The present attitude toward safety held by the utilities, by the sup­pliers, and by the Atomic Energy Commission (aec) is disciplined and based on a proper concern for the true safety of atomic power reactors. It is fully appreciated by those associated with the design, construction, and operation of power reactors that the primary safety objective for power reactors is to minimize the release of radioactive materials. Very early in the design of power reactors this motivation led to what is known as the multiple-barrier concept. As pointed out earlier, the technologies required to generate power by nuclear reactors are well established. The additional and very important design requirement of providing multiple barriers to fission product release receives a considerable percentage of the design ef­fort associated with power reactors. Briefly, this multiple-barrier design concept consists of the recognition that the radioactive material, which is principally the nuclear fission products, must be retained within the nu­clear system to avoid exposing the public to radiation. This is achieved by keeping the fission products within the fuel pellets, within the fuel rod clad, within the reactor primary system, within the primary containment, which in some designs is within a secondary containment. This is a very effective multiple barrier.

Obviously, a considerable amount of the design effort that goes into the specification and construction of the five barriers does not result from requirements with respect to power generation but only with respect to safety. The fact that so many barriers can be found in today’s nuclear power reactor is a demonstration that an extremely conservative attitude does exist with respect to safety and an assurance that the nuclear designs have public health and safety considerations as their primary objective.

Safety is an important consideration, not only with respect to normal operation of a power reactor, but also with respect to potential accidents.

In the nuclear industry a demanding approach has evolved for evaluating potential accidents. A spectrum of particular accidents are selected for de­tailed analyses in order to determine all of the requirements with respect to safety systems. These accidents covering the spectrum of potential ab­normal events which might occur to a nuclear power reactor are associ­ated with such hypothetical considerations as possible excess power in­creases owing to disturbances in the fission process in the reactor; me­chanical failure, such as the dropping of a fuel bundle during refueling; and loss of coolant, such as might result if one of the recirculation loops on a power reactor were broken arbitrarily. Engineered safeguards are provided to assure complete protection against such potential accidents. Therefore, we consider all types of accidents as well as the big and the lit­tle accident possibilities — the day-to-day deviations from normal opera­tion and the end-of-spectrum accident that requires a ridiculously improb­able combination of calamities.

This protection is offered for events down through very low proba­bility situations. For instance, we consider a loss-of-coolant accident in which a major pipeline, 24 to 28 inches in diameter with a wall thickness of stainless steel in excess of 1 inch, is assumed to break off completely and instantaneously. To any designer in the power industry, this is known to be an incredibly remote possibility, and yet it serves as the end-of-spec — trum accident for the provision of safeguards. This again demonstrates the properly conservative attitude toward safety that the nuclear industry has today.

Another important aspect in the design of the safeguards associated with these theoretical accidents is the demanding manner in which de­tailed failure mode studies are done on all of the equipment provided. Evaluations are made to see whether any adverse situation could cause the safeguards to fail. Detailed design criteria existing within the supplier or­ganizations as well as within the aec itself specify just what these equip­ment requirements and considerations must be.

With respect to normal operation of a nuclear power plant, a parallel design effort just as diligent as the design effort directed toward accident considerations is carried out. In the design of any large power plant there are waste products. A fossil-fired power plant burning coal or oil must be designed to dispose properly of such wastes as smoke, fly ash, and various chemicals which are released as part of the burning process in the boilers. The design of nuclear power stations ensures that the total waste release — whether gaseous or liquid — is always well within the specified regulations of the aec. In fact, as one would certainly expect, every feasible effort is made to minimize wastes which might include radioactive materials, in or­der to make radioactive waste discharge as small as practically feasible. Thus, the radioactive wastes of the nuclear power station are insignificant with respect to other radioactive considerations had the plant not been there at all.

Another important part of the industry’s attitude toward safety is the detailed emphasis placed on design review, construction review, and op­eration review of power reactors. Not only does a nuclear steam system supplier such as General Electric have various audit organizations to en­sure that its product is well designed and safe, but also the supplier and the applicant (the utility) subject each nuclear power plant to a detailed technical review at every phase of its design, construction, and operation. The aec’s regulatory staff performs a detailed review of the power plant applicant. Many meetings are held; detailed questions are answered and placed in the public record; experimental and analytical work is per­formed. At the completion of the aec review, the project is again re­viewed, by the congressionally established Advisory Committee on Re­actor Safeguards, (acrs). Then it moves to a third technical review con­ducted by the Atomic Safety and Licensing Board; at a public hearing the Board permits anyone to raise any safety question and sees that the aec and acrs have covered all of the safety considerations satisfactorily. This entire program of review demonstrates the considerable effort put forth by the suppliers, utilities, and the aec and is certainly a further demon­stration of a proper attitude toward the safety of nuclear power reactors. No other industry receives this degree of governmental attention to its safety.