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NUREG 0933

Displaying 1 - 5 of 5

DESCRIPTION Background This issue addressed the high rate of reactor coolant pump (RCP) seal failures that challenge the makeup capacity of the ECCS in PWRs. At the time this issue was identified [1] in 1980, RCP seal failures in BWRs occurred at a …
DESCRIPTION Historical Background This issue was initiated in response to an immediate action memorandum [1] issued by AEOD in September 1981 regarding desiccant contamination of instrument air lines. NRR responded to the AEOD memorandum by establishing a …
DESCRIPTION Historical Background PORVs and block valves were originally designed as non-safety components in the reactor pressure control system for use only when plants are in operation. The block valves were installed because of expected leakage from …
DESCRIPTION Historical Background The HPCI steam supply line has two containment isolation valves in series: one inside and one outside of the containment. Both are normally open in most plants; however, two plants were found to operate with the HPCI …
EXECUTIVE SUMMARY The issue of potential blockage in the containment sumps was first identified in Unresolved Safety Issue (USI) A-43, "Containment Emergency Sump Performance." It identified a concern for the availability of adequate recirculation cooling …

Page Last Reviewed/Updated 3/1/2026

Disclaimer: Some of the formatting in NUREG-0933 may not be correct. We are currently working on fixing the formatting.