Maintenance experience of the fuel failure detection system (Delayed neutron monitoring system) in experimental fast reactor[JOYO]; Countermeasure for electrical noise

not registered; not registered; not registered; not registered; Miyaguchi, Kimihide; not registered

At the Delayed Monitoring system, which in one of the Fuel Failure Detection System in JOYO, some probrems had occurred since the 6th cycle of 75MW power operation at MK-I core. As a result of inspection from Feb. 1983 to Mar. 1984, it was found that the various electrical noises interface with it's normal function. So many kinds of noise appeared at power supply circuit, pre-amplifier circuit and cable lines. Though this Phenomenon was a difficult problem to deal with, We could remove injurious electrical noises successfully. lt's working effects were indicated as follows, (1)At first an AC Line Conditioner was built in power supply circuit. (2)An adjustment was made on the pre-amplifier circuit and some circuit parts were replaced in order to alter the circuit. (3)Most of signal line at BF-3 monitoring system was changed from coaxial cable to glass fiber cable partially.