Another environmental consideration in the question of nuclear power reactors is the management of the radioactive wastes or effluents which are generated. These wastes fall into two general categories — high and low level — and it is important to distinguish between them. High — level wastes are produced during the reprocessing of spent fuel elements from nuclear reactors. They are not processed or disposed of at the reactor site. The spent reactor fuel is removed from the reactor, securely pack­aged, and shipped to a reprocessing plant. Only during reprocessing are high-level wastes removed from the fuel elements and concentrated in liquid form for permanent storage. Such storage has been safe and effec­tive, but we have long had research and development efforts to convert liquid wastes to solid form, aec Press Release M-132 (June 2, 1969) an­nounced a proposed policy for handling the high-level wastes from nuclear power plant fuels. Under this policy the liquid wastes will be further con­centrated, changed into solids, and stored at a federal repository, possibly in salt formations deep underground.

The other category, low level, refers to the very low levels of radio­activity such as those which occur in air, water, and solids outside the fuel elements in the routine operation of nuclear reactors. The regulations on the radioactive content of effluent air and water control the maximum amount of radioactivity permitted to be discharged to the environment. It is these wastes and their control which are at issue in Minnesota.

The limits on concentrations of radioactivity permitted in any power reactor liquid effluents leaving the plant area, before dilution in a body of water, are sufficiently low that a member of the public could drink this water throughout his lifetime without exceeding the radiation protection guide. Concentrations in the effluents, of course, are further reduced by dilution in the body of water into which they are discharged.

Limits on rates of release of radioactive gases are based on a con­servative calculation which — at the point of highest radiation level aver­aged over a year, on or near the site boundary — would result in an ex­posure to an individual equal to the frc radiation protection guide, if he remains on or near the site boundary for the entire year. Of course, at greater distances, radiation levels decrease owing to diffusion, dispersion, and decay of the radioactive material.

We have now had about 10 years’ experience in the operation of li­censed nuclear power reactors. This experience has shown that low-level wastes released during operation have been generally less than a few per cent of authorized limits. Monitoring programs are carried out by licen­sees, some states, the Public Health Service, and the aec. The quantities of radioactivity released are so small that it has been difficult to measure any increase in radioactivity above natural background levels in rivers and streams.

There are those who believe present limits on releases are too liberal when viewed in comparison with the even lower levels that reactors are capable of achieving as shown by operating experience. We fully agree that, within radiation protection guides, exposures to the public should be kept “as low as practicable.” However, the point at which “as low as prac­ticable” has been achieved is always a matter of degree and involves judg­ment. From a regulatory standpoint, we believe that this concept can be implemented in a fair and effective manner only by the development of definitive criteria and standards which will provide guidance as to what constitutes “as low as practicable.” A major consideration in developing such criteria and standards is whether the degree of reduction in risk to the public by a regulatory requirement justifies the measures that may be required by both the regulatory agency and the licensee to implement the requirement. A point is reached where the extent of the measures required to achieve a small incremental reduction in the amount of radioactivity released from a facility is disproportionate to the very small reduction in risk to the public. Thus, the question of what is “as low as practicable” is a difficult one — but it is a valid question, and one to which we have de­voted much attention. It is something we shall continue to explore.