Document: NUREG-0800
Document ID: 2768345e-44b7-48d8-bfa7-69652aa4faa8
Document Type: srp
Title: CONCRETE CONTAINMENT
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1319/ML13198A245.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.8.1
CFR Part: 
CFR Title: 

Content:
of the various LOCA-induced loads may be combined in accordance with their actual time-dependent mutual occurrence. 2. SAFETY/RELIEF VALVE DISCHARGE A. Safety/relief valve (SRV) loads (such as single valve, single valve plus adjacent valve, automatic depressurization system valves, and all valves) should be included in all load combinations as defined in the ASME Boiler and Pressure Vessel Code, Section III, Division 2, Subsection CC. However for the load combination that contains 1.5 Pa, a load factor of 1.25 should be applied to the appropriate SRV loads. Also, for the severe environmental load combination, the load factor should be 1.3, which is consistent with the practice of treating SRV as a live load. B. A single active failure causing one SRV discharge must be considered in combination with the design-basis accident. C. Appropriate multiple SRV discharges should be considered in combination with the small-break accident and intermediate-break accident. D. Thermal loads resulting from SRV discharge should be treated as To for normal operation and Ta for accident conditions. 3. COMBINATION OF DYNAMIC LOADS Revision 1 of NUREG-0484 presents guidance on the acceptable methods for combining LOCA, SRV, and the safe-shutdown earthquake (SSE). This report states that the square root of sum of the squares method is appropriate for the following: A. Combination of SSE and LOCA dynamic responses for all ASME Class 1, 2, or 3 systems, components, or supports. For dynamic responses resulting from the same initiating event, when the time-phase relationship between the responses 3.8.1-30 Revision 4 - September 2013 cannot be established, the absolute summation of these dynamic responses should be used. B. Combining responses of dynamic loads other than LOCA and SSE, if a nonexceedance probability of 84% or higher is achieved for the combined SRSS response. Although the above criteria were prepared for ASME systems, components, and supports, they are applicable to seismic