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NUREG 0933
Displaying 26 - 50 of 51
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 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 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 In December 1984, the staff recommended in SECY-83-357B [1] that rulemaking with regard to H 2 control for LWRs with large, dry containments could be safely deferred due to the greater inherent capability of these containments to accommodate …
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 by NRR/EIB in February 1986 when it was suggested that Issue 106, "Piping and the Use of Highly Combustible Gases in Vital Areas," be expanded to include new safety concerns associated with the …
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 Issue 106 was resolved with the issuance of Generic Letter 93-06, "Research Results on Generic Safety Issue 106, Piping and the Use of Highly Combustible Gases in Vital Areas," dated October 25, 1993, [1] which included …
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
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 The issue of potential hazards from combustible gases was raised [1] after two events involving hydrogen combustion occurred within 2 months in late-2001 at two foreign BWRs. Both these events involved sudden rupture of …
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 This issue was initiated [1] in response to a recommendation in the screening analysis of Generic Issue (A) I-195, "Potential Hydrogen Combustion in BWR Piping." GI-195 investigated the potential safety …
1
Page Last Reviewed/Updated 3/1/2026
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