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Nuclear plant safety evaluation system

  • US 4,632,802 A
  • Filed: 09/16/1982
  • Issued: 12/30/1986
  • Est. Priority Date: 09/16/1982
  • Status: Expired due to Term
First Claim
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1. In a nuclear power plant having a reactor core, a multiplicity of plant components for providing reactor safety functions including reactor shutdown, reactor coolant inventory control, reactor coolant pressure control, reactor core heat removal, and reactor coolant heat removal, and a plant control room including means for generating a status signal indicative of the availability of at least some of said components, an improved safety evaluation system comprising:

  • means for storing a plant-specific data base including component level core damage logic paths and the failure probability of each component, said logic paths being in the form of constituent cutsets, each of said cutsets consisting of a representation of an initiating event and the necessary component failures that would prevent an adequate plant response to avoid core damage;

    means for selecing plant condition scenarios by modifying at least one of said component failure probabilities to represent plant components actually or potentially unavailable;

    means responsive to the means for storing a plant-specific data base and the means for selecting plant condition scenarios, for associating a risk figure of merit with the change in the core damage occurrence rate resulting from the unavailable components, said means for associating a risk figure of merit including a computer implemented program for determining the core damage occurrence rate according to ##EQU4## where W is the sum of the cutset occurrence rates, N equals the number of core damage cutset, and wherein ##EQU5## where λ

    i is the initiating event occurrence rate and qij is the failure probability of component j during the period of time that the cutset i scenario is in progress; and

    means for displaying the figure of merit relative to a base reference value, including a console screen having means for projecting a graph representing the risk figure of merit over a period of at least several days preceding and following the present moment of interest, said graph including a base line indication of the risk figure of merit associated with the nominal availability of all components.

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