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Abstract

Signals from redundant sensors located throughout a pressurized water reactor (PWR) nuclear power plant are processed in four independent channel sets each of which includes a plurality of independent microcomputers which calibrate, convert to engineering units and calculate partial trip signals and engineered safeguard actuation signals from the sensor signals for use in the conventional voting logic of a plant protection system. The primary and secondary partial trip and engineered safeguard actuation functions associated with various postulated abnormal events are allocated to different independent microcomputers in the channel set for reliability. A test unit common to the channel set automatically, rapidly bypasses and tests each protection function independently while the other protection functions in the channel set remain on-line and also continually tests each microcomputer through a dummy test function performed along with the assigned protection functions. Signals representative of the analog value of the sensor signals are stored by the microcomputers and are transmitted by a serial data link through a common electrical isolation unit to a common analog output device for use by the plant control and monitoring systems under the control of a communication processor common to a group of microcomputers in the channel set.

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First Claim