Document: NUREG-0800
Document ID: 3ab8ae04-e11b-4993-a907-f644301c5af2
Document Type: srp
Title: MAIN STEAM SUPPLY SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070577.pdf
Revision Date: 2023-06
Chapter: 10
Section ID: 10.3
CFR Part: 
CFR Title: 

Content:
n meeting Regulatory Guide 1.155 as it relates to the design of the MSSS. 48 Technical Rationale:49 The technical rationale for application of the above acceptance criteria to the MSSS is discussed in the following paragraphs. 1. GDC 2 requires that structures, systems, and components important to safety be designed to withstand the effects of postulated local natural phenomena, such as earthquakes, tornadoes, floods, etc., without loss of the capability to perform their safety functions. The safety functions of the MSSS are plant design specific and may include: steam supply to safety-related auxiliaries and ESF pumps, provision of a heat sink during certain transients and accidents, limiting RCS pressure during certain transients, steam generator and MSSS overpressure protection, and termination of MSLB events. For BWRs, the MSSS provides fission product isolation during and following postulated accidents, and for BWRs without a MSIVLCS, fission product retention and holdup during and following an accident. The MSSS must be able to perform its safety functions while withstanding natural phenomena that may reasonably be expected to occur at the plant site. Regulatory Guide 1.29 provides specific guidance for determining which structures, systems, and components should be designated seismic category I and designed to meet the SSE. Regulatory Guide 1.117 provides specific guidance for determining which structures, systems, and components should be designed to withstand the effects of a Design Basis Tornado. Meeting the requirements of GDC 2 and the positions of Regulatory Guide 1.29 and Regulatory Guide 1.117 will ensure that the MSSS can perform its required safety functions in the event of adverse natural phenomena. 2. GDC 4 requires that structures, systems, and components important to safety be designed to withstand potential dynamic effects, such as missile impact, pipe whip, jet impingement, etc., caused by equipment failure or outside events. The safety