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:
a main steam line in a PWR plant, the design will preclude the blowdown of more than one steam generator, assuming a concurrent single active component failure. In this regard, all main steam shut-off valves downstream of the MSIVs, the turbine stop valves, and the control valves are considered to be functional. The reviewer should verify that the main steam isolation valves, shut-off valves in connected connecting piping, 65 turbine stop valves, and bypass valves can close against maximum steam flow. The reviewer verifies that the SAR provides a tabulation and descriptive text of all flow paths that branch off the main steam lines between the MSIVs and the turbine stop valves. The descriptive information shall include the following for each flow path: (1) System identification (2) Maximum steam flow in kilograms per second (pounds per hour) 66 (3) Type of shut-off valve(s) (4) Size of valve(s) (5) Quality of the valve(s) (6) Design code of the valve(s) (7) Closure time of the valve(s) (8) Actuation mechanism of the valve(s) (i.e., solenoid operated, motor operated, air operated diaphragm valve, etc.) (9) Motive or power source for the valve actuating mechanism. e. In the event of a main steam line break, termination of steam flow from all systems identified in d, above, except those that can be used for mitigation of the accident, is required to bring the reactor to a safe cold shutdown. For these systems the reviewer verifies that the SAR describes what design features have been incorporated to assure closure of the steam shut-off valve(s) and what operator actions, if any, are required. If the systems that can be used for mitigation of the accident are not available, or the decision is made to use other means to shut down the reactor, the reviewer verifies that the SAR describes how these systems are secured to assure positive steam shut-off and what operator actions, if any, are required. f. Assure that in the event of a postulated safe shutdown earthquake in a