Document: NRC Regulatory Guide
Document ID: 60ac4a53-3f72-4e92-9ad2-39c736cf2135
Document Type: regulatory_guide
Title: Functional Specification for Active Valve Assemblies in Systems Important to Safety in Nuclear Power Plants
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003739979.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.148
CFR Part: 
CFR Title: 

Content:
Pressure Vessel Code 2 (the Code) do not, as indicated in NCA-2142(b) of the 1977 Edition, IAs identified in accordance with Section 3.9.3.2 of Regulatory Guide 1.70, Revision 3, "Standard Format and Content of Safety Analysis Reports for Nuclear Power Plants." 2Copies may be obtained from the American Society of Mechan ical Engineers United Engineering Center, 345 East 47th Street, New York, N.Y. 10017. ensure operability of components in which mechanical motion is required. Since valve assembly 3 operability is necessary to ensure performance of some systems important to safety in nuclear power plants, the American National Standards Institute (ANSI) established a group to provide direction for development of the necessary standards that would provide assurance of the operability of valve assem blies. The first standard published as a result of that effort was ANSI N278.1-1975, "Self-Operated and Power-Operated Safety-Related Valves Functional Specification Standard." 2 This standard requires that a functional specification be prepared that (I)identifies the function of the valve assembly in systems important to safety and (2) delineates the set of conditions important to valve assembly operability. ANSI N278.1-1975 establishes a consistent approach to specifying the minimum information needed to identify the requirements for function and operability of valve assem blies in systems important to safety. Although the standard has not been extensively used, it is apparent that it would be useful for any Quality Group A, B, C, or D valve assembly in systems important to safety. However, there are questions relative to whether this detailed functional specification is necessary for all (or for certain specified) valve assemblies in systems important to safety. It is anticipated that the breadth of application of this standard might develop gradually with user experience, quality group classification of a particular valve assembly, and valve assembly function within a