CNS Programs: IONP

Swords into Ploughshares: Electricity from Surplus

Weapons Plutonium Burn-Up in Canadian 'CANDU' Reactors

by Tariq Rauf and Joanne Charnetski

While Canada has never possessed any nuclear weapons or significant quantities of weapon-usable fissionable materials, it now finds itself poised on the brink of an historic opportunity to contribute to the safe disposition of a legacy of the Cold War -- excess fissionable materials from the nuclear arsenals of the Cold War adversaries. Canada's civilian nuclear power reactor, the CANDU, could be efficiently and safely used to burn up plutonium from tens of thousands of US and Russian nuclear warheads, dismantled as a result of sweeping arms reduction agreements. According to one plan, excess plutonium from warheads would be converted to mixed-oxide fuel in the US and Russia and could safely be used as fuel in CANDU reactors to generate electricity -- in other words converting (nuclear) swords into (electric) ploughshares.

The Lingering Legacy of the Cold War

With the dramatic ending of the Cold War, the United States (US) and the former Soviet republics (FSR) are engaged in nuclear arms reductions on an unprecedented scale. Dealing with the radioactive materials released from dismantled nuclear warheads will be a major challenge in terms of assuring their physical safety, accountability, and storage or disposal, under proper monitoring. As such, safe and secure disposal of weapon-usable fissionable material from tens of thousands of nuclear warheads to be dismantled, has become one of the most important challenges for international security.

Under the 1991 and 1993 Strategic Arms Reduction Agreements (START I and II) and unilateral initiatives of Presidents Bush, Gorbachev and Yeltsin, several thousands of US and FSR nuclear warheads are being dismantled -- a process that will not be completed until the year 2003, at the earliest. Weapon-usable fissionable materials are defined as uranium with a fissile isotopic content of 20 percent or more, usually above 90 percent which is highly-enriched uranium (HEU); and plutonium (Pu) of any isotopic composition. Weapon-usable plutonium includes plutonium separated from the spent fuel of commercial nuclear power reactors (reactor-grade Pu) and plutonium from nuclear warheads (weapon-grade Pu).

Reportedly, the US has produced about 500 tons of HEU and some 100 tons of Pu, while the former USSR has produced up to 950 tons of HEU and 100-150 tons of Pu, for weapons purposes. According to estimates, fissionable materials to be released from nuclear warheads as a result of disarmament include: for the US, 50 to 60 tons of Pu, and 210 tons of HEU; and for the FSR, up to 89 tons of Pu and over 500 tons of HEU. The US has not produced any HEU or Pu, for weapons-purposes, since the 1970s; while Russia still has three plutonium producing reactors in operation -- these provide needed electricity and heating, and will not be closed down until the year 2000.

These two types of fissionable materials are the key ingredients of nuclear warheads, limiting access to them is the primary technical barrier to preventing nuclear proliferation -- that is, preventing such materials from falling into illegitimate hands. Only about 5 kg of weapon-grade (or 7 kg of reactor-grade) plutonium, or 15 kg of HEU, are required to make a primitive nuclear explosive device. By the year 2003, there will be enough surplus plutonium from dismantled nuclear warheads to make nearly 40,000 primitive nuclear bombs. In addition, growing stockpiles of civilian (or reactor-grade) plutonium in Western Europe and Japan will be sufficient for 47,000 bombs; and HEU from dismantled warheads would be enough for 65,000 bombs.

The existence of such excessive stockpiles of surplus weapon-usable material has been characterized as constituting a clear and present danger to international security. The management and disposition of these weapon-usable materials will take place in a complex international context that includes not only nuclear arms reductions and strengthened non-proliferation norms, but also continuing crises in the former Soviet Union and elsewhere, reliance on civilian plutonium for energy in Western Europe and Japan, and the lack of long-term disposal options for such materials.

While both HEU and plutonium can be utilized to make nuclear warheads, there are two important differences between them. The first is that HEU can be diluted with other isotopes of uranium to yield low-enriched uranium (LEU), which cannot sustain the fast-neutron chain reaction required for a nuclear explosion. LEU is the fuel for most of world's nuclear power reactors, but Canadian (deuterium-uranium) or CANDU reactors use natural uranium. Plutonium, in contrast, cannot be diluted with other isotopes of plutonium to render it unusable for weapons. Re-enriching LEU to weapon-grade or HEU requires complex enrichment technology, which is both costly and not easily accessible. Reactor-grade plutonium, however, requires chemical reprocessing, which is not overly complex. Hence, managing plutonium in any form is more complex and requires greater security than does the management of LEU.

In the current and foreseeable market for nuclear fuel, the use of plutonium fuels is generally more expensive than the use of widely available LEU and natural uranium -- even if the (weapons) plutonium is considered as "free" -- because of the high fuel fabrication costs resulting from plutonium's radiological toxicity and the greater security precautions required for handling it. While most of the 400 existing nuclear power reactors in the world could in principle burn plutonium in a fuel mixture of uranium and plutonium (mixed oxide or MOX), few -- and none in Canada and the US -- are currently licensed to do so.

Disposition Options for Weapons Plutonium

Over the past year, a number of expert studies have been commissioned in the United States to recommend possible options for dealing with the management and disposition of excess fissionable material from dismantled nuclear weapons in both the US and the FSR. In summary, three key security objectives need to be addressed:

  • minimizing the risk of nuclear warheads or fissionable materials falling into unauthorized hands;

  • minimizing the risk that nuclear warheads or fissionable materials are reintroduced into their original arsenals;

  • strengthening international arms control mechanisms and incentives to ensure continued nuclear arms reductions and the prevention of the spread of nuclear weapons to additional countries.

While keeping these security objectives in perspective, four principal options have been identified for short- to medium-term management of excess weapons plutonium: none of these options eliminate the danger, all they can achieve is to reduce the risks. Moreover, these options cannot be expected to reduce substantially the inventory of excess weapons plutonium for at least a decade:

  • the establishment of a new weapons and fissile materials regime between the US and the FSR to include:

  • declarations of stockpiles of nuclear weapons and all fissionable materials;

  • cooperative measures to clarify and confirm such declarations;

  • an agreed cessation of the production of fissionable materials for weapon- use; and

  • agreed, monitored net reductions of stockpiles of weapons and fissionable materials;
  • internationally safeguarded, or verified, storage of fissionable material, to ensure that inventory in storage is withdrawn only for peaceful, or non-weapon, uses;
  • agreement on long-term plutonium disposition options that:

  • minimize the time that plutonium is stored in forms readily usable for nuclear weapons;

  • preserve safeguards and security during the disposal process, while maintaining the same high level of security and accounting applied to nuclear weapons in storage, i.e. the "stored weapons standard";

  • render plutonium into a form which is as difficult to recover for making nuclear weapons as is contained-plutonium in spent fuel from nuclear reactors, i.e. the "spent fuel standard";

  • meet the highest standards for public and worker safety, as well as environmental protection; and.

  • the establishment of new international arrangements to enhance safeguards and physical security over all forms of HEU and plutonium worldwide.

Several options can be considered for achieving these objectives. Exotic options such as sending the plutonium into the Sun (for incineration) or into deep space aboard rockets, or using surplus nuclear warheads to destroy asteroids in space (on projected collision paths with Earth), or underground nuclear explosions to also incinerate other hazardous materials (including chemical weapons), or sub-seabed disposal, or dilution in the open ocean, or disposal in the Earth's magma, can be ruled out as either they do not meet the basic requirements of human and environmental safety or are inimical to existing arms control processes. Workable options include:

  • fabrication and use as fuel, without reprocessing, in existing or modified nuclear power reactors;

  • vitrification, that is combining the plutonium with high-level radioactive wastes as these are melted into large glass logs for long-term underground storage; and burial in deep boreholes, an option that requires further study and could turn out to be comparatively attractive.

These options are currently under consideration in the United States and the FSR. The principal concern of the US is to prevent the misuse of plutonium (and HEU) in the unstable FSR, and thus to find ways acceptable to Russia for disposing of these materials. Russia and some of the other former Soviet republics, however, regard both the plutonium and HEU as having an economic value and thus are not amenable to plutonium disposition through vitrification or burial in deep boreholes. The US has already agreed to purchase 500 tons of HEU from Russia, for a sum of US$11.9 billion, over the next two decades, in order to prevent this material's misuse or diversion. As such, it is highly unlikely that Russia will approve of any plutonium disposition option, other than converting it to MOX for use in civilian reactors (either domestically and/or for export).

Given the importance of plutonium and HEU in the context of global security, while the cost of disposition is a significant factor, cost alone should not be the primary criterion in selecting among the competing options outlined above. Exploiting the energy value of weapon-usable plutonium must not be a central criterion in decision-making, because: a) the cost of fabricating and safeguarding plutonium fuels makes them currently uncompetitive with cheap and abundant low-enriched and natural uranium fuels; and b) whatever economic value the excess weapons plutonium might represent now or in the future is insignificant by comparison to the international security stakes. As such, global security considerations must be the primary criteria for choice among the long-term disposition options.

Long-term storage of excess plutonium at nuclear reactor or nuclear warhead sites entails significant costs, a continuing risk of theft, damage, or risk of breakout, and these could undermine arms reduction and non-proliferation regimes. Another security criterion is to minimize or eliminate the risk of recovery of the plutonium after disposal. Chemical spiking or other ways of changing the composition of the plutonium are not irreversible, and thus entail continuing risks.

It must also be recognized that plutonium disposition options might well differ in the US and the FSR, given their different economies, reactor and waste infrastructures, and plutonium fuel policies. However, using surplus weapons plutonium in nuclear power reactors to generate electricity may well be workable (albeit in different ways) in both the US and Russia, and this is where Canada can lend a helping hand.

Electricity from Excess Weapons Plutonium

A wide range of existing, evolutionary, and advanced, nuclear reactors could be configured to use weapons plutonium in their fuel. New reactors built for such a purpose, particularly those of advanced designs, would require considerable amounts of time and money, as such the most feasible and expedient option would be to utilize existing types of reactors. Currently operational light-water reactors (LWRs) in the US and Russia could use fuels consisting of mixed oxides of plutonium and uranium, without major modifications. Four existing LWRs in the US (three operational at Palo Verde in Arizona, and one 75 percent complete in Washington State) were designed to use MOX in 100 percent of their cores, and could transform 50 tons of weapons plutonium into spent fuel in 30 years. Four Russian VVER-1000 reactors (out of the seven currently operational) -- the only existing models likely to be safe enough for this purpose -- could also burn MOX as fuel (and ten VVER-1000s are operational in Ukraine). Two VVER-1000 reactors could transform 50 metric tons of weapons plutonium into spent fuel in 30 years. The RBMK (or Chornobyl-type) reactors could also burn plutonium, but their age and dubious safety record disqualifies them for such use.

Canadian CANDU Reactors: Canada's (deuterium-uranium) CANDU reactors offer the best technical possibility for the mission of eliminating weapons plutonium, because the reactor design inherently allows for the handling of full-MOX cores and would involve less change from the usual physics of the reactor than in the case of the LWRs. Further, CANDU reactors are refuelled on-line, that is, they do not have to be shut-down for refuelling as do LWRs. Further, CANDUs use a "once-through" fuel cycle which, in principle, would make them an efficient burner of MOX derived from weapons plutonium; and the fissile content would be burned down to a lower level than in a LWR, with the extraction of more energy per kg of plutonium. CANDU fuel is produced in smaller and simpler units than those typical of LWRs, thus potentially reducing the cost of fuel fabrication, which is a substantial fraction of the total cost of MOX use. CANDU reactors have the best safety record in the world -- there are 22 CANDUs operational in Canada. Recently, a CANDU reactor, operated by Ontario Hydro, set a world record for continuous operation and electricity production. Atomic Energy of Canada Limited (AECL), the designer and builder of CANDU reactors is experienced in dealing with MOX fuels and is in a position to supply technical expertise in support of plutonium burn up in CANDUs.

In sum, using plutonium as MOX in existing CANDU reactors is a leading contender for long-term disposition of weapons plutonium. According to one estimate, two of the current standard design CANDU reactors could transform 50 metric tons of weapons plutonium into spent fuel in 25 years.

Any MOX burned in Canadian CANDUs would be fabricated as fuel either at a suitable facility in the US, or at the Krasnoyarsk facility in Russia, before being transported to Canada. Fuel fabrication for CANDU use would be simpler than for LWRs, and fewer modifications would be needed for burning plutonium.

AECL has already completed a technical study on aspects of using MOX from surplus US weapons plutonium in CANDU reactors for the Department of Energy, but this study still remains to be declassified. A similar study is underway with the involvement of Russian scientists, to examine the technical aspects of converting excess weapons plutonium into MOX and then fabricating fuel rods for use in CANDU reactors in Canada. Following a visit to Ottawa in fall 1995, the Russian Minister for Atomic Energy authorized the use of some 10 kg of excess Russian weapons Pu for this technical study, thus possibly signalling some serious interest in considering the CANDU option. However, in order for Russia to choose the CANDU option for disposing of some its excess weapons Pu, it would be politically necessary for the United States to also dispose of some of its excess weapons Pu utilizing the CANDU option, as well as to subsidize some of Russia's costs in this regard.

Canada's Role

Canada has traditionally had one of the world's most stringent nuclear non-proliferation policies, and it has been an active participant in and contributor to global non-proliferation norms. Though Canada was a member of the war-time Manhattan Project to develop an atomic bomb, it was also the first country to voluntarily give up its expertise and capability to develop nuclear weapons and since then it has consistently and actively contributed to preventing the spread of nuclear weapons. The potential use of Canadian CANDU reactors to help in the safe and efficient disposition of one the Cold War's most enduring legacies -- long-lived weapon-usable fissionable materials -- offers Canadians the unique opportunity to once again make a significant contribution to making the world a safer place, in the absence of large stockpiles of plutonium from dismantled nuclear warheads.

In order for Canada to play such a role, it will have to meet the criteria both in Canada and the US governing the transport, storage, and disposition of MOX fuel fabricated from weapons plutonium (in the US and Russia), and will have to continue to ensure that all of its nuclear activities and facilities remain under the watchful eyes of the International Atomic Energy Agency. While some Canadians might be concerned about the possible dangers of using MOX fuel in Canadian CANDUs, given prudent precautions and safe operating procedures, MOX burnup could be done as safely as natural uranium is currently burned to generate electricity for millions of Canadians -- and would create additional long-term jobs in the Canadian nuclear industry. Furthermore, the quantity of spent fuel produced by using MOX fuel would be less than that created by using natural uranium--thus providing cost savings in terms of spent fuel storage.

The burn up of weapons plutonium in the form of MOX fuel in Canadian CANDU reactors would meet the "spent fuel standard", as the safeguards requirements would not differ substantially from those required for existing Canadian spent fuel.

When it comes to radiologically hazardous materials as weapons plutonium, there is no room for a "not in my backyard" syndrome, as the environmental and security consequences of any accident or misuse befalling such material in Russia (or elsewhere) would also impact on this country. Since no feasible options currently exist for the safe long-term storage of weapons plutonium, burning the material under proper international supervision in commercial power reactors remains a viable option. Given the suitability of the CANDU for this purpose, Canada should also actively explore the possibilities of selling CANDU reactors to the US and Russia to assist in the safe and efficient disposition of weapons plutonium. In this regard, the Canadian government needs to make an informed political decision to pursue the CANDU option in assisting the US and Russia safely dispose of their stockpiles of weapons plutonium. Having lived under the US nuclear umbrella for nearly 50 years, and being a strong proponent of nuclear arms control, Canada has an obligation to play a constructive role in helping the world deal with its burden of excess weapons plutonium.

(Tariq Rauf is Director of the International Organizations and Nonproliferation Program of the Centre for Nonproliferation at the Monterey Institute of International Studies; and Joanne Charnetski, is President of JCI - Global Strategists--an Ottawa-based consortium of Canadian specialists in global security.)

Published as "Swords into Ploughshares: Canada Could Play Key Role in Transforming Nuclear Arms Material into Electricity," in The Ottawa Citizen (22 August 1994).

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