I would like to thank ICRP for the opportunity to provide comments the draft document. On behalf of FEPC RMC I would like to submit our comments on the document as followsD
(General comment)
1. This document is a supplementary guideline for the use of effective dose described in Publ.103.@So, ICRP should give us a possible scientific evidence for the items mentioned in this document@as a reference.
2. ICRP should provide us with the practical guidance on how to evaluate radiation@effect on tissue reaction at actual plant when new general recommendation on tissue reaction is issued.
(Specific comment)
1. In this draft document (46) it is mentioned that for doses in excess of 100mSv delivered at high dose rate, a DDREF of two applied in determining solid cancer risk at low dose /dose rates will not apply. ICRP should identify the value of high dose rate above which a DDREF of two is not applicable to evaluate radiation risk at an actual plant while showing the scientific evidence.
2. We can understand the concept of changing the settings of dose limit from equivalent@doses to absorbed doses to prevent tissue reaction. However, ICRP is required to clarify the following points in advance. In updating the dose limit associated with tissue reaction, ICRP should consider the establishment of a factor substituting the radiation weighting factor so that radiation risks can be easily evaluated even in a mixed radiation field.
EConcept of setting the dose limit (how are the effects of high LET radiation and the distribution of tissue doses incorporated in setting the dose limit)
EEvaluation of doses associated with tissue reaction (a specific way of evaluating doses in the work place exposed to mixed low and high LET radiation)
3.As described in this draft document (63) the use of committed doses introduces conservatism into calculation of doses from annual intakes for the radionuclide with long half-lives and long retention time. ICRP should reconsider how to evaluate internal exposures from the scientific point of view to avoid irrational anxiety or excess concern about internal exposure among the public and workers.
4. The paragraph (126) describes the thyroid tissue reaction; if there was a significant contribution to the effective dose from radionuclides concentrated in particular organs (e.g., iodine-131 in the thyroid, inhaled insoluble radionuclides in the lung), tissue damage could occur. Notable for 131I, for example, an effective dose of 250 mSv could correspond to a thyroid dose of >6 Gy.
On the other hand, ICRP Publ. 41 notes that if the whole thyroid is exposed to approximately 25`30 Gyx-ray doses in fractions for 30 days, it could result in serious functional damage. It is necessary to clearly describe the effects that may be caused by the difference in the thyroid tissue reaction from Publ. 41 description.
5. According to the report of TG84 they mentioned that the lack of a formal quantity for a radiation-weighted dose for high doses was an issue in the current radiological protection system. We think that ICRP should add the comment to this issue in this draft document.