Tracking highly enriched uranium and plutonium, the key nuclear weapon materials

GE-Hitachi announced that it intends to leave the Global Laser Enrichment joint venture that was formed to develop Silex technology. Here is the statement that the company made available to IPFM:


GE Hitachi Nuclear Energy (GEH) has informed Cameco and Silex of its desire to reduce its equity interest in Global Laser Enrichment (GLE). This decision was made due to evolving business priorities at GEH and follows the restructuring of GLE operations announced in 2014. GEH remains committed to maintaining the safety and security of the technology and any sale or transfer of GEH's interest in GLE would be subject to government review and approval.

The company received an NRC license to build an enrichment facility in Wilmington, NC in 2012 and indicated its intent to build an enrichment plant in Paducah, KY in 2014. No construction has started at either site.

Australian company Silex Systems reportedly expressed interest in acquiring the GE-Hitachi share in GLE.

Yves Marignac and Mycle Schneider

On 24 February 2016, operator Areva and the French Nuclear Safety Authority (ASN) released information about serious corrosion problems challenging the safety of high-level liquid waste evaporators at the French spent fuel reprocessing plants at La Hague. Impact on the operational performance will also increase pressure on spent fuel storage capacities and exacerbate the financial situation of the virtually bankrupt operator.

The corrosion problems at La Hague were identified through conformity checks requested as part of an in-depth decennial safety review of the UP3 plant. Such a procedure, which has been applied to French reactors since startup, was only introduced for fuel-chain facilities by the 2006 nuclear security and transparency law. The first application to UP3 started in 2010. This plant and its sister plant UP2-800 respectively started operation in 1989 and 1994 with a 30-year design lifetime.

The evaporator corrosion is the first of a number of ageing problems expected to develop over the coming years. The six evaporators (three on each reprocessing line) are large stainless steel boilers heated by pressurized half-tubular welded circuits circulating on their outer surface, which concentrate liquid waste arising for the chemical separation of plutonium and uranium in spent fuel, prior to the vitrification and conditioning of this waste. While their safety requires a designated minimal thickness of steel to be maintained in the circuits, they are subject to corrosion mostly due to the acid nature of the solution they are exposed to.

A projected rate of the corrosion mechanism was accounted for in the initial design. However, it was not planned to closely monitor the evolution of the corrosion, as the lack of access within the reinforced concrete structures surrounding the evaporators and the level of radioactivity in the rooms make direct measurement difficult. Under request of ASN, measurements were performed for the first time in 2011 on two evaporators (one for each plant). These tests, confirmed in 2012, showed a corrosion rate higher than projected.

The ASN therefore requested Areva to conduct more extensive measurements on all evaporators. The latest results of the tests conducted in 2014-2015, obtained in December 2015, confirm the initial findings. Although Areva claims to modify operation to reduce the ongoing corrosion, at the observed rate, the wall thickness could still rapidly drop below the required minimum, which ASN said could trigger the decision "to enforce the shutdown of the plant" as early as 2018 for the most corroded evaporator, and gradually until 2021 for the others . The Institute for Radiation Protection and Nuclear Safety (IRSN) issued a number of recommendations including upgrading of inspections, monitoring and more frequent rinsing of the piping system. All of the recommendations will likely affect the performance of the facilities.

The operator hardly anticipated this situation. In a meeting of the Local Information Commission (CLI), on 25 February 2016 in Cherbourg, Areva said it plans for the replacement of all evaporators by 2021 (the presentation is not yet available online). This would be faster than ASN's own estimate, as Chairman Chevet said during a Parliamentary hearing four days later that it would require at least six years to manufacture a new evaporator . The replacement of evaporators is also likely to require the building of new workshops and the subsequent relocation of the piping system, which could prove technically challenging. Areva's trade union representatives stated at the CLI meeting it could require to stop reprocessing for up to three years to carry on replacement work.

The experience of the THORP plant at Sellafield in the UK, where the addition of a fourth evaporator to the reprocessing plant started in 2006, illustrates the kind of delays and cost escalations at stake. The startup of the evaporator is six years beyond schedule and still delayed, while its projected cost skyrocketed from an initial £90 million to a current £670 million estimate. In 2015, Areva's own projected cost was said to be €350 million for the change of three evaporators.

A more or less lengthy interruption of reprocessing could have more dramatic impacts, in a context where spent fuel storage capacity is already feared to fall short in the coming decade.

The cumulative nominal capacity of the four spent fuel pools operating at La Hague is 17,600 tHM, but their actual capacity, taking into account operational conditions, is rated at 12,352 tHM (or 2,796 storage positions). According to Areva's CLI presentation, a total of 9,935 tHM of spent fuel was stored in the pools as of 31 December 2015 . With at least 175 storage positions (equivalent to 780 tHM) occupied by diverse materials and possibly around 110 storage positions (equivalent to 490 tHM) occupied by unirradiated scrap MOX fuel (Areva's estimate does not account for the specific presence of this material in the La Hague pools), the available capacity could be as low as 1,150 tHM. This roughly corresponds to the amount of spent fuel unloaded annually from EDF's 58 reactors.

With EDF's own spent fuel pools at reactors sites close to saturation and ASN vetoing plans to densify storage, it is projected that additional spent fuel storage capacities could be needed by 2025. EDF is therefore planning to introduce later in 2016 a project for a new centralized interim spent fuel storage pool, which it would use in priority for spent MOX and reprocessed uranium fuel that is currently not reprocessed. Under current planning, design, siting, licensing and construction might take at least ten years.

The corrosion of La Hague evaporators might long before lead to the occlusion of the French spent fuel management scheme. With Areva's and EDF's finances stretched to the limits, and the industrial infrastructure reaching the end of the lifetime or simply inexistent--no reprocessed uranium is currently reused--this would be the appropriate time to reassess the entire strategy.

Areva lost €10 billion ($11.3 bn)--six times its stock market value--over the past five years and the French government has promised to save it by injecting €5 billion in capital. However, it is uncertain whether the European Commission will accept the measure under EU competition rules. EDF has rapidly increasing production costs, a shrinking client base that uses decreasing amounts of power and faces ferocious competitors. It is hard to see how EDF will pay back its €37.4 billion ($42.2 bn) debt under these conditions. Both companies have pledged to massively cut jobs. At La Hague alone, Areva plans to cut about 500 jobs of a total workforce of 3,000. Safety and security are at risk.

While the move to dry-storage would also take some initial investment, abandoning the plutonium economy would save huge amounts of money overall. Areva is already a leader in dry-cask fabrication in the U.S. It could add plutonium conditioning, and extend its decommissioning and waste management portfolio. Business guaranteed.

Edwin Lyman and Frank von Hippel

Senators Lindsey Graham and Tim Scott of South Carolina have interpreted remarks by Russian president Putin on the 2000 U.S.-Russian Plutonium Management and Disposition Agreement (PMDA) as requiring that the United States continue with the costly MOX project in South Carolina. President Putin objected to the less costly dilute and dispose approach proposed by the Obama Administration because the plutonium could be recovered and "converted into weapons-grade plutonium again." RT reported a Rosatom spokesman explaining, "The only way to irreversibly turn plutonium into a material not usable in a nuclear weapon is by changing its isotope composition. Any chemical method is reversible."

This position has little technical merit, because the plutonium that will be produced by Russia's disposal approach, irradiation in its BN-800 plutonium breeder reactor, may not be weapon-grade but it will be weapon-usable. Furthermore, Russia, unlike the United States, intends to separate the plutonium in the irradiated BN-800 fuel and the weapon-grade plutonium produced in the plutonium-breeding blankets around the BN-800 core so that it can be reused, which will also make it susceptible again to diversion by non-state groups. (In the PMDA, Russia has committed, however, not to separate the disposition plutonium or the plutonium produced in the BN-800 blankets until all the 34 tons have been irradiated.) In the interim, calculations show that the blanket assemblies would contain such a low admixture of fission products that the plutonium in them would have to be considered separated plutonium by the PMDA's low standard for a protective radiation field.

Nevertheless, if need be, Russia's insistence that the isotopics of U.S. excess weapon-grade plutonium be degraded could be dealt with at a much lower cost than through irradiation in MOX. As the report of DOE's Red Team on plutonium disposition pointed out, reactor-grade plutonium could be imported from the U.K. for blending with U.S. weapon-grade disposition plutonium in order to satisfy Russian concerns. The report estimated that 3-9 MT of plutonium would need to be imported in order to achieve the PMDA standard for non-weapon grade of a Pu-240/Pu-239 ratio greater than 0.1.

Other stocks of reactor-grade plutonium are available around the world, including a Japanese-owned stockpile of 21 tons of plutonium (as of the end of 2014) that is stranded in the U.K.because of the failed UK MOX program. Import of about 7 tons of this material would relieve Japan of part of its plutonium disposition burden and also assist the U.S. in proceeding with plutonium disposition in the most cost-effective manner. Japan could well be willing to pay a modest sum for the U.S. to take this plutonium off its hands. Plutonium transport across the North Atlantic would be required but this would be safer than the ongoing transport of plutonium in MOX fuel between France and Japan.

If the U.S. assumed title to 7 tons of Japanese plutonium, its PMDA-related plutonium disposal problem would be increased from 34 to 41 tons to be disposed of in WIPP or another underground repository. This would still be a small challenge compared to having to convert the 34 tons of plutonium into reactor fuel and either finding or building reactors to irradiate it.

We recommend that NNSA begin studying the isotopic-dilution alternative and highlight it publicly as a possible approach should Russia continue to raise the issue. At a minimum, it would provide a clear and direct response to Russian's government and to those in the U.S. who support Russia's position.

PDF copy of the letter with footnotes

The University of Alberta in Edmonton began shutting down its SLOWPOKE-II reactor. The shutdown process is expected to be completed in late 2017.

SLOWPOKE-II Alberta is one of the two reactors of this type that still use HEU fuel. Another reactor is operated by Saskatchewan Research Council in Saskatoon. Canada is also using HEU targets to produce medical isotopes at its NRU reactor.

President Putin of Russia, speaking at a meeting with journalists, raised concerns about the possible changes in U.S. plutonium disposition plan. According to the official transcript of the meeting, he made the following comments:

[...] back in the early 2000s, the Americans and we agreed on destroying weapons-grade plutonium. [...] Each side had 34 tonnes. We signed this agreement and settled on the procedures for the material's destruction, agreed that this would be done on an industrial basis, which required the construction of special facilities. Russia fulfilled its obligations in this regard and built these facilities, but our American partners did not.

Moreover, only recently, they announced that they plan to dispose of their accumulated highly enriched nuclear fuel by using a method other than what we agreed on when we signed the corresponding agreement, but by diluting and storing it in certain containers. This means that they preserve what is known as the breakout potential, in other words it can be retrieved, reprocessed and converted into weapons-grade plutonium again. This is not what we agreed on. Now we will have to think about what to do about this and how to respond to this. [...] [O]ur partners should understand that [...] serious issues, especially with regard to nuclear arms, are [where] one should be able to meet one's obligations.

The comment refers to the recent U.S. administration decision to discontinue construction of the MOX Fuel Fabrication Facility (MFFF) at the Savannah River Site and to begin conceptual design of the dilute and dispose option, which would not involve irradiation of the disposed plutonium. However, the U.S.-Russian Plutonium Management and Disposition Agreement (PMDA), which was completed in 2010, specifies that the United States will dispose its plutonium by burning it in light water reactors (Article III.2). Changing the disposition method will require formally amending the agreement, which cannot be done without Russia's consent. Supporters of the U.S. MOX program have used this fact to argue that the MFFF construction should continue.

A number of prominent U.S. experts have noted in a letter to the Secretary of Energy that this change would not be unprecedented. Indeed, the initial agreement, reached in 2000, was amended in 2010 to accommodate the changes in plutonium disposition plans in Russia and the United States. However, Russia may choose to argue that the dilute and dispose option that the United States is planning to pursue is not entirely compatible with the PMDA's intent. The original 2000 agreement assumed that plutonium would be either consumed in a reactor or immobilized in containers where it would be protected by a radiation barrier (Article III.2 and Annex on Technical Specifications, Section II).

This appears to be exactly the argument that was made by the Russian president in his remarks. It should be emphasized, however, that he did not say that Russia will reject the U.S. proposal to amend the PMDA (which would be made once the new disposition method is determined). It is very likely, however, that Russia will use this issue to apply certain political pressure on the U.S. administration.

In its national statement at the 2016 Nuclear Security Summit, the United Kingdom announced that

The UK will transfer around 700kg of Highly Enriched Uranium (HEU) to the United States. In return, the United States will provide HEU in a different form for use in European reactors to produce medical isotopes used in the diagnosis and treatment of conditions including thyroid cancer.

The material in question appears to be part of stock of "unirradiated high enriched uranium fuels" described in the "Exotic Fuels and Nuclear Materials - Dounreay: Credible Options" report, issued by the U.K. Nuclear Decommissioning Authority in February 2012. The report describes this material, named "group 2 material" in the text, as follows (p. 11):

There is approximately 1 tonne of group 2 material stored on the site, in the form of oxide powders and pellets, and also some uranium metal and alloys. It is stored individually in several locations in small quantities [...].

The unirradiated high enriched uranium has a wide range of enrichment values, presenting operational and disposability difficulties. Some of the items such as swab ash, slag and graphite crucibles contaminated with small quantities of unirradiated high enriched uranium are irrecoverable, are considered to be uranium contaminated waste which has a lower security classification.

All this material contains uranium with enrichment above 20%, although exact U-235 contents is unknown. It is possible that 700 kg included in the U.K.-U.S. exchange is the amount of recoverable material. It is not clear if it refers to the mass of uranium in the material to be sent to the United States.

The 2012 NDA report identified several "credible" options for long-term handling of this material, one of which was to "send material overseas for reprocessing and utilise product" (p. 15). A subsequent report, released in February 2013, named "[transfer] to Sellafield for long term management" the preferred option for dealing with the material. As documented by CORE, a U.K. environmental group, the decision to send HEU to the United States was made without an appropriate consultation with the public.

According to a comment from NNSA, obtained by Tom Clements of the Savannah River Site Watch, U.K. HEU cannot be directly used in the medical isotope production process. It will be down-blended to LEU that could be then used in reactor fuel. NNSA would not name the where the material will be stored in the United States, but it stated that it will not be sent to the Savannah River Site. Most likely the down-blending will be done at Nuclear Fuel Services in Erwin, Tennessee.

The nuclear security value of the HEU exchange is highly questionable. While the removal of HEU from Dounreay will improve the security situation at the site, the overall security benefit is likely to be much smaller because of the risks associated with the transfer of the material.

More importantly, the terms of the exchange will effectively legitimize the continuing supply of U.S. highly-enriched uranium to Europe, where it is used for medical isotope production. The last transfer of this kind was authorized in February 2015.

At the 2016 Nuclear Security Summit Argentina and the United States announced that Argentina completed elimination of all highly-enriched uranium that remained in the country.

According to GTRI data, most of the material was removed to the United States in 2001-2007. However, about 4 kg of HEU remained in the country, since it was ineligible for take back. At the Nuclear Security Summit Argentina announced that it down-blended and disposed of that material. As a result, Argentina (and indeed the entire Latin America and Caribbean region) is now considered HEU free.

Kazakhstan and the United States announced in a joint statement that Kazakhstan successfully completed conversion of the VVR-K research reactor, operated by the Institute of Nuclear Physics, in Alatau, near Almaty. The HEU associated with the reactor has been eliminated by down-blending "at Kazakhstan's nuclear fuel factory" (apparently the Ulba Metallurgical Plant in Oskemen, formerly Ust-Kamenogorsk). According to the statement, Kazakhstan made a commitment to remove all spent HEU fuel from the site. Some spent fuel of the VVR-K reactor was transferred to Russia in January 2016.

Kazakhstan also confirmed its commitment to convert the IVG.1M and IGR reactors to LEU as soon as suitable fuel is available. IPFM reported earlier that the work on conversion of the IVG reactor is underway.

The U.S. administration published an update on the status of the U.S. stock of highly-enriched uranium:

  • As of September 30, 2013, the total U.S. HEU inventory was 585.6 metric tons.
  • Of this amount, 499.4 metric tons was for national security or non-national security programs including nuclear weapons, naval propulsion, nuclear energy, and science.
  • Of the remaining 86.2 metric tons, 41.6 metric tons was available for potential down-blend to low enriched uranium or, if not possible, disposal as low-level waste, and 44.6 metric tons was in spent reactor fuel.

According to the press-release, the inventory in 1996 was 740.7 metric tons (as reported by DoE in 2001). Also, the ongoing HEU disposition program down-blended additional 7.1 MT of HEU since 30 September 2013, suggesting that the current inventory is 578.5 MT of HEU, of which 34.5 MT is marked for down-blending or disposal.

In another release issued today, the administration reported that "the United States has down-blended 148 MT of this HEU to low-enriched uranium so it can no longer be used for nuclear weapons."

The first of the two China's Miniature Neutron Source Reactors (MNSR) started operations with LEU fuel. The reactor, known as MNSR IAE, is operated by the China Institute of Atomic Energy in Beijing. It first reached criticality in 1984. The conversion was a result of a cooperative project between China Atomic Energy Authority (CAEA) and U.S. Department of Energy.

China has another reactor of this type, MNSR SZ, at the Shenzhen University, Guangdong. The MNSR IAE conversion brings the number of HEU research facilities in China to three - MNSR SZ, ZPR FAST critical assembly, and CEFR experimental fast reactor.