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:
at applicants have evaluated methods to reduce challenges and failures of reactor coolant system relief valves. 27. The reviewer verifies that the applicant has administrative procedures in place that establish limitations on the ECCS cumulative outage times (GI B-61). The reviewer verifies that the applicant will prepare and submit annual reports on ECCS unavailability (II.K.3.17) that also include information on: outage dates, lengths, and causes; ECCS components involved; and any corrective action taken. 28. The reviewer verifies that the applicant has considered the following guidance regarding the design of the ECCS miniflow systems necessary to insure safety related ECCS pump protection: A. Assure that the minimum cooling flow provided for the ECCS pumps is adequate under all conditions, including verification that the system configuration precludes pump-to-pump interaction during miniflow operation that could result in dead- heading one or more of the pumps. The miniflow must be sufficient to prevent damage to the pump(s) under all conditions. 6.3-16 Revision 3 - March 2007 B. The miniflow system shall be designed such that the miniflow function can be performed assuming a single failure. A single failure should not result in conditions causing no flow through the ECCS pumps. C. In cases where only the miniflow return line is available for pump testing, flow instrumentation must be installed on the miniflow return line. This instrumentation is necessary to provide flow rate measurements during pump testing so that this data can be evaluated with the measured pump differential pressure to monitor for pump hydraulic degradation. 29. The reviewer evaluates the ECCS capability to provide reactor coolant system inventory additions during reduced inventory operations as follows: A. PWR designs and related operating procedures should have a means of providing at least two available or operable means of adding inventory to the RCS that are in addition to pumps that