Document: NUREG-0800
Document ID: fd06ef1f-75ea-4f29-9779-8714e92f3050
Document Type: srp
Title: MAIN STEAM ISOLATION VALVE LEAKAGE CONTROL SYSTEM (BWR)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070451.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.7
CFR Part: 
CFR Title: 

Content:
1.96. DRAFT Rev. 3 - April 1996 6.7-6 Technical Rationale38 The technical rationale for application of these acceptance criteria to reviewing the MSIVLCS is discussed in the following paragraphs:39 1. Compliance with GDC 2 requires that nuclear power plant structures, systems, and components important to safety be designed to withstand the effects of natural phenomena such as earthquake, tornado, hurricane, flood, tsunami, and seiche without loss of capability to perform their safety functions. In the event of a LOCA, the function of the MSIVLCS is to reduce the amount of direct, untreated leakage from the main steam isolation valves (MSIVs) when isolation of the primary system and containment is required. Typically, a sealing fluid for the isolation valves has been used. As an alternative, the applicant may use a passive method of controlling offsite doses from leakage past the steam line isolation valves in the event of a LOCA by taking credit for fission product plateout and holdup in the large volume and surface area of the main steam piping, main steam drain lines, turbine bypass line, turbine, and main condenser. Regulatory Guide 1.29, position C.1, and Regulatory Guide 1.96, position C.1, provide guidance on meeting this requirement. The requirements of GDC 2 are imposed on the MSIVLCS to ensure that engineered safety features, including those associated with control of MSIV leakage, function under the appropriate combination of normal and accident conditions, including the effects of natural phenomena. Meeting the requirements of GDC 2 provides assurance that equipment associated with managing MSIV leakage will limit the releases of fission products to the environment to levels that will not exceed the offsite doses specified in 10 CFR Part 100.40 2. Compliance with GDC 4 requires that structures, systems, and components important to safety be designed to accommodate the effects of, and be compatible with, the environmental conditions associated with normal