Reference 2 Regarding Genetic Effects of Radiation on the Ordinary Citizen

Review of the Ideas about the standard citizen's genetic dose in the Guidelines for Examination of Reactor Locations in relation to the Nuclear Reactors Regulation Law

• "Guidelines for Examination of Reactor Locations" (decided by the Atomic Energy Commission on May 27, 1964)
  These Guidelines are used by the Task Force for Reactor Safety for its safety examination prior to installation of a nuclear reactor to determine if the conditions of location are appropriate should an accident occur.
  
  These Guidelines stipulate in "Section 2: Guidelines for examination of location" as follows: "2.3 The site for the reactor concerned shall be away by a required distance from dense population areas. The required distance from dense population areas here means the distance far enough to reduce, in a hypothetical accident, an integrated whole body exposure dose to such an extent as fully acceptable from the viewpoint of the standard citizen's genetic dose."

• Report issued by the Special Task Group on Reactor Safety Standards (on November 2, 1963)
  This Report gives the explanation by the Special Task Group on Reactor Safety Standards which established the above-described Guidelines, regarding the Guidelines.
  
  The Group considered that the standard citizen's genetic dose is equivalent to 0.5 x10⁸ manrem on the basis of the yardstick given by the ICRP (International Commission on Radiological Protection), and thus drew the conclusion that "the integrated whole body exposure dose in a hypothetical accident should be much smaller than the value of 0.5 x10⁸ manrem."
  
  In other words, this explanatory Report accepts the pre-condition that "the standard citizen's genetic dose in a hypothetical accident should account for only a small portion of the allocation to the genetic dose for the standard citizen according to the idea of allocation of exposure dose proposed by the ICRP" and refers to the ICRP's recommendation (in 1958) regarding the allocation to the category of exposure to the population as a whole, which is 2 rem (consisting of 1.5 rem for exposure inside the body and 0.5 rem for exposure outside the body), of the maximal permissible genetic dose of 5 rem (excluding exposure attributable to natural background and medical exposure). The Report then explains that the 0.5 rem for exposure outside the body is equivalent to 0.5 x10⁸ manrem assuming that the total population in Japan be approximately 100 million people and that in the idea of exposure to the population as whole, the proportion of people in reproductive age groups in the total population be the same as that in the population suffering from exposure.
  
  One of the foreign cases which the Commission referred to when leading to the specific number upon establishment of guidelines was the Guidance for Sailing of "Savanna," a US nuclear-powered ship, within the Harbor (issued on August 1, 1962), according to which the standard level is 2 million manrem.

• ICRP Publication 6 (Recommendation in 1958)
  It is described as shown below in the section of "exposure to the population."
  As "general views," it is stated that "appropriate projects regarding nuclear power plants and other large-scale peaceful uses of nuclear energy will require limit of exposure to the entire population firstly by limiting dose exposed to the individual and secondly by limiting the number of people to be exposed." It continues to state that "this limitation unavoidably implies a compromise between harmful effects and social benefits." In addition, they admit that "the Commission is not yet able to make a proper judgment regarding the balance between dangers and benefits" and state that "factors influencing balance between dangers and benefits may vary depending on countries and each country should assume responsibilities to make the final decision regarding this issue." It is then described that "the Commission suggested the tentative upper limit for exposure to the entire population in its Recommendation in 1958."
  Regarding "genetic dose," the "genetic dose to the population" is defined as follows: "assuming that each individual within a population is exposed to a dose for a period from the time of fertilization to the time when he/she reaches an average age of reproduction, they suffer from genetic burden caused by the dose to that which they are actually exposed; and a dose which will cause the same extent of genetic burden to the entire population as that in the case above is defined as a genetic dose to the population." The "permissible genetic dose" is defined as follows: "assuming that each individual within a population is exposed to the genetic dose for a period from the time of fertilization to the time when he/she reaches an average age of reproduction, a dose which will cause acceptable burden to the entire population is defined as a permissible genetic dose."
  Regarding the "maximal permissible genetic dose," it is concluded that excluding exposure attributable to natural background and medical exposure, the genetic dose derived from all sources that the population is to be exposed to should not exceed 5 rem and the recommendation is that of the 5 rem, an allocation to the category of exposure to the population as a whole be 2 rem.

Regarding this "2 rem allocated to the category of exposure to the population as whole," it is explained that "this level was intended for development of nuclear energy plans (including related problems of disposal of wastes) and for plans for more wider utilization of radiation resources."

• Foreign Case: The Guidance for Sailing of "Savanna," a US nuclear-powered ship, within the Harbor (on August 1, 1962)
  The Commission referred to, in addition to the ICRP's Recommendation, the Recommendation by the NCRP (National Council on Radiation Protection and Measurements), and indicated the value of 2 x10⁶ manrem (2 millionrem) for genetic exposure due to an accident. They understand that this value "is still valid for the objectives of plans."
  In other words, this Guideline is based on the following estimation made by the former chairman of the ACRS (Advisory Committee on Research Safeguards): assuming that an MCR (maximal conjecture accident) occurs once annually, the collective dose for 30 years is 2 x10⁷ manrem (assuming that the total population in the US is 200 million) and the genetic dose contribution per person for 30 years is 0.1 rem.
  Then, the selection of 0.3 rem as a genetic dose for 30 years is slightly conservative as compared to the value of 2 rem which is allocated by the ICRP to the category of exposure to the population as a whole or the value of 1.5 rem which is allocated by the ICRP to the category of reserves, but provides benefits. (Note that the value of 0.3 rem corresponds to 2 million manrem.)

• The currently effective "On Yardsticks for Making Judgment Regarding the Guidelines for Examination of Reactor Locations and their Application" (partially amended on March 27, 1989)
  One of the three basic objectives is stated as follows: "c. To minimize substantial influences on the collective dose in the case of a hypothetical accident."
  
  It is stipulated in "Section 2: Guidelines for examination of location" as follows: "2.3 The site for the reactor concerned shall be away by a certain distance from dense population areas. The "certain distance" here means the distance far enough to reduce, in a hypothetical accident, an integrated whole body exposure dose to such an extent as fully acceptable from the viewpoint of the collective dose."
  
  (Note: The term "standard citizen's genetic dose" used before the amendment was replaced with "collective dose.")

As a yardstick on which the site for the reactor concerned is "away by a certain distance" or not as stipulated in Section 2.3 of the Guidelines, it is recommended to refer to overseas cases (e.g. 2 million Sv = 2 million manrem: derived from the Guidance for Sailing of "Savanna" within the Harbor mentioned above).

Note: The post-amendment Guidelines have taken over the idea of "collective dose." As the ICRP indicates its view that each country should assume responsibilities for decision-making regarding which factors should be ultimately incorporated her national standards, only Japan and Canada use this concept of collective dose as a standard for examination of nuclear reactor locations.

• The Kingdom of the Netherlands has proposed policies regarding risk management (in connection with environmental policies) including areas other than that of atomic energy. Her policies provide reference to methods of handling risks with accompanying unknown effects.

In the Netherlands, under the recognition that introduction of systemic risk management policies is essential, the "1986-1990 Plan for Environmental Management" determined permissible risk levels for 3 key hazards, i.e. large-scale accidents, chemical substances and radiation exposure.
In this documented Plan, "individual risk" and "group risk" are introduced for humankind and "collective risk", for the ecological system.

When formulating a policy which focuses on the environment, the national government is responsible for identifying a risk and establishing the maximal permissible level, beyond which risk is not acceptable, and the level, below which risk is negligible. For humans, the maximal permissible lethal risks attributable to large-scale accidents, chemical substances and radiation exposure are individually determined so that the total mortality due to each of these hazards will not exceed 10^-5/year. The maximal permissible level for individual activities or individual chemical substances is set at 10^-6/year.

For both humankind and the ecological system, the risk level below which risk is negligible is set whenever possible in any case at 1% of the maximal permissible level.

If an existing activity brings about hazardous situations exceeding a specific limit, then social considerations may often be important to set up a length of period during which the hazard(s) concerned will be suppressed. In the case of a new activity, however, it will immediately be necessary to observe a specific limit.

It is generally understood that evaluation of proper risk level is extremely difficult. However, efforts must be made to minimize uncertainty which has a significant influence on policy formulation. It becomes important to incorporate this uncertainty into policy-formulating process in a clearly identifiable manner

Next

Back to Table of Contents