Reference Docs

The ICRP Proposed Maximum Public Dose Constraint of 0.3 mSv/y:
a Major Issue for the Nuclear Industry

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 (ICRP) is currently developing a new set of Recommendations on Radiological Protection. A value of 0.3mSv/y for the maximum public dose constraint has been discussed by ICRP. This value represents a major concern for the nuclear industry at large.

The primary issue arises from the lack of any new scientific evidence on public health effects from ionising radiation to support, in practice, the proposed reduction by about a factor of 3 (from 1 to 0.3 mSv/y) of the upper bound value for public dose impact from a nuclear activity or site. Such a change would create a de facto limit on public exposure from specific sources at a dose level of about one tenth of average natural background and an even smaller fraction of the typical range of background exposures and exposures from medical sources. This cannot be justified on public health grounds.

The WNA supports ICRP's renewed intention, as expressed at the NEA-ICRP Stakeholder Forum in Lanzarote (April 2003), to retain the concept of a public dose limit at 1 mSv/y. We strongly believe that the current system comprising of the dose limit and the ALARA Principle provides the necessary flexibility and tools for regulators to address all situations in all countries. The WNA consider that the question of setting an upper bound dose constraint (below 1 mSv/y) at the country/site specific level is best left for discussion and agreement between the local stakeholders rather than at an international level.

When considering the potential practical implications of a maximum dose constraint, it is important to look beyond the very low off-site dose impacts (on the public) resulting from annual routine radioactive discharges of nuclear industrial sites. There are many off-site and on-site practical situations, related to public exposures (both workers and the public) and worker classification as well as activities such transportation, decommissioning and site remediation, for which a maximum dose constraint of 0.3 mSv/y would have practical implications. Indeed, implementation of this value will mean that the virtue of the ALARA Principle would in practice be eliminated. Most of the effort would be put at meeting the constraint, with little room for the balance between benefits and detriments. Also, there would be difficulties to ensure that the constraint is systematically met, especially if one were to consider the potential risk (real or theoretical) of exposures.

To be universally acceptable in practice, the ICRP international recommendations must provide a reasonable framework that can be implemented within the multiple situations commonly encountered in different countries across the world. As noted in Lanzarote, ICRP should be aware and sensitive to the fact that there are countries/regions that are striving to meet, or that have not yet adopted, the ICRP60 recommendations. Not accounting for this would have downsides on the world-wide empowerment for continuous progress in radiological protection.

On this basis, we believe that there is no sound basis or reason to set, at the international level, a maximum public dose constraint at a value that differs from the dose limit of 1 mSv/y. Examples of practical situations where this value would be unduly restrictive will be discussed.

Key Points

At the 2nd NEA/ICRP forum in Lanzarote, the WNA flagged that the 0.3 mSv/y value (as the maximum public dose constraint) represents a major concern for the nuclear industry at large.

The primary issue arises from the lack of any new scientific evidence on public health effects from ionising radiation to support, in practice, the proposed reduction by about a factor of 3 (from 1 to 0.3 mSv/y) of the upper bound value for public dose impact from a nuclear activity or site. Such a change would create a de facto limit on public exposure from specific sources at a dose level of about one tenth of average natural background and an even smaller fraction of the typical range of background exposures and exposures from medical sources. This cannot be justified on public health grounds. We therefore question the basis (international or otherwise) for the 0.3 mSv/y value.

We are also concerned that some ICRP members viewed the proposed maximum public dose constraint as "fact" in the light of its post-ICRP60 inclusion (i.e. in ICRP77). We would point out that the Lanzarote forum was the first opportunity for stakeholders such as WNA to engage in any debate on ICRP's thinking on this topic. We would have particular concern at the extension of this concept from the ICRP 77 waste disposal focus to its application as a generic exposure constraint. A factor of three reduction below the limit implies an enormous conservatism of overlapping sources which cannot be valid at the international level.

We understand that it is now ICRP's intention to retain the concept of a public dose limit at 1 mSv/y, which we fully support. We strongly believe that the current system comprising of the dose limit and the ALARA Principle provides the necessary flexibility and tools for regulators to address all situations. The question of setting an upper bound dose constraint (below 1 mSv/y) at the country/site specific level is best left for discussion and agreement between the local stakeholders rather than at an international level.

In fact, for many off-site and on-site practical situations that we illustrate in the present document, a maximum dose constraint of 0.3 mSv/y would mean that the virtue of the ALARA Principle would in practice be eliminated. Most of the effort would be put at meeting the constraint, with little room for the balance between benefits and detriments. Also, there would be difficulties to ensure that the constraint is systematically met, especially if one were to consider the potential risk (real or theoretical) of exposures.

To be universally acceptable in practice, the ICRP international recommendations must provide a reasonable framework that can be implemented within the multiple situations commonly encountered in different countries across the world. As noted in Lanzarote, ICRP should be aware and sensitive to the fact that there are countries/regions that are striving to meet, or that have not yet adopted, the ICRP60 recommendations. Not accounting for this would have downsides on the world-wide empowerment for continuous progress in radiological protection.

On this basis, we believe that there is no sound basis or reason to set, at the international level, a maximum public dose constraint at a value that differs from the dose limit of 1 mSv/y. We have attached (see Appendix A) for your consideration, some thoughts on the interaction between limits and constraints, with the aim of contributing to a clear position.

Summary of potential practical implications on the nuclear fuel cycle industry from the proposed maximum public dose constraint (0.3 mSv/y):

When considering the potential practical implications of a maximum public dose constraint, there is a tendency to focus on the very low off-site dose impacts (on the public) resulting from annual routine radioactive discharges of nuclear industrial sites, which are often well below the value of 0.3 mSv/y.

However, beyond the specific situation just mentioned, the WNA would like to stress that there are a wide range of "other situations/activities" commonly encountered in the world-wide nuclear industry for which the value of 0.3 mSv/y, set at the international level, would be unduly restrictive with significant practical implications. It is essential that these situations/activities are not overlooked. For this purpose, your attention is drawn to the following key examples that illustrate the broad areas for which the most significant potential implications are foreseen:

Consider the off-site impacts from:

Also consider:

This set of key examples is further elaborated in Appendix B.

Although not directly an issue for WNA, we are aware that many other sectors such as medicine, general industry and teaching would also be impacted by directly analogous 'knock-on' effects of a generic public dose constraint. ICRP should carefully review the impact of developing recommendations in all such areas.

Conclusion

The WNA believes that it is essential that the driving factors for considering the application of the 0.3 mSv/y value as a generic public constraint must be based on a clear demonstration of the overall benefits, accounting for:

1) scientific progress in public health effects from ionising radiation (though also accounting for the range of exposures from background or other practices: e.g. medical), and

2) a sound analysis of the potential practical implications (including implementation difficulties and incremental costs) for the nuclear industry and other users of radioactivity and radiation sources.

On both counts, we are not aware of significant evidence in support of the present ICRP proposal. We would argue that the proposal is not sound on public health grounds and/or on practical grounds, and that a significant portion of the nuclear industry situations/activities have been overlooked.

Appendix A

Limits and Constraints

Many types of sources result in both occupational and public exposures being significantly below the relevant dose limits when the sources are operated in a manner commensurate with good practice. Also, in some specific circumstances, regulatory authorities may need to take account of local circumstances where specific individuals could be exposed to more than one source.

However, there is no evidence, either from theory or practice, which supports the establishment of generic and universally applicable maximum dose constraints at levels below the dose limits for either occupational or public exposure. In order to have real value and utility within the radiation protection framework, the establishment of a constraint on the optimisation process must take full account of circumstances relating to the type of source and any necessary relevant local factors.

For occupational exposure, practical experience demonstrates that the majority of workers are subject to significant exposure to only a single source. However, a smaller fraction of workers may move from site to site and hence receive exposures from multiple sources. In such circumstances the control regime must continue to be based on ALARA within the occupational dose limit, together with locally-agreed constraints according to the nature of the source and the workforce.

WNA can see no reason for ICRP to change from the ICRP 60 recommendation of a dose limit of 100 mSv in 5 years, provided that exposures in the range 20 -50 mSv in any single year are subject to specific mechanisms with the ultimate aim of seeking to reduce such exposures below 20 mSv/y.

For public exposure the limit of 1 mSv/y should be applied, subject to the application of locally-determined source constraints which take account of the nature of the source and other relevant local considerations such as the potential for other significant contributions to individual exposure.

APPENDIX B: I - Nuclear Industrial Sites

1. Licensing

In many countries, nuclear industrial sites have been subject to full-scale licensing procedures with public hearings in the context of 1 mSv/y (5 mSv/y for older sites).

The possibility of introducing the 0.3 mSv/y value in the regulatory regime would have broad implications on the whole spectrum of the nuclear industrial activities from the conversion of uranium concentrate, to enrichment, fuel fabrication, reactors, spent fuel reprocessing, recycling and disposal, as well as on vital supporting activities such as the storage and transport of radioactive materials.

2. Off-Site Impacts

a) Multiple Sites - Sites are often located at long distances (e.g. several 10's or 100's of kilometres) from each other, with virtually no or extremely small possibilities for a cumulative dose impact of significance on a single group of people. For example, consider the sites located in large countries such as Australia, Canada and USA. Setting the value of 0.3 mSv/y at the international level would be unduly restrictive in many countries and regions.

 b) Historical discharges - For some sites, although the cumulative impact from historical discharges (routine and else) on the off-site public is below the dose limit of 1 mSv/y, excesses of 0.3 mSv/y are possible with virtually no reasonable option to reduce exposures. Setting the bar at 0.3 mSv/y would make this topic unnecessarily problematical with subsequent significant implications for the industry.

c) Conservative regulatory assessments of discharge authorisations - It is regulatory practice in many countries for assessments to be made, using conservative modelling parameters, of the impact of authorised levels of discharge at the limit values for all specified discharge components from a site. Such conservative assessment regimes can result in assessed maximal theoretical doses exceeding the expected practical impact from actual operations by a very significant factor (typically up to about four). Current experience indicates that for some key sites these theoretical assessments result in assessed doses exceeding 0.3 mSv/y, although usually significantly less than 1 mSv/y. The application of the lower constraints value to such a regime could impose significant and costly operating restrictions even though the actual impact of operations is already significantly below 0.3 mSv/y.

d) Hypothetical site boundary situations - To reduce worker exposures, large inventories of radioactive materials are often stored at the site perimeter. The exposures of the closest residents (critical groups) from these sources are generally very low if not nil. Nevertheless, there are situations where the public can possibly be exposed near-by the site boundary (e.g. portion of a public road,…), and especially if one assumes exposure scenarios that tend to be abnormal or extreme. In some countries, stringent interpretations (e.g. 8760 hours/y at the site property boundary or fence line) that arose from this issue have led to significant difficulties for operators. The 0.3 mSv/y would further complicate this issue.

Comment - It is recognised that several of the examples presented in this paper demonstrate the problems arising from seeking to apply a public dose constraint at 0.3 mSv/y together with a conservative theoretical dose assessment regime. Whilst the actual practical doses arising from such activities are usually well below 0.3 mSv/y, WNA is nonetheless very concerned that these situations present a real and credible challenge to the possible introduction of a generic dose constraint, given the inevitable application of current regulatory processes.

3. On-Site Issues

a) Classification of Nuclear Workers and Related Requirements - In many countries, the public dose limit value of 1 mSv/y is used as the reference value above which workers are classified as nuclear workers. This classification generally triggers a series of related requirements (e.g. training, medical health monitoring, dosimetry monitoring , and zoning) and of worker contractual benefits that often result from tedious negotiations.

With the current dose limit of 1 mSv/y, there are many workers at nuclear facilities that are not subject to a nuclear worker classification and to the related requirements. For example, for some large facilities, it is not uncommon to have a significant fraction of plant staff considered as non-exposed workers. Relative to 0.3 mSv/y, many of these workers would become nuclear workers, thus adding-up to 1000's of company wide extra nuclear workers. Several large operators can potentially be affected by this change.

Setting the bar at 0.3 mSv/y would therefore have significant implications on site activities, work practices and basic designs. Also, it would contribute to give a perception of increased radiation hazards on-site - a highly sensitive matter for the industry.

b) Public Exposures (Workers and Else) - The corollary of items "3a" is that one should also ensure that non-exposed workers and the public who access the site would not be exposed in excess of 0.3 mSv/y, thus representing an extra challenge.

c) Storage and Zoning - Further to items "3a and 3b", implications for the storage of radioactive materials and for source-related (storage or process equipment) zoning would be straightforward : e.g. more shielding and more distance would be required in many cases. Again, this would have significant implications on site activities, work practices and basic designs.

4. Decommissioning and Reclamation

The bulk of decommissioning and reclamation work planned for the current generation of nuclear industrial sites lies ahead in many countries. Substantial funds have been put aside by nuclear operators to handle that liability in due time. The industry is concerned with the significant impact that the 0.3 mSv/y value might have on these plans and funds. For example, consider :

5. Future Nuclear Facilities

All of the above items are based on the long term experience of the nuclear industry with respect to the existing nuclear facilities. One should also keep in sight future facilities (e.g. final disposal sites for high level radioactive wastes) for which we have little practical large scale operational experience or that have not yet been designed or built.

APPENDIX B : II - Transport of Radioactive Materials

1. Licensing

The transport of radioactive materials, vital for the industry, is a licensed activity. The possibility of introducing the 0.3 mSv/y value in the regulatory regime have broad implications on the whole spectrum of transport activities from packages and containers designs, to the various aspects of the transport logistics (e.g. transfer stations, transport modes, transport routes,…).

2. Basic Safety Standards (BSS)

The current transport activities have been primarily designed on the basis of the IAEA Basic Safety Standards and of the potential risks of exposures for workers and the public. Many considerations within the BSS have a traceable assessment link to the allowable public exposure limit - including for example package radiation limits and package radioactivity content limits. Any consideration by ICRP to place a generic constraint on public exposure down to 0.3 mSv/y would make the BSS more challengeable (and perhaps, incoherent in some cases). This would make more complex and costly the transport of most of the key radioactive materials necessary for the industry with no obvious gains : e.g. more shielding and less material transported by package versus more transports.

The transport of spent fuel and its by-products which are already subject to very stringent rules may also be particularly vulnerable. Also, the industry is highly concerned on the perception of increased off-site radiation hazards that it would give to transport workers and to the public.

3. Transport Packages and Containers

The design of transport packages and containers is a long rigorous process as it is at the basis of the transport radiation and nuclear safety. Once approved and licensed, transport package and container units are manufactured and used on a world scale to support the needs of the nuclear industry. Any significant change to this has substantial world-wide implications.

4. Transfer Stations (sea ports, airports, rail and road terminals)

A report of the World Nuclear Transport Institute (WNTI Studies Series 2, August 2001, Radiation Dose Assessment for the Transport of Nuclear Fuel Cycle Materials) clearly indicated the potential for excess of 0.3 mSv/y at key facilities of the transport logistics such as transfer stations, thus triggering concerns for classification of nuclear workers, public exposures (workers or else), and storage & zoning that would be analogous to those indicated earlier: items "3a" to "3c" in the section on "Nuclear Industrial Sites".

In the case of front-end, non-irradiated material transports, in general the transfer stations involved are not dedicated to nuclear cargoes and there is presently, with the limit of 1mSv/y, no need to consider workers as nuclear workers. According to the report indicated above, with a value of 0.3 mSv/y, nuclear classification of workers would then be required. At the strategic transfer points represented by sea ports for instance, this would certainly contribute to a perception of increased radiation hazards in areas where industrial relations are often difficult and where the smooth flow of cargoes is fundamental to the nuclear fuel cycle.

For back-end materials (spent fuel, waste (LLW/ILW), high level waste and MOX/plutonium, the above report demonstrates that a value of 0.3 mSv/y would trigger potential implications for all transport mode handlers. For all transport modes, a large increase in numbers of nuclear workers would be required.

For a typical back-end transfer facility, it is not unusual to have 10 to 20 workers classified as nuclear workers. Reducing the permissible exposures below 1 mSv/y would significantly increase the number of nuclear workers at these facilities and beyond. For example, down to 0.3 mSv/y, it would not be surprising to end up with a number of nuclear workers that increases by up to 2 to 5 fold. This issue would be amplified by the number of transfer stations spread around the world.

5. Sea transport

For the case of sea transport of front-end materials, the vessels used today are often non-dedicated cargo ships on which the nuclear cargo represents a small percentage of the total cargo. The report shown above indicates for the crews of such vessels, today not considered as nuclear workers, that a value of 0.3 mSv/y almost certainly would require nuclear classification of crew members and so increased perception of radiation hazard linked to cargoes. The refusal of certain maritime companies to ship class 7 materials is common and the impact of this new change on future attitudes of other companies could be very damaging to the smooth performance of the nuclear fuel cycle.

For back-end materials the reduction in limit would require almost systematic classification of crews for all transport modes as radiation workers

APPENDIX B : III - Uranium Mine and Mill Sites

1. Licensing

In many countries, uranium mine and mill sites have been subject to full-scale licensing procedures with public hearings in the context of 1 mSv/y (5 mSv/y for older sites).

The possibility of introducing the 0.3 mSv/y value in the regulatory regime would have broad implications on the whole spectrum of mining sector activities from ore mining, to milling, waste management, site decommissioning & reclamation, and thereafter.

2. Operating Sites

Off-site Impacts - Nowadays operating sites tend to be located in remote areas further away from populated areas. Though, groups of people can be exposed to the off-site discharges.

Sites are often located at long distances (e.g. several 10's or 100's of kilometres) from each other, with virtually no or extremely small possibilities for a cumulative dose impact of significance on a single group of people. For example, consider the sites in large countries such as Australia, Canada and USA.

Although these sites comply with the 1 mSv/y dose limit, modelling indicates that the 0.3 mSv/y value can be exceeded in many circumstances, especially due to the releases of radon gas - with such releases been quite variable (e.g. a factor 2 or larger) at the sources.

The 0.3 mSv/y value would also no doubt augment significantly the difficulty of interpreting the naturally enhanced background radiation levels (and especially radon and radon progeny levels) that characterized uranium mining regions. Environmental measurements in proximity of sites would therefore become more problematical.

For some sites, the concerns for historical discharges would be analogous to those indicated earlier under item "2b" in the section on "Nuclear Industrial Sites".

On-Site Issues - Concerns for classification of nuclear workers, public exposures (workers or else), and storage & zoning would be analogous to those indicated earlier under items "3a" to "3c" in the section on "Nuclear Industrial Sites".

3. Decommissioning and Reclaimed Sites

Off-Site Impacts - In the past, operating sites in proximity of populated areas where not uncommon. This means that even if these sites were decommissioned and reclaimed, groups of people can still be exposed to off-site residual discharges. For example, consider the sites in some European countries such as Germany and France.

The fact that many sites have been decommissioned and reclaimed in a 5 mSv/y context must also be fully recognized. (Same for the sites that were subject to the 1 mSv/y context). It is vital to have clarity on the relevance and applicability of any proposed public dose constraint to the decommissioning and reclamation of current operational or historical sites.

Although radioactive sources at these sites have been decommissioned and reclaimed (e.g. placement of tailings cover), the proximity of the populated areas makes it often challenging to demonstrate compliance with 1 mSv/y. The 0.3 mSv/y value would impose that compliance would not be possible for many sites unless further site decommissioning and reclamation is undertaken over very large areas with associated high incurred costs.

As for operating sites, the variability in the releases of radon gas at the sources adds an extra level of difficulty with respect to compliance.

For obvious reasons (proximity of populated areas), environmental measurements in proximity of the sites would become even more polemical than for operating sites.

The concerns for historical discharges and for hypothetical site boundary situations would be analogous but more generalized than indicated earlier under items "2b" and "2c" in the section on "Nuclear Industrial Sites".

On-Site Issues - During decommissioning, the concerns would be analogous to those indicated earlier : items "3a" to "3c" in the previous section on "Nuclear Industrial Sites".

APPENDIX C : 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