In 2011, following a review by the NDA, a revised programme was put in place to decommission Winfrith by 2021. The delivery of the Winfrith optimisation programme covers work to:
- Decommission redundant facilities on site
- Make radioactive waste passively safe
- Empty the Treated Radwaste Store (TRS)
- Transfer waste off site
- Demolish redundant buildings
- Remediate contaminated ground
- Restore and landscape site
Fifty per cent of the original land on the Winfrith site has been sold, with another 25 per cent ready for disposal. Ten hectares of land have been de-licensed.
Many facilities closed in the 1990s have been decommissioned and demolished, including the ZEBRA and six other reactors, the Plutonium Manufacturing Facility, the Active Handling Facility and various laboratories.
Major liabilities left to be decommissioned include: the Dragon and SGHWR reactors and the Active Liquid Effluent System (ALES).
Working towards interim end state – 2013 to 2021
The SGHWR’s secondary containment has been decommissioned and de-planted previously. Work will now proceed with the decommissioning of the primary containment.
The next phase is to de-plant the peripheral areas of the primary containment in readiness for building a shielded, remotely-operated arrangement for removing and packaging the radioactive waste from the reactor core. The design for this arrangement is also being progressed in this phase, as is the physical decontamination of the secondary containment areas. Work on the cable mezzanine was completed in February 2013.
Once the waste has been removed from the facility, the structure will be decontaminated and demolished.
Most of the Dragon plant has been removed, with the exception of the reactor pressure vessel at the core of the reactor. This included the helium clean-up plant, primary heat exchangers, fuelling machine, fuel carousel and upper bioshield.
The next phase involves the design and build of a new shielded, remotely-operated facility over the core. This will allow the intermediate waste (ILW) to be removed and safely packaged for disposal. Once the radioactive waste has been removed from the building, the Dragon facility will be decontaminated and demolished along with adjacent (non-nuclear) buildings.
The Active Liquid Effluent System (ALES) will continue to operate in support of the Winfrith decommissioning programme until it is no longer required to support site decommissioning operations. At that stage the plant will be closed and decommissioned. RSRL is currently planning the decommissioning of ALES and reviewing options for the overland sea discharge pipeline.
When ALES operations cease, there will still be a requirement to deal with foul arisings from the site. This will require installation of a new transient foul system to handle effluent from toilets and showers etc. during the final stages of the site decommissioning. The transient foul will also require decommissioning at the end of its use.
Decommissioning of redundant plant and equipment will continue to take place in the interim period prior to ALES closure. The Active Break Tank (ABT) is one such decommissioning activity that is currently underway. It will involve the removal and encapsulation of sludge currently held in the tank so it is suitable for waste disposal, followed by decontamination and disposal of the empty tank.
With its work done, the purpose-built Waste Encapsulation Treatment Plant (WETP) has been decommissioned and demolished. A total of 1068 encapsulated sludge drums were processed.
Decommissioning of the External Active Sludge Tanks (EAST) is now complete following the final cutting of the tank base into blocks ready for disposal.
Once the remaining structures on the SGHWR and Dragon complexes have been demolished, the land will be remediated to meet the criteria set for the site interim end state.
Treated Radioactive Waste Store
Waste currently stored in Winfrith’s Treated Radwaste Store (TRS) will be transferred to the planned Harwell ILW store where it will be stored until a Geological Disposal Facility (GDF) is available. The empty TRS will then be decommissioned and the associated land remediated.
Waste on site
Legacy LLW processing and disposal will be carried out from A58. ILW and LLW generated from reactor decommissioning will be processed and packaged within the two remaining reactor buildings, prior to disposal or off site transfer.
Non-nuclear hazardous waste
Work to recover, repackage and dispose of sodium metal stored at Winfrith ended in February 2013. The legacy sodium was size reduced and packed into 10kg units for incineration at a specialist facility off site.
Waste off site
Low Level Waste (LLW) is either transported to the national LLW repository or supercompacted on site for disposal or recycling.
Very Low Level Waste (VLLW) and Low Activity Low Level Waste (LA-LLW) are processed on site and transported to a specialised facility in Northamptonshire.
Intermediate Level Waste (ILW) produced as a result of the decommissioning of Dragon and the SGHWR will be packaged and processed before being transferred to the ILW store at Harwell, prior to final transfer to the Geological Disposal Facility (GDF).
Interim end state – 2021
The interim end state will be achieved when all remaining facilities have been decommissioned and all ILW transferred off the Winfrith site to Harwell for storage.
Final end state – post 2021
The Winfrith final end state will set a precedent for other UK nuclear sites. The land will be surveyed, remediated where appropriate and the site gradually restored to heathland, with public access. After 2021, there will be an additional period of time between 2021 and a final end point.
During this time, the site will remain under institutional control until the condition is reached such that the remaining institutional controls can be removed. At that time the final end state will have been achieved, when the site has been delicensed by the Office for Nuclear Regulation (ONR) and de-designated by the Nuclear Decommissioning Authority (NDA).
Winfrith at a glance
2013 to 2021 - decommissioning, transferring waste off the site, and site remediation
2021 to final end point – interim end state
Final end point – Final end state achieved, delicensing, and de-designation.
Please note: while dates for the Winfrith site programme are correct at the time of posting, they may be subject to later revision due the results of the ongoing end state options assessment, or to funding, technical and other changes.
Updated August 2013