Critical flow has significant impact on the reactor safety. Critical flow models are considered as an important module in all system thermal–hydraulic (STH) codes, with several optional models. But each model has its own scope of application. Consequently, the STH simulation results largely dependent on the model choice, i.e. on the user effect. A full-range critical flow model may be used to deal with this issue. The aim of this work was to develop a full-range 6-equation critical flow model with higher accuracy and plug it into ATHLET. The model was validated in Henry tests. The results show that the new model could predict mostly within the error band ±20%, better than other models of ATHLET. To verify the ability of ATHLET with the new model, it was applied to several Marviken full scale critical flow tests in transient, showing better (or at least comparable) results than before.

临界流量对反应堆安全有重大影响。临界流量模型被认为是所有系统热工（STH）规范中的重要模块，并具有多个可选模型。但是每种模型都有其自己的应用范围。因此，STH仿真结果很大程度上取决于模型选择，即取决于用户效果。可以使用全范围的临界流量模型来处理此问题。这项工作的目的是开发一种具有更高精确度的全范围6方程临界流模型，并将其插入ATHLET。该模型在亨利测试中得到了验证。结果表明，新模型的预测范围主要在±20％的误差范围内，优于其他ATHLET模型。为了验证ATHLET在新模型中的功能，该模型已应用于多个Marviken瞬态全尺寸关键流量测试中，