The scope of radiological protection

Draft document: The scope of radiological protection
Submitted by John W Stather, UK Health Protection Agency, RP Division
Commenting on behalf of the organisation

Comments from the Health Protection Agency – Radiation Protection Division on the ICRP Draft Publication The Scope of Radiological Protection Regulations General Points This document is too long, repetitive and in places the language used is unnecessarily complex. ICRP should make its recommendations clearly and concisely. Details of the evolution of the concept are unnecessary and should be omitted or relegated to an appendix. Section 7 alone contains almost all that is needed. Whilst the document may not be about regulations as such the title gives the wrong message. ICRP should not be addressing regulations which are the responsibility of others. The document should reflect the new Recommendations of ICRP. The fundamental message is that the ICRP system applies to all sources of ionising radiation but that there are situations that can not or should not be included in regulations. The aim of the document and this basic premise should be clear from the abstract and the executive summary. The distinction between exclusion – where the situation is not amenable to control and exemption – where it is not worth controlling the situation is a valid one but could be expressed much more concisely without the use of Latin. The document needs editorial work to correct typos etc. The way in which the recently issued revised draft ICRP recommendations addresses the scope of regulation with regard to exemption and exclusion is clear and concise and covers much of the material within this document. The principles for exemption for artificial nuclides are well established. Those for naturally occurring nuclides are not. The document spends a lot of time discussing why the same dose criteria do not apply. This should be addressed once, preferably with discussion in an appendix. When using the term ‘disposal’ it should be clear whether this also includes reuse and recycling. ICRP should content itself with defining exposure situations/types that are excluded, and with defining a framework or basis for regulators (and/or the IAEA) to determine exemptions. It is not clear whether it is advisable for ICRP to specify numerical levels for exemptions. There are enough internationally agreed values without adding to the list. There is a recommendation for an exclusion level for radon of 40 Bq m-3. Given that the mean level in UK homes is 20 Bq m-3, in Germany about 50 Bq m-3 and in the Republic of Ireland about 90 Bq m-3 I do not think that this is appropriate or can fly. Is a specific value needed anyway? Specific Points Abstract Use of Latin phrases is unnecessary and should be avoided. A fundamental principle is that doses from exemption are ‘trivial’, not just ‘low’ as stated in the report. This should be corrected. ICRP are introducing a new concept of exemption at higher levels of dose if regulation is not warranted on grounds other than those of trivial dose. This is then used to introduce a 1mSv dose criterion for naturally occurring radionuclides. Rather than trying to introduce a new general principle, would it not be better to just address the two specific situations involved: naturally occurring nuclides and emergency response? ICRP need to specify how the activity in mixtures or members of decay chains are to be considered against the values given for naturals. Why not refer to IAEA RSG1.7 directly in the last paragraph? Executive Summary This is too long and lacks structure and clarity. There is no need for extensive discussion. The clear rationale for the document, as stated in the introduction chapter, needs to be given here. Use of Latin phrases is unnecessary and should be avoided. Authorised discharges are subject to monitoring, not control. Hence ‘regulatory control’ needs to be defined more clearly. Para d – antepenultimate sentence is totally obscure. Para e – The ICRP view that the origin of the exposure (natural or artificial) is not important should be made more strongly: at the moment it is weakly stated and surrounded by text discussing different perceptions and suggesting that this also needs to be taken into account. Suggest the removal of all the discussion on dichotomy. Do ICRP really want to link the level of control to the level of concern? This could have the effect of driving the exemption levels lower. Para f – The basic point that is being made here is that situations involving naturally occurring radionuclides below levels quoted do not need to be controlled and it is up to the country to decide how they do this in regulations. This point is lost in the discussions about exemption and exclusion. It does not really matter which it is! The values given are all a bit vague: what is ‘about 1Bq/g’? Why not give firm values, or refer to RSG1.7? The suggestion that cultural perceptions are a good basis for deciding what can be amenable to control is not convincing. Para g – The last sentence is vague: what is meant by significant? Reference to examples e.g. EC and IAEA BSS and RSG1.7 would help clarity. The dose calculations were not for average individuals but to representative members of critical groups. The rounding process introduces an uncertainty of a factor of 3. Para h – Exemption should be qualified by exemption from something e.g. from the reporting requirement. This is addressed in para 39 but should be here also. The text on exemption only applying to persons is not appropriate for an executive summary. The three principles are fine but the wording is convoluted. Individual doses should be trivial, not low. It should also be mentioned that all apply not just one. These are principles for practices. Suggest a new para for discussion of exemption of naturally occurring nuclides and accidents: these are intervention style situations. Given the new ICRP framework this is no longer relevant and should be explained. Para I – The second sentence essentially repeats para f and could be shortened. The values are vague, should be related to RSG1.7 and summation over nuclides should be addressed. The problem with building materials is that the concentrations given for exemption would give rise to doses above 300 microSv/y and given that other material could be chosen then these doses are amenable to control. The last sentence is specifying minimum exemption levels. Thus any level could be exemptable: e.g. legislation could specify exemption if conc<300Bq/m3 or even if conc<800Bq/m3 for dwellings. Para m – The introduction of the term clearance could be made shorter and clearer. The example of a discharged patient is confusing. ICRP could just make the point that it is possible to authorise disposal with no further control. Does disposal in this sense include recycling and reuse? Para n – The term intervention exemption levels has suddenly appeared. This para appears to confuse the dose saved with the residual dose: does the exemption level refer to the residual dose? Clarification is needed. Para p – This is unnecessary repetition of earlier ideas. Main Text Section 1 Introduction The first para is important and should be in the abstract and Executive Summary. It would benefit from simplification. 3rd para – The introduction of the term indicator seems unnecessary. There is too much repetition here and too many Latin quotes. Suggest delete Section 1.3 Section 2 This is very long and could be shortened. The summary provided by para 21 is all that is needed! However, it is not clear what the difference is between background exposure and existing exposure. Presumably what ever level is excluded is subtracted from the existing level to determine the level that is considered for the intervention optimisation study. Section 3 This section is very long and could be shortened. The principle of optimisation is the underlying reason for apparent variations in protection standards and this is not addressed in the document. Section 4 Exclusion Para 32 is a clear recommendation. The other paras discuss the issues but do not come to a conclusion. Section 5 Exemption Para 40 penultimate sentence is not clear and should refer to a trivial level of dose. The basis for exemption given in IAEA SS89 is described in paras 41 to 43. Paras 44 and 45 describing interpretations are unnecessary. Simplify by referring to ICRP formulation at outset and then both lines of argument can be developed. Para 47 is unhelpful Section 5.3 relates to practices and should say so. Para 53 last sentence – Exemption levels were calculated on the basis of very unlikely scenarios giving less than the dose limit. The rounding process leads to a range, not the ‘unavoidable dose distribution’. Section 5.4 there is too much discussion on the incorrect and correct use of the term clearance, resulting in the message being diluted. Para 58 discussion of meanings being confused by translation from English is not particularly useful. Clearance applies to disposal and recycling and reuse of solid materials, not to discharges of liquids or gases and this is not stated anywhere. The ICRP concern over the release of patients containing large quantities of radioactivity with no further control is described in para 60. This did not come over in the executive summary. Para 69 – This appears to suggest that levels expressed in terms of avertable dose can be used as exemption levels, which is not logical. Section 6 6.1 – it is only necessary to quote the current ICRP advice. 6.2 – The argument for ceasing to control exposure to aircrew is weak: it is done already so it is not ‘infeasible’. Control of frequent flyers is obviously more difficult and the situation is more analogous to ‘intervention’ than ‘practice’. 6.3 – The discussion for non nuclear industries is convoluted. It is possible to argue that it is not feasible to regulate concentrations that are essentially unmodified natural levels. However, if the concentration is increased or the form made more accessible so that the doses are higher, then some form of control is warranted. Para 92 and 95 therefore appear to contradict each other. It is not clear what the ICRP approach is. It appears to be ‘Exclude natural levels, these correspond to about 1mSv, hence exclude on basis of 1mSv’ but this is not clearly stated. 6.3.1 – It is inappropriate to refer to the formula in a draft document as the formula may change. Reference to the formula in EC guidance would be more appropriate. This is designed to meet 0.3mSv. 6.4 – A history of radon recommendations is not necessary in this document. The proposed use of exclusion and exemption levels for dwellings and for workplaces are not considered helpful. . 6.5 – RSG1.7 gives exemption levels of 0.1Bq/g for many alpha emitters and 1Bq/g for many beta and gammas. Hence it is not true to say that international criteria establish exemption values of about 1Bq/g and 10Bq/g respectively as stated in para 123. Para 124 suggests that ICRP are uncomfortable with the fact that the exclusion levels for naturals may give rise to relatively high doses. However, in para125 ICRP support these values for naturals and therefore appear to be inconsistent. 6.6 – it is not clear what point ICRP is making here. Section 7 7.1 – Paras 130-133 essentially summarise the discussion in earlier chapters. Hence they should either be removed or, preferably used to replace the more extensive earlier sections. Para 134 – The values of 1Bq/g given for alpha and 10Bq/g for beta and gamma are higher than those given in the internationally agreed exemption and exclusion report IAEA RSG1.7. This para excludes a mixture of types of situation and amounts or levels of exposure. Is the latter more appropriately linked with exemption? 7.2 – Para 135 – I agree that these situations should not be exempt but it would be clearer without the first sentence so it was simply ‘the Commission recommend that the following situations should not be considered for exemption’. Para 136 – Begins by referring to exposure situations to cosmic radiation above ground level. This is predominantly air travel but the only example given is space flight. There are regulations that could be introduced regarding space flight – e.g. insisting that the radiation exposure is declared before someone signs up to a ‘tourist’ trip; preventing pregnant women or children going into space for such trips. Para 138 – This is unhelpful, especially as it is confusing to give an exemption level and then to state that it may not apply in all circumstances. This blurs the logical boundaries between exemption and exclusion, and is therefore, extremely unhelpful. Para 141 – This is essentially repeating the international agreements and should state this clearly. Para 142 – ICRP have not derived this but are supporting existing approaches and this should be stated or the entire para omitted. Para 143 is new in that it states that deliberate dilution of material may be permitted to meet exemption levels. The case is made for diluting enhanced levels of naturals back to natural levels and from a radiological protection view it may be the optimum solution. Similarly this may be true for artificials. However, this is contrary to the modern concept of concentrate and contain for waste management. Is this reflected in the draft main recommendations?