Abstract Similar to commercial nuclear reactors, research reactors are recommended to be designed with sufficient safety margins for thermalhydraulic issues such as critical heat flux (CHF) in both normal and accident conditions. In the MARS-KS system code, developed based on RELAP5, the 2006 Groeneveld CHF look-up table (Groeneveld et al., 2007) is adopted to predict CHF for plate-type fuel. The applicability of this table to CHF in rectangular channels for high pressure conditions of over 40 bar has been confirmed (Choi et al., 2015); however, its applicability to pressure conditions under 40 bar has yet to be clarified. While Sudo and Kaminaga previously suggested a rectangular CHF model for a wide experimental range, some notifications have indicated the inclusion of flow excursion data in their model. In this paper, a rectangular channel CHF database was constructed for wide experimental ranges and used to assess the 2006 Groeneveld CHF look-up table and Sudo-Kaminaga correlation to confirm their applicability to rectangular channels under low pressure. Then, with several parameters selected by the Random Forest method in the R package (Reynolds number, quality, aspect ratio, diameter ratio, and length over diameter), a new correction factor was suggested by applying a non-linear regression method from a statistical software package to correct the CHF values in the CHF look-up table for rectangular channels. Results confirmed that the CHF LUT with the newly suggested correction factor is capable to predict CHF in rectangular channels.

中文翻译：

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低压下矩形通道的 2006 Groeneveld CHF 查找表的校正因子开发

摘要 与商用核反应堆类似，建议研究堆在设计时应为热工水力问题（例如正常和事故工况下的临界热通量 (CHF)）提供足够的安全裕度。在基于 RELAP5 开发的 MARS-KS 系统代码中，采用 2006 Groeneveld CHF 查找表（Groeneveld 等，2007）来预测板式燃料的 CHF。该表适用于 40 bar 以上高压条件下矩形通道中的 CHF（Choi 等，2015）；然而，它对 40 bar 以下压力条件的适用性还有待澄清。虽然 Sudo 和 Kaminaga 之前建议了一个用于广泛实验范围的矩形 CHF 模型，但一些通知表明他们的模型中包含了流动偏移数据。在本文中，为广泛的实验范围构建了矩形通道 CHF 数据库，用于评估 2006 Groeneveld CHF 查找表和 Sudo-Kaminaga 相关性，以确认它们在低压下对矩形通道的适用性。然后，通过 R 包中的随机森林方法选择的几个参数（雷诺数、质量、纵横比、直径比和长度对直径），通过应用统计数据的非线性回归方法建议了一个新的校正因子。用于校正矩形通道 CHF 查找表中的 CHF 值的软件包。结果证实，具有新建议的校正因子的 CHF LUT 能够预测矩形通道中的 CHF。