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Title: Probabilistic Structural Mechanics Analysis of the Degraged Davis-Besse RPV Head


No abstract prepared.

 [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
Work for Others (WFO)
OSTI Identifier:
DOE Contract Number:
Resource Type:
Resource Relation:
Conference: 2006 ASME Pressure Vessels and Piping Division Conference, Vancouver BC, Canada, 20060723, 20060727
Country of Publication:
United States

Citation Formats

Williams, Paul T, Bass, Bennett Richard, and Yin, Shengjun. Probabilistic Structural Mechanics Analysis of the Degraged Davis-Besse RPV Head. United States: N. p., 2006. Web.
Williams, Paul T, Bass, Bennett Richard, & Yin, Shengjun. Probabilistic Structural Mechanics Analysis of the Degraged Davis-Besse RPV Head. United States.
Williams, Paul T, Bass, Bennett Richard, and Yin, Shengjun. Sun . "Probabilistic Structural Mechanics Analysis of the Degraged Davis-Besse RPV Head". United States. doi:.
title = {Probabilistic Structural Mechanics Analysis of the Degraged Davis-Besse RPV Head},
author = {Williams, Paul T and Bass, Bennett Richard and Yin, Shengjun},
abstractNote = {No abstract prepared.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}

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  • Cracks in Alloy 600 and Alloy 182 upper-head-penetration welded components from the Davis-Besse pressurized-water reactor were characterized by high-resolution analytical transmission electron microscopy. Axial cracks in the Alloy 600 nozzle and both axial and circumferential cracks in the weld metal were examined at scales ranging from mm to less than 1 nm. Despite different metallurgical structures in the wrought nozzle and weld alloys, the observations in both materials revealed characteristic penetrative intergranular attack and corrosion products indicating that the degradation occurred by intergranular stress corrosion cracking (IGSCC) during service. Sulfur impurities and sulfide particles found near crack tips in themore » Alloy 600 nozzle also indicated that the IGSCC in this material was assisted by impurities from the primary-water environment.« less
  • At the request of the US Nuclear Regulatory Commission (NRC), we performed a rapid-response analysis of the loss-of-feedwater (LOFW) event that occurred at the Toledo Edison Davis-Besse plant on June 9, 1985. The initial 831 s of the plant transient were simulated and, in addition, four postulated transients were calculated to determine how the plant would have responded if feedwater had not been restored, and how it would have responded to a feed-and-bleed (FAB) decay-heat removal procedure initiated at different times. The Transient Reactor Analysis Code was used for this analysis. We completed these calculations within a two-week period andmore » provided a report to the NRC 30 days later. Our analysis showed that FAB was a viable decay-heat-removal procedure for the Davis-Besse plant for the initiation times analyzed. With complete LOFW and no alternate decay-heat removal procedure, we calculated that core uncovery would have occurred at about 9200 s. FAB initiated at 8 min and 13 min after complete LOFW, which in the actual LOFW transient occurred 6 min after the initiating event of a main-feedwater pump trip, was successful in that the primary system remained subcooled and water-solid throughout the transient. FAB initiated at 28 min after complete LOFW was considered successful even though it resulted in a loss of subcooling, a net loss in primary inventory, and a slow voiding of the primary system. The core would have remained covered for the nine hours that we estimated for the primary pressure to decrease to the residual-heat-removal pressure.« less
  • An ingrained cultural attitude toward diligent pursuit of the root causes of plant anomalies and equipment malfunctions, and effective implementation of corrective actions is essential to achieve and maintain desired safety and performance standards at a nuclear power plant. At the Davis-Besse nuclear power station, a demonstrated management commitment to these actions, coupled with an effective root-cause training program has made root-cause analysis an important engineering function. The dedication of engineering and maintenance department resources to problem investigation and troubleshooting, root-cause analysis, and corrective action implementation has eliminated several complex operational problems. Reactor trips, unplanned challenges to safety systems, andmore » unplanned plant transients have been significantly reduced as a result. The benefits of these plant performance improvements far outweigh the expense of these resources.« less
  • Equipment failures and human errors have not been designed out of nuclear power plants. Although the tolerance of plants to accept multiple failures and errors without direct harm to the public has been demonstrated repeatedly around the nation, they must find the root causes of failures and errors to assure optimum nuclear safety and protection of their investment and generating facilities. This paper addresses the root causes analysis techniques used following a loss-of-auxiliary-feedwater event on June 9, 1985, at the Davis-Besse Nuclear Power Station. The event started with a capacitor failure causing loss of main feedwater. This was followed bymore » an operator pushing the wrong buttons during the transient. This error was multiplied in impact by steam feedwater rupture control system and auxiliary feedwater pump design deficiencies, equipment failures, and human factors problems. Other equipment failed to perform properly or was damaged as a result of the transient.« less