Document: NUREG-0800
Document ID: 7e9d3620-7a94-488e-b2d5-992282113080
Document Type: srp
Title: NUREG408OO
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052350480.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
on of Regulatory Guide 1.47. 22. Guidance for Application of Regulatory Guide 1.22. 25. [BTP has been superseded by Standard Technical Specifications.] I 26. Requirements for Reactor Protection System Anticipatory Trips. 7A-2 Rev. 2 - July 1981 BRANCH TECHNICAL POSITION ICSB I (DOR) BACKFITTING OF THE PROTECTION AND EMERGENCY POWER SYSTEMS OF NUCLEAR REACTORS [BTP ICSB 1 has been deleted] I 7A-3 Rev. 2 - July 1981 BRANCH TECHNICAL POSITION ICSB 3 ISOLATION OF LOW PRESSURE SYSTEMS FROM THE HIGH PRESSURE REACTOR COOLANT SYSTEM A. BACKGROUND During normal and emergency conditions, it is necessary to keep low pressure systems that are connected to the high pressure reactor coolant system properly isolated in order to avoid'damage by overpressurization or the potential for loss of integrity of the low pressure system and possible radioactive releases. The residual heat removal system used for cold shutdown conditions when in service becomes an extension of the reactor coolant pressure boundary. General Design Criteria 15 requires that reactor coolant system and associated auxiliary, control and protection systems shall be designed with sufficient margin to assure that the design conditions of the reactor coolant pressure boundary are not exceeded during any condition of normal operation, including anticipated operational occurrences. There have been a number of recommendations for accomplishing this aim. Until a more definitive guide is published, the criteria in Part B, below, provide an adequate and acceptable design solution for this concern. B. BRANCH TECHNICAL POSITION The bbllowing measures should be incorporated in designs of the interfaces between low pressure systems and the high pressure reactor coolant system: 1. At least two valves in series should be provided to isolate any subsystem whenever the primary system pressure is above the pressure rating of the subsystem. 2. For system interfaces where both valves are motor-operated, the valves should have