科研之友
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摘要
Long term in situ diffusion experiments in the Callovian-Oxfordian mudstone (France) are designed in the context of nuclear waste management. beta-emitters HTO and Cl-36 radiotracers are representative of neutral and anionic species in these experiments. Studies have been carried out to design an in situ beta monitoring system in order to quantify tracer migration in the rock pore water over time. The development, design and calibration of beta-emitter radiation sensors were performed. An optimised geometry was calculated for the detection chamber of Cl-36 in solution (empty set x L= 30 x 2 mm(2)) via Monte-Carlo N-Particle transport simulation tools. A better SNR (Signal to Noise Ratio) was obtained with YSO cylindrical crystal (0 x L= 6.5 x 0.5 mm2). A sensitivity of 0.21 cpm/Bq/mL was measured using Cl-36 standards. The Cl-36 detection limits were 18 Bq/mL and 14.2 Bq/mL after 1 h and 24 h of accumulation time respectively. Such beta sensors, placed 350 mm from the radiotracer injection borehole, could successfully discriminate Cl-36 anisotropic diffusion in various directions within 4 years. It will be tested in situ and can be adapted to other in situ experience.
- 出版日期2017-7
- 单位中国地震局
