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The Plutonium Problem: Reprocessing, MOX, and Fast Neutron Reactors

Nuclear Monitor Issue: 

Conventional 'Purex' reprocessing involves dissolving spent nuclear fuel in acid and separating the unused uranium (about 96% of the mass), plutonium (1%) and high-level wastes (3%).

Most commercial reprocessing takes place in the UK (Sellafield) and France (La Hague). There are smaller plants in India, Russia and Japan. In addition, a number of countries have military reprocessing plants. Including both civil and military plants, the International Panel on Fissile Materials lists 19 reprocessing plants in nine countries − China, France, India, Israel, North Korea, Pakistan, Russia, the UK and the US.

Reprocessing is arguably the most dangerous and dirty phase of the nuclear fuel chain. It generates large waste streams with no management solution and it separates weapons-useable plutonium from spent fuel.

Proponents of reprocessing give the following four justifications:

1. Reducing the volume and facilitating the management of high level radioactive waste.
However reprocessing does nothing to reduce radioactivity or toxicity, and the overall waste volume, including low and intermediate level waste, is increased by reprocessing. Steve Kidd from the World Nuclear Association noted in 2004: "It is true that the current Purex reprocessing technology (used at Sellafield and La Hague) is less than satisfactory. Environmentally dirty, it produces significant quantities of lower level wastes."

2. 'Recycling' uranium to reduce reliance on natural reserves.
However, only an improbably large expansion of nuclear power would result in any problems with uranium supply this century. A large majority of the uranium separated from spent fuel at reprocessing plants is not reused, but is stockpiled. Uranium from reprocessing is used only in France and Russia and accounts for only 1% of global uranium usage [IAEA, 2006]. It contains isotopes such as uranium-232 which complicate its use as a reactor fuel.

3. Separating plutonium for use as nuclear fuel.
However there is very little demand for plutonium as a nuclear fuel. It is used in 'MOX' reactor fuel (mixed uranium-plutonium oxide), which accounts for 2−5% of worldwide nuclear fuel, and in a very small number of fast neutron reactors.

4. Using plutonium as a fuel so that it can no longer be used in nuclear weapons.
However, reactors which can use plutonium as fuel can produce more plutonium than they consume (either by design or modification). Moreover, since there is so little demand for plutonium as a reactor fuel, stockpiles of separated plutonium continually grow and now amount to about 260 tonnes [Fissile Materials Working Group, 2013]. That amount of plutonium would suffice to build around 26,000 nuclear weapons (around 10 kgs of 'reactor grade' plutonium per weapon).

Reprocessing has clearly worsened rather than reduced proliferation risks. Addressing the problem of growing stockpiles of separated plutonium could hardly be simpler – it only requires that reprocessing be slowed, suspended, or stopped altogether.

The main reason reprocessing proceeds is that reprocessing plants act as long-term, de facto storage facilities for spent nuclear fuel. Unfortunately this sets up a series of events which can be likened to the old woman who swallowed a fly – every solution is worse than the problem it was supposed to solve:

1. The perceived need to do something about growing spent fuel stockpiles at reactor sites (not least to maintain or obtain reactor operating licences), coupled with the lack of repositories for permanent disposal, encourages nuclear utilities to send spent fuel to commercial reprocessing plants, which act as long-term, de facto storage sites.
2. Eventually the spent fuel must be reprocessed, which brings with it serious proliferation, public health and environmental risks.
3. Reprocessing has led to a large and growing stockpile of separated plutonium, which is an unacceptable and unnecessary proliferation risk.
4. Reprocessing creates the 'need' to develop mixed uranium-plutonium fuel (MOX) or fast neutron reactors to make use of the plutonium separated by reprocessing.
5. All of the above necessitates a global pattern of transportation of spent fuel, high level waste, separated plutonium and MOX, with the attendant risks of accidents, terrorist strikes and theft leading to the production of nuclear weapons.

None of this is logical or justifiable on non-proliferation, environmental, public health or economic grounds but it suits the short-term political and commercial objectives of those involved.

In a May 6 article in the Bulletin of the Atomic Scientists, the Fissile Materials Working Group proposes:

1. Limit the current scale of reprocessing operations and work to decrease it over time.
2. Stop the expansion of current stockpiles and work to reduce them over time.
3. Apply the most stringent standards of safety, security, accounting, and protection of public health to all processes that result in or use separated plutonium, including fuel fabrication.
4. Minimise the number of sites where separated plutonium is used and handled, and the number and length of transports of such material.
5. Pursue options for dry storage of spent fuel, particularly in multilateral cooperative repositories

Current practices worsen the problems in all respects. As the Fissile Materials Working Group notes: "Where is the plan to reduce the plutonium risk? Negotiations on an international treaty to ban plutonium (and [highly enriched uranium]) production for weapons have been in a stalemate for more than two decades, while states outside the Nuclear Non-Proliferation Treaty − India, Pakistan, and North Korea − are increasing their capacity to separate plutonium for weapons. Although the United States and Russia agreed in 2000 to dispose of 34 tons of excess military stocks under the Plutonium Management and Disposition Agreement, this only constitutes about 15 percent of global military-owned separated plutonium."

The Fissile Materials Working Group further states: "Through the Nuclear Security Summit process initiated in 2010, countries have started securing some of the most vulnerable nuclear materials. But they have largely left plutonium untouched."

At the 2012 Nuclear Security Summit in Seoul, the US was also the only significant plutonium holder to address the material in its national statement to the Summit. Sharon Squassoni, director of the Proliferation Prevention Program at the Center for Strategic and International Security, says that taking up the matter seriously would require leaders to address associated sensitive questions that they might rather avoid, such as how to deal with nuclear waste if not by reprocessing. [Schneidmiller, 2013]

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