The UK Nuclear Decommissioning Authority has concluded that there are three "credible options" for reuse of the UK’s civil plutonium stockpile, including in CANDU EC6 pressurized heavy water reactors or PRISM fast reactors.

In a position paper released 20 January, NDA said that reuse remains its preferred option for the 140 tonnes of separated plutonium that will be in storage in the UK at the end of planned reprocessing operations. The other options considered were the current strategy of long-term storage followed by disposal and immobilzation and direct disposal.

NDA said the three credible options for the plutonium reuse include:

  • reuse as mixed oxide (MOX) fuel in light water reactors;
  • reuse in Candu Energy’s Enhanced CANDU 6 (EC6) reactors, and
  • reuse in GE Hitachi Nuclear Energy’s sodium-cooled PRISM fast reactor.

The announcement follows a two-year review of options for managing the UK’s plutonium stocks.

No perfect solution

NDA noted that all the technologies being considered have pros and cons and that no ‘perfect’ solution exists. "It may be that a multi-track approach offers best value for money," it said.

The paper highlighted potential benefits of each option. For PRISM those included a reduced time to disposition the UK plutonium stockpile (given the high plutonium content in the fuel), a simplified fuel manufacturing process and reactor construction, and the ability to utilise the full inventory of plutonium.

"The UK has the largest storage of civil plutonium anywhere in the world and its Government is committed to re-using that material as an asset rather than a liability, maximizing taxpayer benefits," said Mark Elborne, President and CEO of GE UK & Ireland, which said its 600MWe PRISM reactor could power 600,000 homes a year using a sodium-bonded U/Pu/Zr metal fuel.

Potential benefits of using CANDU reactors to manage separated plutonium include: a simplified CANMOX fuel manufacturing process, compared to light water reactor MOX; a track record of on schedule, on budget reactor construction; and their ability to utilise a wide range of the plutonium inventory, according to NDA

Further study of the options is needed

According to the position paper, NDA believes there is currently "insufficient understanding of the options to confidently move in to implementation."

"Significant further work must be undertaken, focusing on technical and commercial risks and uncertainties"

"Significant further work must be undertaken, focusing on technical and commercial risks and uncertainties, to enable the Department of Energy and Climate Change (DECC) and UK Government to ultimately select and subsequently implement its preferred reuse option," the paper said.

The NDA now intends to embark on one to two years of technical studies with the technology suppliers to establish a "consistent level of understanding of risks and uncertainties for each option."

NDA plans to work on regulatory and licensing aspects with the Office of Nuclear Regulation (ONR) and the Environment Agency to define licensing needs and understand deployment risks such as fuel performance demonstration.It is also developing options for implementing a commercial procurement process, should it be required.

Bulk reuse of UK plutonium likely to start around 2030-2035, ending several decades later.

Photo: Sellafield site where most of the UK’s plutonium is stored