Hunterston A

Power stations Hunterston A and Hunterston B are situated near West Kilbride, on the Hunterston Peninsula of the Ayrshire coast.

Hunterston A ceased electricity power production at the end of March 1990. Magnox Electric operates Hunterston A on behalf of the Nuclear Decommissioning Authority (NDA), and is facilitating the decommissioning of the site. Part of this process involves disposing of solid, liquid and gaseous radioactive waste, and Magnox Electric hold three authorisations for this purpose.

SEPA’s Advice to Magnox Ltd on its Hunterston A Graphite Pathfinder Project

Background

Magnox Limited (“Magnox”) has carried out a study into the feasibility of disposing of higher activity radioactive waste (HAW)1 to a proposed near-surface facility at its Hunterston A decommissioning nuclear power station site in North Ayrshire. (For more information see the Magnox website external link )

This radioactive waste is a mixture of graphite and metal components, which were removed from Hunterston A’s reactors over the course of their operational lifetime and placed in a shielded on-site store. Magnox’s study, known as the “Graphite Pathfinder Project”, was funded by the Nuclear Decommissioning Authority (NDA) to help it decide whether near-surface disposal could be an acceptable option for the long-term management of graphite reactor decommissioning waste.

Before a disposal facility for such waste could be constructed and operated, Magnox would have to apply successfully to SEPA for an authorisation under the Radioactive Substances Act 1993 (RSA 93). Last year Magnox asked SEPA to give it early regulatory advice on its feasibility study, to help it understand what information would be needed to carry forward the project into a formal authorisation application. SEPA agreed to do so in July 2010, as provided for by section 37 of the Environment Act 19952.  We then began to review a series of documents supplied to us by Magnox between August and December 2010.

In May 2011 we delivered SEPA’s final advice to Magnox under this agreement.  Our advice was mainly based upon SEPA’s primary guidance in this field, “Near-surface Disposal Facilities on Land for Solid Radioactive Wastes: Guidance on Requirements for Authorisation” (also known as the “Near-Surface GRA”), which requires that any application for RSA 93 authorisation for this type of facility must be supported by an Environmental Safety Case (ESC)3. In developing our advice, we drew upon a range of technical expertise from within SEPA, and upon advice from the Health Protection Agency.

SEPA’s advice

SEPA's advice can be found in our final advice report (208kb pdf link) and our covering letter (16kbpdf link). Our aim at this early stage was focused on giving clarity on the type and quality of information we would require if Magnox decided in future to make an authorisation application, supported by an ESC, to meet the requirements of the Near-Surface GRA.

In our advice, we have raised a number of issues regarding Magnox’s approach.  These centre on the omission of a suitable options selection and optimisation4 process for the design of the facility, and inadequate investigations into the consequences of human intrusion5.  We were also concerned that the actual waste (operational graphite and metal components) covered by Magnox’s Preliminary ESC did not reflect the full quantity and type of reactor graphite wastes that will need to be managed during the decommissioning of Hunterston A.

SEPA recognises that Magnox’s Graphite Pathfinder Project is challenging and innovative for a number of reasons:

  • Near-surface disposal of this type and amount of intermediate level radioactive waste (ILW) has not been authorised in the UK before. 
  • This is the first time SEPA has used the Near-Surface GRA to assess this type of disposal. 
  • This project is the first to explore the option of near-surface, near-site disposal of ILW, now allowed under the Scottish Government’s recently published “Scotland's Higher Activity Radioactive Waste Policy 2011” external link

SEPA concludes that the feasibility of near-surface disposal of reactor graphite at Hunterston A requires more robust investigation. While many of our concerns pose substantial challenges to Magnox’s overall approach in its Graphite Pathfinder Project and to the work presented in its Preliminary ESC, we have no reason, at this point in time, to regard these concerns as being irresolvable in principle. The advice provided in this report should not therefore be misinterpreted as SEPA dismissing the viability of near-surface disposal of graphite wastes. It remains open to Magnox to improve its approach and its ESC in light of our advice, and to request our advice again, or to make a formal application for authorisation under RSA 93.


Footnotes

  1. Higher Activity Radioactive Waste (HAW): Paragraph 2.03 of Scotland's Higher Activity Radioactive Waste Policy 2011 defines this as:

    Radioactive waste defined in current UK categorisations as Intermediate Level Waste (ILW). Intermediate Level Waste is waste which has radioactivity levels exceeding the upper boundaries for Low Level Waste and which does not generate enough heat for this to need to be taken into account in the design of treatment or storage or disposal facilities.

  2. “[SEPA] may by agreement with any person charge that person a fee in respect of work done, or services or facilities provided, as a result of a request made by him for advice or assistance, whether of a general or specific character, in connection with any matter involving or relating to environmental licences.” Subsection 37(7) Environment Act 1995: Elizabeth II. Chapter 25. ISBN 0105425958.
  3. Environmental Safety Case: “The collection of arguments, provided by the developer or operator of a disposal facility, that seeks to demonstrate that the required standard of Environmental safety is achieved.” Taken from Glossary of Near-Surface GRA.
  4. Optimisation: “Optimisation is the principle of ensuring that radiation exposures are as low as reasonably achievable (ALARA) in the given circumstances. Optimisation is a key principle of radiation protection recommended by the International Commission on Radiological Protection (ICRP) and incorporated into UK legislation.” Taken from Glossary of Near-Surface GRA.
  5. Human intrusion: “Any human action that accesses the waste or that damages a barrier providing an Environmental safety function after the Period of authorisation.” Taken from Glossary of Near-Surface GRA.