Method for calculating probability of dangerous failure on demand (PFD) and probability of dangerous failure per hour (PFH) in two out of four channel logic structure system

A technology of channel logic and calculation method, which is applied in the field of evaluation of non-common cause safety failure probability based on PFD and PFH based on two-out-of-four logic architecture, which can solve problems such as errors, failure to provide four-channel safety calculation formulas, and time-consuming
CN102938014AActive Publication Date: 2013-02-20CHINA TECHENERGY +1
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Patent Information

Authority / Receiving Office
CN Β· China
Current Assignee / Owner
CHINA TECHENERGY
Publication Date
2013-02-20

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Abstract

The invention discloses a method for calculating a probability of dangerous failure on demand (PFD) and a probability of dangerous failure per hour (PFH) in a two out of four channel logic structure system. The method includes firstly calculating a common cause failure probability of the PFD and the PFH respectively according to a common cause failure formula of a common channel logic structure, then calculating formulas of probabilities of non-common cause danger failure which occurs in different channels of four channels respectively, and adding the formulas of the probabilities of non-common cause danger failure of different channels and the corresponding common cause failure formula to obtain a calculating method of a danger failure rate of the four channel logic structure. According to the method for calculating the PFD and the PFH in the two out of four channel logic structure system, a result obtained by the method is verified to be completely identical to a standard result and is capable of meeting normative requirements when compared with the result obtained through a reliability basic theory method. Calculating formulas can be directly written without establishing models, and the calculating result is more accurate and low in time consumption.
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Description

Technical field

[0001] The invention relates to a safety evaluation method, in particular to a non-common cause safety failure probability evaluation method based on PFD and PFH in a two-out-of-four logic architecture in a protection system of a nuclear power plant. Background technique

[0002] PFD (Probability of Dangerous Failure on Demand), PFH (Average frequency of dangerous failure[h -1 ]) is a proper term derived from the IEC 61508 standard. PFD is used to evaluate the probability of dangerous failures of the system when required under low-demand operation mode, while PFH is used to evaluate the frequency of dangerous failures of the system under high-demand or continuous operation mode.

[0003] IEC 61508-6 (2010 (Edition) is the top-level standard for functional safety. The standard gives the PFD and PFH calculation formulas for the following structures, including: 1oo1 (1out of 1 channel architecture), 1oo2, 2oo2, 1oo2D (1 out of 2 channel architecture with Diagnostics),...

Claims

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