By David Lowry and Johan Swahn

The Swedish government is set to approve the transfer of ownership of 834 kg of separated plutonium from the Swedish nuclear power company OKG to the UK Nuclear Decommissioning Authority, NDA. OKG has applied to the government for permission for the transfer. On March 14 the regulator, the Swedish Radiation Safety Authority, announced that it supported the transaction in a consultation brief to the government (in Swedish).

The main part of the plutonium, 833 kg, comes from reprocessing of 140 tonnes of spent fuel from the Oskarshamn nuclear power plant under a contract from 1969. The spent fuel was sent to Sellafield between 1975 and 1982. It was not reprocessed until 1997 and the plutonium was to be returned to Sweden as MOX fuel to be used in the Oskarshamn 2 and 3 nuclear power plants.

The plutonium to be transferred also includes 1.2 kg of plutonium from 4.8 tonnes of spent fuel from the Swedish R-1 research reactor exported to Sellafield in 2007. The R-1 fuel was in metallic form and not considered suitable for final disposal using the Swedish KBS method for spent fuel disposition.

The Swedish MOX fuel was not produced before the shutdown of the dysfunctional Sellafield MOX Plant, SMP, in 2011. In its brief the Swedish Radiation Safety Authority considers four possible ways of managing the Swedish plutonium; waiting for a new MOX production facility to be built in the UK; the production of MOX in a third country; the return of the plutonium in separated form to Sweden; and the transfer of ownership of the plutonium to the UK. The regulator considers that the transfer of ownership to the UK is the best option as it avoids transportation of separated plutonium or MOX-fuel to Sweden.

Since 2010 the UK Government has been working on policies to manage foreign plutonium and foreign spent fuel that may never be reprocessed in Sellafield. In a policy statement in a consultation response in December 2011 the UK government stated:

In the consultation paper we said that the UK would be open to consider the merits of taking over ownership of that foreign plutonium and to manage it with existing UK plutonium; any such change in ownership would need to be in compliance with inter-governmental agreements and subject to conclusion of acceptable commercial arrangements. For clarity, this does not include waste products from reprocessing which would be returned to the original owner of the fuel.

The UK Government has concluded that overseas owners of plutonium stored in the UK could, subject to commercial terms that are acceptable to the UK Government, have that plutonium managed in line with this policy. In addition, subject to compliance with inter-governmental agreements and acceptable commercial arrangements, the UK is prepared to take ownership of overseas plutonium stored in the UK after which it would be treated in line with this policy.

For each instance where there is a proposal for the UK to take title to overseas plutonium, the NDA will be required to demonstrate to the UK Government that there is an overall benefit to the UK in doing so.

Since then several transactions have been made between NDA and foreign owners of plutonium in the UK to transfer ownership of plutonium. The planned Swedish transfer is one of the larger. Mainly of historical interest, the OKG reprocessing contract did not specify that the reprocessing waste be returned to Sweden.

The decision to accept the transfer of the Swedish plutonium may still prove politically contentious in the UK, because it effectively reverses a policy adopted by the UK's then Labour government in the mid-1970s, to return all radioactive products from reprocessing.

Following a political row arising from revelations in the Observer newspaper in April 1975, Mr. Benn,the UK minister responsible for the so-called return-to-sender policy, made this statement on March 12, 1976, to the UK Parliament setting out the change of policy:

The Government have given full consideration to the safety and environmental implications of accepting more work of this kind, taking account particularly of the views which have been expressed in the recent extensive public discussion of the question. They have decided that the company may, subject to the negotiation of satisfactory terms, take on further work on the basis that the contracts will include terms to ensure that the company will have the option to return residual radioactive waste and will not be obliged to retain it in this country for long-term storage; and that suitable understandings in support of the return option are reached between the United Kingdom Government and the Government of the country concerned.

As a result of the decision to shut the Thorp reprocessing plant in Sellafield in 2018 the UK Government is also in the process of consulting on the possibility to take over ownership of about 30 tonnes of spent fuel that is under contract for reprocessing in the UK but that for various reasons may not be reprocessed before Thorp is to be shut down.