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Managing Radioactive Waste Update  NuClear News December 2018 A meeting planned for December between NGOs and the Nuclear Decommissioning Authority’s Radioactive Waste Management Ltd (NDA/RWM) has been postponed until February 2019 due to a delay in BEIS announcing the next steps in the Geological Disposal Facility (GDF) process (originally scheduled for November 2018). Brexit is most likely to blame for this delay. (1)

Writing on the GDF Watch website before the cancellation, Roy Payne said “there’s no doubting the commitment in Whitehall to try and finalise GDF siting policy before Christmas. But if you ask about timing, you get the same silent stoic smiles revealing the lack of certainty across Whitehall about getting Ministerial decisions on anything at the moment”. He says it’s likely that it will be many months after the policy is launched before we see any sign of active community participation. (2)

The Committee on Radioactive Waste Management (CoRWM) which advises BEIS on dealing with nuclear waste, has recently published a paper in response to calls during the most recent consultation exercise to select a site for a Geological Disposal Facility (GDF) based on the ‘best geology’

CoRWM says RWM, the UK’s delivery body for a GDF, has developed generic environmental safety cases (gESC) for the three rock types: hard rocks (metamorphic and igneous rocks), soft rocks (clays and mudstones) and evaporites (salt deposits). CoRWM says the recognition that three very different rock types can provide for a safe GDF highlights the difficulty associated with selecting a ‘best’ geology as each rock type have their own advantages and disadvantages. For example, from the technical assessment carried out to support CoRWM’s initial work:

“Strong indurated1 rocks can provide repository concepts at depth that could provide long pathways and isolation from human intrusion. Weak indurated rocks could provide hydrogeological isolation but be constrained by depth limitations. Evaporites could provide hydrogeological isolation and low gas permeability. Excavations of some evaporites would be difficult to maintain over long time periods.”

CoRWM concludes that geologic attributes or parameters cannot be compared across rock types, and the concept of a site which scores ‘highest’ on all parameters’ simply cannot occur. The different and various roles played by geological settings proposed for GDFs across the world highlight this issue.

CoRWM says it recommended against geological screening in 2014 because the level of knowledge of the geology of much of the UK at the depths under consideration is too rudimentary to support a ‘screening out/in’ process. This position could only be changed by introducing, country-wide, a level of geological investigation, including investigative boreholes. This would clearly be unsupportable on both economic and public acceptability grounds. (3)

Cumbria Trust believes CoRWM’s paper calls into question their independence. They are supposed to act as an independent body, but some of their recent actions suggest to us that they are too close to BEIS and failing to adequately perform their advisory function and to challenge poor decision-making. Cumbria Trust has written to CoRWM expressing its concerns. The letter says:

“We feel that you are using an over-literal interpretation in responding to stakeholder consultation replies which advocated a search for the best geology, by taking this to mean the single best site in England and Wales. While a few stakeholders may have intended that in its very narrowest sense, which is clearly incompatible with voluntarism, we believe that the majority did not. By confining your response to this narrow interpretation, you have missed the opportunity to examine a more realistic and widely-held view. It is quite possible to combine the principle of voluntarism in site selection, which we accept, with some level of geological pre-selection. Cumbria Trust advocates actively seeking volunteers from areas which have promising geology, as recommended by many experts including the Lead Inspector of the Nirex Inquiry, Chris McDonald.”

The Trust also refers to a statement made in 2013 by Professor Yardley, who subsequently became RWM’s Chief Geologist, in which he pointed out that due to the UK’s extensive programme of spent fuel reprocessing there is a significant amount of carbon-14 present in the UK inventory. This poses a particular risk to a GDF project and increases the need for an effective gas barrier to prevent radioactive methane, amongst other gases, from escaping. This is a further reason why a clay host rock may well be preferable for the UK. (4)

1 in a million CoRWM also points out that:

A Geological Disposal Facility must isolate the waste it contains from people and the environment such that the risk levels to individuals that are most susceptible is kept within 1 in 1 million (10-6) into the very distant future. This is assured by developing a Safety Case which models the behaviour of the repository system.

The Environment Agency (EA) has set a limit on the risk that may be caused by the burial of radioactive wastes of 10-6 (i.e. one in a million). (5) However, the NDA Disposability Assessment Report for waste arising from new EPR reactors states:

“…a risk of 5.3 x 10-7 per year for the lifetime arisings of a fleet of six EPR reactors each generating a lifetime total of 900 canisters is calculated” (6)

This is more than half the total risk of 10-6 allowable for a GDF for 9.6GW of new capacity. If the Government succeeds in persuading the nuclear industry to go ahead with 18GW of new capacity clearly this will exceed the risk targets set by the EA.

Two ways round this have been suggested. Firstly there could be two repositories, but although both dumps might share the same access shaft, there would be a sufficient distance between two separate groups of disposal chambers so that you have in effect two dumps giving a potential dose to two different populations.

The second excuse seems to be that if the probability of such an outcome is very low then the Environment Agency may allow a risk higher than 10-6. This kind of ‘make-it-up as you go along’ technique of risk assessment will not go down well with communities surrounding a proposed GDF http://www.no2nuclearpower.org.uk/wp/wp-content/uploads/2018/11/NuClearNewsNo113.pdf