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:
ovide a means to detect steam leakage from the system if a steamline were to break. Temperature or pressure sensors are an acceptable means for initiating signals to close the main steamline isolation valves and/or turbine stop valves to limit the release of steam during a steamline break accident. E. Assure that, in the event of a postulated break in a main steamline 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 shutoff valves downstream of the MSIVs, the turbine stop valves, and the control valves are considered to be functional. The reviewer should verify that the MSIVs, shutoff valves in connected piping, 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 flowpaths that branch off the main steamlines between the MSIVs and the turbine stop valves. The descriptive information should include the following for each flowpath: i. System identification ii. Maximum steam flow in pounds per hour (kilograms per second) iii. Type of shutoff valves iv. Size of valves v. Quality of the valves vi. Design code of the valves vii. Closure time of the valves 10.3-11 Revision 4 - March 2007 viii. Actuation mechanism of the valves (i.e., solenoid-operated, motor- operated, air-operated diaphragm, and the like) ix. Motive or power source for the valve actuating mechanism F. In the event of a main steamline break, terminate steam flow from all systems identified in item E above, except those that can be used for mitigation of the accident, as required to bring the reactor to a safe cold shutdown. For these systems, the reviewer verifies that the SAR describes the design features that have been incorporated to assure closure of the steam shutoff valves as well as any required operator actions. If the systems that can be used to mitigate the accident