Application of Raman distributed temperature sensor to the nuclear measurement

Optical fiber sensors (OFSs) have many advantages like flexible configuration, intrinsic immunity for electromagnetic fields, and so on. Furthermore, by some of them, continuous or discrete distribution of physical parameters can be measured. Therefore, they have been widely used for industrial measurements and medical examinations. In order to investigate the applicability of optical fiber sensors to nuclear facilities, Raman Distributed Temperature Sensor (RDTS; one of the OFSs) has been installed at the primary coolant loop of the experimental fast reactor JOYO of JNC (Japan Nuclear Cycle Development Institute). Two correction techniques for radiation induced errors have been developed and demonstrated. During the continuous measurements with the total dose of more than 3 x 107[R], the radiation induced errors showed a saturation tendency and the feasibility of the loss correction techniques was demonstrated. The lifetime of RDTS is expected to be more than 35 years in LWR. (author)