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NUREG 0933
Displaying 26 - 47 of 47
DESCRIPTION Historical Background This issue was identified [1] when AEOD expressed concerns about the use inside containment of a particular polymer coating that could flake off and fail when subjected to DBA conditions. In addition to the concern for …
1
DESCRIPTION Historical Background The containment flooding issue stems from a flooding event that occurred at the Indian Point 2 reactor in October 1980. [1] A large quantity of water leaked from fan coolers onto the containment building floor and …
1
DESCRIPTION Historical Background The SRVs of a BWR plant provide protection against overpressurization of the reactor primary system. During normal operation, the SRVs which are mounted in the main steam lines open on high pressure permitting steam to …
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 The HPCI steam supply line has two containment isolation valves in series: one inside and one outside of the containment. Both are normally open in most plants; however, two plants were found to operate with the HPCI …
1
DESCRIPTION Historical Background This concern was raised by an NRC resident inspector who questioned the practice of leaving the refueling canal drain valve in the closed position during operations at H. B. Robinson Unit 2. [1] A subsequent investigation …
1
DESCRIPTION Historical Background This issue was identified during the staff review of the Indian Point 2 and Zion PRAs [1] ; in both of these studies, the dominant interfacing systems LOCA events were estimated to be through the RHR suction valves. The …
1
DESCRIPTION Historical Background Combustible gases such as H 2 , propane, and acetylene are used during normal operations of nuclear power plants in limited quantities and for relatively short periods of time. H 2 , the most prevalent of these gases in …
1
DESCRIPTION Historical Background BWRs are equipped with SRVs to control primary system pressurization. Upon SRV actuation and following the clearing of air from the discharge lines, essentially pure steam is injected into the pool. Experiments indicate …
1
DESCRIPTION Historical Background On January 27, 1985, a dented and leaking tendon grease cap was found during inspections at Farley Unit 2 prior to the integrated leak rate test of the prestressed concrete containment structure. Subsequent detailed …
1
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 …
1
DESCRIPTION Historical Background The issue of deinerting upon discovery of RCS leakage was identified [1] by DL/NRR, based on data collected by OIE. The related but separate concern of deinerting with one train of a safety system inoperable was also …
1
DESCRIPTION The issue, as originally proposed, [1] addressed the concern for fission product removal by the containment sprays and suppression pools in PWRs and BWRs, respectively; however, it was expanded to include PWR plants that use ice condenser …
1
DESCRIPTION Historical Background This issue was identified [1] by DSIR/RES and addressed the concern for overpressurization of containment piping penetrations following a containment isolation and subsequent heat-up. Containment isolation at all nuclear …
1
The results of ongoing staff-sponsored research which culminated in the assessment of risk at five U.S. nuclear reactors (NUREG-1150 [1] ) indicated that, for the Peach Bottom MARK I containment, the core-melt probability was relatively low. However, it …
1
DESCRIPTION Historical Background This issue was identified [1] by NRR following a request from Region I to review GE SIL 477 which identified the possibility of early containment bypass in a BWR, if any one of the MSIVs inside containment should fail to …
1
DESCRIPTION Historical Background At 6:53 a.m. on February 7, 1993, an intruder drove into the TMI site owner-controlled area, through a gate into the protected area of Unit 1, and crashed through a roll-up door on the turbine building. TMI security …
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
DESCRIPTION Historical Background This generic issue was proposed [1] in response to SECY-00-198 [2] which explored means of risk informing 10 CFR 50.44. As a part of this effort, the paper recommended that safety enhancements that have the potential to …
1
DESCRIPTION Historical Background This issue was raised [1] by NRR and addresses the adequacy of the calculations, testing, and acceptance criteria related to the creation of a vacuum in the reactor building of a BWR, following an engineered safeguards …
1
The Chernobyl accident, with its absence of effective containment, has focused attention on the strengths and performance limits of the substantial containments for U.S. LWRs. It has led to added recognition of the significance of ongoing work on the …
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.