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NUREG 0933
Displaying 1 - 25 of 29
DESCRIPTION The issue was raised after the occurrence of various incidents of water hammer that involved steam generator feedrings and piping, emergency core cooling systems, RHR systems, containment spray, service water, feedwater, and steam lines. The …
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DESCRIPTION By letter dated June 18, 1975, licensees of operating reactor facilities were sent a preliminary copy of a staff paper, "Guidance for Proposed License Amendments Relating to Refueling," and "Refueling Information Request Form." The purpose was …
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DESCRIPTION Historical Background This NUREG-0371 [1] item involves the development of consistent and formalized acceptance criteria regarding the conversion to higher density storage racks (increased storage capacity) in existing spent fuel storage …
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DESCRIPTION Historical Background Individual reactor fuel rods sometimes fail during normal operations and many fuel rods are expected to fail during severe accidents. To ensure that these fuel failures do not result in unacceptable releases to the …
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DESCRIPTION This NUREG-0471 [1] task covers a spectrum of technical efforts related to the staff review of LMFBR fuel designs. The efforts include: (1) evaluating licensing requirements for the behavior of stainless steel cladding and hexcans in an LMFBR …
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DESCRIPTION The fuel assembly is a highly nonlinear structure which can be subjected to substantial loadings during seismic excitations and LOCA transients. The integrity of this assembly is critical for plant safety. Extensive work has been completed by …
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DESCRIPTION BWRs are operated in such a manner as to attempt to produce an axial power distribution with as little peaking as possible. When the reactor moderator is not boiling (e.g., during startup and heatup), the axial flux distribution is much more …
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DESCRIPTION This issue was raised in an AEOD memorandum [1] to NRR and OIE in October 1980 and addressed the problem of flow blockage by Asiatic clams (Corbicula) in redundant safety-related cooling water systems at Arkansas Nuclear One. CONCLUSION This …
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DESCRIPTION Historical Background On June 19, 1981, AEOD issued a preliminary report [1] on the incident at Calvert Cliffs Unit 1 in which the plant lost both redundant trains of service water when the service water system became air-bound as a result of …
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DESCRIPTION While operating at 100% power on March 10, 1980, San Onofre Unit 1 experienced a complete loss of the salt water cooling system. The event involved an unlikely triple failure and desiccant contamination of the instrument air system was found …
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DESCRIPTION Historical Background This issue was raised in a DL memorandum [1] to DST in March 1982 and addressed the subject of service water system (SWS) fouling at operating plants primarily by aquatic bivalves. Prior to and following this memorandum, …
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DESCRIPTION This issue was raised in an AEOD memorandum [1] to NRR in May 1982 and addressed the problem of flow blockage by blue mussels (Mytilus Edilus) in the reactor building closed cooling water system at Pilgrim. CONCLUSION This issue has been …
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DESCRIPTION Historical Background In response to a 1967 ACRS concern relative to the potential of melting and subsequent disintegration of a portion of a fuel assembly due to inlet orifice flow blockage, GE submitted NEDO-10174 [1] in May 1970. As a …
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DESCRIPTION Historical Background This issue was identified at an NRC Operating Reactor Events meeting on January 7, 1982, [1] and addressed fire protection system (FPS) actuations that resulted in adverse interactions with safety-related equipment at …
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DESCRIPTION Historical Background On November 11, 1981, the DAILY REPORT-REGION I carried a "prompt report" from Calvert Cliffs Units 1 and 2 indicating the licensee had been notified that the water tight integrity of the service water pump rooms in both …
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DESCRIPTION Historical Background Experiments conducted at several test facilities prior to 1984 showed that irradiated fuel can fragment (crumble) into small pieces during a LOCA. Some evaluation of this effect was made for NRC by EG&G. [1] Although it …
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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 …
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DESCRIPTION Historical Background This issue was identified [1] when the staff found the Byron Unit 1 vulnerable to core-melt sequences in the absence of the availability of Byron Unit 2 which was not yet operational. Because of the licensing status of …
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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 …
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DESCRIPTION Historical Background This issue was raised in SECY-89-170 [1] and addressed the potential for control system vulnerabilities as a result of fire-induced alternate shutdown/control room panel interactions. Concern for these interactions arose …
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DESCRIPTION Historical Background This issue was raised in SECY-89-170 [1] and addressed the effectiveness of manual fire-fighting in the presence of smoke. This concern arose as a result of an NRC-sponsored Fire Risk Scoping Study [2] which focused on …
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DESCRIPTION Historical Background This issue was raised in SECY-89-170 [1] and addressed the effect of premature failure of fire barriers on CDF. Concern for fire barriers arose as a result of an NRC-sponsored Fire Risk Scoping Study [2] which focused on …
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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. …
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DESCRIPTION Historical Background Following the TMI-2 accident, the NRC converted its fuel behavior research program into a severe accident research program and, consequently, no further confirmatory work on fuel damage criteria was pursued. However, some …
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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 …
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Page Last Reviewed/Updated 3/1/2026
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