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:
vided 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 independent and diverse interlocks to prevent both from opening unless the primary system pressure is below the subsystem design pressure. Also, the valve operators should receive a signal to close automatically whenever the primary system pressure exceeds the subsystem design pressure. 3. For those system interfaces where one check valve and one motor-operated valve are provided, the motor-operated valve should be interlocked to prevent the valve from opening whenever the primary pressure is above the subsystem design pressure, and to close automatically whenever the primary system pressure exceeds the subsystem design pressure. 4. Suitable valve position indication should be provided in the control room for the interface valves. 5. For those interfaces where the subsystem is required for ECCS operation, the above recommendations need not be implemented. System interfaces of this type should be evaluated on an individual case basis. 6. The system should satisfy the requirements of the General Design Criteria and Section 50.55a(h) of 10 CFR Part 50 with regards to the protection system requirements (IEEE Std 279). C. REFERENCES None 7A-4 Rev. 2 - July 1981 BRANCH TECHNICAL POSITION ICSB 4 REQUIREMENTS OF MOTOR-OPERATED VALVES IN THE ECCS ACCUMULATOR LINES A. BACKGROUND For many postulated loss-of-coolant accidents, the performance of the emergency core cooling-system (ECCS) in pressurized water reactor plants depends upon properftnctioning of the safety injection tanks (also referred to as "accumulators" or "flooding tanks" in some applications). In these plants, a motor-operated isolation valve (MOIV) and two check valves are provided in series between each safety injection tank and the reactor coolant (primary) system. The MOIVs must be considered to be "operating