Abstract The treatment of chemistry and thermodynamics in the integral severe accident codes is typically limited. A more accurate treatment of the chemistry during the severe accident modelling is, therefore, of great interest. For this purpose, the work is focused on the development of coupling of the MELCOR code with chemical thermodynamic calculations using GEMS codes and HERACLES database. Developed coupling between the two codes, called cGEMS, allowed for the improved thermodynamic description of the fission product release from the nuclear fuel under severe accident conditions. VERDON-1 test was selected as an experimental reference for the simulations. Experimental release behaviour of Mo, Cs and Ba observed in VERDON-1 experiment was reproduced by the developed coupled code. Performed simulations provided detailed information about the fission product speciation at different redox conditions. The obtained information and the developed code provides a more accurate description of the fission product behaviour and release during severe accidents.

中文翻译：

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使用 cGEMS 在 VERDON-1 实验中模拟裂变产物释放：严重事故代码 MELCOR 与 GEMS 热力学建模包的耦合

摘要 综合严重事故规范中化学和热力学的处理通常是有限的。因此，在严重事故建模期间对化学进行更准确的处理是非常有意义的。为此，工作重点是开发 MELCOR 代码与使用 GEMS 代码和 HERACLES 数据库的化学热力学计算的耦合。两个代码之间开发的耦合，称为 cGEMS，允许改进严重事故条件下核燃料裂变产物释放的热力学描述。VERDON-1 测试被选为模拟的实验参考。在 VERDON-1 实验中观察到的 Mo、Cs 和 Ba 的实验释放行为由开发的耦合代码重现。执行的模拟提供了有关不同氧化还原条件下裂变产物形态的详细信息。获得的信息和开发的代码可以更准确地描述严重事故中裂变产物的行为和释放。