RRFM 2009 Transactions - European Nuclear Society

DECOMMISSIONING PROGRESS OF THE DOUNREAY SITE.
However in both cases, at levels below relevant limits in Exemption Orders under
the Act. (Clearance and Exemption Principles, Processes and Practices for Use by
the Nuclear Industry - A Nuclear Industry Code of Practice).
The key to making the most of the waste routes available is good characterisation and
planning.
4 Fuel Routes
All the research work undertaken at Dounreay has obviously left the site with a wide variety
of fuels in all forms. This legacy of fuels now requires to be dealt with. In order to achieve
this Dounreay will require tomake them safe and suitable for long term storage without
foreclosing the option for some of the fuels to be used in nuclear new build.
New facilities will be built to repack the fuels into industry standard packages and this will
allow long term storage on site.
The site has both irradiated and unirradiated fuels and Dounreay is working with NDA
(Nuclear Decommissioning Authority) to develop a United Kingdom strategy for the
treatment and long term storage of the both fuel types. The site currently has a reference
treatment and stabilising option for each fuel type, these do not foreclose the option of the
Plutonium and Uranium being re-used in the future.
4.1 Irradiated fuels (primarily from Prototype Fast Reactor - PFR)
The majority of this fuel is mixed Plutonium fuels in oxide form. Due to the specific nature
and design of the fuel elements and the burn up, these will not be processed but will be
conditioned and are currently undergoing evaluation to establish their suitability for direct
disposal to a national spent fuel repository.
4.2 Unirradiated Plutonium and mixed Plutonium/Uranium oxides
The NDA are currently working on this particular fuel type and have published a high level
draft of the options. At Dounreay a new facility is being designed to allow better
characterisation of the material and then repackaging into containers which are used
elsewhere in the UK to store Plutonium. This will allow all the Plutonium stocks to potentially
be co-located and treated in the future once the UK strategy is finalised.
4.3 High enriched Uranium (HEU)
During its operational life Dounreay had a facility which dealt with a variety of enrichments of
uranium (from LEU to 93% HEU). Some of this material is still on site in various forms from
liquid to solid billet form. The material will be stabilised to allow continued storage, until
another use can be identified. The HEU is an asset which has a value and with further
treatment will be suitable for re-use.
4.4 Miscellaneous
The site also has carbides, natural/depleted uranium, metallic uranium (ex DFR
breeder),thorium and these are in various forms. These fuels will also be stabilised and put
in industry standard containers suitable for long term storage or transport if required.
5 Summary
Just as Dounreay lead the world in research reactors it is now leading the world in
decommissioning through the removal of some of the most challenging facilities. This paper
has just given a very brief outline of the work being undertaken on site.
There is still a lot of work and challenges to be undertaken at Dounreay with a number of
new facilities to be constructed to allow the decommissioning of the site and many old
facilities to be removed and demolished.
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