A HIERARCHICAL, DISTRIBUTED, FAULT-TOLERANT NETWORK FOR ADVANCED REACTOR CONTROL SYSTEMS

THIS RESEARCH WILL INVESTIGATE THE SUITABILITY OF A NEW DESIGN FOR AN ADVANCED AUTOMATED CONTROL SYSTEM FOR NUCLEAR POWERPLANTS. THIS DESIGN, CALLED THE HIERARCHICAL DISTRIBUTED RECOVERY BLOCK NHDFT) CONSISTS OF THREE SUBSYSTEMS: (1) THE KERNEL NETWORK: A SIMPLE, THOROUGHLY TESTED AND TRUSTWORTHY NETWORK OF COMPUTERS CAPABLE OF MAINTAINING THE PLANT IN A SAFE CONDITION EVEN IF OTHER PARTS OF THE HDFT SYSTEM FAIL; (2) THE ADVANCED CONTROL NETWORKS: NETWORKS OF COMPUTERS PROGRAMMED TO PERFORM ADVANCED CONTROL FUNCTIONS SUCH AS DATA REDUCTION AND DISPLAY, SOPHISTICATED AUTOMATED CONTROL OF THE PLANT, AND RELATED FUNCTIONS; AND (3) GATEKEEPERS: SUBSYSTEMS TO GUARD THE KERNEL NETWORK FROM DATA AND OTHER FAILURES OF THE ADVANCED CONTROL NETWORKS. THE DESIGN PHILOSOPHY OF THE HDFT IS SIMILAR TO THE STRATEGY OF DEFENSE IN DEPTH USED IN CONSTRUCTION OF THE NUCLEAR POWERPLANTS THEMSELVES. DIFFERENT PARTS OF THE SYSTEM ARE PARTITIONED AND ISOLATED INTO FAULT-CONTAINMENT REGIONS AND PROTECTED FROM EACH OTHERBY MEANS OF THE GATEKEEPERS. THE MOST CRITICAL FUNCTIONS ARE ISOLATED IN THE KERNEL AND ARE KEPT SIMPLE SO THAT THOROUGH VERIFICATION AND TESTING IS POSSIBLE. IF THE FUNCTIONS WITHIN ANOTHER FAULT CONTAINMENT REGION CONTAININGADVANCED CONTROL FUNCTIONS FAIL, THE KERNAL NETWORK IS ABLE TO CONTROL THE PLANT AND KEEP IT IN A SAFE STATE UNTIL RECOVERY OCCURS.