Some Aspects of Operational Reliability of the JET Central Interlock and Safety System (CISS) In the Period March 1984 to December 1986

摘要

The Central Interlock and Safety System (CISS) provides basic safety functions for the JET plant. It monitors the status of emergency push buttons, access doors and plant equipment and takes corrective shutdown actions in the case that plant conditions are not compatible with safe operation. CISS consists of a hierarchical network of PLCs (programmable logic controllers) paralleling the CODAS architecture. It has been successfully in operation since June 1983 and has intervened many times and halted operation to protect JET from (further) damage or personnel against danger. The note will analyse genuine CISS failures only, and as will be shown, these failures are all due to malfunctioning of PLC hardware. All CISS failures have failed-safe and resulted in the expected shutdown action. Hence CISS failures have never resulted in a dangerous situation but they have restricted operational availability of JET. (ERA citation 13:010447)