Document: NRC Regulatory Guide
Document ID: 0ae1e098-eccd-43e7-b12e-43b05aa1fe48
Document Type: regulatory_guide
Title: Safety-Related Concrete Structures for Nuclear Power Plants (Rev. 3)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1617/ML16172A240.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.142
CFR Part: 
CFR Title: 

Content:
rd, the structural systems could function as a direct barrier or as a support for a direct barrier. Also, the characteristics of the pressure transients would depend, in most cases, on the appropriate functioning of various engineered safety features and other backup systems. Considering a band of uncertainty in the magnitude and duration of the energy levels associated with a pipe rupture, the NRC staff position is to use a comparatively conservative load factor for Pa in Regulatory Position 3.1. DG-1283, Page 6 Piping and equipment reaction. According to Section 2.1 of ACI 349-13, Ro does not include dead load and earthquake reactions (those components of Ro are included in D and Eo/Ess). Assessing Ro is associated with larger uncertainty than dead load. ACI 349-13, Appendix C, applies a load factor of 1.7 to Ro, which is similar to a live load. In Regulatory Position 3.1, the staff modified the load factor for Ro to treat it as a live load in load combinations (9-2), (9-3), and (9-4). Live load. To be consistent with ACI 318-08 and Appendix C to ACI 349-13, the NRC staff position is to use a load factor of 1.0 in place of 0.8 for the live load in load combinations (9-6), (9-7), and (9-8). Stress, strain, and deformation limits for the operating-basis earthquake. Consistent with Appendix S to 10 CFR Part 50, SSCs important to safety must remain functional and within applicable stress, strain, and deformation limits for operating-basis earthquake Eo. Hence, when the effects of Eo are considered in load combination (9-4), the NRC staff position is to include Ccr as an operating load with a load factor of 1.4. 3.2 Structural integrity is achieved during construction by implementing appropriate construction sequences to avoid creating vulnerabilities in partially completed structures, and by considering in the design the construction loads induced in partially completed structures and temporary structures and supports, as well as applicable load combinations.