Enrichment and measurement of tag gas (No.1); Fabrication of enrichment system and cryogenic adsorption test

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The purpose of this study is to establish the method for enrichment of trace tagging gas in cover gas and the method for measuring isotopic ratios of tagging gas in resultant emriched gas in the program of developing the gas tagging method for failed fuel detection and location system in PNC. Based on above purpose, a full automatic tagging gas enrichment system which consists of a control unit and a cryogenic adsorption unit with activated charcoal bed was fabricated, and examinations were conducted to confirm automatic function of this system, enrichment conditions of krypton and xenon having natural isotopic compositions, and optimum measuring conditions of tbeir isotopic ratios by the magnet-type mass spectrometric technique. The results are as follows. (1)It was confirmed that this enrichment system which was scaled up to about ten times of basic test system was satisfactory in its automatic function and performance. (2)By this cryogenic adsorption method, it was found that Kr and Xe contained at the concentration rate of 0.1 ppb in feed gas could be enriched to 9800 and 34500 times, respectively. (3)It was found that the contents of Kr and Xe in commercial Ar gas were 0.2 1.310 ppb and 610 ppb, respectively. (4)To measure the isotopic ratios of Kr and Xe, on optimum condition of mass spectrometer was established. It was found that the precision was 2.5 % at isotopic content of 1 ppm.