Determination of Cl in biological shield concrete using pyrohydrolysis and liquid scintillation counting

Ito, Mitsuo; Watanabe, Kazuo; Hatakeyama, Mutsuo; Tachibana, Mitsuo

A method for the determination of Cl-36 in biological shield concrete of nuclear reactor was developed. Cl in the concrete sample was extracted quantitatively by pyrohydrolysis at 900 ºC and recovered in Na2CO3 solution for subsequent measurement of Cl-36 by liquid scintillation counting. WO3 was used as an accelerator in the pyrohydrolysis. The Cl extraction procedure was optimized by investigating experimental conditions with the use of ion chromatography and its recovery was evaluated by the analysis of the geochemical reference samples. Detection limit of Cl-36 was 0.02 Bq g-1 for sample weight of 2g. Relative standard deviation was 3 – 7 % for the samples containing 0.5 Bq g-1 levels of 36Cl. The newly developed method was applied to determine Cl-36 in biological shield concrete of the Japan Power Demonstration Reactor.