Abstract Interest on development of computational tools for calculations of radiation field due to decay of radioactive activation and fission products (delayed radiation) has increased in recent years, mainly due to requirements on shutdown dose rate for the future ITER fusion reactor and material testing reactors (MTR), where gamma heating values of several 10 Wg − 1 can be reached in reactor structural components during reactor steady state operation and for characterization of research reactor irradiation facilities. Previous experimental work shows a roughly 30% contribution of delayed gamma rays to the total gamma ray flux. An extensive experimental campaign at the JSI TRIGA reactor has been carried out using multiple ionization and fission chamber detectors for gamma and neutron field characterization. A series of reactor power steps was performed with said detectors in different irradiation positions during steady reactor power and after shutdown. The reactor and the used detectors, along with irradiation power steps have been modelled in detail using the JSIR2S code system framework to compare measured and calculated fluxes and dose rates. Simulated results are in good agreement with measurements and with experimentally obtained values of delayed gamma fractions from previous work.

中文翻译：

---

用于延迟辐射模拟的 JSIR2S 代码：根据 JSI TRIGA 反应堆的测量值进行验证

摘要 近年来，由于放射性活化和裂变产物（延迟辐射）衰变引起的辐射场计算工具的开发兴趣增加，主要是由于未来 ITER 聚变反应堆和材料测试反应堆对停堆剂量率的要求。 MTR)，其中在反应堆稳态运行期间和用于表征研究堆辐照设施的反应堆结构部件中可以达到几个 10 Wg - 1 的伽马热值。先前的实验工作表明，延迟伽马射线对总伽马射线通量的贡献大约为 30%。在 JSI TRIGA 反应堆中进行了广泛的实验活动，使用多个电离和裂变室探测器进行伽马和中子场表征。在稳定的反应堆功率期间和停堆之后，利用处于不同辐照位置的所述探测器执行一系列反应堆功率步骤。使用 JSIR2S 代码系统框架对反应堆和使用的探测器以及辐照功率步骤进行了详细建模，以比较测量和计算的通量和剂量率。模拟结果与测量结果以及从先前工作中通过实验获得的延迟伽马分数的值非常一致。