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NUREG 0933
Displaying 26 - 48 of 48
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 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 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 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 The loss of all feedwater event at Davis-Besse on June 9, 1985, resulted in the formation of an NRC project team to investigate the event. The team's findings were published in NUREG-1154 [1] and were subsequently reviewed by DL/NRR. As a …
1
DESCRIPTION In 1985, operating experience as well as staff and industry studies indicated that AFW systems continued to fail at a high rate. These studies also indicated that plants with similar AFW system reliabilities (as calculated in accordance with …
1
DESCRIPTION Background The reliability of PWR main steam safety valves (MSSVs) was identified as a generic issue in a DSRO memorandum on March 1986 [1] in which it was noted that individual PWR plant FSARs assume credit for MSSV functional capability to …
1
DESCRIPTION Historical Background This issue was identified in a May 1986 DSI memorandum [1] in which 21 instances of BWR vessel draining through various paths in the RHR system piping were described. Later, in August 1986, AEOD/E609 [2] was issued …
1
DESCRIPTION Historical Background This issue was identified as an alternative approach to the Finding 15 recommendation [1] discussed in Issue 125.I.5, "Safety Systems Tested in All Conditions Required by DBA," which states that "[t]horough integrated …
1
DESCRIPTION Historical Background This issue was identified [1] by DSIR/RES following ACRS concerns raised during the review of the resolution of Issue 87, "Failure of HPCI Steam Line Without Isolation," which addressed the design bases for those MOVs …
1
DESCRIPTION Historical Background The reliability of essential service water (ESW) systems and related problems have been an ongoing staff concern which has been documented in NUREG/CR-2797, [1] IE Bulletins 80-24 [2] and 81-03, [3] Generic Letter No. …
1
DESCRIPTION Historical Background This issue was identified [1] by NRR after reactor operating experience and research results on MOVs, SOVs, AOVs, and HOVs indicated that testing under static conditions did not always reveal how these valves would …
1
DESCRIPTION Historical Background This issue was identified [1] by NRR and addressed concerns involving centrifugal pumps operating at some point below the best efficiency point (BEP) on their characteristic curves that could cause hydraulic instability …
1
DESCRIPTION Historical Background This issue was identified [1] by NRR as a result of a diagnostic evaluation team inspection of the SWS at Zion, a multiplant site. The inspection identified the potential for some additional shared systems to have an …
1
DESCRIPTION Historical Background This issue was identified [1] by NRR when it was found that, on a number of occasions, licensees reported that spring-actuated safety and relief valves failed to meet setpoint criteria within the desired tolerance. Other …
1
DESCRIPTION Historical Background This issue was identified [1] by NRR following a request from Region I to review GE SIL 477 which identified the possibility of early containment bypass in a BWR, if any one of the MSIVs inside containment should fail to …
1
In November 1992, two engineers who had previously worked under contract for the Pennsylvania Power and Light Company (PP&L) filed a report contending that the design of the Susquehanna station failed to meet regulatory requirements with respect to …
1
DESCRIPTION Historical Background The Office of Nuclear Reactor Regulation (NRR) identified this issue in April 1999, [1] when the concern was raised that licensees operating within the regulatory guidelines of Generic Letter (GL) 85-11, Completion of …
1
DESCRIPTION Historical Background This issue was identified [1] , [2] by a Region III inspector and addressed the possible failure of low pressure emergency core cooling systems due to unanticipated, large quantities of entrained gas in the suction piping …
1
DESCRIPTION Historical Background This issue was raised [1] , [2] by an NMSS staff member whose concern arose from the observation that spent fuel pool racks using Boral for neutron absorption had experienced some problems with swelling and degradation of …
1
DESCRIPTION Historical Background Spent fuel pools (SFPs) at PWRs are Seismic Category I structures that contain borated water, maintain spent fuel temperatures, and provide radiation shielding. The SFPs are typically lined with stainless steel plates, …
1
DESCRIPTION This issue was identified by an NMSS engineer in December 2006 and addressed concerns about potential safety issues with cranes that are used to lift spent fuel casks at nuclear power plants. The areas of concern involved questions about the …
1
Page Last Reviewed/Updated 3/1/2026
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