Development of a Variable Baseline Type Distance Sensor in the High Radiation Environment

Abstract

The International Thermonuclear Experimental Reactor (ITER) is underway as joint effort of EU, Japan and RF. Remote maintenance technology is essential to realize ITER since the reactor components are activated by 14-MeV neutrons and have to be maintained remotely. For this purpose, the Japan Atomic Energy Research Institute (JAERI) has been conducting remote handling technology development mainly for in-vessel components. On the other hand, a critical accident at the JCO occurred in September 1999, which was the most serious nuclear accident in Japan. It took long time to gain the information on the accident and then to stop the critical reaction since human access was limited due to high radiation level. Therefore, the JAERI has developed a Radiation-proof Robot (called RaBOT) operating under high γ-radiation field up to 10⁵Gy. Under such a background, a variable baseline type distance sensor has been developed for use under the severe conditions such as γ-radiation. This sensor is composed of optical fiber, mirror, motor and so on. The aim of the sensor is to be used for the measurement of the distance between a robot and an object under the severe conditions of the maintenance for fusion plants and atomic disaster. The sensing method is also applicable to the general distance sensor. This report describes the outline of the variable baseline type distance sensor and the results of the basic performance test.