ACME台架非能动水箱热工水力现象研究

Study on Thermal Hydraulic Phenomena in Passive Tank of ACME Facility

针对非能动水箱在超设计基准事故(BDBA)下的安全性能,基于先进堆芯冷却机理试验(ACME)台架开展了非能动余热排出系统(PRHR)热交换器(HX)入口管线破口失水试验,本文结合试验结果分析了堆芯补水箱(CMT)、安全壳内置换料水箱(IRWST)等非能动水箱在失水事故(LOCA)中的作用及其关键参数变化特点,研究了非能动水箱内的主要热工水力现象。结果表明,ACME台架PRHR HX入口管线破口失水试验再现了非能动核电厂小破口失水事故(SBLOCA)中自然循环、自动卸压喷放和IRWST安注等阶段的瞬态过程,CMT、安注箱(ACC)和IRWST等非能动水箱按照预期响应并投运;事故期间CMT内会出现明显的冷热水置换与分层过程,随着重力排水和蒸汽冷凝过程,CMT壁面温度先升高后降低,其内壁面温度变化最为剧烈;PRHR管线破口时,自动卸压阶段喷放出的蒸汽及其冷凝效应是影响IRWST水温的主要因素,沿水平方向水箱内温度差异不显著,沿竖直方向存在明显的冷热分层。

Aiming at the safety performance of the passive water tank in case of beyond design basis accident(BDBA),the loss of coolant accident(LOCA)integral effect tests,in which the break is located at the bottom of the horizontal pipe connected to the inlet of passive residual heat removal heat exchanger(PRHR HX),were conducted at the Advanced Core-cooling Mechanism Experiment(ACME)facility.The function of PWTs,including Core Makeup Tank(CMT)and In-containment Refueling Water Storage Tank(IRWST),and the variation of key parameters during LOCA accident were analyzed in combination with experimental data.The main thermal hydraulic phenomena in PWTs were also investigated.The results show that the transient process of natural circulation phase,automatic depressurization system(ADS)blow-down phase and IRWST injection phase in small break LOCA of passive nuclear power plant are presented in PRHR HX inlet line break(PRHR ILB)test on ACME.The passive tank,namely CMT,accumulator(ACC)and IRWST,responses and operates as expected.The significant replacement and stratification between hot and cold water occur within CMT during the accident.The CMT wall temperature increases at first and then decreases with gravity drain and steam condensation process,in which the inner wall temperature changes dramatically.The water temperature variation of IRWST are mainly determined by the condensation effects of steam sprayed via ADS.The temperature distribution along the horizontal direction shows little difference,while along the vertical direction it shows obvious thermal stratifications.