Defense against common mode failures in protection system design

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The introduction of digital instrumentation and control into reactor safety systems creates a heightened concern about common-mode failure. This paper discusses the concern and methods to cope with the concern. Common-mode failures have been a ``fact-of-life`` in existing systems. The informal introduction of defense-in-depth and diversity (D-in-D&D)-coupled with the fact that hardware common-mode failures are often distributed in time-has allowed systems to deal with past common-mode failures. However, identical software operating in identical redundant systems presents the potential for simultaneous failure. Consequently, the use of digital systems raises the concern about common-mode failure to a new level. A more methodical ... continued below

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12 p.; Other: FDE: PDF; PL:

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Wyman, R. H. & Johnson, G. L. August 27, 1997.

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Description

The introduction of digital instrumentation and control into reactor safety systems creates a heightened concern about common-mode failure. This paper discusses the concern and methods to cope with the concern. Common-mode failures have been a ``fact-of-life`` in existing systems. The informal introduction of defense-in-depth and diversity (D-in-D&D)-coupled with the fact that hardware common-mode failures are often distributed in time-has allowed systems to deal with past common-mode failures. However, identical software operating in identical redundant systems presents the potential for simultaneous failure. Consequently, the use of digital systems raises the concern about common-mode failure to a new level. A more methodical approach to mitigating common-mode failure is needed to address these concerns. Purposeful introduction of D-in-D&D has been used as a defense against common-mode failure in reactor protection systems. At least two diverse systems are provided to mitigate any potential initiating event. Additionally, diverse displays and controls are provided to allow the operator to monitor plant status and manually initiate engineered safety features. A special form of conimon-mode failure analysis called ``defense-in-depth and diversity analysis`` has been developed to identify possible conimon-mode failure vulnerabilities in digital systems. An overview of this analysis technique is provided.

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12 p.; Other: FDE: PDF; PL:

Notes

INIS; OSTI as DE98050943

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  • International Atomic Energy Agency (IAEA) technical committee meeting on advanced technologies for improving availability and reliability of current and future water cooled nuclear power plants, Argonne, IL (United States), 8-11 Sep 1997

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  • Other: DE98050943
  • Report No.: UCRL-JC--128414
  • Report No.: CONF-9709106--
  • Grant Number: W-7405-ENG-48
  • Office of Scientific & Technical Information Report Number: 358846
  • Archival Resource Key: ark:/67531/metadc685851

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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  • August 27, 1997

Added to The UNT Digital Library

  • July 25, 2015, 2:20 a.m.

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  • May 16, 2016, 1:58 p.m.

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Wyman, R. H. & Johnson, G. L. Defense against common mode failures in protection system design, article, August 27, 1997; California. (digital.library.unt.edu/ark:/67531/metadc685851/: accessed December 13, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.