The Nuclear Decommissioning Authority

Last Updated: 21 February 2013

In addition to bulk Magnox and oxide fuels, the NDA manages a smaller inventory of approximately 500 tonnes of non-standard fuels, commonly referred to as 'exotics'. Although smaller in quantity than our bulk fuels, exotics present their own particular management challenges due to their diverse properties and include metallic, oxide and carbide materials. These fuels are a legacy from earlier nuclear industry activities such as the development of research, experimental or prototype reactors. Although exotics often share the physical characteristics and properties of Magnox and oxide fuel, their composition and enrichment is varied with a substantial number containing plutonium. Much of the material has been irradiated.  

Examples of exotic fuel types include:

• Dounreay Fast Reactor (DFR) breeder material
• • Credible and Preferred Options for Exotic Fuel DFR - July 2011

 Exotic Fuels - Dounreay Fast Reactor (DFR) Breeder - NDA Response to Stakeholder Comments on Credible and Preferred Options November 2011 (1Mb)

• Dounreay Prototype Fast Reactor (PFR) spent fuel

 Exotic Fuels and Nuclear Materials Dounreay Prefered Options February 2013

• Dragon reactor fuel at Harwell

• Credible and Preferred Options for management of Harwell exotic fuels, nuclear materials and wastes - August 2011

 Exotic Fuels Nuclear Materials and Waste Management - RSRL Harwell - NDA Response to Stakeholder Comments on Credile and Preferred Options November 2011 (1Mb)

• Steam Generating Heavy Water Reactor (SGHWR) spent fuel at Sellafield

• Carbide fuels High Enriched Uranium (HEU) fuels.

 Exotic Fuels and Nuclear Materials - Dounreay - Credible Options February 2012 (1Mb)

 Exotic Fuels and Nuclear Materials - Dounreay - Stakeholder comments in response to Credible Options May 2012 (1Mb)
A number of facilities exist across the NDA estate that could potentially be used to manage some exotic fuels. There is an additional requirement on us to safely and securely protect MoD fuel stored on our sites.

Objective

To ensure that all exotic fuels are managed in a safe and secure way for the lifetime of the fuel.

Scope and Boundaries

Exotic fuels are located on various sites across the NDA estate and usually fall outside the standard arrangements for transport, storage, reprocessing and waste disposal associated with bulk Magnox and Oxide fuels. In most cases they are unlikely to meet the usual specification for reprocessing or direct disposal and therefore present some unique challenges when potential treatment options are considered.  

The diverse nature of exotic fuels means that it is likely that individual tailored solutions will be required for their treatment and ultimate disposition, although some may be considered for treatment of other nuclear material or spent fuel Topic Strategies.

Interfaces

The Exotic fuel strategy interfaces with a number of other Topic Strategies including:

• Oxide fuel strategy is related because of the potential treatment options
• Magnox fuel strategy is related because of the potential treatment options
• Plutonium strategy is related because some of Exotic fuels contain plutonium  
• Higher Activity Waste strategy is related because treatment or reprocessing of Exotic fuels may increase stocks
• Transport and logistics strategy is related because of the potential need to move Exotic fuels. 

Credible Options

Due to the diverse nature of the materials concerned a variety of treatment options are likely to be deployed. The treatment options for a specific exotic fuel will be evaluated through a lifecycle impact analysis that considers such factors as hazard, risk reduction, commercial opportunity and liability, security and safeguards, resource utilisation and technology maturity.

Treatment options will be underpinned through ongoing R&D activities and could include:

• Immobilisation – encapsulation or dispersion of fuel in a matrix such as cement, ceramic, glass or polymer
• Stabilisation – treatment and packaging of the fuel to underpin long term storage prior to disposal in a Geological Disposal Facility
• Reprocessing either in the UK or overseas as appropriate

Current Position

The current strategy for Exotic fuel is to store the fuel until suitable treatment options for disposition have been developed although treatment options for some Exotic fuels are being implemented.  For other Exotic fuels further research and development activities are required prior to establishing the best disposition option.

The NDA is continuing to examine the strategic options associated with the disposition of exotic fuels.  A range of studies and research activities is being undertaken to explore storage, transport and treatment routes to establish an optimised lifecycle approach.  The NDA is supporting Site Licence Companies (SLCs) in developing and underpinning technical options for the disposition of Exotic fuels.