A unitized magnetic jack driven control-safety rod has been developed for the 45.5 thermal megawatt organic moderated reactor (Piqua). The rod assembly, including neutron absorber, magnetic jack drive, shock absorber and position indicator, is designed to be installed inside the reactor core tank and to operate immersed in the reactor coolant (Santowax-R) at temperatures of 550 - 600°F. Results of component tests have been reported in NAA-SR-3172. Two prototype rods, representative of the type to be used in the Piqua plant, have been sub¬jected to extensive performance and life tests in hot Santowax-R. Requirements on rod speed (10 inches per minute) scram time (800 microseconds maximum) and position indicator accuracy (± 1/4 inch) were met in these tests. Total rod travel without failure or maintenance of 86,000 feet and 65,000 feet respectively (equivalent to 10,750 and 8,125 full excursions) by the two prototypes has demon¬strated the reliability of the magnetic jack drive in this application.
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