Optimisation of radiological protection

Draft document: Optimisation of radiological protection
Submitted by Hiroshi Noguchi, Japan Atomic Energy Research Institute
Commenting on behalf of the organisation

General Comments (1) The simplification of dose matrix is required bearing practical application in mind. The concept of gdose matrixh would be effective to overcome the limitations associated with collective dose in the decision-making process. However, the dose matrix in this draft is too complex to use in practice, even though good in theory, because there are too many components, such as local, regional, global in space, short, medium, long in time, gender, age, etc. in individual characteristics, in the matrix. (2) The document should more describe the process and techniques of optimization for occupational exposure. The draft devotes many pages to the application of optimization to public exposure, except Annex 1. But Annex 1 mainly describes a success story of ALARA concept in various industries. If ICRP recognizes conventional optimization process and techniques in occupational exposure situation has been still successfully applicable, this should be clearly described in the document. Furthermore, the sentence in Annex 1 (p.40, paragraph 2), gIn case of occupational exposure, there is no need to built a large list of dose attribute because the collective dose of the concerned workers is already a group dose (called workdose).h should be also described in the text since this is an important characteristic of occupational exposure. (3) The optimization for public exposure can be classified into two levels: generic optimization and site-specific one. The former is carried out in national level by the competent authorities, for example, in the selection of radioactive waste disposal site. The latter is done mainly by operating management, for example, in the selection of protective measure for the site. The draft seems to be concentrated on describing the generic optimization process. There should be a difference in the process, such as in the stakeholder involvement, between the generic and site-specific optimization. These should be explained in the document. Chapter 6 is insufficient on this subject. (4) The document should explain the new concept of relative weighting of group dose in detail. The explanation of group dose weighting in Annex 2 is insufficient to understand. In particular, there is no description about the relationship between the new dose weighting factor and the LNT-hypothesis, and how to use in the process of optimization, such as a dose matrix. For example, are the new weighting factors used to aggregate group doses? In addition, while the weighting factors for time are shown as an example in Fig. 7 in Annex 2, there is no explanation about the selection of the numerical values and the rationale. Examples of relative weighting for other attributes should be also indicated. (5) The document should describe the relationship with the representative individual discussed in the other foundation document, in particular, the probabilistic assessments and three age categories. Specific Comments Page 7, paragraph 2, etc. The term gtotal group doseh is often used in the text. However the difference between gtotal group doseh and ggroup doseh used in Figure 3 is not clear. The definition of the total group dose should be given. Page 16, Figure 1 Detailed explanation in Fig. 1 is required for better understanding, in particular, about the Authorized Level and Intervention Level. Figure 1 would lead to misinterpretation that the optimization performed in each licensed facility means reducing doses to the Levels. Therefore, the figure should be revised to avoid such misinterpretation. We have also concerned the Authorized Level cannot be determined for all practices. In addition, explanation is insufficient for the relationship between the figure and a series of optimization processes including the stakeholder involvement. Page 25, paragraph (58) and (59) The term gresidual doseh used in existing situations is ease to understand. However, the definition shown in paragraph (58) seems not to be adequate in a planned situation. The definition or the term gresidual doseh should be reconsidered. Page 26, Section 5 It would be better to understand that an applied example of dose matrix is included in the document as a case study, if the dose matrix has been actually applied or there has been a road-test result. Page 35, Annex 1 The document should explain the interpretation of ga single sourceh in occupational exposure situation. The selection of dose constraints needs an interpretation of ga single sourceh. The draft describes the interpretation and the selection of dose constraints in public exposure situation in paragraph (24) and Annex 2, respectively. However, nothing is described concerning on those in occupational exposure situation. The interpretation of ga single sourceh in occupational exposure situation is quite important in applying dose constraints to optimization. Page 44, Annex 2 The document should describe the relation between ALARA and BAT in detail. In the draft, ALARA is used in the context of public exposure while BAT is used to control effluent releases, or in situations where humans are not directly affected or not the primary protection target. However, there seems to be many cases that the both are related each other, such as in waste disposals. In the cases, which is more important? The document should clearly explain on the matter.