PERFORMANCE OF A PROTOTYPE SPENT FUEL BUNDLE COUNTER FOR 600 MW CANDU* REACTORS

The International Atomic Energy Agency (IAEA) Safeguards System for 600 MW CANDU reactors combines inspection with unattended surveillance and unit bundle accounting to detect and deter spent fuel diversion. It is expected that tamperindicating bundle counters, located at the entry ports, will be used to establish the inventory of irradiated fuel in the storage bay. The spent fuel counters detect the passage of fuel by the gamma-ray field from the bundles, and the inputs from four strategically placed Geiger counters are decoded by a microprocessor-based readout unit. The paper presents results obtained with a prototype bundle counter on a fuel transfer simulator and it discusses the detection limits which can be expected from the bundle counters. The printed logs of bundle movements, like those which will be provided to the IAEA, and the operation of safeguards-oriented features are presented.