|Comments on the ICRP and IAEA ‘scope of radiological protection’ documents
Overall, both the IAEA and ICRP documents closely examine the multiple issues and subtleties of the scope of RP regulations and requirements. This, of course, included particular attention to the concepts of exclusion, exemption and clearance for both sources and exposures of ionizing radiation. The two documents have been helpful in revealing the areas for which more consistency and coherence in the scope of RP regulations and requirements would improve the RP system.
We agree that these two documents provide an important starting point for discussion of the requirements of the Basic Safety Standards (BSS) that relate to the scope of regulatory controls for radiation safety. Moreover it is clear that these two documents should have direct implications on the overall RP system. Given the overlapping content of the ICRP and IAEA documents we have chosen to offer general comment on the broad topic of the scope of the RP system, giving particular emphasis to the subject of exemption and clearance. We also attach for information a recently developed WNA Position Statement on Exemption and Clearance which further amplifies our views. British Nuclear Group is fully supportive of this statement.
British Nuclear Group notes with some apprehension the detail and complexity of the arguments developed in the documents. Whilst we recognize that ICRP and IAEA must address the wide range of philosophical issues inherent within the scope of the RP system, we believe that there is one issue of over-riding importance to practitioners for which it is vital that the simplest, coherent and readily understandable platform is provided. For many thousands of practitioners, by no means confined to the nuclear industry, the key issue is the control of materials containing very small amounts of radioactivity.
We recognize the subtle difference between the concepts of exclusion, exemption and clearance within the overall radiological protection framework. However, we believe that for practical purposes, and to secure public understanding, there must be particular emphasis on establishing simple common terminology that applies to substances and materials that are not subhect to regulatory control, no matter what decision has led to that situation. Such material, which of course still contains some radioactivity, is clearly ‘unrestricted’.
The importance of establishing a clear, simple and easily understood framework for the control of materials should therefore be a key practical outcome of this debate on ‘scope’. The nuclear industry fully supports the use of the term ‘clearance’ which we believe is generally well established and understood, although we recognize that it could be more clearly circumscribed. As an aid to increasing the understanding relating to material control we offer Fig. 1 (attached in a letter to ICRP) which we believe provides a basis for a simple, common set of terminology.
Noting the particular importance of securing public understanding in this field, we have great concern over ICRP’s decision to choose arbitrarily the numerical values of 1 Bq/kg alpha and 10 Bq/kg beta as the boundary of exclusion. This introduces a further set of numerical values, in addition to the principal set of numerical values defined in IAEA’s RS-G-1.7, is unnecessary, introduces obfuscation, and presents a serious impediment to the case of public (and practitioner) understanding. We would invite ICRP to seriously reconsidering the need for such a set of numerical values (and note in passing that similar arguments may apply to the choice of 40 Bq/m3 as the lower level for the exclusion of radon exposures).
British Nuclear Group recognizes that there are differences in practicability of control between natural and man-made radioactivity. When translated into practical control Ievels, this can imply that society may choose to impose differing control levels on such activity, with higher dose and activity concentration levels applying to natural radionuclides. We also also recognise that in some situations, there are higher levels of perceived public concern regarding artificial radionuclides. We believe that the overall objective for control should be to seek a greater convergence over a period of time towards a simpler and more risk-based system. We acknowledge that greater public confidence and understanding, than is currently the case, would add to this convergence.
British Nuclear Group welcomes the recognition in both documents that the strict application of a 10 microsievert per annum individual dose criterion is inappropriate as a sole basis, or indeed the principal basis, for the determination of exemption and clearance. In practice the dose criterion must be more broadly interpreted and subject also to wider considerations such as whether control is unwarranted.
We also note and support the important step provided by the recent IAEA safety guide The application of the concepts of exclusion, exemption and clearance (RS-G-1.7). It is of the greatest importance to international trade to seek a consistent international practice on the identification of those materials that should be subject or not to regulatory control. We consider that the IAEA guide is a good basis for initiating international agreement. However, noting the above comments on the application of the 10 microsievert dose level, we believe that the scientific underpinning of the numerical values and broader judgements relating to the establishment of banded numerical values should be subject to an ongoing programme of review and improvement.
Finally, we believe that both the lCRP and IAEA documents provide an underpinning basis for the determination of the scope of the RP system which is capable of wider acceptance and public understanding. A simple visible expression of ‘A Consolidated Framework for the Radiological Protection System’, based on the ideas being.developed by the WNA, is attached (in a letter to ICRP) for your consideration. This illustrates the range of individual dose in a simple, colour-coded approach incorporating the ‘Three Band’ approach being developed by ICRP. Such a diagram could provide the basis for promoting wider understanding of the RP system.
In summary, British Nuclear Group supports the work being undertaken by ICRP and IAEA to develop the understanding of the scope of the RP system. Within such a development we believe that the importance of establishing a simple, clear and understandable basis for the topic of over-riding practical significance - i.e. materials control - should be paramount.