Nuclear Waste

Operational waste
The responsibility for radioactive waste management on the EDF Energy Nuclear Generation nuclear licensed sites rests with EDF Energy Nuclear Generation Limited as Licensee.  The safe management of radioactive waste on nuclear licensed sites in the UK is regulated by the Health and Safety Executive’s (HSE) Nuclear Installations Inspectorate (NII) under the Nuclear Installations Act 1965 (as amended). The disposal of radioactive waste is regulated by the Environment Agency (EA) in England and in Scotland by the Scottish Environment Protection Agency (SEPA). The Office for Nuclear Regulation (ONR) grants a Nuclear Site Licence for each nuclear site, a number of conditions of which are relevant to the management of radioactive waste.

In the UK, nuclear waste is classified under three headings: Low Level Waste (LLW), Intermediate Level Waste (ILW) and High Level Waste (HLW). Examples of LLW are redundant equipment and waste from maintenance activities, plastic, rubble and damaged protective clothing from nuclear power stations. It is either sent for treatment (e.g. volume reduction by supercompaction) or disposed of at the Low Level Waste Repository (LLWR) in Cumbria, and a small amount of combustible waste is sent for incineration at Hythe.  Intermediate level waste includes such things as sludges and resins arising from the treatment of radioactive liquids and filters from active ventilation systems. The ILW produced at our power stations is stored for the medium term in safe, purpose built facilities at our stations while we await a longer term National solution. 

Under historic contractual arrangements spent fuel from our Advanced Gas-cooled Reactors (AGRs) is transported to Sellafield for reprocessing or storage, and spent fuel from our Pressurised Water Reactor (PWR) remains on our site.  HLW comes from the reprocessing of our AGR spent fuel at Sellafield. HLW contains high levels of radioactivity which generates large amounts of heat. It is initially produced in liquid form and is converted into glass blocks for safe, long term storage at Sellafield, there is no HLW stored at any of our sites.  Spent nuclear fuel is not currently classified as a waste since it can be reprocessed and re-usable uranium and plutonium can be extracted.

However, unreprocessed spent fuel will require disposal in a similar way to HLW because of the amount of heat that it creates.  At our Sizewell B PWR station, the spent fuel is stored on site and we are planning to build a further storage facility to allow us to continue to safely store all of the spent fuel that will be generated over Sizewell B’s life.

EDF Energy Nuclear Generation has developed two key documents which form part of the Environmental Management System and together define the fundamental arrangements for radioactive waste management.

The first document defines the waste management techniques that will aid EDF Energy Nuclear Generation’s sites to minimise the production and disposal of lower activity radioactive wastes, predominantly those that are LLW. This document presents information on available treatment and disposal routes for lower activity radioactive wastes and makes recommendations for:

• Minimising waste arisings and use of the waste hierarchy;
• Segregation and streaming of waste;
• Processing and treatment techniques;
• Storage, packaging and transport requirements;
• Waste radioactivity assessment procedures.

The waste hierarchy is commonly used by EDF Energy Nuclear Generation to inform decisions on matters of radioactive waste management. The hierarchy goes beyond the requirement to minimise the generation of waste but also ensures that any wastes that do arise are sent down the most appropriate route according to the hierarchy.

The most favoured option is to look for ways to avoid creating waste in the first place, however, if waste needs to be created then it is important to minimise the overall amounts that need to be managed. Items should always be used again wherever possible, for example certain items can be used only during outages, but rather than dispose of them at the end of the outage they are stored and then re-used again at the next outage.

Once an item comes to the end of its life it is important to see if the waste can be recycled, and in the case of some radioactive metals, this is now possible.  Energy recovery from the waste would be the next preferred option, though very limited options to do this exist, and there are none currently that the Company has access to.  The final and least desirable option is to dispose of the waste, there are however, a variety of options available depending upon the waste type and its characteristics and many wastes can be treated prior to final disposal, for example to reduce the final amounts that are disposed of.

The second document outlines the strategy for the management of all radioactive waste streams generated by EDF Energy Nuclear Generation’s sites and provides guidance to ensure that a consistent safe approach is adopted in the taking of decisions on radioactive waste management matters.  This covers material from the point where it is initially classified as waste, through to final disposal, through some or all of the following steps:

• Waste Arising
• Accumulation
• Storage
• Retrieval
• Conditioning
• Interim Conditioned Storage
• Transport
• Disposal

The document sets out the following objectives:

• To maintain radiation doses to the workforce and the general public from radioactive waste management operations, including disposal, within legal limits and As Low As Reasonably Practicable (ALARP).
• Apply best practicable means (BPM) to ensure the generation of radioactive wastes is minimised as far as is reasonably practicable.
• To dispose of all wastes as soon as practicable where a safe and economic route has been established.
• To maintain adequate safety cases for all waste management activities including handling, accumulation and storage of wastes on Nuclear Generation sites.
• To develop the technology and processes required for the safe retrieval, treatment, packaging, and interim storage of wastes.
• To co-operate with other UK waste producers on radioactive waste policy and strategy issues, and manage major stakeholder relationships effectively.
• To maintain an inventory and records of radioactive waste arisings accumulations.

And the following principles:

• Waste will at all times be adequately controlled and/or contained so that it cannot leak or escape
• Waste will be accumulated and stored in a manner that is safe and consideration will be given to the benefits of passive safety
• Waste will be characterised in terms of the rate of arising, the chemical, physical and radiochemical composition and inventory records will be maintained
• Waste with different chemical, physical and radiochemical properties will be segregated where practicable
• Volume reduction and decontamination techniques will be employed where practicable
• Waste for which there is no available disposal route will be accumulated, conditioned and stored as appropriate pending the availability of a disposal route
• The condition of accumulated waste will be monitored in accordance with site licence requirements
• For each waste stream the optimum method and timing for the retrieval, processing and packaging will be determined, taking account of safety, costs, the availability of a disposal route, the decommissioning strategy, and non foreclosure of future options
• Methods of packaging and conditioning wastes are expected to be acceptable for final disposal

In addition to complying with and maintaining a certified Environmental Management System EDF Energy Nuclear Generation dedicates resource specifically to driving improvement in the area of radioactive waste management; the principle objectives being to:

• Optimise the onsite management and processing of waste.
• Station radioactive waste management facility and equipment improvements
• Implementation of training
• Ensure optimal use is made of existing treatment and disposal routes.
• Incineration
• Waste processing services offered by the supply chain
• Metals recycling
• Supercompaction
• Collaborate with providers of radioactive waste management services to establish new improved waste disposal routes
• Determine the Best Practicable Environmental Option (BPEO) for new waste streams
• Update existing radioactive waste management strategies to ensure that they remain the BPEO
• Collaborate with the regulator and other government organisations to aid implementation of the UK radioactive waste policy
• Reduce volumes of radioactive waste stored at EDF Energy Nuclear Generation locations

Recent successes in this area have included:

• The introduction of a new waste processing route which enables the decontamination of radioactively contaminated metal.  This substantially reduces the volume of waste being sent for final disposal at the UK LLWR in Cumbria by up to 95%.  The decontaminated metal is clean enough to be recycled and sold for general use.  This route has been utilised by three of EDF Energy Nuclear Generation’s power stations and is being rolled out across the remainder of the fleet.
• EDF Energy Nuclear Generation’s Advanced Gas Cooled Reactors (AGR) are cooled by Carbon Dioxide (CO2) which must be must be maintained within set moisture concentration parameters in order to comply with the safety case.  Moisture control is performed by drying towers which require periodic desiccant replacements.  The options for managing spent desiccant were reviewed in 2009.  This review, which was supported by laboratory scale and full-scale trials, identified a new method for processing and disposal that reduced the final disposal volume by approximately 50%. Further improvements were identified during 2010 reducing the final disposal volume by a further 20%. EDF Energy Nuclear Generation is in year 2 of a programme of work to implement this improved waste management strategy at its gas-cooled power stations.  Work is currently being undertaking to identify / improve the waste disposal methods for several other waste streams in 2011.

To the extent EDF Energy Nuclear Generation carries out activities relating to waste management – e.g. minimisation, handling and packaging prior to shipment, these activities are carried out by Suitably Qualified and Experienced Personnel. These personnel receive training specific to their duties. This training would include use of Best Available Techniques (BAT) to minimise Waste and Radiological risks.  Waste metrics and reduction goals are set, reviewed, and monitored regularly thereby demonstrating a commitment to continuous improvement in the area.

EDF Energy has plans to build a new generation of nuclear power plants in the UK.  Prior to any investment decision in new plants, EDF Energy would seek to ensure that the plant designers have taken into account BAT in order to minimise the nuclear waste arising from future decommissioning of their plant designs.