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NUREG 0933
Displaying 301 - 325 of 458
DESCRIPTION Historical Background This issue was identified during the staff review of the Indian Point 2 and Zion PRAs [1] ; in both of these studies, the dominant interfacing systems LOCA events were estimated to be through the RHR suction valves. The …
1
DESCRIPTION Historical Background Over the past several years, the NRC staff has noted an unacceptably large number of overexposures and uncontrolled exposures associated with pressurized water reactor cavity entries while incore detectors were withdrawn. …
1
DESCRIPTION Historical Background During the review of LaSalle, ASB identified a potential problem which could be generic to all BWRs. [1] [2] The problem relates to ability of the CRD accumulators to retain pressure for a sufficient period of time after …
1
DESCRIPTION Historical Background On April 17, 1984, a DSI memorandum [1] on the subject of RHR interlocks for W plants described staff concerns that the design basis for RHR interlocks had been misunderstood and that these concerns had not been …
1
DESCRIPTION Historical Background Once-through steam generators (OTSGs) are a feature unique to B&W reactor designs. Main feedwater is injected from a header, located at approximately mid-elevation of the OTSG, into an annular downcomer region. As the …
1
DESCRIPTION Historical Background Issue 50 addressed several areas of concern with BWR water level instrumentation and its resolution involved voluntary implementation of water level measurement improvements for all of the staff concerns, except the one …
1
DESCRIPTION Historical Background In January 1984, AEOD issued a special study report (AEOD/S401) [1] describing the number of events that resulted from human error in identification of the correct unit or train. This study focused on LERs issued during …
1
DESCRIPTION Historical Background The issue of using the most recent NOAA procedures for determining probable maximum precipitation (PMP) was raised [1] after an OL applicant disputed the NRC use of NOAA Hydrometeorological Report (HMR) Nos. 51 [2] and …
1
DESCRIPTION In the prioritization of Issue 22, "Inadvertent Boron Dilution," it was found that inadvertent boron dilution events during cold shutdown operation do not constitute a significant risk to the public. Further work by DSI confirmed this …
1
DESCRIPTION Historical Background Issue B-63, which was resolved and implemented as MPA B-45, required leak-testing of the check valves that isolate those low pressure systems that are connected to the RCS outside the containment. However, except for …
1
DESCRIPTION Historical Background Combustible gases such as H 2 , propane, and acetylene are used during normal operations of nuclear power plants in limited quantities and for relatively short periods of time. H 2 , the most prevalent of these gases in …
1
DESCRIPTION Historical Background This issue was identified in a DL/NRR memorandum [1] which called for an assessment of the high failure frequency of main transformers and the resultant safety implications. Concern for this issue arose when the North …
1
DESCRIPTION Historical Background BWRs are equipped with SRVs to control primary system pressurization. Upon SRV actuation and following the clearing of air from the discharge lines, essentially pure steam is injected into the pool. Experiments indicate …
1
DESCRIPTION Historical Background Potential stress corrosion cracking (SCC) of reactor vessel (RV) closure studs was raised as a GSI in December 1984. [1] Concerns were expressed that two contributors to SCC had not been subject to careful research and …
1
DESCRIPTION Historical Background This issue was identified in a DST/NRR memorandum [1] which addressed a condition in which some protective devices intended to trip active engineered safety features (ESF) components, under indication of equipment …
1
DESCRIPTION Historical Background Indications of possible stress corrosion cracking (SCC) in the Indian Point Unit 3 (IP-3) steam generator prompted MTEB to review foreign and domestic operating experiences related to possible indications of SCC in …
1
DESCRIPTION Historical Background In February 1983, the Westinghouse Owners Group submitted WCAP-10271, "Evaluation of Surveillance Frequencies and Out of Service Times for the Reactor Protection Instrumentation System," to the NRC for review and …
1
DESCRIPTION Historical Background This issue was raised [1] in March 1985 to address the staff's concern that there were no requirements for dynamic qualification testing or dynamic surveillance testing of large bore hydraulic snubbers (> 50 kips load …
1
DESCRIPTION Historical Background This issue was identified in a RRAB memorandum [1] in March 1985 and addressed the possibility of relay contact chatter during a seismic event and its resulting effect upon safety and safety-related electrical control …
1
DESCRIPTION Historical Background The ATWS rule [1] , [2] for W plants requires the implementation of a diverse ATWS mitigation system, Auxiliary [or ATWS] Mitigating Systems Actuation Circuitry (AMSAC). The functions prescribed for AMSAC are turbine trip …
1
DESCRIPTION Historical Background This issue was identified in a NRR/DST memorandum [1] and addressed the potential risk reduction that might result from training operators and having procedures developed to assist the operators in managing accidents …
1
DESCRIPTION Historical Background This issue was identified in 1985 when a concern was raised that, due to non-obvious interactions between diverse equipment, TS may permit a plant to be in a dangerous configuration by the simultaneous outage of equipment …
1
DESCRIPTION Historical Background On January 27, 1985, a dented and leaking tendon grease cap was found during inspections at Farley Unit 2 prior to the integrated leak rate test of the prestressed concrete containment structure. Subsequent detailed …
1
DESCRIPTION In an August 1983 memorandum, [1] the EDO requested a comprehensive review of NRC requirements in the area of nuclear power plant piping. In response to this request, the NRC Piping Review Committee (PRC) was formed to review and evaluate …
1
DESCRIPTION Historical Background This issue was raised [1] by the staff in 1985 during the review of several plant TS when it was found that the protection system designs of some older plants did not provide as complete a degree of on-line protection …
1
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.