Abstract Passive safety systems are widely used in the advance reactors, such as AP1000 and CAP1400. As an important component in the passive safety system, the core makeup tank (CMT) plays a key role for the safety injection and the core decay heat removal. Since the CMT not only provides the full-pressure injection but also triggers the auto depressurization system by its level signal during small-break loss of coolant accident (SBLOCA), the CMT thermal hydraulic behaviors affect the SBLOCA transient process. The thermal hydraulic behaviors of the CMT were investigated by conducting different SBLOCA tests on the ACME integral effect test facility, which includes the 2.5 cm, 5 cm and 20 cm breaks, and double ended direct vessel injection (DVI) line break. Based on the test observations, the CMT injection response to SBLOCA was divided into four phases: the circulation, the drain transition, the injection inhabitation and the final drain. The CMT injection characteristics and the dominate factors were scrutinized based on the phase division. It was found that the break condition has significant impacts on the CMT operating characteristics in each phase. The CMT circulation flow rate can be predicted, and the break size determines the circulation phase length. The CMT drain transition process is controlled by the PBL voiding process that has a close relation to the liquid level change in the cold leg. The ACC-CMT interaction was modeled, and the prediction result agreed with the test result. The comparison tests showed that the ACC nitrogen gas injection still affected the CMT drain behavior. A similar thermal stratification pattern formed during the different SBLCOA tests, and the thermal stratification remained not only in the CMT internal fluid but also in the CMT wall. The estimation of the flashing amount showed it did not play a significant role for the CMT liquid level decline, but it could induce the increases in the pressure difference between the CMT and the system and thus accelerate the CMT drain rate. The CMT internal fluid temperature determined the wall temperature, and a reverse heat transfer process occurred due to the flashing induced wall cooling during the ADS depressurization.

中文翻译：

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ACME 积分效应试验期间岩心补给罐的行为研究

摘要 AP1000、CAP1400等先进反应堆广泛采用无源安全系统。作为被动安全系统的重要组成部分，堆芯补充罐（CMT）在安全注入和堆芯衰变热排出中起着关键作用。由于 CMT 不仅提供全压喷射，而且在冷却剂小损事故 (SBLOCA) 期间通过其液位信号触发自动减压系统，因此 CMT 热工水力行为会影响 SBLOCA 瞬态过程。通过在 ACME 整体效应测试设备上进行不同的 SBLOCA 测试来研究 CMT 的热水力行为，其中包括 2.5 cm、5 cm 和 20 cm 断裂以及双端直接容器注入 (DVI) 线断裂。根据试验观察，CMT 对 SBLOCA 的注入响应分为四个阶段：循环、引流过渡、注入驻留和最终引流。CMT 注入特性和主导因素基于相划分进行了仔细检查。结果表明，断路条件对每个阶段的 CMT 操作特性都有显着影响。CMT循环流量可预测，断点大小决定循环相长。CMT 排液过渡过程受 PBL 排空过程控制，该过程与冷段液位变化密切相关。ACC-CMT 相互作用被建模，预测结果与测试结果一致。对比试验表明，ACC 氮气注入仍然影响 CMT 排放行为。在不同的 SBLCOA 测试过程中形成了类似的热分层模式，热分层不仅存在于 CMT 内部流体中，而且存在于 CMT 壁中。闪蒸量的估计表明它对CMT液位下降没有起到显着的作用，但它可以引起CMT与系统之间的压差增加，从而加速CMT的排放速度。CMT 内部流体温度决定了壁温，由于 ADS 降压期间闪蒸引起的壁冷却，发生了反向传热过程。闪蒸量的估计表明它对CMT液位下降没有起到显着的作用，但它可以引起CMT与系统之间的压差增加，从而加速CMT的排放速度。CMT 内部流体温度决定了壁温，由于 ADS 降压期间闪蒸引起的壁冷却，发生了反向传热过程。闪蒸量的估计表明它对CMT液位下降没有起到显着的作用，但它可以引起CMT与系统之间的压差增加，从而加速CMT的排放速度。CMT 内部流体温度决定了壁温，由于 ADS 降压期间闪蒸引起的壁冷却，发生了反向传热过程。