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Plant maintenance and aging management: Are they the same?

Description: As part of the NRC`s Nuclear Plant Aging Research Program, a number of aging studies were performed on safety-related systems and components which found that, even with current maintenance and monitoring practices in place, a large number of the reported failures are related to aging. This suggests that current practices are not sufficient to completely manage aging degradation, and other factors need to be considered. This paper examines the aging management process and the degree to which maintenance plays a part in it. Component failures and degradation mechanisms identified in aging studies of several different safety systems are summarized and evaluated, then con-elated with the components most frequently failed. This information, along with an analysis of failure causes, is then used to determine the extent to which aging is managed by current maintenance practices. Conclusions and recommendations for proper aging management arc also presented.
Date: June 1, 1995
Creator: Lofaro, R.J.
Partner: UNT Libraries Government Documents Department

Detecting and mitigating aging in component cooling water systems

Description: The time-dependent effects of aging on component cooling water (CCW) systems in nuclear power plants has been studied and documented as part of a research program sponsored by the US Nuclear Regulatory Commission. It was found that age related degradation leads to failures in the CCW system which can result in an increase in system unavailability, if not properly detected and mitigated. To identify effective methods of managing this degradation, information on inspection, monitoring, and maintenance practices currently available was obtained from various operating plants and reviewed. The findings were correlated with the most common aging mechanisms and failure modes, and a compilation of aging detection and mitigation practices was formulated. This paper discusses the results of this work.
Date: January 1, 1992
Creator: Lofaro, R. J. & Aggarwal, S.
Partner: UNT Libraries Government Documents Department

Detecting and mitigating aging in component cooling water systems

Description: The time-dependent effects of aging on component cooling water (CCW) systems in nuclear power plants has been studied and documented as part of a research program sponsored by the US Nuclear Regulatory Commission. It was found that age related degradation leads to failures in the CCW system which can result in an increase in system unavailability, if not properly detected and mitigated. To identify effective methods of managing this degradation, information on inspection, monitoring, and maintenance practices currently available was obtained from various operating plants and reviewed. The findings were correlated with the most common aging mechanisms and failure modes and a compilation of aging detection and mitigation practices was formulated. This paper discusses the results of this work.
Date: January 1, 1991
Creator: Lofaro, R.J.
Partner: UNT Libraries Government Documents Department

Understanding aging in containment cooling systems

Description: A study has been performed to assess the effects of aging in nuclear power plant containment cooling systems. Failure records from national databases, as well as plant specific data were reviewed and analyzed to identify aging characteristics for this system. The predominant aging mechanisms were determined, along with the most frequently failed components and their associated failure modes. This paper discusses the aging mechanisms present in the containment spray system and the containment fan cooler system, which are two systems used to provide the containment cooling function. The failure modes, along with the relative frequency of each is also discussed.
Date: December 1, 1993
Creator: Lofaro, R. J.
Partner: UNT Libraries Government Documents Department

Detecting and mitigating aging in component cooling water systems

Description: The time-dependent effects of aging on component cooling water (CCW) systems in nuclear power plants has been studied and documented as part of a research program sponsored by the US Nuclear Regulatory Commission. It was found that age related degradation leads to failures in the CCW system which can result in an increase in system unavailability, if not properly detected and mitigated. To identify effective methods of managing this degradation, information on inspection, monitoring, and maintenance practices currently available was obtained from various operating plants and reviewed. The findings were correlated with the most common aging mechanisms and failure modes and a compilation of aging detection and mitigation practices was formulated. This paper discusses the results of this work.
Date: December 31, 1991
Creator: Lofaro, R. J.
Partner: UNT Libraries Government Documents Department

Aging assessment of Residual Heat Removal systems in Boiling Water Reactors

Description: The effects of aging on Residual Heat Removal systems in Boiling Water Reactors have been studied as part of the Nuclear Plant Aging Research Program. The aging phenomena has been characterized by analyzing operating experience from various national data bases. In addition, actual plant data was obtained to supplement and validate the data base findings.
Date: June 1, 1992
Creator: Lofaro, R. J. & Aggarwal, S.
Partner: UNT Libraries Government Documents Department

Detecting and mitigating aging in component cooling water systems

Description: The time-dependent effects of aging on component cooling water (CCW) systems in nuclear power plants has been studied and documented as part of a research program sponsored by the US Nuclear Regulatory Commission. It was found that age related degradation leads to failures in the CCW system which can result in an increase in system unavailability, if not properly detected and mitigated. To identify effective methods of managing this degradation, information on inspection, monitoring, and maintenance practices currently available was obtained from various operating plants and reviewed. The findings were correlated with the most common aging mechanisms and failure modes, and a compilation of aging detection and mitigation practices was formulated. This paper discusses the results of this work.
Date: June 1, 1992
Creator: Lofaro, R. J. & Aggarwal, S.
Partner: UNT Libraries Government Documents Department

Aging and condition monitoring of electric cables in nuclear power plants

Description: There are a variety of environmental stressors in nuclear power plants that can influence the aging rate of components; these include elevated temperatures, high radiation fields, and humid conditions. Exposure to these stressors over long periods of time can cause degradation of components that may go undetected unless the aging mechanisms are identified and monitored. In some cases the degradation may be mitigated by maintenance or replacement. However, some components receive neither and are thus more susceptible to aging degradation, which might lead to failure. One class of components that falls in this category is electric cables. Cables are very often overlooked in aging analyses since they are passive components that require no maintenance. However, they are very important components since they provide power to safety related equipment and transmit signals to and from instruments and controls. This paper will look at the various aging mechanisms and failure modes associated with electric cables. Condition monitoring techniques that may be useful for monitoring degradation of cables will also be discussed.
Date: May 1998
Creator: Lofaro, R. J.; Grove, E. & Soo, P.
Partner: UNT Libraries Government Documents Department

Aging assessment of Residual Heat Removal systems in Boiling Water Reactors

Description: The effects of aging on Residual Heat Removal systems in Boiling Water Reactors have been studied as part of the Nuclear Plant Aging Research Program. The aging phenomena has been characterized by analyzing operating experience from various national data bases. In addition, actual plant data was obtained to supplement and validate the data base findings.
Date: January 1, 1992
Creator: Lofaro, R.J. (Brookhaven National Lab., Upton, NY (United States)) & Aggarwal, S. (Nuclear Regulatory Commission, Washington, DC (United States))
Partner: UNT Libraries Government Documents Department