Meeting the Latest Qualification Requirements for Class 1E Protection System Equipment - A Practical Approach

The requirements for qualifying Class 1E equipment for Nuclear Power Generating Stations were significantly revised in 1974 and 1975. These new requirements reflect the desire of the industry to provide improved methods of determining the qualification of this vital equipment. The revised standards do, in fact, meet these industry goals in a generally acceptable manner. The Nuclear Regulatory Commission is presently requiring utilities to comply with these revised standards and regulatory guides in order to obtain the necessary permits. Manufacturers are developing and implementing programs to comply with the new requirements. One of the more difficult new requirements of qualification is aging to achieve advanced life condition. The objectives and methods described for aging are difficult for much of the equipment within the Protection System. The use of thermal and vibrational techniques to simulate aging is valid for some components (i.e., capacitors, transistors, cable and/or motor insulation) but may be neither valid nor practical for many items (e.g., complete instrument systems, etc.). A seemingly obvious approach, although rarely followed, in regarding new or revised standards is to refrain from making any type of commitment until the standards are thoroughly understood. Often too hasty a decision is made by a utility (concerned about licensing) or a manufacturer (concerned about being competitive) to commit to new requirements. Consequently, the broad range of interpretations that usually develops for a given set of requirements may result in difficult relations between organizations.