This study presents the time-dependent analyses of transmutations of long-lived fission products (LLFPs) and medium-lived fission products (MLFPs) occurring in thermal reactors in a conceptual helium gas-cooled accelerator-driven system (ADS). In accordance with this purpose, the CANDU-37 and PWR 15 × 15 spent fuels are separately considered. The ADS consists of LBE-spallation neutron target, subcritical fuel zone, and graphite reflector zone. While the considered ADS is fueled with the spent nuclear fuels extracted from each thermal reactor without the use of additional fuel, fission products extracted from same thermal reactor are also placed into transmutation zone in graphite reflector zone. The LLFP transmutation performance of the modified ADS is analyzed by considering three different spent fuels extracted from the thermal reactors. Spent fuels are extracted from CANDU-37 in case A, from PWR-15 × 15 in case B, and from CANDU-37 fueled with mixture of PWR 15 × 15 spent fuel and 46% ThO₂ in case C. The LBE target is bombard with protons of 1000 MeV. The proton beam power is assumed as 20 MW, which corresponds to 1.24828·10¹⁷ protons per second. MCNPX 2.7 and CINDER 90 computer codes are used for the time-dependent burn calculations. The ADS is operated under subcritical mode until the value of k_eff increases to 0.984, and the maximum operation times are obtained as 3400, 3270, and 5040 days according to the spent fuel cases of A, B, and C, respectively. The calculations bring out that in the modified ADS, LLFPs and MLFPs, which are extracted from thermal reactors, can be transformed to stable isotopes in significant amounts along with energy production.

中文翻译：

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加速器驱动系统中从CANDU和PWR乏燃料中提取的长寿命和中寿命裂变产物的变

这项研究提出了在概念性氦气冷却加速器驱动系统（ADS）的热反应堆中发生的长寿命裂变产物（LLFP）和中寿命裂变产物（MLFP）的trans变的时变分析。根据此目的，分别考虑了CANDU-37和PWR 15×15乏燃料。ADS由LBE散射中子靶，亚临界燃料区和石墨反射器区组成。虽然考虑的ADS将从每个热反应堆中提取的乏核燃料用作燃料，而无需使用额外的燃料，但从同一热反应堆中提取的裂变产物也被置于石墨反射器区的trans变区中。通过考虑从热反应堆中提取的三种不同的乏燃料来分析改性ADS的LLFP转化性能。₂在壳体C的LBE靶轰击用1000兆电子伏的质子。质子束功率假定为20 MW，相当于每秒1.24828·10 ^17个质子。MCNPX 2.7和CINDER 90计算机代码用于与时间有关的燃烧计算。ADS在亚临界模式下运行，直到k _eff值增加到0.984，并且根据A，B和C的乏燃料情况，最大运行时间分别为3400、3270和5040天。计算结果表明，在改进的ADS中，从热反应堆中提取的LLFP和MLFP可以大量转化为稳定的同位素，同时还能产生能量。