Section
Resolution Product Category
Facilities Type
Related Technical Area
Image
NUREG 0933
Applied Filters
Displaying 26 - 50 of 59
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 …
1
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 …
1
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 …
1
DESCRIPTION Historical Background Following the steam generator tube rupture (SGTR) event at Ginna in January 1982, [1] the staff proceeded to develop generic steam generator requirements which would help mitigate or reduce steam generator tube …
1
DESCRIPTION Following the SGTR event at Ginna on January 25, 1982, increased staff effort was placed on developing means to mitigate and reduce steam generator tube degradations and ruptures. To meet these objectives, two steps were taken. The first step …
1
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 …
1
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 …
1
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 …
1
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 …
1
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 …
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 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
On June 9, 1985, Davis-Besse had a partial loss of feedwater while operating at 90% power. Following a reactor trip, the loss of all feedwater occurred. The two OTSGs became dry and were ineffective as a heat sink. Consequently, the RCS pressure increased …
1
DESCRIPTION Historical Background In IE Circular No. 80-02, [1] the concern of overtime work for licensee staff who perform safety-related functions was discussed and limits on maximum working hours were recommended. In July 1980, a letter [2] was issued …
1
DESCRIPTION Since the TMI-2 accident in March 1979, to which human error was a major contributor, the issue of academic requirements for reactor operators has been a major concern of the NRC. In October 1985, the NRC issued a Policy Statement on …
1
DESCRIPTION Steam generator overfill and its consequences have received staff and industry attention because of the frequency and severity of overfill events. Over the years, a number of issues have been raised concerning steam generator overfill …
1
DESCRIPTION Historical Background This issue arose as the result of an event at the Palo Verde Nuclear Generating Station (PVNGS) Unit 3 in which inadequate lighting conditions exacerbated an unrelated reactor trip. [1] During this event, half of the …
1
Issue Identification The NRC identified [1] this issue in June 1992 to address an NRC staff members concern, given in a DPO dated December 3, 1991, [2] and modified March 27, 1992, [3] about the potential for a main steamline break (MSLB) accident to …
1
In resolving GSIs over the years, the staff generally found it necessary to make assumptions and establish limitations on the scope of the issues. As a result of its review of the resolution of some GSIs, the ACRS expressed concerns that the assumptions …
1
DESCRIPTION Historical Background The NRC post-TMI-2 accident shift staffing policy was codified through the issuance of 10 CFR 50.54(m) which specified minimum requirements for licensed operators at nuclear power reactor sites but not for non-licensed …
1
DESCRIPTION Historical Background This issue was identified when it was believed [1] that the validity of steam generator (SG) tube leak and rupture analyses could be affected by resonance vibrations in steam generator tubes during steam line break …
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.