Modification of fuel failure detection system at multi-purpose reactor

Haruyama, Mitsuo; Shitomi, Hajimu; Nakamura, Kiyoshi

As one of the technical cooperation activity based on the Annex III, the Cooperation in the Area of Reactor Physics and Technology, of the Arrangement between the National Nuclear Energy Agency (BATAN) and the Japan Atomic Energy Research Institute (JAERI), the modification of the Fuel Failure Detection System (FFDS) was carried out by the joint work at the Multi-purpose Reactor RSG-G.A. Siwabessy (RSG-GAS). The system takes the delayed neutron detection method. The design requirements of the modification are, (1) to save the system units currently used and the spares on hand as long as practicable, and / or (2) to replace the system units with those easy to maintain or to obtain at the markets. The modified system obtained around twice of higher sensitivity for delayed neutron detection than before and more reliable monitoring possibility with redundancy. The specification, installation, adjustment methods and characteristics of the modified system and the modus operandi of FFDS at high power reactor operation are described in this paper.