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NUREG 0933
Displaying 1 - 25 of 62
DESCRIPTION Background This issue was identified [1] after a review of LERs involving the failure or degraded performance of essential equipment that resulted from the failure of protective devices such as fuses and circuit breakers. The affected systems …
1
DESCRIPTION Historical Background This issue is identified in Appendix D of NUREG-0572 [1] and is one of the key observations made after the ACRS requested its members and consultants to make comprehensive reviews of all LERs issued during the years 1976, …
1
DESCRIPTION Background Flow-induced vibrations caused by vortex shedding resulting from rapid area change, buffeting due to random flow turbulence, fluid structures interaction instability, leakage excitation, steady operation of positive displacement …
1
DESCRIPTION Historical Background This issue apparently originated as a DOR proposal and was discussed in SECY-80-325. [1] The issue as previously evaluated [2] is whether periodic replacement of the squib charges and circuit checks of the traveling …
1
DESCRIPTION Historical Background A memorandum [1] from AEOD to NRR dated May 23, 1980 drew attention to the generic issue of BWR jet pump integrity. The concern that motivated the AEOD memo was a February 1980 jet pump failure at Dresden Unit 3, together …
1
DESCRIPTION Historical Background This is an ACRS concern raised by the Subcommittee on TMI-2 Implications in October 1979. This issue centers around the possibility of a breach in the reactor coolant system boundary caused by the failure of nonsafety …
1
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 …
1
DESCRIPTION Historical Background This issue addressed the potential problem of radiation embrittlement of reactor vessel support structures (RVSS). It was originally identified as a Candidate USI in NUREG-0705 [1] where it was recommended for further …
1
DESCRIPTION This issue involves a potential deficiency in the ability to control leakage past the main steam isolation valves (MSIV) in BWR plants. Requirements for MSIV leakage control systems outlined in Regulatory Guide 1.96 [1] were developed as a …
1
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 …
1
DESCRIPTION On November 10, 1979, an event occurred at the Oconee Power Station, Unit 3, that resulted in loss of power to a non-Class 1E 120-volt AC single-phase power panel that supplied power to the integrated control system (ICS) and the nonnuclear …
1
DESCRIPTION Historical Background This concern was raised [1] because of the potential for a high-altitude nuclear weapon detonation causing a large electromagnetic pulse (EMP) which subsequently could induce large currents and voltages in electrical …
1
DESCRIPTION This issue concerns the slow loss of control air pressure in the scram system of BWRs. [1] Air pressure dropping at a certain rate will first allow some of the CRD scram outlet valves to open slightly, thus filling the scram discharge volume …
1
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 …
1
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 …
1
DESCRIPTION Pressurized water reactors are susceptible to certain types of hypothetical accidents that, under circumstances such as operation of the reactor beyond a critical time in its life, could result in failure of the pressure vessel as a result of …
1
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 …
1
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 …
1
DESCRIPTION This issue was identified in an AEOD memorandum [1] to NRR in May 1980. The concern is related to a feature on some B&W reactors in which the failure of the Non-Nuclear Instrumentation and Integrated Control System (NNI/ICS) power supply …
1
DESCRIPTION Historical Background This issue was raised by AEOD [1] , [2] and involved isolation of the reactor coolant system charging and letdown system following a spurious safety injection transient at H. B. Robinson on January 29, 1981. Following the …
1
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 …
1
DESCRIPTION Concerns for inoperability of instrumentation due to extreme cold weather were raised [1] by AEOD after an event at Arkansas Nuclear One, Unit 2 (ANO-2) in which all four RWST instrumentation channels were lost when the level transmitters …
1
DESCRIPTION An AEOD memorandum [1] to NRR on July 15, 1980, identified the concern that some operating nuclear power plants do not have technical specifications or Administrative controls governing operational restrictions for Class 1E 120 VAC vital …
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 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 …
1
Page Last Reviewed/Updated 3/1/2026
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