Document: NRC Regulatory Guide
Document ID: cf1737d6-2a8a-4765-aaf5-f5f2a617ef91
Document Type: regulatory_guide
Title: Design of Main Steam Isolation Valve Leakage Control Systems for Boiling Water Reactor Nuclear Power Plants
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003740263.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.96
CFR Part: 
CFR Title: 

Content:
le times for operator action. 8. Instrumentation and circuits necessary for ti functioning of the LCS should be designed in accordan with standards applicable to an engineered safe feature. 9. The LCS controls should include interlocks prevent inadvertent operation of the LCS. In particul, interlocks should be provided to prevent damage to ti LCS or possibly to the main steam system due inadvertent opening of any LCS isolation valves whe ever the pressure in the connecting main steam pipi exceeds LCS design pressure and to prevent significa release of radioactivity to the environment. Whe appropriate to the LCS design, interlocks should I provided to preclude direct communication with t post-LOCA containment atmosphere in the event th the inboard main steam isolation valve does not ful close. AU such controls and interlocks should 1 activated from appropriately designed safety systems circuits. k, 10.'The plant should be designed to permit testing of nt the operability of controls and actuating devices of the ip LCS during power operation to the extent practical and it- testing of the complete functioning of the system during th plant shutdowns. Is he 11. The LCS should be designed so that (a) any ,m effects resulting from use of a fluid sealing medium, e.g., ng thermal stresses, pressures associated with flashing, and is thermal deformations under the loading conditions associated with the activated system, will not affect the structural integrity or operability of the main steam lines Its or main steam isolation valves and (b) any deformation le of Isolation valve internals will not induce leakage of the in main steam line isolation valve beyond the capacity or capability of the LCS. :ts 12. Equipment should be provided, as part of the ie LCS or other systems, to prevent or control valve stem or packing leakage or other direct leakage from main steam m line isolation valves outside containment. If such equip ment is not part of the LCS, it should meet the same