Although considerable effort has been directed toward accident considerations (e. g., emergency core cooling and containment), normal plant releases are also of extremely high importance. The reason I have thus far dwelt upon accident considerations is that accidents are the only means by which it can be hypothesized that appreciable radioactivity could be released from a nuclear plant to the public. Under normal opera­tion there are traces of radioactive release, but they are always well within release rates established by the aec. In fact, they are kept at insignificant levels.

Before embarking on a discussion of the radiological systems asso­ciated with normal releases from a nuclear plant, I shall set forth the philosophical aspects of the design — the design criteria.

Appreciation for Background or Boundary Conditions. It doesn’t make any sense to design a dirt-free automobile tire for use on country roads. It doesn’t make any sense to design a silent controller for use on a jackhammer. In both cases the design objective — dirt-free and noiseless — are frustrated by the original environment.

This same design consideration faces the nuclear industry, reflected in the questions, What is the proper goal in the reduction of radioactive releases when our environment is naturally at a radiation level? What does radiation-free or — clean mean when people naturally receive from 100 to 300 milliroentgens equivalent for man (mrem) per year depending on where they live, what they do, and whether they travel by air or land? The answers demand that design objectives and goals be set properly with respect to background or boundary conditions.

Appreciation of Governmental Criteria. A system designer or a utility employee who operates a nuclear plant must comply with all of the applicable regulations with respect to radioactive release. The design may be based on more stringent considerations also for other reasons, but all of the applicable regulations will be met.

In the case of nuclear power reactor design, appropriate government criteria and regulations do exist, aec regulation 10CFR20 (Code of Fed­eral Regulations, Title 10, Pt. 20) provides the basis for accident consid­erations, and 10CFR20 regulates the allowable releases for normal oper­ation. Most people in the industry believe that of all the government regulations, these two are based on firm ground with respect to allowable releases.

Secondary Goals — Good Neighbor Policy. In addition to determin­ing the natural background and the applicable government regulations, a third very important design question has been, What goals for release minimization should be employed, including all practical considerations? For instance, the normal radioactive background dose to persons in a certain locality might be 200 mrem/yr. Thus, although the government regulation for radiation doses contributed by a nuclear plant to any neigh­bor is 500 mrem/yr, designers would attempt to keep the plant discharges below 5 mrem/yr to any neighbor averaged over plant life in order to make the contribution of the nuclear power plant insignificant (approxi­mately 1 per cent of allowable) with respect to the exposure the public normally receives. This is not to say that should something unusual happen within the plant and the release climb to a rate of 25 mrem/yr for a short period of time, the plant would be causing a critical radioactive release and would shut down. No, it would simply be exceeding the design objec­tive — releases would still be at one-twentieth of the government regula­tion. A weekend air flight to visit a relative in Denver might be more consequential as far as radiation is concerned.

Thus, in any consideration of design action taken in a nuclear plant to handle radioactive release, one must always remember the normal radiation levels that exist, all of the government regulations which are in force, and also the design attitude toward the desired insignificance of any releases.