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:
ed. Note II is identical to Note 6 to the regulatory position except that the design limits for non0-active pumps and valves may be used for the applicable loading combinations if appropriate analyses and/or testing confirnms that operability will not be impaired when the component is designed to these limits. Non-Active ASME Code Class 2 and 3 Valves The design of Co de Class 2 and 3 valves encompasses the use of pressure-temllperature ratings. The design limits (Oven herein are in terms of Pr which is the prinlary-pressure rating corresponding to the maximunm transient temperature for each plant condition as specified in NC-3511 and ND-351 I for Code Class 2 and 3 valves, respectively. This definition 'of Pr differs froim the Section III of the ASME Code definitiot•i of Pr in tile same manner 'as that for Code Class I valves and the same considerations apply. To assure pressure-retainiung integrity, the limits for Pr are lower than those given for Code Class 1 valves for the same loading combinationis involving emergency and faulted plant conditions. Pr should n6t be exceeded by more than 10 percent for the combination of loadings delineated in regulatoiy positions I i.a.(1), and I l.a.(2), and Pr should not be exceeded by more than 20 percent for the combination of loadings delineated in regulatory position 1I .b. Active ASME Code Class 2 and 3 Valves To provide greater assurance of operability for active valves of Code Class 2 and 3, Pr should not be exceeded for the comnbination of loadings delineated in - regulatory positions 12.a,(i), 12.a.(2), and 12.a.(3). Note I I to ,ie regulatory position applies. However, as I .48-4 allowed! by' Note 11, if the design limits for non-active valves are used, appropriate testing should demonstrate operability in lieu of analysis since detailed analytical techniques are. not applied to design pressure-temperature rated valves. C. REGULATORY POSITION Seismic Category I fluid system components should be designed to