Round-robin irradiation test of radiation resistant optical fibers for ITER diagnostic application

Fused silica core optical fibers are expected to play crucial roles especially in the size-reduced International Thermonuclear Experimental Reactor (ITER-FEAT). Several radiation resistant optical fibers have been developed in Japan and the Russian Federation. The task force on radiation effects in diagnostic components in the ITER-EDA (engineering and design activity) promoted international round-robin irradiation experiments on the developed optical fibers. Ten different optical fibers were tested in a cobalt-60 gamma-ray irradiation facility and in the Japan Materials Testing Reactor. The paper reports results obtained on five different optical fibers, which include purified, hydrogen loaded, and fluorine doped ones. Results show that the developed optical fibers could be deployed in remote handling and out-of-vessel applications. But, for the in-vessel diagnostics in the visible range optical spectroscopy, further improvement of the radiation resistance of optical fibers will be needed.