Document: NUREG-0800
Document ID: eb0ea00d-43e4-45d1-8a5e-4daa4263d2cf
Document Type: srp
Title: EMERGENCY CORE COOLING SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070550068.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.3
CFR Part: 
CFR Title: 

Content:
bility and design of the pneumatic supply system is reviewed under SRP Section 9.3.1. 6.3-12 Revision 3 - March 2007 D. The applicant’s evaluation of the ADS with respect to reactor vessel integrity limits is reviewed. If integrity limits could be exceeded during rapid cooldown, the applicant should evaluate alternate depressurization methods, other than full actuation of the ADS system, such as early depressurization with one or two relief valves. E. The ADS design is reviewed to verify that the depressurization/safety valves be provided with a positive indication in the control room of flow in the discharge pipe. 11. The design of ECCS injection lines is reviewed to confirm that the isolation provisions at the interface with the reactor coolant system are adequate. The number and type of valves used to form the interface between low pressure portions of the ECCS and the reactor coolant system must provide adequate assurance that the ECCS will not be subjected to a pressure greater than its design pressure. This may be accomplished by any of the following provisions: A. One or more check valves in series with a normally closed motor-operated valve. The motor-operated valve is to be opened upon receipt of a safety injection signal once the reactor coolant pressure has decreased below the ECCS design pressure. B. Three check valves in series. C. Two check valves in series, provided that there are design provisions to permit periodic testing of the check valves for leaktightness and the testing is performed at least annually. 12. The reviewer should identify those portions of nonsafety-related systems which could have an adverse effect on ECCS and should ensure that design provisions are in place to prevent these situations. 13. Motor-operated isolation valves in ECCS lines connecting the accumulators to the reactor coolant system in a pressurized water reactor (PWR) are reviewed to ensure that adequate provisions are made against inadvertent isolation.