【摘要】 为了分析测量退役反应堆堆材料中的14C活度,需要克服材料中14C制样的难点,基于智能化自动控制原理,研制一套14C制样系统。系统主要由缓冲器、解析室、催化床、吸附床和吸收床等部件构成。将样品在高温下有氧的气氛中完全分解,并将生成的气体通过催化氧化成CO2,用乳化闪烁液的固体悬浮法在液闪谱仪上测量14C放射性活度。研究结果表明,该方法对14C的探测限为0.033 1 Bq·g-1(石墨)和0.021 8 Bq·g-1(混凝土),全程加标回收率大于70%;整套仪器稳定性良好,能实现对反应堆堆本体材料中低浓度石墨和混凝土样品的制备,准确给出材料中14C活度,为反应堆退役提供重要数据参考。更多还原

【Abstract】 Background: The sample preparation system of 14 C is necessary for measuring the radioactive contents of 14 C and 3H for the decommissioning of nuclear reactor. Previous works were concentrated on the glass container and heating furnace which is not suitable for automatic sample process and exists safety risk. Purpose: In order to resolve the difficulty in main materials of nuclear reactor samples preparation of 14 C, an intellectual preparation system of 14 C samples was designed and developed. Methods: The system is designed to consist of buffer, decomposition chamber, catalysis bed, adsorption bed and absorbing bed. Samples were decomposed at high temperature in oxygen whilst the generated gas was translated to CO2 by catalysis oxidation. The activity of 14 C was measured by liquid scintillation counter using suspension method. Results: The radiochemical recovery rate of 14 C was above 70%. The calculated detection limit for 14 C was 0.033 1 Bq·g-1 for graphite and 0.021 8 Bq·g-1 for concrete, respectively. Conclusion: This system was stable enough to be used for preparing graphite and concrete samples which contain low level or medium level radioactivity in nuclear reactor.更多还原