Reference Docs

The Evolving System of Radiological Protection:
The Nuclear Industry Perspective

R. Coatesa, S. Saint-Pierrea‡, RPWGb

aWorld Nuclear Association (WNA), London, United Kingdom
bWNA, Radiological Protection Working Group‡, London, United Kingdom

Abstract - The International Commission on Radiological Protection is currently developing a new set of Recommendations on Radiological Protection. How these recommendations evolve from the current Recommendations (ICRP 60) could have direct practical implications on the nuclear industry. This paper will present the World Nuclear Association's (WNA) perspective, as a key international nuclear industry representative, on the current proposals by ICRP.

The need for evolutionary development and the need for regulatory stability have been acknowledged by ICRP. This point is strongly supported by the industry. We believe that the case for a significant change to the system of protection is not compelling, and any rationalisations need to be carefully judged. Any changes should be evolutionary, requiring minimal changes to practical regulation, and should assure adequate protection of human health and safety and the protection of the environment, promote optimal use of public and private resources and help build public trust and confidence.

ICRP has decided to reduce its current 30 or so specified values for various situations to just four, and to focus on sources in setting those (rather than dose limits from all sources, which is of less practical use). The principal concern for the industry is the proposal for a maximum dose constraint of 0.3mSv/y on public exposure, and the resulting practical implications. To carefully examine this, one must look beyond the very low off-site impacts from routine radioactive discharges from typical nuclear facilities and consider the nuclear industry in its totality, such as transportation, decommissioning and site remediation. The paper will look at the practical implications of the maximum dose constraint of 0.3 mSv/y for the public, as well as the other three values currently under consideration by ICRP, including occupational exposure.

The establishment of an international approach to defining a level of dose below which society may legitimately maintain that an individual is adequately protected, is strongly supported by the industry. The WNA considers that this dose is not less than a few tens of microSieverts. This approach should be supported by guidance on the appropriate level of conservatism within dose assessments, both in the context of exclusion/clearance/exemption and critical groups in general.

The continued use of collective dose will also be discussed. The WNA considers this is a useful concept in the optimisation of occupational exposure: in addition it needs to be supplemented by the consideration of the number of workers exposed at the higher levels and by wider pragmatic experience. Public collective dose is of very limited utility in decision making, and little if any weight should be given to exposures at long timescales and exceedingly trivial levels of individual exposure.

Finally, the WNA welcomes both the lead taken by ICRP to bring the protection of non-human biota into a coherent overall framework addressing the totality of radiological protection, and the recognition by ICRP that the current system has in practice served to protect the environment. In fact, ICRP's decision to develop a systematic approach to radiological assessment of non-human species has not been driven by any particular concern over environmental radiation hazards, but rather aims to fill a conceptual gap in radiological protection. The industry considers that the focus for protection of non-human biota should be at the species and ecosystems level whilst endorsing that humans are protected at the individual level. Noting that all energy sources give rise to environmental detriments of different kinds, the fundamental issue is not simply how to avoid environmental harm, but how to balance and optimise the totality of benefits and detriments.

Executive Summary

The WNA believes that the case for a significant change to the system of protection is not compelling, and any rationalisations need to be carefully judged. We have concern at some apparent over-simplification and vagueness by ICRP in its furtherance of the search for simplicity and coherence. Any changes should be evolutionary, allowing reasonable regulatory stability, and should assure adequate protection of human health and safety and the protection of the environment, promote optimal use of public and private resources and help build public trust and confidence.

The proposal for a maximum constraint of 20 mSv/y on occupational exposure is too inflexible. The control of exposures in the range 20-50 mSv/y should take account of exceptional circumstances and is a matter best left for discussion and agreement between the local stakeholders – i.e. the regulators, the operator and the workforce.

Our principal concern is the proposal for a maximum constraint of 0.3 mSv/y on public exposure. This level, equivalent to one tenth of average natural background exposure, cannot be justified on public health grounds or in comparison with the range of exposures from background or other practices (e.g. medical). It represents a major and unjustified change from the current limit of 1 mSv pa, and its application in a regulatory regime would have a very significant impact on the nuclear industry, particularly on uranium mining and milling and many other current major nuclear sites. There would be significant cost implications with insignificant consequential gains in health protection.

To carefully examine the issue of practical implications, one must look beyond the very low off-site impacts from routine radioactive discharges from typical nuclear facilities. In particular, there is a wide range of specific situations in the nuclear industry for which a maximum constraint of 0.3 mSv/y set at the international level would be unduly unrestrictive. (A set of key examples is listed herein.) In our view, the current system comprising of the dose limit (1 mSv/y) and the ALARA Principle provides the necessary flexibility and tools to regulators for addressing any country specific or site specific settings, and there are already good examples of this. Again, we believe that this matter is best left for discussion and agreement between the local stakeholders rather than at an international level.

We strongly support the need to establish an international approach to defining a level of dose below which society may legitimately maintain that an individual is adequately protected, and hence the allocation of further resources to control the source on radiological health grounds would be inappropriate. WNA considers that this dose is not less than a few tens of microsieverts. This approach should be supported by guidance on the appropriate level of conservatism within dose assessments, both in the context of exclusion/clearance/exemption and critical groups in general.

WNA supports the continued use of the term 'ALARA, economic and social factors being taken into account'. Collective dose is a useful concept in the optimisation of occupational exposure: in addition it needs to be supplemented by the consideration of the number of workers exposed at the higher levels and by wider pragmatic experience. Public collective dose is of very limited utility in decision making, and little if any weight should be given to exposures at long timescales and exceedingly trivial levels of individual exposure.

WNA welcomes both the lead taken by ICRP to bring the protection of non-human biota into a coherent overall framework addressing the totality of radiological protection, and the recognition that the current system has in practice provided an appropriate standard of environmental protection. On this basis the development of the future system of protection must not impose a disproportionate burden on operators. The focus for protection of non-human biota should be at the species and ecosystems level whilst endorsing that humans are protected at the individual level. Noting that all energy sources give rise to environmental detriments of different kinds, the fundamental issue is not simply how to avoid environmental harm, but how to balance and optimise the totality of benefits and detriments.

Introduction

The objective of radiological protection is to provide a framework which facilitates the safe and responsible use of radiation sources which provide very significant benefits to society. These benefits cover many fields, including medical diagnosis, cancer therapy and food preservation. The area of particular interest to the World Nuclear Association (WNA) is the generation of electricity by means of nuclear fission.

Nuclear power provides 16% of the world's electricity and is a major sustainable non-fossil means of providing continuous, reliable supplies of electricity on a large scale. There are currently 440 nuclear power plants in over 31 countries worldwide, with more than 15 countries utilising nuclear power for 25% or more of their electricity. Nuclear power can generate electricity with no carbon dioxide or other greenhouse gas emissions. In fact, unlike many forms of electricity generation most health and environmental costs from nuclear electricity are internalised in the price to the customer. With world energy consumption predicted to double by 2050, nuclear power offers clean, reliable energy to meet this demand.

As an organisation fully involved in the world energy debate, the WNA is aware that there are no risk-free methods of energy generation, nor are there any generation activities which do not have an environmental impact. It is therefore important to ensure that in the ongoing debate on the future system of radiological protection, the emphasis is firmly focused on assessing the benefits and detriments of radiation sources in a balanced, coherent way rather than simply addressing a system of protection which seeks continually to reduce or minimise actual or perceived risks from radiation. This latter approach could serve to foreclose options with the greatest overall advantage to society.

International and national radiation protection organisations including ICRP are presently engaged in updating, clarifying and enhancing radiation protection principles - and rightly so, given our culture of pursuing excellence in radiation safety through a process of continuous improvement. Accordingly, the nuclear energy industry appreciates the opportunity to provide its perspective on this effort.

The nuclear energy industry's perspective is shaped in several ways - as an operator, we carry out a primary responsibility for protecting human health and safety and the environment; as a licensee, we are responsible for complying with government regulations; and as an energy producer, we are responsible for the safe, reliable, and economic generation of electricity for consumers. Our objective in regard to improving radiation protection principles is to help promote an outcome that has a clearly articulated basis in science, is flexible in regard to how it might be applied to a very wide range of current and future regulated activities, and is practical and cost-effective in terms of how it can be implemented and maintained.

Why change?

In WNA's view the current radiological protection system has provided an adequate basis for protecting workers, the public and the environment. We are not aware of any significant changes in scientific knowledge which would indicate a need for a change in approach, although we recognise the need to fill a conceptual gap regarding the protection of non-human biota. However, we note the view that the current ICRP system of protection is complex and difficult to understand, with potential inconsistencies and unnecessary duplication across the various fields of application. In this sense we welcome the general idea of simplifying the system and making it clearer for practical use, particularly where this could help a wider perception and understanding of radiation. It would also be helpful if ICRP could seek to clarify the reasons why it advocates common internationally relevant numerical constraints, particularly where it could be argued that social judgements (for example on the acceptability of risk) form a significant input. ICRP should also consider the practical implications of specific numerical choices for key constraints.

However, in reviewing the recent presentations and discussion documents by ICRP we have some concerns that ICRP may become too vague and generalised in this quest for simplicity and coherence, and hence lose the value of much of its previous work as expressed in ICRP 60. In our experience most practical interactions and debates on radiological protection take place within specific components of the system, and relevant detailed considerations should not unnecessarily be lost or sacrificed simply to achieve a perceived wider coherence or simplicity.

Whilst not primarily a matter for ICRP, the WNA has concerns that a significant change to ICRP recommendations can unnecessarily and inappropriately reopen regulatory approaches and interpretations. Recent experience has shown that in such situations there is very rarely a tendency to rationalise towards a higher level of allowable exposure, no matter what rational arguments exist: 'the same level or lower' is a common approach when faced with public debate.

Based on the above, it is WNA's view that it is right to explore whether the system of protection can be simplified, provided that any changes to its application in practice are evolutionary in nature, based on adapting and re-emphasising current processes rather than wholesale change. In particular there should not need to be any major consequent change to the regulatory regime. Proposed changes should arise from an expectation of substantive improvement to the level of radiation safety provided and should not unnecessarily restrict societal access to the vast benefits of nuclear technology. In total, changes should meet the following objectives:

System of Protection

The nuclear industry can in principle accept the proposed conceptual change to the system of protection, based on justification, a source-related upper constraint, with optimisation below this level leading to authorised levels. The generation of electricity by nuclear means is a practice with well-controlled sources. We anticipate that our sources will continue to be regulated within numerical levels relating to assumed occupational and public risk and environmental protection. These numerical levels have usually been referred to as 'limits', but terminology which avoids any implication of a safe/unsafe boundary would be welcome.

The principle of justification is accepted as an underpinning component of risk protection philosophy. As indicated by ICRP, radiation protection is only one part of the overall picture: society must judge the totality of benefits from a practice against the totality of risks. The problem with the concept arises through its implementation in regulatory systems, usually solely in the context of radiological protection legislation. This creates additional burdens for activities with radiation risks compared to other activities. It is therefore essential for ICRP to emphasise that the justification principle is not specific solely to radiation risk and that its application in practice should be in the context of the totality of risk management.

In considering the concepts of constraints and optimisation, which are addressed in detail below, ICRP should also note that practical decision making rarely occurs within the confined world of radiological protection. Most real decisions involve trade-offs between radiological and other risks as well as between workers and the public, etc. ICRP should ensure that the system of protection is capable of linking into this wider context and should consider what substantive guidance could be developed in these areas to supplement the general thrust of stakeholder involvement.

Constraints

WNA strongly supports ICRP's proposal to use comparisons with the range of natural background exposure to give a context for the selection of constraints on exposure. In creating decade 'bands of concern' it would however be more appropriate to base the boundaries on the concept of 'a few' (e.g. a few mSvs etc) rather than the rather precise multiples of 10 as currently indicated. This would more accurately reflect the linkage to natural background.

In previous ICRP recommendations some limits/constraints have been justified by comparison with risk acceptance in society. However, this creates difficulties on an international scale because of national and regional differences, although it is nonetheless a factor which national stakeholders may take into consideration in order to help achieve an appropriate balanced use of national resources in managing societal risks.

ICRP's comments on the large number of currently defined constraints are noted. Each had some value and utility within the system in which they were derived. Any simplification of the overall system must not lead to a choice of inappropriate numerical values purely in pursuit of rationalisation. WNA offers particular comment on the following key proposed constraints:

Given that there are no changes in risk estimates since ICRP's previous recommendations, WNA can see no reason to change from the previous 50 mSv/y upper limit for any year, subject to 100 mSv in 5 years. The need to give priority ALARA focus to the highest exposures is fully supported, but the application of a limit (or upper constraint) at 20 mSv/y will present significant practical difficulties to some parts of the nuclear industry, particularly in some uranium mining operations and specialist reactor maintenance activities, without realising significant benefit. The detailed control mechanism for exposures in this highest dose range should be a matter for discussion and agreement between the local stakeholders – primarily the regulators, the operator, and the workers.

WNA notes with great concern that ICRP are proposing that a source-related constraint of 0.3 mSv/y should in effect replace the 1 mSv/y dose limit for public exposure from all sources (which itself was a contentious change from the previous limit of 5 mSv/y). We cannot understand why a further factor of 3 reduction should now be applied - this implies an enormous conservatism of overlapping sources whereby an individual would be a critical group member for three or more independent sources. In practice there is very rarely more than one relevant contributor to dose at the level of a significant fraction of a mSv, hence the choice of a maximum constraint of 0.3 mSv/y for public exposure represents a very significant and unjustified change in the ICRP recommendation. Such a change would in effect create a limit on public exposure from specific sources at a dose level of one tenth of average natural background and an even smaller fraction of the typical range of background exposures; this cannot be justified on public health grounds.

In practical terms there are many situations where activities are currently indicated to exceed 0.3 mSv/y, usually within the range up to 1 mSv/y. These include the following examples where:

Hence the use of a public dose constraint at 0.3 mSv/y, if applied as currently anticipated within regulatory systems, would have very significant cost implications for the nuclear industry with insignificant consequential gains in health protection. WNA notes that there has been no consideration of the impact of this proposal, nor of the merits of alternative numerical values for this constraint. With the current value of 1mSv pa and the ALARA Principle, regulators have the necessary flexibility and tools to address any site-specific issues. The choice of a public dose constraint below 1 mSv/y should be subject to discussion and determination at national rather than international level and should take account of its context for current activities.

Exclusion, exemption and clearance

The nuclear industry agrees with the view that clearance and exemption are in effect generic authorised releases from the system of protection. However, they are nonetheless extremely important issues and there are strong philosophical and practical reasons for ensuring alignment between clearance, exemption and exclusion so that material, once outside the system of protection, remains outside. Also given the movement of materials in trade, there is a need to secure an internationally based underpinning of these concepts.

The key issue here is the link to the level of dose which is sometimes referred to as trivial or Below Regulatory Concern. This is a complex area which interacts with judgements about the acceptability of specific sources or practices and where differences in national cultures and approaches can be significant. However, it is important that ICRP moves to establish an international approach to defining a level of dose below which society may legitimately maintain that an individual is adequately protected, and hence the allocation of further resources to control the source on radiological health grounds would be inappropriate. Any further consideration of the source taking account of non-radiological issues could, if necessary, be a matter for local stakeholders at national level, and in this case it would be essential to clearly distinguish where social or political factors influenced the decision.

Noting previous comments above on the link between natural background and the choice of constraints, WNA strongly believes that this low level of dose should not be less than 'a few tens of µSv pa' rather than the unduly precise 10 µSv/y currently advocated by some parties. In addition, further consideration needs to be given to obtaining greater coherence between the treatment of natural (ie NORM) and artificial nuclides. This more flexible approach must also be supported by more realistic assessment models for defining derived quantities (e.g. Bq g-1). Current approaches often involve multiple conservatisms which bias the derived quantities to unnecessarily restrictive levels. Whilst not primarily an issue for ICRP, it would be helpful to have clear advice on the level of conservatism appropriate for such models.

Optimisation

The WNA considers that optimisation is the vital cornerstone of practical radiological protection, and that the new recommendations should build on and strengthen this position. We are concerned at the proposed re-working of the well-recognised term "As Low As Reasonably Achievable, economic and social factors being taken into account". Whilst supporting the involvement of appropriate stakeholders in the optimisation process, we are concerned about the vagueness of some of the ICRP discussion on this topic which seems to ignore some well established practical inputs into optimisation.

Occupational exposure:

Collective dose has been a useful management tool for promoting and measuring improvement in repeated tasks (e.g. steam generator replacement) and for monitoring temporal changes in the performance of working groups. It is also a useful tool for stimulating increased focus on specific key tasks and activities (e.g. maintenance work). The doses are received within a clearly defined exposure scenario with a relatively narrow range of individual exposures and time periods (in comparison with public exposure - see below). The industry expects collective dose to continue to play an important role in occupational protection practice. It is acknowledged that collective dose does not give the complete picture - in particular it is necessary to take account of the higher levels of individual exposure, for example by considering the number of workers exposed in the higher level dose bands: priority in focusing ALARA efforts on these higher exposures is certainly important. (NB: average dose is not necessarily a good indicator: its utility in practice is often confounded by a relatively large number of low dose individuals).

However, collective dose is only one component of workforce dose optimisation. It is important to address all the three widely recognised components of a balanced ALARA programme i.e. engineering options, management system controls and safety culture/awareness. In this latter respect, the importance of fully involving the workforce (i.e. the key stakeholders) in contributing to the ALARA programme cannot be overstated, particularly noting their detailed knowledge of the work being undertaken, the importance of self-awareness in reducing individual exposure and the power of peer evaluation and peer pressure. There is also much experience and common sense guidance on practical optimisation approaches which has been codified in guides and 'best practice' codes at international, national and industry/company level. This practical experience is the key to effective optimisation implementation.

Public exposure:

WNA shares ICRP's concern over the difficulties experienced in using collective dose in the optimisation of public exposure. Emotive 'deaths' assessments have received much publicity, although the assessments are usually based on minute doses aggregated over hundreds of thousands of years, way beyond the validity of the radiation risk estimates and realistic modelling capability and the normal societal decision making considerations. Such work also usually omits to mention that alternative technologies which could give equivalent benefits also have similar detriments which are far less visible and quantifiable.

Hence it is clear that collective dose cannot be a key determinant in decision making when choosing between a wide choice of options such as in the energy field. It is accepted that collective dose may have some limited utility in comparing between related radiological options, provided that as advised by ICRP the dose is not over-aggregated. In particular the presentation of data should give greatest emphasis to near-term exposures and also place low emphasis on individual dose components received at small fractions of the internationally-accepted 'trivial' dose rate as discussed above. These weightings would more closely align with normal decision-making considerations in wider fields beyond radiological protection. Further consideration should be given to concepts inherent in the valuation of detriment delivered at very low risk levels, including the option of declaring a zero weighting for such low exposures.

Looking at the broader picture of public dose optimisation, we recognise the importance of involving appropriate stakeholders including, for example, representatives of the local communities and wider interested parties. The nuclear industry has extensive and growing experience of such exercises, and recognises that there are many ways in which such involvement can be achieved. It is important to match the process to the local circumstances and cultures, and avoid prescription, although it is important to ensure segregation of scientific and factual inputs from social and political judgments so that the basis of any consensus or decision is transparent.

The Critical Group Concept

The critical group concept is a well-established and important component of the existing system of protection, although the use of 'reference group' may perhaps be more appropriate terminology. The key issue to be addressed is the extent of conservatism which is necessary in the assessment of critical group dose. The wider context here is the need to pursue the societal benefits from practices whilst achieving an adequate level of protection of the individual: excessive conservatism within assessment regimes can foreclose radiological options and hence distort the overall societal balance of risk, giving rise to the inefficient use of resources.

In further refining the critical group concept, WNA believes that the following issues should be taken into account:

Protection of the Environment

WNA supports the lead taken by ICRP to bring the protection of non-human biota into a coherent overall framework addressing the totality of radiological protection. We welcome the recognition that the current system has in practice provided an appropriate standard of environmental protection, although there is a need to close a conceptual gap. Given this fact it is important to ensure that the future system of protection, and any consequential burden placed on industry through its likely incorporation into regulatory processes, is not in disproportion with this evidence.

However, in moving towards a common framework, we believe that it is essential to recognise differing emphases for the protection of human and non-human organisms: humans are protected at the level of the individual whilst non-human biota are protected at the population and ecosystem level. Such an approach is consistent with other fields of environmental protection. The development of the framework for protection should assist in focusing the science on more clearly establishing the linkage between effects at the individual and population/ecosystem levels.

Beyond the protection of populations and ecosystems, we recognise that approaches to conservation do in practice in many cases address issues at the level of individual organisms. However, these are special cases which need to be addressed on a case by case basis, and are entirely inappropriate for the basis of a general framework.

As we have stated earlier, all alternative energy sources give rise to environmental detriments of different kinds, and indeed the lack of energy would give the greatest dis-benefit to society. The fundamental issue therefore is not how to avoid environmental harm, but how to balance and optimise the totality of benefits and detriments. A key challenge for ICRP is now to move forward and develop an approach to optimisation which includes environmental effects. The inclusion of non-human effects in such considerations should in general only be necessary at the higher levels of exposure where these could be manifest - in effect a threshold approach.

Given the wide range of natural background levels and organism sensitivities to radiation, together with the lack of clarity on how individual effects contribute at the population/ecosystem level, it is at best premature to move forward with the concept of Derived Consideration Levels linked to natural background. Whilst requiring some further work, scientific evidence does not indicate the likelihood of significant ecosystem or population effects at a level of dose one order of magnitude above background.

Conclusions

The current system of radiological protection is generally effective and well-regarded, and has facilitated the development of many benefits to society from the controlled use of radiation sources. Whilst there are some simplifications, clarifications and rationalisations which could and should be achieved, it is important that these are addressed in an evolutionary manner which avoids significant and unnecessary change to the practical implementation of radiological protection at the working level.

The greatest concern of the nuclear industry within the current developments is the proposal to set the public exposure constraint at 0.3 mSv/y. This has not been adequately considered and would result in very significant issues and cost which cannot be justified.

APPENDIX A : List of Radiological Protection Working Group (RPWG) Members of the World Nuclear Association (WNA)

Canada Al Shypth Cameco
Canada Cliff Davison AECL
France Sylvain Saint-Pierre COGEMA
France Yves Garcier EDF
Japan Shinichiro Miyazaki KANSAI
Sweden Carl Göran Lindvall Barsebackkraft
UK Roger Coates BNFL
USA Wallace Mays WM Mining Inc
USA Ralph Andersen NEI
International Gordon Linsley IAEA