基于ORIGEN程序的后处理尾气氙同位素关联乏燃料燃耗技术

    Reprocessing Exhaust Gas Xenon Isotope Correlation Spent Fuel Burn-Up Based on ORIGEN Code

    • 摘要: 同位素关联乏燃料燃耗技术在核保障监督、乏燃料后处理监测中具有重要意义。针对后处理活动剪切和溶解过程中乏燃料燃耗的检测需求,开展了稳定氙同位素关联燃耗技术研究,以101重水研究堆和大亚湾压水堆乏燃料作为研究对象,通过ORIGEN2程序开展了乏燃料燃耗及裂变产物理论计算,基于核保障监督核查场景,建立了裂变产物稳定氙同位素与乏燃料燃耗关联模型,分别得到了101重水研究堆和大亚湾压水堆乏燃料燃耗与131Xe /134Xe、132Xe /134Xe同位素比的线性拟合关系式,通过实际乏燃料后处理过程中的剪切和溶解尾气氙取样、气体质谱仪测量得到的氙同位素比数据,推算101重水研究堆和大亚湾压水堆乏燃料燃耗,结果表明:132Xe /134Xe同位素比线性拟合得到的燃耗值与其参考值相比,相对偏差均在6%以内,验证了关联模型的有效性和实用性。

       

      Abstract: Environmental sampling analysis technology is one of the safeguards measures used by International Atomic Energy Agency to detect undeclared nuclear materials and nuclear activities. Noble gas isotope correlations technique is of great significance in nuclear safeguards supervision and monitoring of large-scale reprocessing facilities, which is far from the reprocessing process and less invasive. This study focuses on the measurement needs of spent fuel burn-up during the chopping and dissolution processes of the spent fuel, and conducted research on stable xenon isotope correlation spent fuel burn-up technique. The spent fuel of 101 Heavy Water Research Reactors and Daya Bay Pressurized Water Reactors was taken as the research object. Physical calculations of burn-up and quantity of fission products were carried out through ORIGEN2 code. Based on the nuclear safeguards supervision and verification scenario, a stable xenon isotope correlation model for quantity of fission products and spent fuel burn-up is established, and linear fitting relationships between spent fuel burn-up in 101 Heavy Water Research Reactors and Daya Bay Pressurized Water Reactors and 131Xe/134Xe, 132Xe/134Xe isotopes ratio are obtained. The xenon were obtained by xenon sampling from stack gases during chopping and dissolution of spent fuel through low temperature activated carbon sampling method, and the measurement of xenon isotope ratio by high resolution gas mass spectrometer measurement in the actual reprocessing process are used to calculate the burn-up. The results of 101 Heavy Water Research Reactors and Daya Bay Pressurized Water Reactors both show that the relative deviation between the spent fuel burn-up value which inferred by linear fitting based on 132Xe/134Xe isotope ratio and the burn-up reference value is within 6% relatively, which verifies the effectiveness and practicality of the correlation model. Prospects were given for the practical application of this technology in nuclear safeguards verification and detecting.

       

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