Document: NUREG-0800
Document ID: 87477809-7581-4701-b6f2-91410029e1c8
Document Type: srp
Title: MAIN STEAM SUPPLY SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0703/ML070380206.pdf
Revision Date: 2023-06
Chapter: 10
Section ID: 10.3
CFR Part: 
CFR Title: 

Content:
airplane crash. Regulatory Guide 1.115 provides specific guidance for protecting safety-related SSCs from low-trajectory missiles resulting from turbine failure. Meeting the requirements of GDC 4 and the positions of Regulatory Guide 1.115 will offer assurance that the MSSS is capable of executing its safety functions in the event of adverse conditions caused by equipment failure or events outside the plant. 3. GDC 5 prohibits sharing of SSCs important to safety among nuclear units unless such sharing will not impair the ability of the SSCs to perform design safety functions in their respective units. The MSSS safety functions are specific to plant design and may include steam supply to safety-related auxiliaries and ESF pumps, provision of a heat sink during certain transients and accidents, limiting of RCS pressure during certain transients, steam generator and MSSS overpressure protection, and termination of MSLB events. The MSSS provides (1) for BWRs, fission product isolation during and following postulated accidents and (2) for BWRs without an MSIVLCS, fission product 10.3-8 Revision 4 - March 2007 retention and holdup during and following an accident. For multiple-unit sites, units may cross-connect the MSSSs for startup, maintenance, or other related purposes. For such shared systems, the licensee must show that each MSSS can perform all of its required safety functions for its respective unit. Meeting GDC 5 will ensure that shared MSSSs at multiple-unit sites will execute their respective safety functions regardless of malfunctions in the other units. 4. GDC 34 requires provision of an RHR system to remove decay and residual heat from the reactor and to maintain the fuel and reactor coolant pressure boundary within design limits. GDC 34 further requires that such RHR systems are designed with redundancy so that they can accomplish their safety functions, assuming a single failure in either the onsite or offsite electric power system. The MSSS may be used