The scope of radiological protection

Draft document: The scope of radiological protection
Submitted by Takatoshi Hattori, CRIEPI (Central Research Institute of Electric Power Industry)
Commenting on behalf of the organisation

General comments The concept of exclusion in the radiation protection regulations is not simple to understand. Numerical criteria for artificial radioactive nuclides and radon in ambient air should be removed from the definition of exclusion to avoid making double standards. (Reasons) In the BSS (Basic Safety Standard) and the 1990 recommendations of the ICRP (International Commission on Radiological Protection), excluded exposures are those that are essentially unamenable to control regardless of their magnitude (para. 32). In the case that the magnitude or amount of exposure is trivial, the concept of exemption has been applied by quantitative estimation. These two concepts, exclusion and exemption in the BSS and the 1990 recommendations are obviously classifiable and comprehensible. On the other hand, the foundation document has defined the term g exclusion h as exclusion from the radiological protection legislation (para. 7, Section 7.1). For naturally occurring sources of exposure, examples of exclusion have been given as exposure to radon in ambient air at an activity concentration below 40 Bq m-3, exposure to unmodified concentrations of radionuclides in most raw materials, in addition to obviously uncontrollable exposure to potassium-40 incorporated into the body, potassium being a basic constituent of tissue and, exposure from cosmic rays at ground level. For radionuclides of artificial origin, it has been recommended that the materials excluded from radiological protection legislation are substances containing an activity concentration of less than approximately 1 Bq per kilogram for alpha-emitting radionuclides and approximately 10 Bq per kilogram for beta- and gamma-emitting radionuclides. These numerical exclusion levels are the quantitative criteria and are easily confused with the concept of exemption that is based on the triviality of the exposure. This numerical definition of exclusion has induced the lack of clarification of the concept of exclusion. (Detailed descriptions) There is an unreasonable logic in the following statement in paragraph 110; gan activity concentration of radon below 40 Bq m-3 may be regarded as unamenable to control and could therefore be used as an exclusion level specific for situations of ambient exposure to this radionuclideh. For example, we cannot answer the question of whether or not an activity concentration of radon of 50 Bq m-3 (slightly higher than 40 Bq m-3) should be treated as unamenable. The numerical criteria of the minimum exemption levels (in dwellings: 200 Bq m-3, in workplaces: 500 Bq m-3) and the exclusion level (40 Bq m-3) may indicate double standards. This proposal on the numerical exclusion levels is in opposition to the policy of ICRP that has aimed to consolidate the multiple numerical standards and to simplify the recommendations. The exclusion levels for artificial radionuclides (1 Bq kg-1 for alpha emitters and 10 Bq kg-1 for beta and gamma emitters) must be based on the guideline level (the dose criterion used for the derivation of the values is 0.1 mSv y-1) for drinking water from WHO. There is also an unreasonable logic in the statement in paragraph 123; gObserving that such levels are minute and difficult to monitor, the Commission considers that they can therefore be taken to be unamenable to control in practiceh. The dose criteria used for the derivation of the guideline level for drinking water specified by WHO, the guideline level for food specified by CODEX and the exemption level in the IAEA safety guide RS-G-1.7 are all different, but all the levels are types of exemption levels. The minimum of the three levels should NOT be adopted as the definite exclusion level. Many numerical values for exemption have been derived by international organizations such as IAEA, in accordance with the recommendations of ICRP. In this document, we find that ICRP will determine the exclusion level on the basis the levels adopted by the other international organizations. This indicates that ICRP will get their priorities wrong in rule making on radiation protection. Technical comments (para.142)@hXm is the derived value of the activity or activity concentration for exemptionh@The parameter Xm is unitless, but is expressed as an activity or activity concentration in this document. Please clarify this. Editorial comments (para. 69) The description gIAEA 1999h should be revised to gIAEA 1996h. (para.142)@The description g(139)h should be revised to g(138)h.