The most common compound of UOC is triuranium octoxide (U3O8), often called yellowcake, though some processes produce other compounds such as ammonium diuranate (ADU), uranium tetrafluoride (UF4), uranyl peroxide (UO4) or uranium trioxide (UO3). U3O8 contains 85 per cent uranium by weight. The U3O8 content of UOC can vary from around 76 per cent to more than 99 per cent.
There are four primary techniques for uranium recovery: open pit mining, underground mining, in situ leaching and heap leaching. Open pit mining is used to recover uranium located near the earth’s surface. Explosives are used to break up the rock, which is loaded on to large dump trucks and then to crushers and separators to prepare the ore for leaching. Uranium mines such as the Ranger mine in Australia, the Rössing mine in Namibia and the Arlit mine in Niger are open pit. When uranium is located at depths that make the open pit method uneconomical, extraction is done by digging a shaft underground into the uranium deposit. Horizontal tunnels are then excavated to access the ore, which is broken up by explosives or boring machines. Mechanical conveyors then hoist the broken rock to the surface. Russia’s Priargunsky mine and Canada’s MacArthur River and Cigar Lake mines are underground. At Cigar Lake, where concentration levels are higher than average, the rock is crushed to a finer consistency and mixed with water to produce a slurry that is pumped to the surface and transferred to a mill for further processing. Given its high concentrations, Canada is the only producer that has to ‘water down’ its rock.
Heap leaching uses a series of chemical reactions that absorbs specific minerals and then re-separates them after extraction. After the ore has been removed and crushed, it is placed into heaps on a protective liner which is sprayed with a leaching solution (alkali solution or sulphuric acid) to separate the uranium from the ore. The Caetité uranium mine in Brazil is open-pit and uses the heap leaching technique as does AREVA’s Somair mine in Niger.
In situ leaching (ISL), also known as in situ recovery (ISR), is similar except that the ore is not mined; instead the leaching solution is pumped through a network of piping into the deposit, dissolves the uranium and pulls a pregnant solution up to the surface. As such, ISL extracts uranium without excavating it. Mines in Kazakhstan and United States are predominantly ISL.
The uranium is then precipitated and finally filtered, dried and packaged into 200 litre drums (400kg/881lbs) or four-ton hoppers ready for transport by land and/or sea to a conversion facility. During conversion, the high purity required for nuclear fuel is achieved by dissolving UOC in nitric acid, and then filtering and treating the solution with chemical solvents. The resulting uranyl nitrate is more than 99.95 per cent pure. It is reconverted into uranium oxide, which in turn is converted into highly volatile UF6 which is the feedstock for centrifuges in the enrichment process. For heavy water reactor fuel, enrichment is not required; instead UO2 is produced from the uranyl nitrate and shipped directly to a fuel fabrication plant.
The output from approximately 50 operating uranium mines worldwide is delivered to only a handful of conversion facilities – in Canada, China, France, India, Russia, and the United States. Until its closure in August 2014, UOC was converted at the Springfields conversion plant in the United Kingdom.
Of these countries, Canada is the only one that does not possess nuclear weapons. China, France, Russia, the United Kingdom and the United States are officially recognized nuclear weapons states under the Nuclear Non-Proliferation Treaty (NPT) while India – not a party to the NPT – became the sixth major destination for UOC after its re-entry in 2008 to the global civilian market.
The majority of the world’s uranium therefore passes through one of these countries before it is further processed as fuel for a nuclear reactor. For example, a drum of yellowcake leaving a mill in Australia can travel 5,000 km (approx. 3,106 mi) to China, 15,000 km (approx. 9,320 mi) to Europe or upwards of 20,000 km (approx. 12,427 mi) to conversion facilities in Illinois, United States or Ontario, Canada.
The transport of shipping containers of UOC from mine site to conversion facility creates a potential security vulnerability, given the significant distances travelled, the number of transfers of authority that a shipping container goes through, often across several borders, requiring multiple approvals in multiple jurisdictions. Such vulnerabilities are addressed by the IAEA through its safety and security standards and through industry best practice.
Physical protection practices can be quite rigorous – as mine owners in conjunction with transporters and in some instances governments put in place specific measures to manage and mitigate risk. Precautions often include designated routes requiring designated rest stops, requirements for additional drivers, and GPS tracking on trucks to monitor location and driving behavior. The fitting of container bolt seals to shipping containers or dry van trailers assists in detecting any tampering with cargo containers during intermediate or long-term storage, a technique used for many high value cargoes.
A container carries around 20-35 drums, or approximately 7-12 tonnes of uranium. Ten metric tonnes of uranium is defined as a “significant quantity,” i.e. the quantity for which the possibility of manufacturing a nuclear explosive device cannot be excluded. The “significant quantity” is the standard agreed to by the international community as a basic parameter for IAEA safeguards.
As of mid-2017, no accident beyond level 1 on the International Nuclear Event Scale (INES) has ever been reported for nuclear material transportation. UOC transportation follows international rules related to nuclear material transportation with respect to both containment and control. These measures should be continuously evaluated against threats to ensure a graded approach when suppliers are experiencing heightened security environments and the risk of sabotage and unauthorized acquisition requires increased protection, inspection and enforcement.
Conversion facilities face a number of economic and efficiency challenges. Currently, countries are aiming or attempting to optimize conversion rates and cut costs as existing conversion facilities are aging and the uranium market is struggling with oversupply, low demand and a low spot price.
Along with the conversion facilities in Canada, China, France, Russia, and the United States (and more recently India), there are a handful of smaller conversion facilities located in Argentina, Brazil, Iran, Israel, North Korea, Romania and Pakistan.
Of these countries, Israel, North Korea and Pakistan are non-NPT states that possess nuclear weapons and are therefore military facilities and not part of the civilian nuclear fuel cycle.
Brazil is running a pilot facility for its nuclear propulsion program at the Aramar Experimental Center while South Korea operated a small, pilot conversion facility between 1982 – 1992.
Secure transport of “yellowcake” is just one area of concern as uranium flows around the globe. Another is the path from “ore to bomb.”
In most cases the transport of UOC involves lengthy transits from mine sites to conversion facilities. The shipment of UOC from Australia involves multi-modal road, rail and sea transport, whether transported to Asia, Europe or the United States. As the mines are located in relatively remote regions, UOC travels by truck to ports in Adelaide (in South Australia) or Darwin (Northern Territory). Operations are well managed and monitored by the mining companies, with oversight from the federal, state and territory governments. From the Olympic Dam uranium mine to North America, UOC is transported by truck from the mine to Adelaide where the then crosses the Pacific Ocean to the west coast of America. Deliveries are then transported by road to conversion facilities in USA or Canada.
UOC shipped from Kazakhstan to India travels at least 21,000 km from mines in the central south Chu-Sarysu province to India’s Hyderabad conversion facility. The route includes 4-5,000 km by rail in Kazakhstan and Russia to reach the port of St. Petersburg where UOC is then loaded onto ships for another 16,000 km (8675 nautical miles) through the Baltic and North Seas, the Strait of Gibraltar and the Mediterranean Sea before sailing through the Suez Canal, the Gulf of Aden and the Arabian Sea to reach the port of Mumbai. UOC then travels on land to the conversion facility at Hyderabad.
In Africa, UOC from the Arlit mine in Niger travels 1,600 km (approx. 994mi) by truck to Parakou in Benin. The road it travels was constructed especially for transporting uranium to the Benin border in the 1970s. This road, dubbed the “Uranium Highway,” is part of the Trans-Sahara Highway system. In Parakou, drums are loaded onto trains which travel another 400 km (approx. 248 mi) to Cotonou harbor from where they are shipped 4,500 km (approx. 2,796 mi) to Le Havre in France and then transferred onto rail for the final journey into the conversion facility in the south of France.
In 2014, the longest uranium transport route in Africa was for the uranium mined at Kayelekera in Malawi, which passes 2,500 km (approx. 1,553mi) through Malawi, Zambia and Namibia to Walvis Bay. Access to points of exports along the east coast of Africa would substantially reduce the inland transit from Malawi and this remains a “work in progress”. Early in 2014 the mine was put on care and maintenance until the price and economics of uranium production improve.
ALTONA IN DETAIL
In December 2010, some 340 tonnes of UOC, packed inside 24 shipping containers (each loaded with 35 drums) were loaded onto the MCP Altona, headed out of Vancouver to China. Somewhere between Hawaii and Midway Islands a number of drums and containers were damaged, spilling yellowcake into the cargo hold. No yellowcake was spilled into the ocean. Cameco made the decision for the vessel to return to British Columbia where it was docked at the Port of Vancouver while Cameco and Canadian authorities oversaw a well-managed cleanup process. By April the spilled yellowcake had been recovered, sent back to Saskatchewan and the ship cleaned. The Canadian Nuclear Safety Commission and Transport Canada declared the Altona clean and safe by early May 2011. The clean-up cost $8 million. Post-clean-up the lawsuits ensued, leaving the Altona docked in Vancouver until a court ruling in 2013 allowed the ship to be re-sold. It has been renamed and bought by an Indonesian company. In 2014, after two years of negotiations with industry, the Port of Vancouver re-allowed UOC shipments.
CONVERSION BY COUNTRY
The conversion plant in Cordoba produces UO2 via nitrate (NO3/UO3) from Argentinean yellowcake or impure (usually imported) U308 with a design capacity of 200tU/yr, however it operates normally at 140tU/y. The process implemented at Cordoba covers all the steps to filtering and purifying uranyl nitrate liquors and the corresponding steps to adjust the concentration in order to precipitate pure ammonium uranyl carbonate and its subsequent reduction to UO2. In this facility, natural or low enriched uranium scrap recovery campaigns are scheduled once or twice a year linked to the country’s operational plans for the fuel fabrication plant. The feed material during these scrappage campaigns are under safeguards. The facility re-started the operations in 2017. The operations were suspended during 2016 and part of 2017 due to local licensing issues.
There is another conversion facility located in Pilcaniyeu, Bariloche, which had a 60tU/yr capacity to produce UF6 starting from pure UO2. The plant was shut down in late 80´s but was declared under IAEA safeguards agreement (1994) as well as bilateral safeguards (1992) under the Brazilian-Argentine Agency for Accounting and Control of Nuclear Materials (ABACC). There is a diffusion enrichment plant co-located at Pilcaniyeu, which operated from 1983 to 1989. A mock-up at this facility re-started operations in 2015.
There is a new conversion plant under construction in Formosa to produce UO2 with a design capacity of 230 tU/y. It uses the same process as the Cordoba plant and its operation should start in 2020
In Brazil, the navy runs pilot and testing facilities for its nuclear submarine propulsion programme at the Aramar Experimental Center, located in Iperó, Region of Sorocaba, in the state of São Paulo. Aramar’s infrastructure includes a partially constructed uranium conversion plant, which will produce UF6 (via nitrate) for use in the Brazilian enrichment programme. The process route is UOC → NO3 → ADU → UO3 → UF4 → UF6. According to the Brazilian-Argentine Agency for Accounting and Control of Nuclear Materials (ABACC), the conversion plant at Aramar has been redesigned to allow for verification of material. It has a designed capacity of 40t/yr. As of January 2018, the UF6 Conversion Pilot Plan at Aramar is in the process of commissioning to obtain the operation authorization from the Nuclear National Authority (CNEN) and Environmental Authority (IBAMA).
In addition to the Aramar Experimental Center, Brazil is planning to build another UF6 conversion unit at the Nuclear Fuel Factory (FCN), located in Resende in the state of Rio de Janeiro. An industrial complex of production units, the FCN currently operates four stages of the nuclear fuel cycle—uranium enrichment, UF6 to UO2 conversion (reconversion), production of pellets, and fabrication of the fuel assemblies for energy generation in nuclear reactors. Canada had converted Brazil’s UOC until AREVA took it over in 2010 under a 5-year contract with the INB. In 2015, the two sides extended the contract until December 2018. With the completion of this unit, the FCN will complete the nuclear fuel cycle.
Although technically a single process, the refining and conversion of natural uranium in Canada takes place at two separate facilities located approximately 700 km (435 miles) apart: refining in Blind River and conversion in Port Hope, both located in the province of Ontario and both owned by Cameco Corporation.
Cameco’s Blind River Refinery is the world’s largest commercial uranium refinery. In operation since 1983, it receives UOC from mines and mills in Canada and around the world and refines it into uranium trioxide (UO3), most of which is sent directly to Cameco Port Hope, although some is exported. The capacity of Blind River is approximately 18,000 tUO3 per year. The current license is valid until February 2022 and includes an increase in production capacity from 18,000 tUO3 to 24,000 tUO3 when certain conditions (including upgrades) have been met and the uranium market becomes more profitable.
The conversion plant at Port Hope has a longer history, going back to 1935 as a radium extraction facility. Today, it converts UO3 into either UF6, which is exported for subsequent enrichment, or UO2, which is primarily used for the domestic production of CANDU fuel. The throughput of the UF6 plant is approximately 12,500tU per year while the UO2 plant processes around 2,000tU per year. In February 2017, Port Hope was granted a ten-year license until February 28, 2027.
There is very little information publicly available on China’s uranium conversion facilities. What is known is that its conversion capacity has historically been small, far below that of other international converters, but facilities are rapidly being modernized with annual capacity expanding to meet a growing nuclear energy program.
A conversion facility at Lanzhou in Gansu province with a capacity of 1,000 tU started operation in 1980 but likely closed in the late 1990s. A plant with a 5,000 tU throughput is reportedly operating at the site at about 80% capacity. Another facility with a 9,000 tU capacity is expected to come online in 2017 or 2018.
Another conversion plant is located at Diwopu, Jiuquan, near Yumen in northwest Gansu province. The World Nuclear Association estimates the facility’s capacity at 500 tU, whereas Ux Consulting Company (UxC) reports the plant’s 2016 capacity at 5 million kgU/year (5,000 tU per year). According to a 2016 report by UxC, a new conversion facility was built at the Jiuquan nuclear fuel complex and should be operational in 2017, more than doubling the site’s capacity to 11,000 tU per year.
China Nuclear Fuel Corp is building a plant at Hengyang in Hunan province. UxC quotes this as 3000 tU/yr, with construction permit issued in October 2014 and operation expected in 2018.
The China National Nuclear Corporation (CNNC), owns and operates all of China’s domestic nuclear fuel cycle facilities.
Meanwhile, China’s plans for further conversion capacity at the new China Nuclear Fuel Element Co (CNFEC) plant at Daying Industrial Park in Heshan city, Guangdon province was cancelled in July 2013 in response to protests by the public. China National Nuclear Corporation (CNNC) and China General Nuclear Power Group (CGN) are currently exploring other locations in the Guangdong Province to resume the project. The plant’s conversion capacity is expected to be approximately 10,000 tU/yr.
The CNNC has also decided to pursue another nuclear fuel complex at the Cangdong Economic Development Zone near Cangzhou City in Hebei Province. The complex is set to reach full capacity in 2020 with a conversion capacity of 10,000 tU/year.
In 1958, France built a conversion plant at Malvesi (inaugurated in 1969), releasing the facility at Le Bouchet, which had been operating since 1948, for special or complementary production. Le Bouchet closed in 1971. Today, conversion is carried out at two separate sites in France. Natural uranium is purified and converted into UF4 at the AREVA Malvési plant, located in Narbonne, in the Aude region of France. Malvési receives UOC from AREVA (and other) mines globally and is the first step of fluorination to product uranium tetrafluoride (UF4). All UF4 produced at Malvési is transported to AREVA’s Pierrelatte industrial site (in France’s Drôme region) where it is converted into UF6.
Since 2007, both the Malvesi and the Pierrelatte plants have expanded and modernized, reaching a conversion capacity of 15,000 tU/yr.
The Nuclear Fuel Complex (NFC) at Hyderabad processes magnesium di-uranate (MDU, MgU2O7) from the uranium mine and mill at Jaduguda, Jharkhand. Impure MDU is dissolved in nitric acid to get Ammonium Di-uranate (ADU) and then calcined and further refined into sinterable UO2 powder which is converted into sintered pellets. All UOC imported into India is also processed at the NFC.
The Complex was established in 1971 and is responsible for the supply of nuclear fuel bundles and reactor core components for all the nuclear power reactors operating in India. The complex is operated by India’s Department of Atomic Energy. Natural uranium as well as enriched uranium fuel, zirconium alloy cladding and reactor core components are all manufactured at the NFC.
The Uranium Conversion Facility (UCF) at Esfahan contains process lines to convert yellowcake into uranium oxide and UF6. It began operations in June 2006. According to information provided to the IAEA, Iran carried out most of its experiments in uranium conversion between 1981 and 1993 at the Tehran Nuclear Research Center (TNRC) and other facilities at Esfahan. In 1991, Iran contracted to purchase a turnkey, industrial scale conversion facility from China. This contract was cancelled, but Iran retained the design information and built the plant on its own. Construction of the UCF began in the late 1990s.
The UCF consists of several conversion lines, mainly that for the conversion of yellowcake to UF6. The annual production capacity of the UCF is 200 tonnes of UF6. The UF6 is made for the uranium enrichment facilities at Natanz and Fordow. The UCF is also able to convert yellowcake, LEU and depleted uranium into uranium oxide and depleted uranium metal.
Israel is widely believed to possess a sizeable nuclear arsenal, but maintains a policy of nuclear opacity. It reportedly has a uranium conversion facility at Dimona that produces UO2 which can subsequently be manufactured into fuel for the IRR- 2 reactor. A UF6 conversion facility is also reported to be in operation, but its capacity remains unknown.
Kazakhstan is considering building what would be its first uranium refinery plant, following a 2012 agreement with Cameco. A feasibility study began in 2016. The plant will have the capacity to produce 6,000 tonnes of UO3 per year, and upon completion, Cameco’s Port Hope Facility also plans to provide UF6 conversion services. The project is still in the design stages.
Not much is publicly available on North Korea’s conversion capabilities, although it is understood that there are conversion activities located at the Yongbyon Nuclear site, which at least years ago, was known to convert yellowcake into UO2. The facility likely receives its UOC from mines at Pakchon and Pyongsan and is suspected of producing at least 18,800 kg of UF6 annually.
The Yongbyon Nuclear site was built in 1962 after an atomic energy agreement between North Korea and the Soviet Union, and has been the center of North Korea’s nuclear activity. The center reportedly includes a 5MWe reactor, an abandoned 50MWe reactor, a 25-30MWe light water reactor that is under construction, an enrichment plant, a radiochemical laboratory, centrifuge plants, and three waste storage facilities.
The Chemical Plant Complex (CPC), at the Dera Ghazi Khan Nuclear Site is Pakistan’s main conversion facility. It produces ammonium diuranate (ADU) from Pakistani yellowcake which in turn is converted to UO2, then UF4 and finally UF6. The site can produce 220 tonnes of UF6 per year and operates outside of IAEA safeguards.
The chemical purification and finishing of product as UO2 or UF4/UF6 is done at CPC. Reduction of uranium compound to uranium metal is carried out at the Uranium Metal Laboratory (UML), Atomic Energy and Nuclear Research Institute (PINSTECH), near Islamabad. All mining for uranium, its subsequent extraction and processing into UOC, chemical purification and refining into UO2 – or any other chemically pure uranium compound – and fabrication falls is solely carried out by the Pakistan Atomic Energy Commission (PAEC).
In November 2006, PAEC announced the construction of a Nuclear Power Fuel Complex (NPFC) for civil conversion, enrichment, and fuel fabrication under IAEA safeguards at Faisalabad, Pakistan.. The conversion facility within the NPFC- the Chemical Processing Plant (CPP) – is still under construction, but is expected to produce 400 tons of natural UF6 gas, 40 tons of enriched UO2 powder, and 30 Zr-4 ingots annually. The complex will fabricate fuel for local nuclear power plants, in particular for the reactors at Chashma Nuclear Power Complex. It will be under IAEA safeguards and managed separately from existing nuclear facilities.
Pakistan reportedly operates another conversion plant, the Islamabad Conversion Facility, at Islamabad that converts U3O8 into UO2, but the production capacity (and exact location) is unknown.
Uranium ore is processed at the Feldioara Uranium Ore Processing Plant, owned by the National Uranium Company (CNU). It has two modules. One (‘R’ type) is for uranium milling and concentration, with an annual capacity of 300t/yr U3O8. The other (’E’ type) is for refining and conversion to nuclear grade UO2. Both are operating at a reduced capacity of approximately 100t/yr. Feldioara has been qualified by the Atomic Energy of Canada Ltd (AECL) as a UO2 fuel provider for CANDU (Canadian deuterium uranium) reactors.
The Feldioara plant was built in 1976 for the extraction of uranium from the ore (using the depression alkaline leaching technique). Uranium transfer from the Bihor and Banat mines to the processing plant at Feldioara started in 1977 and the first samples of yellowcake (ammonium diuranate) were produced. The uranium refining facility (E plant) was commissioned in 1986 and the first batch of uranium dioxide sinterable powder for fabrication of nuclear fuel type CANDU was produced in Romania and delivered to the Pitesti Nuclear Fuel Plant.
Natural uranium is used by TVEL fuel company, a subsidiary of Rosatom, to make nuclear fuel for Russia’s own nuclear power plants and nuclear power plants in foreign countries, as well as to fulfill Techsnabexport contracts for uranium enrichment services and deliveries of enriched uranium product. As part of that process, natural uranium undergoes a conversion to uranium hexafluoride (UF6) and is then delivered to uranium enrichment plants.
Until recently, Russia had three uranium conversion facilities in operation: the Siberian Chemical Combine (SKhK, Tomsk Region, Siberian Federal District), the Angarsk Electrolysis Chemical Combine (AEKhK, Irkutsk Region, Siberian Federal District), and the Chepetsk Mechanical Plant (ChMZ, the Republic of Udmurtia, Volga Federal District). The former two facilities produced uranium hexafluoride (UF6). The facility at ChMZ produced uranium tetrafluoride (UF4), which was then supplied to AEKhK, where it was converted to hexafluoride. The combined annual output capacity of the three facilities was 25,000 tonnes of uranium (tonnes U as UF6). According to various estimates, however, only 35-55 percent of that capacity was actually in use. The equivalent figure for large uranium conversion facilities in other countries is in the range of 70-85 percent.
As part of its optimization and cost cutting program, Rosatom state nuclear energy corporation has decided to concentrate all its UF6 production at a single facility. The new conversion facility will be set up at SKhK to replace the existing one, which was built in 1949 for the Soviet nuclear weapons program. The SKhK site offers advantages over ChMZ and AEKhK in terms of the convenience of transportation of raw materials (i.e. natural and reprocessed uranium) and the UF6.
The conversion facility at AEKhK was shut down on April 1, 2014. ChMZ will follow after the launch of the first stage of the new conversion facility at SKhK. An estimated 12 billion rubles (more than $350 million USD) will be spent on building the new Rosatom conversion plant.
The new conversion facility will use natural as well as reprocessed uranium (RepU). Its projected output is 18,000tU per year for natural uranium, and 2,000tU per year for RepU. The original plan was to start building the new facility at SKhK in late 2013 and launch it in 2016. The decision however has been postponed with no specification of new deadlines due to an unfavorable market situation following the Fukushima accident and low prices for fossil fuels. The current annual output of SKhK is 12,000 tonnes and used for domestic purposes and foreign contracts.
The Korea Atomic Energy Research Institute (KAERI) at Taejon constructed a pilot conversion plant in 1982. The plant produced ceramic UO2 powder, which was then fabricated to fuel the Wolsong-1 CANDU reactor. The plant’s capacity was 100 tU per year, and produced a total of 320 tons of UO2 powder in its short lifetime. All of the UO2 was supplied to the KAERI fuel fabrication plant for the fuel of the Wolson-1 CANDU reactor.
KAERI subsequently added an Ammonium Uranyl Carbonate process to convert UF6 into UO2 and experimented with components for automatic operation. The plant ceased operation in 1992 as it could not compete with the international market. The plant began its dismantling and decontamination process in 2004 and is now fully decommissioned.
One conversion plant is operating in the United States, the Honeywell Metropolis Works Plant (MTW) in Metropolis, Illinois. The facility began operation in 1958, was mothballed in 1964 and rehabilitated and re-opened in 1968 as a private converter. ConverDyn was created in 1992 and is a partnership between Honeywell and General Atomics and is the exclusive agent for conversion sales from Metropolis, including coordinating and managing conversion-related services to nuclear utilities in the USA, Europe and Asia. These services include uranium deliveries, sampling, materials storage and product delivery. The MTW is capable of converting over 36 million pounds (16,000 tonnes) of U3O8 into UF6 annually.
The MTW shut down production in May 2012 to address upgrades required by the U.S. Nuclear Regulatory Commission (NRC) focused on preparedness for extreme natural disasters such as earthquakes and tornados. In November 2012, Honeywell began comprehensive upgrades at a cost of more than $40 million to reinforce the plant. Operations were restarted in July 2013 after NRC approval.
In November 2017, Honeywell announced that it was temporarily suspending UF6 production at the ConverDyn plant until market conditions improve. It stated that a global oversupply of UF6 coupled with decreased demand since the 2011 Fukushima accident has had a significant impact on the uranium market. Honeywell said it would maintain minimal operations and restart production when business conditions improve.