|United Kingdom Ministry of Defence comments on ICRP 2005 recommendations
The United Kingdom Ministry of Defence (MOD) has reviewed the ICRP recommendations and have the following comments to make:
Summary of the recommendations
1. The short summary of the main proposals contained in the document is welcomed.
Chapter 1 - Introduction
2. It is unclear whether the new ICRP recommendations are to replace the ICRP 60 recommendations in their entirety. The new recommendations should make this clear. If some parts of ICRP 60 are to remain extant, this should be specified in the document.
3. This document does not have the clarity of earlier ICRP documents. The scientific concepts e.g. the use of constraints are not clearly explained and some of the wording is quite ambiguous. We would suggest that the wording of the document be reviewed.
Chapter 2 - The aim and scope of the Commission’s recommendations
4. It is understood that foundation documents are being drawn up on a series of topics to underpin the ICRP recommendations. These include the representative individual, biological and epidemiological information on health risks from ionising radiation and dosimetric quantities. As some of these documents are not going to be available until after the proposed closure date of this consultation it is recommended that this consultation be extended into 2005, or a new consultation undertaken so that the whole package of documents can be considered in their totality.
Chapter 3 - Quantities used in radiological protection
5. The replacement of the name of the quantity equivalent dose by radiation weighted dose is helpful as it better describes the quantity. The need for a new unit for radiation weighted dose is questioned. Radiation units are at best difficult to comprehend and explain to workforces, to members of the general public and emergency services. Therefore we believe that a new additional unit is considered unnecessary and should not be introduced.
Chapter 4 – Biological aspects of radiological protection
6. MOD welcomes the revision of the risk estimates and note that there is little change to the values that were contained in ICRP 60. This provides us with greater confidence in these values.
Chapters 5 - The general system of protection and Chapter 7 - The optimisation of protection
7. ALARA, supported by dose limits, has been key to reducing radiation exposure over the last 20 years. In view of its continued success, it is recommended that this concept should not only be retained but to have the same prominence as in the past. There is a danger that ALARA will be undermined by the increased emphasis on source related constraints.
8. The role of constraints should be made clearer. There is a danger that they could become dose limits or pseudo dose limits. ICRP should state in the publication that this is not their intention. Their function should be clearly defined in the draft ICRP recommendations. It is suggested that the use of constraints should be the subject of a foundation document to support the new recommendations, and it may be useful to have some examples to describe how they would operate. We would suggest that constraints should continue to have a similar role as stated in ICRP publication 60.
Chapter 6 – The Commission’s required levels of protection for individuals
9. The constraint values given are termed maximum constraints but it is believed that it is acceptable for a proportion of workers to exceed these values. It is suggested that the term maximum be removed. Furthermore, the lower value of 0.01 mSv does not fit into this matrix and should be deleted. The draft recommendations do not make clear whether constraints applicable to emergency intervention (eg evacuation of public – Table 7) relate to the total dose likely to be received, or dose which can be averted. This should be clarified.
10. MOD notes that the radiation dose limits remain unchanged. This will deliver a longer period of stability. However, MOD like most other organisations in UK has reduced the doses for its workforce well below these values.
Chapter 7 -The optimisation of protection
11. MOD welcomes the statement made by ICRP that “the integral of large exposures over large populations, large geographic areas and over large periods of time is generally not a useful tool for decision aiding because this may aggregate information excessively”. We strongly support this view and hope that ICRP will carry this statement into the final document. We look forward to seeing the foundation document being drafted by ICRP Committee 4 on the principles and methods to implement optimisation of protection.
Chapter 8 – Exclusion of sources from the scope of the recommendations
12. A late inclusion into the ICRP draft recommendations has been the exclusion of sources from the scope of the recommendations. ICRP has in the past gone to significant lengths to show that the effects of radiation are the same for both artificial and naturally occurring radiations of the same. Yet when considering exclusion of sources from the scope of the recommendations it uses figures of 0.01 mSv for artificial radionuclides but for naturally occurring substances of 0.2 mSv. This clearly conveys the wrong message and it would be best if this entire section of the recommendations is removed.
13. The ICRP approach to exclusion levels, whereby in the case of artificial radionuclides the lowest available figure is taken for exclusion, is considered by the Ministry of Defence to be inconsistent and unacceptable and we would recommend that the figures are removed from the publication. It does not distinguish between a lump of concrete or a steel pipe or foodstuffs. Levels of 0.01 Bq/g alpha and 0.1 Bq/g beta if adopted by national authorities and incorporated into legislation would lead to materials currently considered to be non-radioactive under national regulations suddenly being considered to be radioactive and would require special arrangements for their disposal. It would also raise the question of historic liabilities. This would lead to excessive regulation. We consider that these exclusion figures, if adopted, have the potential to significantly damage the credibility of the ICRP.
14. If this chapter should survive it is recommended that ICRP clearly define in the publication the meaning of exclusion, exemption and clearance levels.
Chapter 11 – The protection of the environment
15. The ICRP proposals in this chapter are intended to “safeguard the environment by reducing the frequency of effect likely to cause early mortality, or reduced reproductive success in animals and plant to a level where they have negligible impact on conservation of species, maintenance of biodiversity or the health and status of natural habitats or communities.” However, ICRP still believes that “the judgement that the standards of environmental control needed to protect man to the degree currently thought desirable will ensure that other human species are not put at risk is correct in general terms.” Researchers have found that the sum effect for the flora and fauna as a result of excluding man from the highly radioactive, restricted zone near to Chernobyl has been overwhelmingly positive in favour of biodiversity and the abundance of individuals. This would suggest that radiation even at these high levels is a lower order effect and that if we wish to protect endangered species and maintain a rich biodiversity, resources would be best expended looking at what changes are required to man’s activities e.g. overfishing, reducing the use of insecticides, rather than expending them upon examining the effects of radiation to show that they are not affecting the reproduction of a species or depleting their population.
16. The concept of developing a reference set of animals and plants is unsatisfactory as it will always be claimed that particular animals or plants do not fit with the reference set. If this is deemed to be case then whole new lines of research will be required and with it significant resources will be expended that could be more effectively used. We believe that the whole concept is flawed and should be rethought.
17. Within the UK, and it is assumed most other developed countries, the levels of radioactive liquid discharges has reduced by orders of magnitudes over the decades often to negligible levels today. We would therefore suggest that ICRP rethink the proposals for the protection of the environment.