Abstract The Egyptian Second Research Reactor (ETRR-2) is a pool-type reactor, 22 MW thermal, with 27 fuel elements loaded with 60Co production facility in the most relative highest flux position for the production of 200 Ci/g specific activity. The production of this specific activity needs a very long irradiation time and continuity of operation to produce useful quantities of 60Co over a reasonable period, which means that the reactor would have to operate 24 h a day, for 5 to 7 days a week. This requirement for the production of cobalt with the required specific activity is difficult to meet in ETRR-2, so this position needs to be reused for the production of other radioisotopes that require shorter irradiation times compared to cobalt. Iridium-192 is the most important radioactive isotope of iridium; it can be used in the production of “sealed sources” for industrial or medical applications. In this study, we did a full neutronic analysis of the ETRR-2 reactor core with iridium and with cobalt and compared both cases. We used two different models: a model using the MCNP code (Monte Carlo Neutron Photon), and another model using the WIMS/CITVAP code (a deterministic code). The models were validated with the results of the experiments done during the commissioning of the radioisotope production facility. We concluded that 500 g of iridium could be used instead of 577 g of cobalt in the core, and 24 molybdenum production plates would fulfil the fixed experiment design criteria, which is lower than 1200 pcm. The average axial/radial flux inside the tube was lower when using iridium disks than when using cobalt pellets because of the difference between the neutron absorption cross sections of 191Ir, 193Ir, and 59Co. When comparing the average radial flux inside the irradiation position near the edge of the iridium pellets inside the tube, we found that the flux would be higher for iridium than cobalt because of the empty part of the tube. We also calculated the power peaking factor over the whole core and found it was 2.12, which fulfilled the design criteria (must be less than 3).

中文翻译：

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用 ETRR-2 的铱放射性同位素设施替代钴放射性同位素设施的中子分析

摘要 埃及第二研究堆（ETRR-2）是一座池式反应堆，22 MW 热反应堆，装有 27 个燃料元件，装有 60Co 生产设施，位于最高通量位置，可生产 200 Ci/g 比活度。这种特定活动的生产需要很长的辐照时间和连续运行才能在合理的时间内生产有用数量的 60Co，这意味着反应堆必须每天运行 24 公顷，每周运行 5 到 7 天。ETRR-2 很难满足生产具有所需比活度的钴的这一要求，因此该位置需要重新用于生产与钴相比需要更短辐照时间的其他放射性同位素。铱192是铱最重要的放射性同位素；它可用于生产工业或医疗应用的“密封源”。在这项研究中，我们用铱和钴对 ETRR-2 反应堆堆芯进行了完整的中子分析，并比较了两种情况。我们使用了两种不同的模型：一个使用 MCNP 代码（蒙特卡洛中子光子）的模型，另一个使用 WIMS/CITVAP 代码（确定性代码）的模型。这些模型通过放射性同位素生产设施调试期间所做的实验结果进行了验证。我们得出结论，可以使用 500 克铱代替 577 克钴在芯中，24 块钼生产板将满足低于 1200 pcm 的固定实验设计标准。由于 191Ir、193Ir 和 59Co 的中子吸收截面不同，使用铱圆盘时管内的平均轴向/径向通量低于使用钴丸粒时。当比较管内铱颗粒边缘附近辐照位置内的平均径向通量时，我们发现铱的通量高于钴，因为管的空部分。我们还计算了整个内核的功率峰值因子，发现它是 2.12，符合设计标准（必须小于 3）。我们发现，由于管子的空部分，铱的通量会高于钴。我们还计算了整个内核的功率峰值因子，发现它是 2.12，符合设计标准（必须小于 3）。我们发现，由于管子的空部分，铱的通量会高于钴。我们还计算了整个内核的功率峰值因子，发现它是 2.12，符合设计标准（必须小于 3）。