Russia formally withdraws from the Protocol for the elimination of military plutonium

On 8 October the lower house of the Russian parliament (the Duma) approved withdrawal from the historic agreement with the United States on the management and disposition of plutonium (the Plutonium Management and Disposition Agreement, PMDA), a pact in force since July 2011 designed to eliminate 34 tonnes of weapons-grade plutonium from each country’s arsenals (an amount sufficient for roughly 17,000 nuclear warheads). After the Duma’s ratification, Russia’s denunciation of the PMDA moves to a vote in the Federation Council before being promulgated into law by President Vladimir Putin.
Before the Duma vote, Deputy Foreign Minister Sergei Ryabkov argued that “the United States have taken a series of new anti-Russian measures that fundamentally change the strategic balance that existed at the time of the Agreement’s signature and create additional threats to strategic stability,” and therefore “none of the envisaged conditions can be satisfied.”
In fact, Russia had already suspended implementation of the pact in 2016, claiming that the United States had violated the original terms for plutonium disposition, in the context of a deterioration in relations between the two states following the occupation of Crimea.
The current formal withdrawal signals a further erosion of arms control, further weakening the already fragile network of nuclear agreements between the United States and Russia amid continuing tensions, and urgently reopens the delicate issue of the vast stocks of plutonium held by various countries.

The problem: the destruction of nuclear weapons

The signing of the START I treaty (31 July 1991) between Russia and the United States and the simultaneous Presidential Nuclear Initiatives imposed drastic reductions (by tens of thousands) in the two countries’ nuclear weapons, with the consequent increase by hundreds of tonnes in the already enormous stocks of fissile materials: highly enriched uranium enriched in uranium-235 (around 93%, HEU) and weapons-grade plutonium (over 90% plutonium-239). It was necessary to prevent the re-use of those fissile materials for new weapons (which would have undermined the agreements reached) and to guard against proliferation and nuclear terrorism risks; the US National Academy of Sciences and its Russian counterpart began joint research in 1992 to identify methods to render such materials permanently unusable for military purposes.
While it is easy to remove conventional components from warheads, HEU and plutonium do not naturally degrade into non-fissile elements and require specific procedures to eliminate their military value.
For HEU there is an almost immediate disposal method: down-blending it to low-enriched uranium (below 5%, LEU) by mixing it with uranium of low uranium-235 content. The LEU thus produced can be used as fuel in nuclear power reactors, thereby recovering it for economically useful purposes.
Particularly important was the intergovernmental Russian-US agreement concerning the disposition of highly enriched uranium extracted from nuclear weapons (“Megatons to Megawatts”) of February 1993, which over 18 years converted roughly 500 t of HEU from 20,000 Russian nuclear bombs into LEU, producing over 14,000 t of LEU for US nuclear power stations and, from the 2000s onwards, covering about 45% of their nuclear fuel needs, while also providing employment for tens of thousands of Russian nuclear technicians.
Plutonium poses greater problems than HEU with respect to reducing its military potential, because unlike HEU it cannot be diluted with non-fissile isotopes — practically all of plutonium’s isotopes are capable of producing an explosive chain reaction.
Studies carried out in 1997 by a specific US-Russian working group (co-chaired by John P. Holdren and Evgeny P. Velikhov) identified as the objective for securing weapons-grade plutonium “its transformation into a form that presents the same inaccessibility as plutonium present in the spent fuel of commercial reactors”, that is, being heavily contaminated by highly radioactive material. Practically, only three methods were considered possible:

• permanent storage of the plutonium in highest-security facilities under continuous surveillance;
• mixing the plutonium with natural or depleted uranium and fabricating MOX (mixed-oxide) fuel to be used in water-moderated nuclear reactors;
• immobilising the plutonium with highly radioactive waste.

The first method immediately appeared inadequate, requiring control and safeguard systems that were practically unimplementable. Both irradiated MOX plutonium and immobilised plutonium become practically inextricably mixed with highly radioactive materials and end up in geological repositories.
The report did not consider the option of producing fuel made of near-pure plutonium for reactors operating with unmoderated neutrons (“fast reactors”), given the negative experiences of the French Phénix and Superphénix reactors and their safety and environmental risks.
To produce MOX, the metal plutonium core is separated from the other warhead components, pulverised and converted to plutonium oxide (PuO2), which is then mixed with uranium oxide (UO2); the mixture is sintered to form cylindrical ceramic pellets for fuel elements, containing 7–11% plutonium (using weapons-grade plutonium, about 5% plutonium in the mix is sufficient).
The rate at which plutonium can be eliminated as MOX fuel in light-water reactors is slower than that for HEU, because for safety reasons only one third of the fuel in such reactors may be MOX; typically a 1 GWe reactor takes three years to eliminate 1 t of plutonium, while it consumes LEU equivalent to roughly 1 t of HEU per year.
Many experts were sceptical about the MOX option, also because it would have given a significant economic impetus to plutonium use, ultimately leading to wider acceptance of plutonium in the civil nuclear industry. Moreover, it was more expensive, more complex and potentially less safe than immobilisation.
In the immobilisation method, plutonium oxide is vitrified or formed into a ceramic together with highly radioactive fission products. Vitrification is a technology already developed for treating highly radioactive waste and is currently used in several countries, but it has limits for plutonium application because glass is thermodynamically unstable and over geological timescales can crystallise, losing containment capacity. Ceramisation appears more chemically stable over long timescales and allows storage of a greater quantity of highly radioactive materials.

The troubled history of the PMDA

The bilateral Russian-American agreement Concerning the Management and Disposition of Plutonium Designated as No Longer Required for Defense Purposes and Related Cooperation (PMDA) was signed in 2000 and amended in 2006; finally, with the Plutonium Disposition Protocol of April 2010, it entered into force in July 2011.
The US had a stockpile of around 92 t of separated plutonium, 61.5 t of which were declared excess to military needs. Russia declared it had 50 t of weapons-grade plutonium in excess of its needs, while total stocks were estimated at 128 t.
The agreement envisaged that each party would eliminate at least 34 t of weapons-grade plutonium (at a rate of at least 1.3 t per year) and jointly work towards disposing of further quantities, either as MOX fuel or by other agreed methods, under reciprocal control and inspections involving the IAEA, ensuring health safety and environmental protection.
The 2000 agreement envisaged reducing the plutonium into MOX for use in reactors with moderated neutrons according to a precise twenty-year programme starting in 2002. The initial plan proved unworkable, both because of delays in constructing MOX production facilities and because of insufficient US contributions to support the Russian programme.
In 2007 Russia cancelled the project to use MOX in water-moderated reactors, having decided to favour the use of plutonium in fast neutron reactors BN-600 and BN-800 (then under construction). In the same year the US began construction of a MOX production plant at the Department of Energy’s Savannah River Site, which immediately proved problematic. Following these difficulties, negotiations to revise the PMDA began in 2008 to adapt it to the new situation, leading to the drafting of the definitive 2010 protocol.
The new protocol allowed Russia to use only fast reactors, introducing specific conditions on their mode of operation and on reprocessing of the spent fuel from all Russian reactors, both fast and water-moderated; more stringent control measures were defined; the two countries committed to begin actual plutonium disposition by 2018; the US envisaged a financial contribution of $400 million to Russia, distributed over the years, in return for the results achieved by the Russians.The protocol also reconfirmed IAEA involvement for international monitoring and verification of the disposal process.
The US programme pursuing the “MOX route” encountered serious technical and organisational problems as well as large cost increases (from a few billion to many tens of billions of dollars), so the Obama administration in January 2016 decided to terminate the project and pursue an alternative “dilute and dispose” approach.
The chosen method consisted of mixing the plutonium with an inert, non-radioactive material for direct disposal in the Waste Isolation Pilot Plant (WIPP) in New Mexico — an experimental geological repository 500 m deep, authorised to store transuranic radioactive waste for 10,000 years. This approach was estimated to be implementable decades sooner than MOX, at much lower cost and with fewer risks.
Russia argued that the new US plan did not respect the terms of the agreement because it did not change the plutonium’s composition from weapons-grade to reactor-grade. The original agreement allowed changes to the disposal method by mutual consent, but the United States had not yet entered into formal talks with Russia about the US alternative approach.
Thus on 3 October 2016 President Vladimir Putin ordered suspension of the agreement because, with the new approach, the United States could “recover the plutonium, reprocess it and reconvert it to weapons-grade.” Since then there have been no attempts to negotiate a revival of the agreement or otherwise address the problem of disposing of weapons-grade plutonium.

Recent developments

Russia continues to consider plutonium a fundamental energy resource. It has developed MOX production, using both weapons-grade and reactor-grade plutonium, for the BN-800 fast reactor, which has been fully operational since 2020. For the fast self-sustaining reactor Brest-300, at an advanced stage of construction, a ceramic fuel composed of uranium-plutonium nitride with 13.2% plutonium has been developed, offering greater thermal stability and radiation resistance than traditional oxide-based fuels.
In the US, the dilute-and-dispose strategy encountered significant technical and organisational problems, as well as issues concerning safety and environmental impact control. Only in January 2024 did the National Nuclear Security Administration release its report with the operational definition of the method, clarifying the roles of the various Department of Energy laboratories involved: the plutonium is to be converted to oxide, mixed with an adulterant, pressed and encapsulated in containers for final disposal in the WIPP repository. It is estimated that 400 kg of weapons-grade plutonium are currently disposed of at WIPP.
On 23 May 2025, by four executive orders, President Donald Trump completely reversed the American position on plutonium, recognising it as a fundamental energy resource.
The executive order Deploying Advanced Nuclear Reactor Technologies for National Security instructs the Department of Energy (DOE) to “identify all uranium and plutonium useful in DOE inventories that can be recycled or converted into nuclear fuel for reactors in the United States,” while the executive order Reinvigorating the Nuclear Industrial Base orders: “the Secretary of Energy will suspend the programme of dilution and disposal of excess plutonium. In place of that programme, the Secretary of Energy will establish a programme for disposition of excess plutonium through its processing and provision to industry in a form that can be used for fuel fabrication for advanced nuclear technologies.”
On 21 October the Department of Energy actually published the plan to “dispose of excess plutonium” — about 19.7 tonnes in both oxide and metal form. A solicitation for private companies describes the plutonium offered and the “thresholds” potential bidders must meet. The DOE requires submissions “with detailed recycling and processing plans, including financing commitments and a schedule for the use of the plutonium materials as nuclear fuel for reactors in the United States.”
Bids must be submitted by 21 November and initial selection is expected by the end of the year. Four companies have already expressed interest in acquiring that plutonium.
According to the International Panel on Fissile Materials, in 2024 world stocks of separated plutonium reached 565 tonnes. Of this material, 425 t were produced outside military programmes, are subject to non-use obligations or are not directly suitable for military use. Non-nuclear-weapon states globally hold 46.08 tonnes of separated plutonium, almost all of it in Japan (45.1 t, of which 9.2 t are on site). Spain, Switzerland and the Netherlands hold civil plutonium all stored abroad. On 26 February this year the 1.58 t of Italian plutonium deposited in the United Kingdom passed into UK ownership.
About 140 tonnes of plutonium remain in weapons or available for such use, sufficient for 35,000 warheads, with no effective international control, since UN efforts to launch “a non-discriminatory, effectively verifiable multilateral treaty that would ban production of fissile material for nuclear weapons or other explosive devices” (the Fissile Material Cut-Off Treaty, FMCT) have been stalled for decades in the Conference on Disarmament in Geneva.
The need for a ban is regularly raised at the review conferences of the Treaty on the Non-Proliferation of Nuclear Weapons, so far without progress: will next year’s conference be able to unblock the situation, or are we definitively entering a “plutonium civilisation”?