Eden NE has led significant BAT/assessment/optimisation projects for Magnox Ltd, including the following.

BAT Assessment of the Winfrith Sea Discharge Pipeline.

Magnox Ltd are responsible for decommissioning the Winfrith nuclear site in Dorset. The decommissioning work involves determining optimised end states for site facilities. One of these facilities is the sea discharge pipeline, which runs from the site to the English Channel and was used historically for the discharge of liquid radioactive effluents from the site. Eden NE, on behalf of Magnox Ltd, managed an optimisation assessment to determine the optimised end state. The assessment provided several novel challenges, as the pipeline passes under a range of different environments, including an historic building and a Ministry of Defence firing range, before passing over a beach and through reefs on the sea bed. To address the technical, land ownership and liability issues posed by each distinct environment, we developed a novel assessment methodology in which we identified optimised end states for each environment, and then integrated these outputs to yield an optimised end state for the whole pipeline. In addition to developing the assessment methodology, we supported Magnox Ltd to:

• identify and agree a suitable set of assessment attributes;
• identify data requirements and needs to support the assessment;
• compile, integrate and analyse the underpinning data;
• plan, facilitate and recorded workshops;
• support Magnox Ltd engagement with external stakeholders.

BAT Assessment of the Steam Generating Heavy Water Reactor (SGHWR) End State Options.

One of the key facilities to decommission at the Winfrith site is the SGHWR, which was a research reactor used until the early 1990s. The relevant Environment Agency regulatory guidance for the decommissioning of nuclear facilities is the Guidance on Requirements for Release of Nuclear Sites from Radioactive Substances Regulation (GRR). The GRR provide site operators with greater flexibility than was previously the case when determining a site (or facility) end state. A key requirement is that end states must be optimised. Winfrith has been a 'lead and learn' site for the application of the GRR and Magnox Ltd has been trialling the application of the new regulations to site end state work at Winfrith. As part of this 'lead and learn' work, Magnox Ltd contracted Eden NE to conduct an optimisation assessment to determine the optimised end state for the SGHWR below-ground structure and the wastes produced during its decommissioning. Working with members of the Winfrith End State Team and other contractors, the assessment determined:

• the optimised level of decontamination of the SGHWR below-ground structure;
• the optimised management route for the wastes produced during decommissioning; and,
• the optimised approach to backfilling the SGHWR below-ground void.

To achieve this, Eden NE undertook a number of activities to achieve this, including:

1. planning and programming the optimisation assessment;
2. preparing a list of credible SGHWR end state options;
3. reviewing information to feed into the optimisation assessment;
4. managing the formal optimisation assessment, including organising, managing and facilitating two workshops: a technical workshop attended by representatives from Magnox Ltd and the NDA, and a second workshop attended by external stakeholders (e.g. site stakeholder group, regulators, etc.);
5. reporting the optimisation assessment and its conclusions.

Magnox Ltd and the NDA used the outcome of this work to feed into their end state decision-making process. Having identified the optimised end state for SGHWR, Eden NE supported Magnox Ltd in subsequent work to identify the optimised end state engineering concept for the SGHWR.