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Tachibana, Mitsuo; Ito, Hirokuni*; Hatakeyama, Mutsuo*; Yanagihara, Satoshi
Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(1), p.120 - 127, 2004/03
The RAPID-1600 was developed to measure a low-level radioactive contamination on building surfaces automatically. The double layered detectors are structured by two gas flow type detectors with a rays shielding plate between the two detectors and it is horizontally positioned. The lower counter measures and rays and the upper counter measures rays. The rays counting rates are derived by subtracting rays counting rates of the upper counter from and rays counting rates of the lower counter. This mechanism results in sensitive to rays against to low background radiation conditions. The driving unit can move omnidirectionally by controlling two driving wheels individually, and has a capability to correct its position if an orbital error is detected by the self-position identification system. The RAPID-1600 was successfully applied to the actual measurement in the radioisotope production facilities. The RAPID-1600 is expected to be a useful tool for measurement of radioactivity in decommissioning nuclear facilities.
Ito, Hirokuni*; Hatakeyama, Mutsuo*; Tachibana, Mitsuo; Yanagihara, Satoshi
JAERI-Tech 2003-012, 34 Pages, 2003/03
The MISE was developed to evaluate low-level radiological contaminations of inner surfaces of piping. The MISE consists of a cylindrically-formed double layered type detector and a piping crawling robot, which were designed and manufactured separately. In measurements of the contaminations, an outer cylindrical detector close to the surface of piping measures -rays and -rays and an inner cylindrical detector set after a shielding plate for shield of -rays measures -rays. The -ray counting rates are derived by subtracting -ray counts measured by the inner detector from - and -ray counts measured by the outer detector. The robot transports the double layered type detector with observing inner surfaces of piping. The detection limit for the contamination of Co was found to be about 0.17Bq/cm with measurement time of 30 seconds. It is expected that 0.2Bq/cm corresponding to clearance level of Co (0.4Bq/g) can be evaluated with measurement time of 2 seconds, which is equal to measurement speed of 54m/h.