IEER ENERGY & SECURITY No. 4

Science For The Critical Masses:

Radiation Protection

Radiation protection regulations are based on three basic recommendations originally made in 1977 by the ICRP and reaffirmed later:1, 2

  • Justification: No practice involving exposures to radiation should be adopted unless it produces enough benefit to the exposed individuals or to society to offset the radiation detriment it causes.

  • Optimization: Exposures to radiation should be as low as reasonably achievable.

  • Individual dose and risk limitation: No individual should receive radiation doses higher than the maximum allowable limits.

The most difficult of these principles, and certainly the one that is rarely adequately addressed, is justification. Assessing the likelihood that any practice will produce a net benefit involves many value judgments that are difficult, if not impossible, to quantify. ICRP recognizes this:

The Commission recommends that, when practices involving exposure, or potential exposure, to radiation are being considered, the radiation detriment should be explicitly included in the process of choice. The detriment to be considered is not confined to that associated with radiation-it includes other detriments and the costs of the practice. Often, the radiation detriment will be a small part of the total. The justification of a practice thus goes far beyond the scope of radiological protection.... To search for the best of all the available options is usually a task beyond the responsibility of radiological protection agencies.3

This point is expanded in a statement by the Committee on Radiation Protection and Public Health of the OECD Nuclear Energy Agency:

Decisions about the justification of a practice or activity involving radiation exposure usually involve a broad range of social, economical and political issues in addition to those concerning radiological protection....Justification is essentially a political decision-making process, in which the technical and purely radiation-related advantages or detriments play an important, but relatively limited role.4

In the early years of nuclear weapons development, the scientists and administrators involved implicitly assumed that national security justified the risks of the enterprise. According to J. Newell Stannard, "In 1947, the data for plutonium and the other actinides were used at a series of three-nation conferences on radiation exposure limits.... They required careful interpretation, for the most conservative interpretation could have closed Los Alamos." 5

The principle of justification continues to be a cornerstone of ICRP philosophy, but the application of this principle to a particular situation in the nuclear industry, whether civil or military, is rarely discussed.6 Optimization implies that measures will be taken to reduce exposures until the benefits of further reductions do not justify their cost. It is not clear how this principle can be rigorously applied, particularly as it requires some quantitative estimate of the monetary value of a life saved. In practice, optimization is applied in two ways: as an exhortation to use "best available technology" and as a recognition that merely complying with dose limits is not enough. If further dose reductions are practicable at reasonable cost, they should be made. Optimization generally refers to collective rather than individual radiation doses.

The principal dose limits recommended in ICRP Publication 26 (1977) were 50 millisieverts (5 rem) per year for radiation workers and 5 millisieverts (500 millirem) per year for members of the public. A subsidiary recommendation to keep doses to the public below 1 millisievert per year if possible has slowly become the primary long-term dose limit for the public, with short-term exposures of 5 millisieverts per year allowed.

The ICRP intended these limits to apply to the total exposure from all sources except natural background radiation. It has developed a methodology for combining the doses from different sources-such as combining exposures from inhaling ore dust with those from gamma exposure-and it is this total that should be compared with the appropriate limit.

In 1991, the ICRP revised its radiation protection standards, largely in response to reevaluation of dosimetry and cancer risk among atomic bomb survivors.7 The most significant change lowered the worker's annual limit to 20 millisieverts. Regulations do not yet widely reflect this change.


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Institute for Energy and Environmental Research

Comments to Outreach Coordinator: ieer@ieer.org
Takoma Park, Maryland, USA

February, 1998

ENDNOTES
  1. Recommendations of the International Committee on Radiological Protection. ICRP Publication 26. Annals of the ICRP, vol. 1, no. 3. Oxford, New York: Pergamon Press, 1977, p. 3.
  2. ICRP 1991, p. 28.
  3. ICRP 1991, para.115.
  4. Nuclear Energy Agency, Committee on Radiation Protection and Public Health. Applicability of the ICRP principle of justification of a practice to radiological protection standards. Journal of the Society for Radiological Protection. vol. 2, no. 4 (1982), p. 15.
  5. J. N. Stannard. Radioactivity and Health: A History. Prepared for the U.S. Department of Energy, Office of Health and Environmental Reserach. Oak Ridge, Tennessee: Office of Scientific and Technical Information, U. S. DOE. October 1988.
  6. QUEST Radiation Database (1992) gave just 5 references to "justification" but 91 to the principle of optimization. (QUEST Radiation Data Base. Vol 2.6, 1992. [Produced and distributed by Radiation Technology, Inc., P;. O. Box 10457, Silver Spring, MD 20914, USA.])
  7. ICRP 1991.