Document: NRC Regulatory Guide
Document ID: 111e064c-2d28-4647-872a-806b29019408
Document Type: regulatory_guide
Title: Design Limit and Loading Combinations for Seismic Category I Fluid System Components
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1229/ML12298A124.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.48
CFR Part: 
CFR Title: 

Content:
is (i.e., the design procedures specified in NB-3200 of Section III). Case 1552 (Interpretations of ASME Boiler and Pressure Vessel Code) allows design by analysis of Code Class I valves if additional requirements are met. Non-active pumps and valves are those pumps and valves thatare ,pot required to perform a mechanical motion during the -course of accomplishing a system safety function. Since -non-active pumps and valves need only be assured of pressure-retaining integrity, the upset, emergency, and faulted operating condition category design limits of NB-3200 should be designated for the combination of loadings delineated in regulatory positions 2.a., 2.b., and 2.c., respectively. Non-Active ASME Code Class 1 Valves (Designed by Standard or Alternative Design Rules). 0 1.48-2 Standard or alternative design rules for Code Class 1 valves are specified by, NB-3512 and NB-3513 of Section III of the ASME Code. These design rules encompass the use of pressure-temperature ratings of valves. The design limits specified in, this guide are in terms of Pr which differs from the definition given by Section III in that Pr is related to maximum transient temperature in lieu of the design temperature.. Pr is defined in this guide. as the primary-pressure rating corresponding to the maximum transient temperature for each plant condition as specified in Tables NB-3531-1 to NB-3531-7 of Section. III..Therefore, the maximum transient temperature for each plant condition should be determined before the pressure rating of, the valve is. selected (e.g., Class 600, 900, or 1500). In order to provide assurance of pressure-retaining integrity, Pr should not be exceeded, by more than 10, 20, and 50 percent when the valve is subjected. to the combination of loadings delineated in regulatory positions 3.a., 3.b., and 3.c., respectively. One hundred ten percent and 120 percent ,of Pr, respectively, are analogous to the upset and emergency operating condition category limits of NB-3200 of