Abstract: An actuation counter is disclosed for counting the number of operation cycles of a valve or other electrically actuated device. The counter provides a real-time output display of the count for analysis by an operator. A battery operated counting circuit is configured in a housing and is responsive to the detection of load or actuation current on a conductor to increment a stored count. The actuation current which corresponds to the operation cycles of the monitored device is detected by a current probe. A preferred embodiment the counting circuit includes a delay circuit which operates to prevent an increment in the count due to spurious signals such as those induced by contact bounce. Access ports associated with the counting circuit are provided so that an operator can determined the presence or absence of magnetic fields by the use of a voltmeter. The counting circuit also preferably includes a threshold setting circuit and reset switch.

Abstract: A control rod drop monitoring method and apparatus for use in a nuclear reactor including dedicated timers and displays to measure and display the drop time for each control rod when a reactor system trip occurs. The timers and displays may be made from CMOS technology, and may have millisecond resolution, if desired. The timers are initiated upon receipt of one or more reactor trip signals and are halted at the closure of switches for detecting the fully inserted or other preselected position of the control rods in the reactor core. The monitor system is designed for continuous operation. Reactor trip signals and limit switch signals are fed to latch circuits following a trip event or limit switch activation and are unaffected by subsequent changes in the state of the limit switches or trip signals. A manual reset is required to clear rod drop times. Also, a test mode is provided wherein all of the timers can be started and stopped, thereby providing a functional test of 100% of the monitor circuitry.