Magnox Reprocessing Plant

The Magnox Reprocessing Plant is a former nuclear reprocessing facility at Sellafield in northern England, which operated from 1964 to 2022. The plant used PUREX chemistry (based on tributyl phosphate (TBP)) to extract plutonium and uranium from used nuclear fuel originating primarily from Magnox reactors. The plant was originally constructed and operated by the United Kingdom Atomic Energy Authority (UKAEA), but in 1971 control was transferred to British Nuclear Fuels Limited (BNFL). From 2005 the plant was operated by Sellafield Ltd.

1. Operation

The plant was commissioned in 1964 as both a replacement for the UK's First Generation Reprocessing Plant, and to process spent fuel from the national fleet of Magnox reactors. The First generation Plant was then converted into a pre-handling plant for Magnox reprocessing and was recommissioned in 1969. In 1973, after both plants had been shut down for one year for maintenance, a violent reaction called a "blowback" occurred in the First Generation Plant which contaminated that plant and 34 workers with ruthenium-106. Following this event the First Generation Plant was permanently closed. Over its lifetime, the Magnox plant handled over 55,000 tons of spent fuel from the UK's fleet of 11 Magnox plants as well as reprocessing Magnox fuel from Italy, Japan, and fast breeder fuel from Dounreay. In total, the plant has returned over 15,000 tons of uranium back into the fuel cycle. As of 2019, all Magnox reactors have now been retired from operation and defueled, with the last load of burnt-up Magnox fuel arrived at Sellafield in 2019. B205 ceased operations on 17 July 2022, when it was announced that it had worked through the remaining spent Magnox fuel stockpiles. Thus completing its mission which spanned nearly 6 decades.

1. Process

The process used mixer settlers as the basis of the plant operation. The unit comprised a set of mixing compartments where the solvent and aqueous liquids mixed. The mix then passed to an associated settler compartment where the solvent separated from the aqueous and forms two separate layers. These then left the settler compartment to the next mixer compartments. The solvent and aqueous flowed in opposite directions through the mixer settler stages (typically 8 or more), controlled by careful design of the transfer ports between the settler stages. The task to extract usable uranium and plutonium began with a process known as "decanning" where the magnesium fuel can was separated from the inner uranium rod. The uranium rod was then sheared and dropped into a hot nitric acid solution within the Dissolver Cell. The aqueous stream was conditioned to the correct temperature and acidity and then passed to the first mixer settler system where fission products were separated from the uranium (U) and plutonium (Pu) by extraction of the U/Pu into the solvent phase comprising tri-butyl-phosphate in odourless kerosene. This had the effect of reducing the radiation levels in subsequent stages of the process and the resulting degradation of the solvents. The solvent stream of U, Pu and remaining fission products passed to the critical mixer settler stages where the U and Pu were transferred into the aqueous phase, and fission products remained in the solvent phase. Separation of the U and Pu was achieved by adding a reductant, which caused the Pu, but not the U, to transfer into the aqueous phase. Once separated, further removal of fission products was undertaken by more mixer settler units. The U and Pu streams were then passed to evaporators to concentrate the U and Pu before further processing in other plants. The plant contributed the majority of liquid discharges from the Sellafield site; around 132 Terabecquerels (TBq) annually.

1. Operation


1. = 50 Not Out =

In 2014 Sellafield Ltd celebrated 50 years of Magnox Reprocessing from 1964 to 2014. Called "50 not out" to highlight that the plant was not shutting down, the events related to this celebration spoke about the history of Magnox and Reprocessing as well as design choices that led to the use of magnesium cladding and overall information about the Magnox Operating Programme.

1. = 2020 controlled shutdown =

In 2020 due to coronavirus, Sellafield Ltd announced that the Magnox reprocessing plant will undergo a controlled shutdown to ensure less maintenance when it is eventually restarted. Whereas turning the facility off quickly in a response to reduced staff members on-site has a possibility to result in unnecessary maintenance or repair work. This will cause the closure date of the facility to be pushed back as no fuel will be reprocessed in this time.

1. = Completion of reprocessing =

Magnox fuel reprocessing ceased on 17 July 2022, when the reprocessing plant completed its last batch of fuel after 58 years of operation. A total of 55,000 tonnes of fuel had been processed during those years.

1. See also

Reprocessed uranium Mixer-settler

1. References

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Thermal Oxide Reprocessing Plant

The Thermal Oxide Reprocessing Plant, or THORP, is a nuclear fuel reprocessing plant at Sellafield in Cumbria, England. THORP is owned by the Nuclear Decommissioning Authority and operated by Sellafield Ltd, the site licensee. Spent nuclear fuel from nuclear reactors was reprocessed to separate the 96% uranium and the 1% plutonium from the 3% radioactive wastes, which are treated and stored at the plant. The uranium is then made available for customers to be manufactured into new fuel, and the plutonium incorporated into mixed oxide fuel. On 14 November 2018 it was announced that reprocessing operations had ended at THORP after earning £9bn in revenue. The receipt and storage facility (which makes up nearly half of THORP's physical footprint), will operate through to the 2070s to receive and store spent nuclear fuel from the UK's PWR and AGR fleet. The decommissioning is expected to start around 2075.

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Sellafield

Sellafield, formerly known as Windscale, is a large multi-function nuclear site close to Seascale on the coast of Cumbria, England. As of August 2022, primary activities are nuclear waste processing and storage and nuclear decommissioning. Former activities included nuclear power generation from 1956 to 2003, and nuclear fuel reprocessing from 1952 to 2022. The licensed site covers an area of 265 hectares (650 acres), and comprises more than 200 nuclear facilities and more than 1,000 buildings. It is Europe's largest nuclear site and has the most diverse range of nuclear facilities in the world on a single site. The site's workforce size varies, and before the COVID-19 pandemic was approximately 10,000 people. The UK's National Nuclear Laboratory has its Central Laboratory and headquarters on the site. Originally built as a Royal Ordnance Factory in 1942, the site briefly passed into the ownership of Courtaulds for rayon manufacture following World War II, but was re-acquired by the Ministry of Supply in 1947 for the production of plutonium for nuclear weapons which required the construction of the Windscale Piles and the First Generation Reprocessing Plant, and it was renamed "Windscale Works". Subsequent key developments have included the building of Calder Hall nuclear power station - the world's first nuclear power station to export electricity on a commercial scale to a public grid, the Magnox fuel reprocessing plant, the prototype Advanced Gas-cooled Reactor (AGR) and the Thermal Oxide Reprocessing Plant (THORP). Decommissioning projects include the Windscale Piles, Calder Hall nuclear power station, and historic reprocessing facilities and waste stores. The site is owned by the Nuclear Decommissioning Authority (NDA) which is a non-departmental public body of the UK government. Following a period 2008–2016 of management by a private consortium, the site was returned to direct government control by making the Site Management Company, Sellafield Ltd, a subsidiary of the NDA. Decommissioning of legacy facilities, some of which date back to the UK's first efforts to produce an atomic bomb, is planned for completion by 2120 at a cost of £121 billion. Sellafield was the site in 1957 of one of the world's worst nuclear incidents. This was the Windscale fire which occurred when uranium metal fuel ignited inside Windscale Pile no.1. Radioactive contamination was released into the environment, which it is now estimated caused around 240 cancers in the long term, with 100 to 240 of these being fatal. The incident was rated 5 out of a possible 7 on the International Nuclear Event Scale.

Historic Site Industrial