile support and maintenance), then well over 90% of their existing plutonium stockpiles would be excess to their military needs. Using the unclassified estimates of material per warhead cited above, the United States would then be expected to have over 90 tons of excess plutonium, and Russia over 150 tons. Under that circumstance, if the two countries agreed that each would also maintain, for example, an additional 50 tons of HEU for naval fuel, the United States would be expected to have over 500 tons of excess HEU, and Russia roughly 1000 tons (17) (see Table 2).

Table 2: Estimated US and Russian separated plutonium and HEU stockpiles, end 1994 a

a Figures rounded to nearest 5 tons; US and Russian stockpiles include both military and civilian separated plutonium, unlike the "military stockpiles" category of Figure 1. Source for estimates of total stockpiles and material per warhead: (17).

None of these dismantlements and declarations of excess material is actually required by current arms control agreements. The agreements reached to date limit mainly strategic launchers (such as missile silos and submarines) and delivery vehicles (such as missiles and bombers). There is no requirement to dismantle, or even to account for, the nuclear warheads retired when a missile is dismantled, and no transparency or verification measures are in place to confirm the ongoing weapons dismantlement.17

While the START II Treaty (not yet ratified) calls for the United States and Russia to reduce their deployed, strategic forces to 3,000-3,500 warheads on each side, as already noted the United States is reportedly planning to retain a total nuclear warhead stockpile (counting tactical warheads and reserves) of some 10,000 warheads, as well as large stockpiles of reserve fissile material (46).18 Indeed, a 1997 General Accounting Office (GAO) report declassified the fact that the United States is planning to retain reserves sufficient to replace 100% of the warheads in the active arsenal— i.e. enough to rapidly double the deployed forces (50). As far as is known, Russia currently plans to maintain similar or even larger stockpiles of both warheads and fissile materials. These large reserve stockpiles of nuclear warheads and fissile materials would allow a rapid return to Cold War levels of nuclear armament should political circumstances change. If the United States and Russia are ever to achieve the goal of ensuring the "irreversibility of nuclear arms reductions" agreed to by Presidents Clinton and Yeltsin, these reserves and non-strategic warheads will have to be addressed, with new measures to verifiably reduce the stockpiles of nuclear warheads themselves and the fissile materials needed to make them.

Stockpile Vulnerability

The security challenges posed by the growing stockpiles of nuclear materials are related not only to the sizes of these stockpiles but also to the characteristics that govern their vulnerability to theft and diversion. [Following the NAS study (8) and International Atomic Energy Agency (IAEA) practice, we use the term "diversion" to refer to actions by the legitimate owners of the material to reincorporate it into nuclear weapons in violation of pledges not to do so, and the term "theft" to refer to acquisition of the material by parties other than its legitimate owners.]

Measures for securing and accounting for nuclear materials can be divided into two basic types. Programs for "domestic safeguards" are applied by individual states to the nuclear materials on their territories; they are designed to prevent theft of nuclear materials by non-state actors (possibly working in conjunction with foreign states) and use for this purpose a range of technologies and procedures known collectively as material protection, control, and accounting (MPC&A). Programs for "international safeguards" are implemented by international organizations [such as the International Atomic Energy Agency (IAEA) and EURATOM]; they are designed to allow international monitors to detect diversion of nuclear materials from peaceful activities to military purposes, and they use primarily accounting and control technologies (and, more recently, an array of additional technologies and approaches to detect covert military activities at undeclared sites).

In the United States, the stringency and effectiveness of the system for securing and accounting for weapon-usable nuclear materials have increased markedly over the past several decades. During the 1970s and 1980s, rapid and large-scale efforts were undertaken to correct identified weaknesses in security and accounting systems (for critiques of these early weaknesses see 51, 52), with the result that, today, US MPC&A programs are widely regarded as some of the most stringent and effective in the world.

MPC&A for materials used in the US Department of Energy (DOE) complex is implemented by DOE's Office of Safeguards and Security, in compliance with a series of DOE orders, with oversight by DOE's separate Office of Security Evaluation. Private firms implement their own MPC&A, in compliance with national laws and regulations, with oversight and licensing by the Nuclear Regulatory Commission (NRC). The NRC has no authority over materials within the DOE or Department of Defense complexes (although an eventual transition to NRC regulation of DOE activities is now being contemplated). Both DOE orders and NRC regulations (which are intended to be generally consistent) rely on a "graded safeguards" system that divides nuclear materials into various categories of attractiveness requiring varying levels of protection. Facilities with significant quantities of weapon-usable materials are required to employ armed guards, fences, alarms, locked vaults, and a variety of other measures to detect any theft. Overall, the system places heavy reliance on security technology to provide effective protection. Both DOE and non-government stockpiles are included in a computerized national plutonium and HEU inventory known as the Nuclear Materials Management and Safeguards System (NMMSS). Despite the availability of NMMSS information, however, recent initiatives to declassify past production and current holdings of plutonium and HEU have required substantial effort to compile the relevant data (43).

Approaches to MPC&A in other countries vary widely and have evolved considerably over time. For example, countries such as France and Britain place reliance on both security technology and armed guard forces (as the United States does), whereas in Japan, no armed guards are in place at civilian nuclear facilities (even where many bombs' worth of separated plutonium is present). Instead, Japan relies on security technologies and the availability of armed police forces some distance away.

Unfortunately, there is no international mechanism in place to ensure that all countries using weapon-usable materials provide an effective and consistent level of security and accounting. The 1980 Convention on the Physical Protection of Nuclear Material was an important step in this direction, but this convention is "quite vague in its requirements, applies primarily to international transport of nuclear materials, and has no provisions for verification or enforcement" (8, p. 56; for the convention text see 53). The IAEA has published somewhat more specific guidelines, but these are purely advisory (54).

Through bilateral agreements, the United States seeks to ensure that other countries using nuclear materials of US origin provide effective security for those materials: US law requires visits to foreign facilities to examine physical protection arrangements and executive branch certification that these arrangements are adequate. Following the US lead, the Nuclear Suppliers Group has adopted guidelines for physical protection of material originating within its member states (55). Nevertheless, no organization monitors or compiles information on physical protection practices worldwide. Similarly, no international convention or agreement regulates the quality of material control and accounting programs that are part of domestic safeguards systems.

By contrast to the US approach, which relies heavily on technology, the Soviet system for securing nuclear weapons and materials was based on loyal, carefully screened, and well-paid personnel; armed guards; closed facilities; closed cities; closed borders; a closed society; and pervasive surveillance by the KGB (for a useful description see 19). As far as is known, this system worked well for decades.

Today, however, the collapse of the Soviet Union and the ensuing transformations in the former Soviet states have greatly weakened nearly all the pillars of the old system, while forcing it to meet challenges it was never designed to face. With little funding forthcoming from the central government, facilities have been unable to maintain existing security systems or to pay for needed upgrades. At the same time, the vast reduction in living standards among nuclear workers, combined with the marketization and criminalization of the economy, is creating new incentives for corruption and theft. Like the United States, moreover, Russia must cope with the unprecedented challenge of safely and securely managing hundreds of tons of weapon-usable material that, with the end of the Cold War, is no longer needed for military purposes. Furthermore, the non-Russian states have had essentially no previous experience with the MPC&A systems necessary to manage the weapon-usable materials left on their soil when the Soviet Union collapsed.

Despite the weakening of many ingredients of the former Soviet Union's security system, US intelligence agencies have judged that protection of intact nuclear weapons in Russia continues to be effective.19 (As noted above, as of November 1996, all of the former Soviet Union's nuclear weapons had been removed from the non-Russian states and transferred to Russia.) Nuclear weapons are easily counted and are typically stored in secure vaults under heavy guard.

Nuclear materials are another matter. As of 1994 (when current cooperative programs first got underway on a substantial scale), essentially no former Soviet nuclear facilities had effective detection equipment (known as portal monitors) at the gates to sound an alarm if a worker were carrying out plutonium or HEU. Fences at many facilities had holes or were overgrown with vegetation. The principal devices used to indicate whether materials had been tampered with were easily-faked wax seals (most workers with access to the material had the stamp needed to create a new seal). Most sites had no accurate, measured inventories of their material, and no accurate national accounting systems or regulatory frameworks were in place. Although work is underway to correct these deficiencies, it will take years to complete.

For these reasons, the US Director of Central Intelligence has testified that weapon-usable nuclear materials "are more accessible now than at any other time in history— due primarily to the dissolution of the former Soviet Union and the region's worsening economic conditions," and that none of the facilities handling plutonium or HEU in the former Soviet states has "adequate safeguards or security measures" in place (18, pp. 304, 312).

Already, authorities have made multiple seizures of kilogram-quantities of stolen weapon-usable nuclear materials, including 1.5 kg of weapon-grade HEU from the "Luch" production association in Podolsk, Russia in 1992; 1.8 kg of 36% enriched HEU from the Andreeva Guba naval base near Russia's Norwegian border in July 1993; 4.5 kg of material enriched to over 19% U-235 from the Sevmorput naval shipyard near Murmansk in November 1993; over 360 g of plutonium on a plane from Moscow as a result of a German "sting" operation in Munich in August 1994; and 2.73 kg of essentially weapon-grade (87.7% U-235) HEU in Prague in December 1994 (23). While there is no evidence that enough material for a bomb has yet fallen into the hands of states such as Iran, Iraq, Libya, or North Korea, it is impossible to know what has not been detected. The fact that many reports of nuclear smuggling are scams or relate to materials with no relevance to nuclear weapons should not obscure the seriousness of the cases that have occurred.

In short, while the dismantlement of many thousands of nuclear weapons and the removal of hundreds of tons of fissile material from military stockpiles reflect a most welcome reduction in the danger of global nuclear war that loomed over civilization for more than 40 years— and a major turning point in the history of attempts to bring the nuclear arms competition under control— deactivating and dismantling the weapons and properly managing the plutonium and HEU they contain pose an immense new set of challenges for international security and arms control, particularly when combined with the risks of nuclear theft arising from the collapse of the Soviet Union. We now turn to the various cooperative programs designed to meet these challenges.

11 Tons used in this chapter are metric, hence 1 ton D 1000 kg.
12 Because of the continued operation of nuclear power reactors and the blending down of a small portion of Russia's excess HEU stockpiles, these figures are estimated to have changed, by the end of 1996, to roughly 1300 tons of plutonium worldwide and 1750 tons of HEU. Throughout this discussion, the estimated number of tons of HEU is in fact tons of weapon-grade (90%) HEU equivalent; these estimates were produced by estimating the amount of enrichment effort [measured in "separative work units" (SWUs)] devoted to production of HEU, but there are no reliable unclassified estimates of the specific enrichment level of this HEU. If the enrichment level of a substantial fraction of this material is much lower than 90%, then the total quantity of material would be larger, though the amount of U-235 in that quantity would be similar.
13 The United States has formally declared that it has 99.5 tons of plutonium in the Department of Energy and Department of Defense stockpiles (43), of which 85 tons is weapon-grade (the only portion counted in the estimates for military plutonium cited in the text), and one US government source (44) estimates that Russia has approximately 170 tons of military plutonium (200 tons of total separated plutonium, including some 30 tons of civilian plutonium).
14 This figure combines the figure for 1993 reported in (45) and the figures for dismantlement since then in (46).
15 This again combines estimates as of 1993 (45) with estimates of dismantlement since then (47).
16 The HEU figure and the lower plutonium figure are based on (17); the higher plutonium figure is based on the larger total amount of plutonium estimated in (44).
17 The one exception is that Ukraine has reached agreement with Russia on procedures to satisfy Ukrainian officials that the warheads returned to Russia from Ukraine are in fact being dismantled. Neither Ukraine nor Russia, however, has provided a detailed account of what these procedures are.
18 Indeed, as part of the Nuclear Posture Review early in the first Clinton term, the United States explicitly adopted a policy of "lead but hedge," meaning that while the United States would reduce its nuclear forces in line with its commitments, it would reserve the capacity to return rapidly to relatively high levels of nuclear armament (49). It is this requirement for a hedge that has led the United States to plan to retain such a large stockpile of intact nuclear weapons.
19 The Director of Central Intelligence has indicated, however, that "the threat from within the Russian military and the deteriorating economy mean that this judgment could change rapidly" (18).