二次侧非能动余热排出系统设计及验证分析

提出了一种新型非能动余热排出系统(PRHRS)设计方案,该方案以高位水箱为最终热阱,采用在蒸汽发生器二次侧建立自然循环的方式间接地带走堆芯余热。以大亚湾核电站主冷却剂系统为载体,用RELAP5/MOD3.2程序分析了全厂断电事故下,PRHRS的运行特性。结果表明:事故发生后,余热排出系统内可较快地建立起循环流动,带走蒸汽发生器二次侧热量,在一段时间内保证反应堆安全,证明系统设计合理、有效。并分析了换热器布置高度、系统投入时间及换热面积对余热排出系统运行特性的影响。     

换料水箱初始水温对非能动余热排出系统运行特性影响试验研究

通过试验对不同内置换料水箱初始水温条件下非能动余热排出系统(PRHRS)投入后堆芯进出口温度、一回路压力、PRHRS自然循环流量和换热功率等试验数据进行了对比分析。试验结果表明:IRWST初始水温较低时,堆芯模拟体进出口水温和压力下降更快,PRHRS热交换器(HX)出口温度低,PRHRS自然循环流量变化趋势基本一致,但换热功率更高。     

全厂断电事故下模块化小堆非能动余热排出系统实验研究

针对模块化小堆非能动安全系统(PRHRS)的设计特点,建立了非能动安全系统综合实验装置CREST。在CREST实验装置上,进行了全厂断电事故短期性能实验,研究了PRHRS的冷却能力及运行特性。研究结果表明:全厂断电事故发生后,PRHRS能正常启动,非能动余热排出冷却器和蒸汽发生器之间能形成0.4 t/h稳定的两相自然循环流量,并有效地将堆芯衰变热量和显热带入安全壳水池(CWT)。堆芯补水箱(CMT)中的冷水可以有效注入反应堆压力容器冷却堆芯。在事故过程中,一回路系统最高压力为16.3 MPa,低于安全阀开启压力16.9 MPa,堆芯冷却剂平均温度可以冷却至210℃以下,反应堆处于安全运行状态。     

一种非能动余热排出系统设计方案

非能动余热排出系统依靠本身的自然循环特性,应能够在较长时间内提供对堆芯的冷却,保证反应堆的安全。提出一种非能动空气冷却余热排出系统(PRHRS)方案,利用应急冷却水箱作为中间缓冲设备,既可以满足事故初期快速冷却的要求,又能保证非能动余热排出系统在相当长一段时间内的可靠运行。基于自然循环系统特性对所设计的PRHRS系统进行设计计算,并使用RELAP5程序对全厂断电事故下反应堆停堆后PRHRS投入运行的过程进行仿真,以验证设计的合理性。反应堆热工水力动态特性的结果表明,该系统可通过自然循环排出堆芯余热,保证堆芯安全。     

二次侧非能动余热排出系统瞬态分析

以AP1000主冷却剂系统为原型,提出了一种二次侧非能动余热排出(PRHR)系统设计方案,并采用RELAP5/MOD3.2程序分析计算了全厂断电事故下该系统的瞬态响应过程,对其余热排出能力进行了评估。此外,根据计算结果分析了影响系统自然循环能力和密度锁内冷热界面稳定性的因素。分析结果表明,合理设计二次侧PRHR系统,可以保证依靠自然循环有效地导出堆芯余热;PRHR系统冷热源中心高度差和密度锁内局部阻力是影响系统工作能力的主要因素。     

小型堆二次侧非能动余热排出系统特性计算分析

为提高反应堆安全性,基于自然循环的非能动余热排出系统在小型反应堆中有着广泛的应用。本文基于已完成的小型一体化核动力装置中间回路换热实验,用RELAP5(Reactor Excursion and Leak Analysis Program)对中间回路自然循环运行特性开展了计算分析工作。研究发现,载热功率的程序计算结果与实验数据符合良好,可表征系统的自然循环特性。在余热排出系统中,系统回路的压力由蒸汽发生器（Steam Generator,SG）一次侧平均温度所决定,SG一次侧入口温度、质量流量与冷热源高度差对余热排出系统换热性能影响显著。当SG一次侧入口温度较高时,余热排出系统换热性能对系统回路阻力更加敏感,这些结果为进一步研究小型堆非能动系统提供了有价值的应用。     

一体化反应堆非能动余热排出系统中的两相自然循环与传热

在整体事故模拟试验（VISTA）装置上进行了一体化反应堆非能动余热排出系统（PRHRS）的热工水力和自然循环特性研究,将试验研究结果与最佳估算系统分析程序SMART的计算结果进行了比较。VISTA装置由一次系统、二次系统和PRHRS组成,模拟了设计验证程序SMART。试验结果表明：在PRHRS回路中的流体非常稳定。当热交换器淹没在应急冷却水箱（ECT）水中时,PRHRS热交换器能很好地完成其功能,排出来自一次冷却回路侧蒸汽发生器的热量。随着PRHRS的运行,衰变热和焓热从一回路充分地排出。SMART程序预测的在PRHRS中的自然循环特性相当好。从计算结果可以看出,PRHRS热交换器通过冷凝传热可以排出来自一次系统的大多数热量。     

AP1000给水丧失事故定性分析

针对AP1000核电站,基于两流体最佳估算系统程序RELAP5建立热工水力模型,基于Matlab/Simulink软件及工业组态软件建立相关控制系统数学模型,用于对正常给水丧失事故的计算分析。建模数据主要参考AP1000 Design Control Document(AP1000 DCD),由于建模数据不够充分、详尽,模型不够精确,文中事故分析以定性分析为主。计算结果表明：RELAP5具备计算自然循环的能力,计算结果与DCD中正常给水丧失事故结果总体趋势基本一致,非能动余热排出系统（PRHRS）、堆芯补水箱（CMT）系统能够及时、有效地排出堆芯余热和堆芯衰变热,确保堆芯安全。PRHRS余热排出能力对事故发展有明显影响,模型中PRHRS余热排出能力较强,使冷却剂温度更快地降低到较低水平,导致CMT更早投入以及随后反应堆各参数响应的不同。     

补水箱水装量对非能动余热排出系统运行的影响分析

为了补充非能动余热排出系统运行过程中蒸汽发生器二次侧流体的损失量,设置了补水箱。采用RELAP5程序进行建模分析,评估不同补水箱初始水装量对非能动余热排出系统运行造成的影响。结果表明,设置补水箱有利于建立蒸汽发生器内部长期的稳定运行状态;补水箱初始水装量越高,在补水阶段对非能动余热排出系统的换热能力抑制效应越明显,但补水结束后的长期阶段,由前期补水对非能动余热排出系统运行所造成的影响不大。     

非能动应急堆芯余热排出系统对核电厂失去厂外电源事故的影响

研究建立了蒸汽发生器二次侧非能动应急堆芯余热排出系统热工水力特性的物理与数学模型，并编制了计算机程序。以中国秦山核电站的数据为依据，计算和分析了在失去厂外电源事故典型工况下，该系统投入运行时对瞬态热工水力特性的影响。     

CPR1000二次侧非能动应急热阱设计与事故缓解能力分析

在主给水管道破裂事故下,利用RELAP5/MOD34程序对CPR1000压水堆一回路热工水力参数瞬态特性进行分析计算,验证采用空冷换热器的CPR1000二次侧非能动应急热阱对事故的缓解能力。计算结果表明：CPR1000在发生主给水管道破裂事故后,二次侧非能动应急热阱完全可及时向蒸汽发生器补水,同时导出堆芯余热,保证反应堆处于安全状态,从而验证了CPR1000二次侧非能动应急热阱的设计是成功的。     

Experiments on the Heat Transfer and Natural Circulation Characteristics of the Passive Residual Heat Removal System for an Advanced Integral Type Reactor

Experiments on the heat transfer characteristics and natural circulation performance of the passive residual heat removal system (PRHRS) for the SMART-P have been performed by using the high temperature/high pressure thermal-hydraulic test facility (VISTA). The VISTA facility consists of the primary loop, the secondary loop, the PRHRS loop, and the auxiliary systems to simulate the SMART-P, a pilot plant of the SMART. The primary loop is composed of the steam generator (SG) primary side, a simulated core, a main coolant pump, and the loop piping, and the PRHRS loop consists of the SG secondary side, a PRHRS heat exchanger, and the loop piping. The natural circulation performance of the PRHRS, the heat transfer characteristics of the PRHRS heat exchangers and the emergency cooldown tank (ECT), and the thermal-hydraulic behavior of the primary loop are intensively investigated. The experimental results show that the coolant flows steadily into the PRHRS loop and that the heat transfers through the PRHRS heat exchanger and the emergency cooldown tank are sufficient enough to enable a natural circulation of the coolant. The results also show that the core decay heat can be sufficiently removed from the primary loop with an operation of the PRHRS.     

Two phase natural circulation and the heat transfer in the passive residual heat removal system of an integral type reactor

An investigation of the thermal hydraulic characteristics and the natural circulation performance in the passive residual heat removal system (PRHRS) for an integral type reactor have been carried out using the VISTA facility and the calculated results using the MARS code, which is a best estimate system analysis code have been compared with the experimental results. The VISTA facility consists of the primary, secondary, and the PRHRS circuits, to simulate the SMART design verification program. The experimental results show that the fluid is well stabilized in the PRHRS loop and the PRHRS heat exchanger accomplishes well its functions in removing the transferred heat from the primary side in the steam generator as long as the heat exchanger is submerged in the water in the emergency cooldown tank (ECT). The decay heat and the sensible heat can be sufficiently removed from the primary loop with the operation of the PRHRS. The MARS code predicts reasonably well the characteristics of the natural circulation in the PRHRS. From the calculation results, most of the heat transferred from the primary system is removed at the PRHRS heat exchanger by a condensation heat transfer.     

主给水管道破口尺寸对CPR1000二次侧非能动应急热阱事故缓解能力影响研究

在主给水管道破裂事故下，针对不同破口面积，利用RELAP5/MOD3.4程序对CPR1000压水堆一回路和二次侧非能动应急热阱的主要热工水力参数瞬态特性进行分析计算，验证采用CPR1000二次侧非能动应急热阱对事故的缓解能力和不同破口面积对主要参数的影响。结果表明：CPR1000在发生主给水管道破裂事故后，二次侧非能动应急热阱可及时向蒸汽发生器补水，同时导出堆芯余热，保证反应堆处于安全状态，随着破口面积的增大，初始时刻一回路压力和温度升高更快，随着二次侧非能动应急热阱的投入，压力和温度又迅速降低，说明CPR1000二次侧非能动应急热阱在文中所研究的破口面积范围内可非常有效地缓解事故。     

非能动余热排出系统的稳态特性研究

以AP1000主冷却剂系统为原型,提出了1种二次侧非能动余热排出系统设计方案,并采用RELAP5/MOD3.2程序分析计算了该系统在主系统正常运行和运行瞬变工况下的稳态特性。结果表明,主系统带功率运行时,二次侧非能动余热排出系统可依靠回路工质的密度差和压力平衡使系统自动处于备用状态,不影响主系统的运行。此外,根据计算结果,分析了冷热源位差对系统稳态特性的影响。     

Experimental study on the natural circulation of a passive residual heat removal system for an integral reactor following a safety related event

Natural circulation characteristics of an integral type reactor during the operation of a passive residual heat removal system (PRHRS) following a safety related event has been experimentally investigated by using the VISTA facility. A PRHRS actuation trip signal is generated by a high power trip signal following a steam flow increasing event. The experimental results show that the single-phase coolant flows steadily in the primary loop by a natural convection process and that it effectively removes the decay heat from the core through a steam generator during the PRHRS operation. The heat transfers through the PRHRS heat exchanger and the emergency cooldown tank (ECT) are sufficient enough to enable a two-phase natural circulation of the coolant in the PRHRS loop.     

核电站非能动辅助给水系统仿真研究

以先进核电站AP1000为研究对象,在其蒸汽发生器二次侧设计了1套耗汽驱动汽动辅助给水泵的非能动辅助给水系统。使用RELAP5程序计算分析全厂断电事故下设计系统的运行特性,研究其应对事故工况的能力。计算结果表明：全厂断电事故下,设计的非能动辅助给水系统可有效地排出堆芯余热,保证反应堆的安全;由于冷却剂体积收缩,170 min时稳压器排空;该系统可连续运行200 min,排出事故后的大部分堆芯余热。非能动辅助给水系统可作为全厂断电事故后的应急缓解方案。     

Development of the analysis tool for the water cooling type passive residual heat removal system of Chinese pressurized reactor

An innovative design for Chinese pressurized reactor is the steam generator (SG) secondary side water cooling passive residual heat removal system (PRHRS). The new design is expected to improve reliability and safety of the Chinese pressurized reactor during the event of feed line break or station blackout (SBO) accident. The new system is comprised of a SG, a cooling water pool, a heat exchanger (HX), an emergency makeup tank (EMT) and corresponding valves and pipes. In order to evaluate the reliability of the water cooling PRHRS, an analysis tool was developed based on the drift flux mixture flow model. The preliminary validation of the analysis tool was made by comparing to the experimental data of ESPRIT facility. Calculation results under both high pressure condition and low pressure condition fitted the experimental data remarkably well. A hypothetical SBO accident was studied by taking the residual power table under SBO accident as the input condition of the analysis tool. The calculation results showed that the EMT could supply the water to the SG shell side successfully during SBO accident. The residual power could be taken away successfully by the two-phase natural circulation established in the water cooling PRHRS loop. Results indicate the analysis tool can be used to study the steady and transient operating characteristics of the water cooling PRHRS during some accidents of the Chinese pressurized reactor. The present work has very important realistic significance to the engineering design and assessment of the water cooling PRHRS for Chinese NPPs.     

CPR1000非能动应急给水系统瞬态特性分析

利用RELAP5/MOD3.4程序对CPR1000压水堆在全厂断电事故下一回路主要参数的瞬态热工水力特性进行分析，验证CPR1000非能动应急给水系统(PEFWS)对事故的缓解能力。计算结果表明，CPR1000在发生全厂断电事故后，PEFWS完全可及时向蒸汽发生器补水，同时导出堆芯余热，保证反应堆处于安全状态，从而验证CPR1000PEFWS的设计成功。