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Fault-tolerant reactor protection system

United States Patent

5,621,776
April 15, 1997
View the Complete Patent at the US Patent & Trademark Office
Lawrence Berkeley National Laboratory - Visit the Technology Transfer and Intellectual Property Management Department Website
A reactor protection system having four divisions, with quad redundant sensors for each scram parameter providing input to four independent microprocessor-based electronic chassis. Each electronic chassis acquires the scram parameter data from its own sensor, digitizes the information, and then transmits the sensor reading to the other three electronic chassis via optical fibers. To increase system availability and reduce false scrams, the reactor protection system employs two levels of voting on a need for reactor scram. The electronic chassis perform software divisional data processing, vote 2/3 with spare based upon information from all four sensors, and send the divisional scram signals to the hardware logic panel, which performs a 2/4 division vote on whether or not to initiate a reactor scram. Each chassis makes a divisional scram decision based on data from all sensors. Each division performs independently of the others (asynchronous operation). All communications between the divisions are asynchronous. Each chassis substitutes its own spare sensor reading in the 2/3 vote if a sensor reading from one of the other chassis is faulty or missing. Therefore the presence of at least two valid sensor readings in excess of a set point is required before terminating the output to the hardware logic of a scram inhibition signal even when one of the four sensors is faulty or when one of the divisions is out of service.
Gaubatz; Donald C. (Cupertino, CA)
General Electric Company (San Jose, CA)
08/ 502,411
July 14, 1995
The Government of the United States of America has rights in this invention in accordance with Contract No. DE-AC03-89SF17445 awarded by the Department of Energy.