Optimisation of radiological protection

Draft document: Optimisation of radiological protection
Submitted by Maurice Phillips, United Kingdom Ministry of Defence
Commenting on behalf of the organisation

The United Kingdom Ministry of Defence (MOD) has reviewed the proposals in the ICRP foundation document titled “Optimisation of Radiological Protection” and has the following comments to make: General Comments This foundation document provides a useful overview and clarification of optimisation in radiological protection. The broadening of the optimisation process (Executive Summary paragraph 3) to include consideration of the avoidance of accidents and other potential exposures is welcomed. Optimisation as one of the three ICRP principles has been largely responsible for the significant radiation exposure reduction over the last 20 years within the UK Ministry of Defence. Today we believe that there is still a role for optimisation and therefore we support the retention of this principle in the 2005 recommendations. Specific Comments Page 4 Abstract. Reference is made to safety culture here and elsewhere in the document but nowhere is it described. Should there be a short section in the document or at least a cross reference to what ICRP means by safety culture? Executive summary – paragraph 5. The last sentence states that “Exclusion or Exemption levels should not, de facto, be considered as relevant endpoints to optimisation.” It is not clear as to whether this means that optimisation below exclusion/exemption levels may be justified (but this begs the question “why?” if outside regulatory control), or that optimisation may be achieved at levels above exclusion/exemption levels. Re-wording of this statement is suggested to remove the ambiguity. Page 15 paragraph 24. The definition of a single source in these general terms as “a licensed facility such as a nuclear power plant, a factory producing radiopharmaceuticals, a hospital” is considered to be too broad a definition. If the concept of a single source remains as “…a nuclear power plant, etc” the vast majority of radiation workers will effectively be considered to be exposed to such a single source; only peripatetic workers will be exposed to multiple sources (not including other sources such as radon ,contaminated land etc). The Commission expects that the resulting values (of dose constraint) will be lower than the maximum value (of 20 mSv) set by the Commission. Hence in most cases the individual dose limit of 20 mSv will not be the constraining upper bound limit; instead the site-wide single source dose constraint of (<)20 mSv will effectively replace it as a surrogate reduced dose limit for employees working with such a “single source” . This is inconsistent with ICRP position on there being no scientific case for reducing dose limits on the basis of the risks associated with exposure to ionising radiation. This anomaly would be removed if the concept of “single source” was narrowed to refer to a discrete activity within a single facility, for example effluent treatment, rather than an entire nuclear facility etc. Page 15 Paragraph 24 and page 45 paragraph 2. It is suggested that “licensed” should read “…..a discrete activity within a single facility ….” as licensing has different interpretations depending upon the national regulatory regime. Page 19 Paragraph 32 and Table titled Representative attributes to select the best protection options (non-exhaustive list). Recognising that the table is non-exhaustive it is nevertheless surprising that it omits important topics such as political considerations, Government policy and regulatory constraints. Page 21 paragraph 39. This refers to Best Available Technology, not entailing excessive costs while Page 44 Paragraph 2 refers to Best Available Techniques, not entailing excessive costs (BAT). Should these be consistent? Page 25 paragraph 56. If levels are sufficiently low to be excluded from the 2005 recommendations it is difficult to justify expending resources further to optimise radiation exposures. It is therefore proposed that either exclusion levels are considered to be a relevant endpoint or an explanation is given in the document explaining why they are not and optimisation at such low levels is necessary. Alternatively ICRP may consider it appropriate to delete the sentence. (see also second specific comment). Page 29 paragraph 73 and page 46 paragraph 3. The use of a dose matrix may be useful aid to decision makers and regulatory authorities but it is thought too complex for stakeholder consultations involving members of the public. It is suggested that the means of conveying this information should be left to be determined by individual organisations that know their stakeholders and would know the best way to deliver such information. Page 27 Paragraph 68. The use of collective dose for radiation workers employed upon a particular task can be a useful concept. However, as stated by ICRP in this paragraph the integral of large exposures over large populations, large geographic areas and over large periods of time is not a useful tool for decision making because it aggregates information excessively. We would strongly support the ICRP position and would wish to see this statement in the published document.