2005 ICRP Recommendation

Draft document: 2005 ICRP Recommendation
Submitted by Hiroshi Noguchi, Japan Atomic Energy Research Institute
Commenting as an individual

General Comments The general recommendations should be a stand-alone document. Appropriate text or explanations from previous recommendations should be included in the document. In particular, it should be clearly described in the text that the rationale of dose limits for workers and public, which has been based on unacceptable radiation risk for occupational exposure and on radiation risk and natural background levels for public exposure in Publication 60, is the same as Publication 60. The use of natural background levels is likely to be appropriate as a relative benchmark for the dose constraints below or around the global average background dose, because the general public can experience or judge properly these dose levels. However, people usually cannot experience the higher levels than the natural background dose. Therefore, peoplefs concern tends to direct towards radiation risk in the high dose level. The use of multiple of the average annual background dose or the ambiguous expression, such as ghighh or gincreasingh, shown in Figure 3 in the draft will lead to great difficulties when even experts of radiation protection explain the rationale of 20 and 100 mSv/year of maximum dose constraints in Table 7. A more detailed description of why these numbers have been selected should be included in the text, preferably based on the risk approach. The use of occupational dose constraints for single source will not be able to ensure that the individual total dose does not exceed annual dose limits. In Japan, occupational exposure is well regulated by the limitation of individual total annual dose supposing exposure from plural sources. Therefore it should be described that for workers whose annual doses are controlled by personal dosimetry monitoring and dose registration system, the application of dose limits is more practical than the application of dose constraints for single source, which is probably difficult to define in nuclear power plants, research institute and so on where many kinds of radiation source exist. The implication or definition of dose constraints should be more clearly described, including the role of constraints in optimization and the relationship to dose limits, particularly 20 mSv/year of constraint and 50 mSv/year of limit. Professor Clarke has often explained to us that dose constraints in the draft have the same meaning as the previous recommendations. If so, as described in paragraph 41 of Publication 77, the use of a constraint should be prospective and the retrospective findings that a constraint has been exceeded should not be regarded as an infringement of regulatory requirements. Therefore, a constraint cannot be used as a standard for judging if the practice violated regulatory requirements. The Commission seems to put on the importance of stakeholder involvement only in Optimisation process for decision making. However, the stakeholder should be also involved in Justification decision making. Or it should be described why the stakeholder involvement is important only in Optimisation but not in Justification. Specific Comments Page 3, (S12), line 2 and page 13, (24), line 2: The phrase of hThe combination of dose and difficulty of applying controlh is not so clear that more explanations are needed. Page 4, (S17), line 2: The different terms of gnominal risk factorsh, gnominal probability coefficientsh, gnominal risk coefficienth, and gnominal detriment coefficientsh seem to be used in the same meaning. Page 9, (6), line 6-7: The sentence of gthere have been societal developments in that more openness or transparency is expected in developing new recommendationsh is not a reason why the recommendations are being changed, but an explanation of the process, i.e. a transparent discussion, that is being followed. This should be referred to in paragraph 8. Page 11, (10), line 4: What is hother risksh? More explanations are helpful to understand the risks. Page 13, (20), line 3-4: What situations are implied in the sentence of hHowever, the system may also be applied in situations where the practice has not been declared justified.h? Some examples should be included. Page 13, 2.3, Title: 2.3. gExclusion and authorization of exposuresh should be changed to gExclusion, exemption and authorization of exposuresh, because this section focuses on exemption also. Page 13, (24), line 4: hSince all materials are radioactive to a greater or lesser degree, g should be changed to hSince cosmic rays are ubiquitous and all materials are radioactive to a greater or lesser degree, g Page 15, (36), line 2-4: With respect to the sentence of hSpecific investigations, such as retrospective assessments of risks of stochastic effects in a known population of identified individuals, are best undertaken using specific data.h, ICRP should show the way how to implement such specific investigations. Page 19, 3.4.1: The fact that there is no change in Q(L) should be mentioned some where in this section. Page 21, (69): It should be noted in this paragraph that the use of a continuous function is introduced as a simplification for calculation, but should not imply additional, more detailed knowledge of effects. Page 22, (73): The reason why the radiation weighting factors for neutron in the energy range between 5 and 150 MeV provided in Publication 92 are not adopted in this recommendations should be described. At least references of the experimental data that do not support such an increase should be cited. Page 24, Table 2: Energy range in the left column refers only to neutrons, so should be moved to the bottom of the right column. gType and energy rangeg should be changed to gRadiation typeh. gA continuous curve is recommended.h should be changed to gA continuous curve, dependent on energy range, is recommended.h Page 27, 3.5.2 Title: gControl of tissue reactionsh should be changed to gRBE-weighted absorbed dose and tissue reactionsh which better reflects the subjects discussed in this section. Page 35, (132), line5-: gThey provide a level of protection for individuals that should be considered as obligatory and not maintaining these levels of protection should be regarded as a failure.h should be changed to gThey provide a level of protection for individuals that may be considered as obligatory and not maintaining these levels of protection may be regarded as a failure.h, because the word of gobligatoryh is seen as being too strong, and constraints are not seen as having the same strength as limits. The suggested changes are intended to allow regulatory flexibility in interpretation. Page 36, (137), line 7: The phrase of hso that exceeding a mandatory constraint may be a statutory offenceh should be deleted, because most countries now use dose limits as legal standards and judgments whether exceeding a constraint is a statutory offence or not are greatly depend on situations of each country. Page 37, Fig.2: The figure of medical exposure should be included to understand the whole structure of the system. Page 37, Fig.2: hand controllable exposure situationsh should be changed to hand existing controllable exposure situationsh. Page 41, (156), line 8-9: In the sentence of hThe Commission now strengthens its recommendations by quantifying constraints for all controllable sources in all situations.h, it should be included that patient exposure is excluded from these situations, as shown in paragraph (148). Page 42, (164), line 12-14: In the sentence of hThe maximum value of 20 mSv/year effective dose is recommended for selecting constraints in situations where there is a direct or indirect benefit for the exposed individuals.h, it should be included that patient exposure is excluded from these situations. Page 42, (164), line 12-20: Since there is no benefit of exposure for the general public in emergency and existing controllable situations, additional explanations are required for these situations. Unless there are such explanations, the maximum constraint of 1 mSv/year should be applied to the situations in theory. Page 42, (164), 1ine 15-16: The phrase of hsituations where exposures are difficult to controlh is not so clear that more explanations are needed. Page 43, (164), line1-3: The reference to the use of 0.3 mSv in Publication 77 was only specified in the context of radioactive waste management, not more generically. Such a step would require more significant and clear argumentation. Therefore, the sentence of gIt would be the maximum public constraint in normal situations while in case of multiple dominant sources a figure of 0.3 mSv/year would be appropriate (Publication 77).h should be deleted or appropriately rewritten. Page 43, Table 7: With respect to heffective dose, mSv in a yearh, countermeasures such as sheltering and iodine prophylaxis in accidents should be regarded as per single event instead of per year. Page 47, (185), line 8-9: hnormal conditionsh should be changed to hnormal situationsh. Page 48, Table 9: The dose limits for individual organs or tissues are referring to tissue reactions, so RBE-weighted absorbed dose should be used in the table, and the unit (mSv) should be changed as appropriate to follow this philosophy. Page 49, Section 7: A collective dose is still useful to control exposures for a small group of workers because they are relatively homogeneous regarding age and gender. Thus the concept of group dose should be included.