scope:

The criteria contained in this standard establish minimum functional and design requirements for the power, instrumentation, and control portions of safety systems for nuclear power generating stations. To satisfy the criteria in this standard, interface requirements may be imposed on the other portions of the safety system as shown in Fig 1. Safety system functional and design criteria are also contained in other standards.¹

Illustration. Figure 2 illustrates the scope of this standard in the form of a 3x3 matrix. The labeling across the top of the matrix illustrates that the safety systems can be subdivided into the three general elements of sense and command features, execute features, and power sources. These general elements represent a grouping of devices that provides similar performance characteristics for many discrete safety functions. The labeling on the left side of the matrix illustrates that the safety systems can also be subdivided into the three operational elements of reactor trip system and engineering safety features, auxiliary supporting features, and other auxiliary features. When viewing an entire row of the matrix, it can be seen that an operational element may form a system.

Illustrating the scope of this standard in matrix form shows that each operational element contains one or more general elements. This matrix should not be interpreted to mean that every operational element shall contain all of the general elements or that a particular general element is limited to application in only one, operational element.

¹ See Section 3 and Appendix B for applicable standards.