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NUREG 0933
Displaying 1 - 25 of 146
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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DISCUSSION On May 7, 1975, the NRC was informed by VEPCO that an asymmetric loading on the reactor vessel supports resulting from a postulated reactor coolant pipe rupture at a specific location (e.g., the vessel nozzle) had not been considered by W or …
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DESCRIPTION Prior to 1978, operating experience with PWR steam generators was characterized by extensive corrosion and mechanically-induced degradation of the steam generator tubes, frequent plant shutdowns to repair primary-to- secondary leaks, and two …
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DESCRIPTION This item was originally identified in NUREG-0371 [1] and was later declared a USI in NUREG-0510. [2] (See Item A-3 for further details.) CONCLUSION This item was RESOLVED and requirements were established. (See Item A-3 for further details.) …
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DESCRIPTION This item was originally identified in NUREG-0371 [1] and was later declared a USI in NUREG-0510. [2] (See Item A-3 for further details.) CONCLUSION This item was RESOLVED and requirements were established. (See Item A-3 for further details.) …
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DESCRIPTION During the conduct of a large scale testing program for an advanced design BWR pressure suppression containment system (MARK III), new suppression pool hydrodynamic loads associated with a postulated LOCA were identified which had not been …
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DESCRIPTION During testing for an advanced BWR containment system design (MARK III), suppression pool hydrodynamic loads were identified which had not been considered in the original design of the MARK I containment system. To address this issue, a MARK I …
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DESCRIPTION As a result of the GE testing program for the MARK III pressure-suppression containment program, new containment loads associated with a postulated LOCA were identified in 1975 which had not been explicitly included in the original design of …
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DESCRIPTION The technical report on ATWS for water-cooled reactors (WASH-1270) [1] discussed the probability of an ATWS event as well as an appropriate safety objective for the event. After several years of discussions with vendors and evaluations of …
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DESCRIPTION Inspections of operating BWRs conducted up to April 1978 revealed cracks in the feedwater nozzles of 20 reactor vessels. Most of these BWRs contained 4 nozzles with diameters ranging from 10 in. to 12 in. Although most cracks ranged from 1/2 …
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DESCRIPTION Because of the remote possibility of failure of nuclear reactor pressure vessels designed to the ASME Boiler and Pressure Vessel Code, the design of nuclear facilities does not provide protection against reactor vessel failure. Prevention of …
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DESCRIPTION During the course of the licensing action for North Anna Units 1 and 2, a number of questions were raised as to the potential for lamellar tearing and low fracture toughness of the steam generator and RCP support materials for these …
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DESCRIPTION Historical Background In May 1978, the ACRS and the staff expressed concern over the substantial number of LERs related to the malfunction of snubbers, the most frequent of which were: (1) seal leakage in hydraulic snubbers; and (2) high …
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DESCRIPTION Historical Background After the 1970 issuance of inspection requirements in Section XI of the ASME Boiler and Pressure Vessel Code, [1] the staff recognized the need to quantify the uncertainty in the existing inspection requirement …
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DESCRIPTION Historical Background Operation of a LWR results in slow corrosion of the interior metal surfaces of the primary coolant system. The resulting corrosion products circulate through the reactor core and are activated by neutron flux from the …
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DESCRIPTION Historical Background Prior to May 1978, tests conducted by GE showed that the presence of steam and/or increased pressure in and above the upper core region of BWRs could adversely affect the distribution of flow from certain types of core …
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DESCRIPTION Nuclear power plants contain many structures, systems, and components (SSCs), some of which are safety- related. Certain SSCs are designed to interact to perform their intended functions. These "systems interactions" are usually well …
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DESCRIPTION Historical Background A major objective of this NUREG-0371 [1] item was the development of consistent criteria for application in licensing processes. Additional research programs to implement licensing positions were to be conducted under …
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DESCRIPTION At the time this issue was identified in NUREG-0371, [1] trends in the design of nuclear power plants showed an increase in the use of digital computer technology in safety-related instrumentation and control systems. The first application of …
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DESCRIPTION At the time this issue was identified in NUREG-0371, [1] compliance with NEPA required that alternatives to a proposed Federal action be considered, and that required alternatives be balanced against the base case in terms of their associated …
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DESCRIPTION Safety-related equipment inside the containment of a nuclear power plant is qualified for the most severe accident conditions under which it is expected to function. In a PWR, this had been previously assumed to be the pressure and temperature …
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DESCRIPTION Historical Background Several aspects of the MSLB analyses as currently provided by applicants and accepted by the NRC have been questioned. The concerns derive principally from Issues 1 and 15b of NUREG-0138. [1] Issue 1 in NUREG-0138 [2] …
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DESCRIPTION Historical Background Since the issuance of Appendix J to 10 CFR Part 50 in February 1973, certain requirements of the appendix have been found to be conflicting, impractical for implementation, or subject to a variety of interpretations by …
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DESCRIPTION CP applicants for which SERs were issued after July 1, 1974, were required by the NRC to qualify all safety- related equipment to IEEE 323. [1] From the time this standard was originated, the industry developed methods that were used to …
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DESCRIPTION Historical Background The Class 1E power sources provide the electric power for the plant systems that are essential to reactor shutdown, containment isolation, reactor core cooling, containment heat removal or are otherwise essential in …
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Page Last Reviewed/Updated 3/1/2026
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