Abstract Helical coil once-through steam generators (HCOTSGs) have been widely used in the design of small modular reactor (SMR) during the past several decades. As the widely accepted system analysis code, RELAP5 underestimates the heat transfer capability and pressure drop of helical coil tube steam generators using the original geometrical parameters of HCOTSG, because the built-in thermal-hydraulic empirical correlations are only suitable for straight tubes. In this study, thermal-hydraulic models for helical coil tubes and tube bundles are implemented in RELAP5 while the original functions of the code are not affected. A new flag for helical component is proposed and heat transfer boundaries for tube side and shell side are developed. The separate-effect validations of friction factor and heat transfer in helical coil tube are carried out based on experimental data and code-to-code verification. Then, the original RELAP5 and developed RELAP5-HCOTSG are used to simulate helical coil tube steam generators of two SMRs. One is the integral reactor IRIS, and the other is MRX. The calculated results are compared to the design parameters. It shows that the HCOTSG module developed in this study can improve the capability of RELAP5 to predict the thermal-hydraulic characteristics in SMR once-through steam generators with helical coil tubes.

中文翻译：

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螺旋盘管直流蒸汽发生器热工水力分析的代码改进、分离效应验证和基准计算

摘要 螺旋盘管直流蒸汽发生器（HCOTSGs）在过去的几十年中被广泛应用于小型模块化反应堆（SMR）的设计中。作为被广泛接受的系统分析代码，RELAP5 使用 HCOTSG 的原始几何参数低估了螺旋盘管蒸汽发生器的传热能力和压降，因为内置的热工水力经验关联仅适用于直管。在本研究中，螺旋盘管和管束的热工水力模型在 RELAP5 中实现，而代码的原始功能不受影响。提出了螺旋部件的新标志，并开发了管侧和壳侧的传热边界。基于实验数据和代码到代码验证，对螺旋盘管中的摩擦系数和传热进行了分离效应验证。然后，使用原始的 RELAP5 和开发的 RELAP5-HCOTSG 来模拟两个 SMR 的螺旋盘管蒸汽发生器。一个是积分反应器IRIS，另一个是MRX。将计算结果与设计参数进行比较。这表明本研究中开发的 HCOTSG 模块可以提高 RELAP5 预测具有螺旋盘管的 SMR 直流蒸汽发生器的热工水力特性的能力。将计算结果与设计参数进行比较。这表明本研究中开发的 HCOTSG 模块可以提高 RELAP5 预测具有螺旋盘管的 SMR 直流蒸汽发生器的热工水力特性的能力。将计算结果与设计参数进行比较。这表明本研究中开发的 HCOTSG 模块可以提高 RELAP5 预测具有螺旋盘管的 SMR 直流蒸汽发生器的热工水力特性的能力。