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NUREG 0933
Displaying 1 - 25 of 37
DESCRIPTION The concern of this issue involves the requirement for verification that the balance-of-plant equipment satisfies the design intent. This issue was identified in NUREG-0705. [1] CONCLUSION Task I.F in NUREG-0660, [2] the TMI Action Plan, is a …
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DESCRIPTION Historical Background This concern was identified by the ACRS as a result of their review [1] of LERs covering a period from 1976 through 1978 and, subsequently, a comprehensive review of the problem was completed which covered the LERs and …
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DESCRIPTION Historical Background Cracking has occurred in PWR piping systems as a result of stress corrosion, vibratory and thermal fatigue, and dynamic loading. However, as of February 1981, no cracking had been experienced in the primary system piping …
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DESCRIPTION Historical Background In the event of a LOCA in which offsite power remains available, the reactor operator may choose to shut down the emergency diesel generators shortly after the LOCA. If, after the diesels are shut down, offsite power is …
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DESCRIPTION Historical Background This issue effects all PWR-type reactors (Westinghouse, CE, B&W). The issue as described, [1] , [2] , [3] concerns postulated accidents resulting from a steam line break which consequentially results in a steam generator …
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DESCRIPTION In a San Onofre Unit 1 Preliminary Notification issued in September 1980, it was reported that, during testing, the licensee had identified a problem with the design of the diesel generator sequencing circuitry. This problem occurred when a …
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DESCRIPTION This issue was identified during plant design and emergency procedure reviews which raised questions as to whether certain safety actions have to be accomplished automatically or whether manual operator action is acceptable. CONCLUSION This …
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DESCRIPTION Historical Background Prior to 1981, the number of bolting-related incidents reported by licensees was on the increase. A large number of these were related to primary pressure boundary applications and major component support structures. As a …
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DESCRIPTION Historical Background This issue corresponds to AEOD recommendation 4 highlighted in an AEOD memorandum [1] to NRR in December 1980. The AEOD recommendation resulted from a natural circulation cooldown event from full power at St. Lucie Unit …
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DESCRIPTION In AEOD/CO05, [1] AEOD identified potential safety problems concerning steam generator overfill due to control system failures and combined primary and secondary blowdown. As a result of discussions with the Commissioners and the EDO, NRR …
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DESCRIPTION AEOD issued a memorandum [1] in which a potential safety issue involving combined primary and secondary system LOCAs was raised. The issue was discussed at Commission meetings on October 16, 1980 and on November 10, 1980. NRR informed AEOD of …
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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 …
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DESCRIPTION Historical Background This proposed generic issue has its origin in a January 1981 event at Millstone Unit 2. [1] An operator inadvertently opened a 125V DC main feeder breaker, causing the loss of one of the two redundant emergency systems …
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DESCRIPTION Historical Background On April 7, 1980, Arkansas Nuclear One (ANO) Units 1 and 2 experienced a significant event resulting from a loss of offsite power. Although both units were safely shut down, the analysis and evaluation of the event …
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DESCRIPTION Historical Background In January 1982, AEOD published a report (AEOD/C201 [1] ) on safety concerns associated with reactor vessel level instrumentation in BWRs. The report was forwared to NRR for further action. Safety Significance BWRs use …
1
DESCRIPTION On April 8, 1981, while operating at 100% power, the Arkansas Nuclear One, Unit 1 experienced a moderate feedwater-overfill transient in one of its once-through steam generators. AEOD performed a case study of this event, concluded that the …
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DESCRIPTION Historical Background Cracks were found in the normal make-up high pressure injection (MU/HPI) nozzles of several B&W plants following an inspection of the 8 B&W plants licensed to operate. These cracks appeared to be directly related to loose …
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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 …
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DESCRIPTION Historical Background On two occasions (February 22 and 25, 1983), Salem Unit 1 failed to scram automatically due to failure of both reactor trip breakers to open on receipt of an actuation signal. In both cases, the unit was successfully …
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DESCRIPTION Historical Background This issue was identified [1] when a number of concerns regarding DC power systems were raised during the review of the proposed resolution of Issue A-30, "Adequacy of Safety-Related DC Power Supplies." The main concerns …
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DESCRIPTION Historical Background In October 1982, the Executive Director for Operations appointed the Committee to Review Safety Requirements at Power Reactors (CRSRPR) to review U.S. Nuclear Regulatory Commission (NRC) security requirements at nuclear …
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DESCRIPTION Historical Background In BWRs, SRVs are mounted on the main steam line inside the drywell. Each SRV discharge is piped through its own discharge line (tailpipe) to a point below the minimum water level in the primary containment suppression …
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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 …
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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 …
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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 …
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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.