Radiological Protection in Geological Disposal of Long-lived Solid Radioactive Waste

Draft document: Radiological Protection in Geological Disposal of Long-lived Solid Radioactive Waste
Submitted by Sylvain Saint-Pierre, WNA
Commenting on behalf of the organisation

Initial WNA views on the ICRP draft report: “Radiological Protection in Geological Disposal of Long-Lived Solid Radioactive Waste”

Dear colleagues,

We are pleased to submit our initial WNA views on the subject ICRP draft document.

As the key concept of geological disposal has gradually incorporated a growing number of extreme assumptions during its development phase in many countries, we therefore see merit in ICRP’s far-sighted views which aim to make this concept much more realistic and practical than currently defined.

We believe that this ICRP draft report is a genuine initial step and that it would be beneficial to pursue this important development through an improved draft followed by another round of consultation.

Thank you for this opportunity to provide our industry input on this draft document.

We look forward to the outcome of the current consultation process.

WNA Initial Views on the ICRP Draft Report: “Radiological Protection in Geological Disposal of Long-Lived Solid Radioactive Waste”

1. Protection versus Containment [ Executive Summary and the Entire Report ]

We encourage ICRP to further reflect with a view to clarifying the practical meaning of ‘Radiological Protection’ in the particular context of geological disposal. For example, if containment partially fails, to which extent does protection become a real issue. If radionuclides do spread over a distance of a few metres, a few tens of metres or even a few hundreds of metres, what would be the implications from a practical protection view point? Would this have any practical meaning in terms of individual doses or collective doses? And if containment is totally lost due to a huge catastrophe, would radioactivity releases be the biggest issue? In other words, the direct link between doses and containment is not self-evident and there would be value in further exploring and clarifying this key issue.

It can be easily argued that in the particular context of geological disposal the overwhelmingly important parameter is the long term containment provided by the combination of a suitable geology and of suitable engineered measures. Moreover, it is emphasized that such containment is not unusual in nature. In fact, mining deposits in which diverse minerals are found in concentrated amounts around the world are repeated proofs of materials which have been concentrated and contained in a same geological location since the Earth creation.

Said simply, geological disposal includes the containment features of a suitable geology that is compensated by engineered measures in order to ‘re-create’ such long term containment for high level nuclear wastes (HLW) or for used nuclear fuel (UNF) - if the latter is not reprocessed and recycled in the first place. The concept of geological disposal is usually achieved through a suitable geological formation, located at several hundreds of metres underground, that tends to be highly impermeable, thus limiting the long term risk of radioactivity releases via the transport of radionuclides by groundwater. Of particular importance is also the fact that for HLW, the vitrified waste matrix also plays a role in long term containment whereas it is the container that plays such a role for UNF. It derives from this that the container for UNF disposal needs special attention.

In comparison to long term containment, many ‘other notions’ such as doses, dose related-risks, and even oversight (direct or indirect) are, in our view, of secondary importance. At the very least, these other notions should not be directly applied to geological disposal just by simply extending their uses from usual industrial sources of radioactive releases. The context of geological disposal is particular and it warrants special consideration. In fact, a deficit of basic understanding of the mineral world and of the related concept of geological disposal by many in radiological protection have led to quasi-surreal applications of notions like dose and risk criteria. Again, we therefore see merit in ICRP’s far-sighted views that would aim at making the concept of geological disposal and of the related radiological protection notions much more realistic and practical than currently defined – including in this draft report.

Regarding oversight, we recognize that it is an important factor but the reality is that if you would have to choose between containment or oversight, it goes without saying that containment is far more important or is ‘crucial’. That said, we see value on the way the draft report is developing the notion of oversight. We would suggest that the shift to an existing exposure situation should logically apply as soon as the defined time period for reversibility of a geological disposal site is ended.

2. Justification [ Section 4.1 ]

Paragraphs11 and 40: As geological disposal is primarily designed for high level waste (HLW) or used nuclear fuel (UNF), it de facto implies that the practice at the origin of the wastes is the generation of nuclear energy. It would therefore be highly inappropriate in terms of policy-making (especially at the international level) to seek to re-justify the use of a large-scale, long term source of energy (such as nuclear energy) on the basis of a national waste disposal policy. The energy source is the driving justification and waste disposal is only one of the many factors that need to be considered once the justification for the energy source has been made. Said differently, it would be really awkward that a change in a national waste policy would impose a re-justification of long term national energy choices.

If ICRP is not convinced of above, it would be interesting that ICRP would come-up with other practical examples of large-scale long term sources of energy supply which are subdue to the concept of a national waste disposal policy in a similar manner than what is mentioned in the ICRP draft report. For sure, this is not the case for the vast majority of fossil fuel energy that is widely used throughout the world over more than a century! The world is in fact just at the beginning of the control of carbon dioxide air emissions and even farther from the control of changes in the climate that such emissions can induce.

We believe that it is inappropriate to single out nuclear energy on the basis of waste disposal as implied in the ICRP draft report. Such a position would more reflect the views of organizations which tend to systematically oppose to nuclear energy. It is one thing for a given country to choose whatever national policies that it sees as appropriate, and another to extend these policies to the international realm. For a scientifically driven organization like ICRP, it is much better to stay clear from politically driven national agendas. Paragraphs 11 and 40 should be re-written in a neutral way that reflects what countries are actually doing (or not) with respect to wastes arising from the use of large-scale energy sources in general.

3. Doses and Risks [ Executive Summary and Chapter 4 ]

There is recognition in the draft report that the basis for doses and risks can be questionable in the context of geological disposal yet, numerical dose and risk criteria are used throughout the report without sufficiently accounting for the particular case of geological disposal. ICRP should further reflect on this matter and provide more clarification in the report.

An example of such numerical dose criteria is the annual dose constraint for the population of 0.3 mSv/y. The draft report simply re-states what ICRP has already recommended for the design of a waste disposal facility. ICRP has already publicly acknowledged that this choice of numerical constraint was arbitrary. Hence, self-referencing it now does not make a more compelling case. Above all, ICRP should be more aware that such arbitrary choices convey the paradoxical message that a geological disposal can be more hazardous than an active nuclear power reactor. We also emphasized that previous ICRP recommendations included a requirement that, of the 0.3 mSv/y, the contribution from long-lived radionuclides should be no more than 0.1 mSv/y. This contributes to worsen the arbitrary way of dealing with numerical dose criteria. We are concerned that such subjective judgment calls contribute to make the RP system more vulnerable to the scrutiny of informed stakeholders. It does not contribute to strengthen trust and confidence in the protection values that ICRP recommends. We noted ICRP plan to pay greater attention to public communications and to trust and confidence, and we correspondingly urge ICRP to pay greater attention to the way it issues numerical dose criteria and the related basis for them.

Another example of odd numerical dose criteria in the draft report is the proposed use of the value of 0.3 mSv/y (or a large excess of it) to trigger a transition to an emergency exposure situation if severe disturbing events outside the design basis occur while there is still oversight (direct and indirect). Again, ICRP should further reflect on the fact that the prime issue is containment and not doses. Moreover, giving the perspectives that 0.3 mSv/y (or a large excess of it) should be associated with an emergency exposure situation brings a huge imbalance in the overall RP system. Deciding if a geological disposal site is in a state of emergency should primarily relate to what characterizes a lost of containment – as opposed to what characterizes doses.

The values given in paragraph 42 are not better either in terms of direct applicability to geological disposal.

4. Optimization, Best Available Techniques (BAT), Volume and Cost [ Executive Summary and Section 4.4 ]

The interconnection between Optimization and BAT is well introduced in the Executive Summary. This should be further expanded in Section 4.4. In particular, it is important to emphasize the overarching importance of the Optimization principle in radiological protection. It is on the basis of Optimization that a balance must be struck between protection and everything else, starting from the beneficial use of activities that are the cause of exposures. The intent is to aim for an optimal protection and this differs from the concepts of maximal protection or of most stringent protection criteria. As BAT is part of Optimization, it must be viewed in this context and applied accordingly in radiological protection.

Socio-economical factors are mentioned (e.g. para. 66) but experience to date on geological disposal repeatedly shows that cost is probably the single key factor that tends to be systematically overlooked. No doubt that the shift from conceptual developments to practical implementation of geological disposal will considerably raise the profile of cost and challenge designs which are not sufficiently realistic and practical. It should not be surprising to hear that disposal capacity (volume) is one of the most important parameter of geological disposal as it is defining the unit cost of disposal.

In addition to due regard for the safety of geological disposal designs, equivalent attention must be paid to the costs of such designs. Should this not be the case, it remains to be seen if governments will find a sufficiently robust justification in safety alone for spending billions of dollars or Euros in geological disposal - especially in an era of overall economic challenges. In this regard, we emphasize that many countries have opted for the creation of waste management agencies that are independent from nuclear power generation. A clear downside from this configuration is possibly the insufficient level of direct accountability on the cost of geological disposal by developers and implementers. There is also there a temptation to simply assume that all disposal costs can be easily covered by revenues from electricity generation. A better balance must be struck between independence and accountability in the case of geological disposal.

5. Protection of the Environment

We noted (Section 5.2) the significant disparities between what is said at the beginning of paragraph 89 about radiological protection of the environment and what is the reality in environmental protection in general. Given that radioactivity is rarely the dominant source of real environmental stress, it goes without saying that a demonstration of radiological protection of the environment is in fact only a demonstration of a minor contribution to the protection of the environment as a whole. In practical terms, undue emphasis on radiological protection in this case could give a misleading impression that the environment is fully protected when in fact the main parameters that really affect the environment are being overlooked or not subject to proportionate regulatory scrutiny.

Nevertheless, we recognize that ICRP developments on the radiological protection of animals and plants have played a positive role in terms of coordinating international effort in this specialized field of expertise towards a common assessment tool. We emphasize though that practical experience shows that such a tool tends to introduce an unnecessary extra level of complexity in modern licensing process as normal operations in the nuclear sector do not pose real safety concerns for animals and plants. On the other hand, such a tool can be more useful for the assessment of localized bioaccumulation issues in the environment or of significantly enhanced environmental radioactive levels that may result from an accident. ICRP should consider adjusting the scope of its simplified assessment tool accordingly.

With due respect to ICRP and to the concept of reference animals and plants that it puts forward, it would be surprising - as suggested by paragraphs 86-87 - if such a simplified concept would play any significant role in the understanding of the biosphere at present or in the future. After all, the process of roughly estimating doses and effects to animals and plants has little to do with the functioning of the whole eco-system. We would expect that experts in these latter fields of expertise should have a more visible role in the ICRP in its future reflections on the radiological protection of the environment.

Again, the draft report should not lose sight that the notion of protection in the case of geological disposal in particular owing to its primarily reliance on long term containment and that, even if containment fails, the applicability of environmental radioactivity criteria is not straightforward from a protection view point.

Finally, application of environmental radioactive criteria to geological disposal itself poses obvious inherent problems, however guidance on the realistic applicability of such criteria at distances from geological disposal may be helpful.