The Geological Society is the national learned and professional body for geoscience, with 10,000 Fellows (members) worldwide. The Fellowship encompasses those working in industry, academia and government, with a wide range of perspectives and views on policy-relevant science, and the Society is a leading communicator of this science to government bodies and other non-technical audiences.
The Geological Society has been actively engaged with aspects of the MRWS programme since its inception, and remains committed to assisting with its successful implementation in any way we can. We support the principles of volunteerism and partnership, and recognise the importance of a wide range of technical and non-technical considerations in decision-making for radioactive waste management. It is vital to recognise too that some geoscientific matters on which the safety case for geological disposal will depend are not susceptible to negotiation or modification; and that geoscientific information, insights and judgments will be essential to building public and professional confidence in decisions and solutions throughout the process. It is therefore essential that geoscientific considerations remain at the heart of the MRWS process, and that the approach to be taken regarding these aspects is explicitly set out and discussed at each stage.
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Do you agree with the proposed process to identify Potential Candidate Sites? If not, why not?
The overall process for identification of Potential Candidate Sites (PCS) is sensible. In particular, we recognise the leading role of local Decision Making Bodies and Community Siting Partnerships in applying the process in each area.
However, it is important that the role of expert geological judgment (both in identifying PCS, and throughout Stage 4) is not unintentionally diminished or sidelined as a result of the understandable wish to keep volunteerism and partnership at the heart of the MRWS programme, and the importance of other factors and criteria. We are concerned that this is a risk of the process as currently set out in the consultation document. The elicitation and demonstrably effective use of appropriate high-quality geoscientific data, expertise and judgment will be essential to building and maintaining public confidence in subsequent phases of siting, construction and long-term safety of a disposal facility. The reconciliation of types of input to the process should not be viewed as a zero-sum game – ensuring that geoscientific expertise is used appropriately at this stage of the process should enhance rather than diminish community input and ownership, and increase the benefit delivered by consideration of other scientific, social and economic factors at this and later stages. It is also important that the geoscience community’s confidence in the process is maintained.
Below, we highlight some particular concerns and comments regarding the use of geoscience data and expertise in Stage 4. The Geological Society is keen to continue working with DECC, NDA and others to ensure the success of the MRWS programme, and would value the opportunity to discuss the role of geoscience inputs in Stage 4 and more widely before plans are finalised.
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Is there anything that could be included to improve the proposed process to identify Potential Candidate Sites, bearing in mind that physical site investigations will not start until later in the process?
There is insufficient information in the consultation document about what safety assessment would be carried out at this stage (though we recognise that this is expected to be at a high level only), and also later in the assessment of PCS. NDA’s recently developed Disposal System Safety Case (DSSC) is very broad, and is regarded as being of limited use other than to illustrate the method in a general way. It is not clear whether this is expected to be used as the basis for safety assessment during the identification or assessment of PCS. If so, it would need significant development to be of value. There is likely to be a lack of sufficient hard geoscientific data during Stage 4, so a well-founded sensitivity analysis will be necessary to generate confidence in any safely assessment during this stage. Effective use of expert judgment will also be important, including through peer review.
Concerning the use of GIS for capturing and analysing information (paragraph 5.4), it will be essential to devise a way of incorporating realistic uncertainties into the manipulation and visualisation of 3D geological and hydrogeological information. NDA have not yet demonstrated how this will be done. Professional evaluation of methods, inputs and outputs should be sought so that the GIS is not just mechanistic, but is an effective complement to expert judgment and consensus.
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Do you agree with the proposal to use local and national criteria to identify Potential Candidate Sites? If not, why not?
We agree with this proposal.
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Do you agree with the proposed criteria for identifying Potential Candidate Sites? If not, why not?
The six criteria identified should all be taken into account in identifying PCS.
However, the ‘geological setting’ criterion is not adequately addressed in the consultation document. It is right to allow some flexibility in how geological setting is assessed at this stage, but there is so little discussion of it here, and it is left so open, that this aspect of the consultation is rather limited. (This is a greater concern with regard to criteria for assessment of PCS – see response to question 6, below.) It is understandable that government would wish not to be over-specific regarding what would make a geological setting acceptable or not, but it is important to strike the right balance by setting out and discussing criteria in more detail at this stage. Following on from the ‘unsuitability screening’ at Stage 2, this will be the first stage in the siting process where geoscience has a significant role to play in ensuring a scientifically, economically and socially acceptable site. Appropriate geoscientific characterisation and assessment is key to all these outcomes, and to building confidence, and failure adequately to address this in the present consultation would represent a significant missed opportunity.
Hydrogeological setting is an essential consideration, even at an early stage, but this is not mentioned in the context of PCS identification (though it is mentioned in passing at the PCS assessment stage). The complexity of the geology at a PCS (and hence the difficulty of ultimately characterising it) is recognised at the assessment stage, but it would be sensible also to consider it in PCS identification.
We note that the likely depth range of a Geological Disposal Facility (GDF) is stated to be 200-1000m, but nowhere is there a discussion and explanation of the rationale for that – this could be a good starting point for discussion of some of the factors involved in geological suitability.
A further concern is that, as just one among six criteria, those involved in implementing the identification of PCS will infer that geological setting should be accorded similar weight and status as the others. Important though the other factors are, with the exception of ‘potential impact on people’ they will not fundamentally underpin development of the safety case throughout the siting process, which will be essential in achieving an acceptable outcome, and in building and maintaining public confidence. Nor does the formulation in the consultation document recognise the dependence of several of these other factors (including ‘potential impact on people’) on geological setting.
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Do you feel a multi-criteria decision analysis (MCDA) should be used to assess Potential Candidate Sites? If not, why not, and what approach do you think should be used?
We support in principle the proposal to use MCDA as part of the assessment process, and recognise its value as a tool for objective decision-making. However, we have some reservations about how it is proposed to be implemented, and about lack of clarity regarding the rest of the decision making process (see responses to questions 6 and 7, below).
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Are there any additional criteria that could realistically be considered at this stage in the process to assess Potential Candidate Sites?
As for the identification of PCS, it is appropriate that all the criteria mentioned should be taken into account, but the explanation and discussion of how it is proposed to interpret and apply the criterion of ‘geological setting’ is inadequate.
Beyond a passing mention of hydrogeological characteristics, there is no exploration of the various geoscientific considerations which will be important in site characterisation and assessment. Nor is it recognised that the geological criteria to be considered (and their relative weightings) may depend in part on the rock type at a PCS.
The four sub-criteria identified at paragraph 6.15 are completely different in type, and the dependencies between them are not recognised. For example, the likely size of the potentially suitable volume of host rock might be known to be sufficient for construction of a GDF; known to be insufficient; or of a size such that this is uncertain. It is therefore hard to see how a PCS could be scored on a scale of 1-9 against this criterion. Furthermore, if the volume of host rock is known to be insufficient, then the remaining geoscientific criteria – and indeed all other criteria – would become irrelevant.
While this first sub-criterion is a specific geological property, the other three are general factors regarding constructability, characterisation and safety case. These are all important, but the present formulation gives the impression that properties of geological setting, other than host rock size, are of somewhat subsidiary importance. This is a missed opportunity to inform stakeholders of the relevance of specific aspects of geoscience, especially hydrogeology.
As noted above, the complexity of the geology at a PCS (and hence the difficulty of ultimately characterising it) is recognised at the assessment stage, but it is inadequately discussed. Simplicity and demonstrability of the geological conditions providing containment and isolation will be key factors in achieving confidence in safety and constructability. Assessing those factors will involve a process of expert judgement of geoscientific information that must be transparent and able to achieve professional consensus. The consultation document does not provide any explanation of how this will be done.
As at the PCS identification stage, the fact that geological setting is characterised as just one among six (each with a similar number of sub-criteria) may be taken to mean it has similar weight and status to the others. While the weighting of criteria is an explicit part of the MCDA, there may be a tendency for the ‘default position’ to be to assign an equal weight to each, and to express judgments and preferences through deviations from this default position. (This concern is exacerbated by lack of clarity regarding who is to carry out the principal weighting exercise – see response to question 7.)
The consultation document refers to CoRWM’s use of MCDA in preparing its 2006 report. We note that the MCDA in the CoRWM process, which is widely recognised as having been a major step towards proper recognition in the UK that radioactive waste disposal is not solely a scientific and technical matter, but which caused some disquiet in parts of the scientific community at the time, used a far greater proportion of principally scientific and technical criteria than is proposed here. These were largely established through extensive public and stakeholder engagement.
One way of improving the balance of scientific and other criteria, while also exploring relevant geoscientific factors in more depth, would be to include more than one top level geoscientific criterion, or to add further sub-criteria to the existing one. There are other possible approaches (e.g. by altering the scoring and weighting mechanism). We would be pleased to discuss further how this might be achieved.
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Do you have any comments on the way we propose to use MCDA to assist in structured, evidence based decision making?
The reference to the ‘established techniques’ of MCDA (paragraph 6.7) glosses over the variety of particular MCDA methods, and the need to consider and justify methodological choices made within this framework. Given the long history of the use of MCDA in the context of radioactive waste management (going back to well before 2006), many of the geoscientists and other professionals who are likely to be involved in the proposed process are likely have some familiarity with (and sensitivity to) the potential methodological subtleties and pitfalls. With this in mind, it would be sensible to ensure that the MCDA itself, and it relationship to the rest of the decision-making process, is well understood ahead of time and is capable of inspiring the confidence of professional experts and other stakeholders.
In a typical MCDA, the principal weighting of criteria is carried out by some identified group (in the CoRWM 2006 case, this was the committee itself, for example), against which sensitivity testing is carried out to investigate the effects of the judgments and preferences of stakeholders. The consultation document does not identify who will carry out the principal weighting – this is likely to be a contentious and sensitive issue, at least from the perspective of geoscience professionals. If there is to be no principal weighting, it is hard to see how an overall weighting is to be established (and indeed how sensitivity analysis could then be carried out). There is no explanation of what would be done should the weightings of different stakeholders lead to different overall scores, other than to say that ‘more work may be needed’ (paragraph 6.36).
It is claimed that MCDA allows decision makers to explore the effects of uncertainty in the data, as well as differences of opinion between stakeholders. This is indeed possible within MCDA, but there is no reference to how any sensitivity testing against uncertainty in the data (as opposed to stakeholder weighting sensitivity testing) is to be achieved.
The consultation document notes that the MCDA will be an aid to thinking and decision making, but will not determine the decision (paragraph 6.7). We support this principle. However, it does not explain what other processes will contribute to decision making, nor how these are to be integrated with the outputs of the MCDA. Section 7 refers in passing to ‘other considerations... for example the extent of local support’. No reference is made to the possibility of Community Siting Partnerships or local Decision Making Bodies calling on expert advice and judgments in reaching final decisions (outside the MCDA), nor indeed to any statutory or advisory role the NDA might have. (CoRWM went some way towards setting out how its 2006 MCDA would be integrated with a Holistic Assessment, and expected roles of the committee and other stakeholders, although the extent of this explanation was nonetheless criticised as a weak point in the process.) In the absence of such an explanation, it is difficult to justify the assertion that MCDA provides an audit trail (paragraph 6.7).
There is a lack of attention, in the MCDA and elsewhere, to the distinction between objective criteria (e.g. sufficiency of rock volume) and subjective criteria (particularly those which are not principally technical), and how these are to be considered in relation to one another. In so far as subjectivity is recognised in the document, this is not clearly distinguished from uncertainty (e.g. regarding data which will inform judgments). In order to allow stakeholders to engage effectively with the process, attention should be paid to helping them understand the differences between different types of criteria and uncertainties.
Paragraph 4.10 refers to review by the ‘independent regulators’. It is not clear what the scope and output of such review might be. A more detailed exploration of this, identifying what the regulators will be deciding and against what criteria, would be of great value to others involved in the process, and would enhance transparency. Examples of well-defined regulatory interest and involvement at a similarly early stage of the process can be seen in the Swedish and Swiss cases.