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压水堆核电厂发生严重事故期间,从主系统释放的蒸汽、氢气以及下封头失效后进入安全壳的堆芯熔融物均对安全壳的完整性构成威胁。以国内典型二代加压水堆为研究对象,采用MAAP程序进行安全壳响应分析。选取了两种典型的严重事故序列:热管段中破口叠加设备冷却水失效和再循环高压安注失效,堆芯因冷却不足升温熔化导致压力容器失效,熔融物与混凝土发生反应(MCCI),安全壳超压失效;冷管段大破口叠加再循环失效,安全壳内蒸汽不断聚集,发生超压失效。通过对两种事故工况的分析,证实了再循环高压安注、安全壳喷淋这两种缓解措施对保证安全壳完整性的重要作用。 相似文献
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为研究先进非能动(AP)型核电厂在非能动系统失效条件下的安全性能,利用我国先进堆芯冷却机理整体试验台架(ACME)开展了非能动余热排出(PRHR)管线破口失水试验研究,分析了主要的试验进程和破口位置对事故过程各阶段关键参数的影响。结果表明,ACME PRHR管线破口试验进程与冷管段小破口失水事故(SBLOCA)进程基本一致,再现了非能动核电厂自然循环阶段、自动卸压系统(ADS)喷放阶段和安全壳内置换料水箱(IRWST)安注阶段的安全特性;在不同破口位置的试验中,非能动堆芯冷却系统(PXS)均可保证堆芯得到补水,堆芯活性区始终处于混合液位以下;破口位置对ACME LOCA事故进程、反应堆冷却剂系统(RCS)初期降压速率、PRHR热交换器(HX)流量、喷放流量、堆芯液位、IRWST安注流量等参数具有显著影响,对堆芯补水箱(CMT)和蓄压安注箱(ACC)安注流量的影响较小。 相似文献
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CPR1000核电站严重事故重要缓解措施与严重事故序列 总被引:2,自引:0,他引:2
CPR1000核电站采用非能动氢气复合器、稳压器卸压功能延伸以及安全壳卸压过滤排放系统作为严重事故的预防和缓解措施,保证在严重事故条件下核电站安全壳的完整性不受损坏,保护环境周围的居民不受核辐射的危害。通过相关严重事故谱分析,选取冷却剂管道热段双段断裂+失去应急堆芯冷却系统、全厂断电、主蒸汽管道断裂+失去喷淋、失水未能紧急停堆的预计瞬态(ATWS)这4种严重事故作为CPR1000核电站的重要严重事故序列,包络了所有安全壳内氢气产生速度快浓度高、安全壳超压、冷却剂系统发生高压熔堆、反应堆不能停堆等最严重的事故。 相似文献
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非能动堆芯冷却系统LOCA下冷却能力分析 总被引:1,自引:0,他引:1
本文基于机理性分析程序建立了包括反应堆一回路冷却剂系统、专设安全设施及相关二次侧管道系统的先进压水堆分析模型,对典型的小破口失水事故和大破口失水事故开展了全面分析。针对不同破口尺寸、破口位置的失水事故,分析了非能动堆芯冷却系统(PXS)中非能动余热排出系统(PRHRS)、堆芯补水箱(CMT)、安注箱(ACC)、自动卸压系统(ADS)和安全壳内置换料水箱(IRWST)等关键系统的堆芯注水能力和冷却效果。研究表明,虽然破口尺寸、破口位置会影响事故进程发展,但所有事故过程中燃料包壳表面峰值温度不超过1 477 K,且反应堆堆芯处于有效淹没状态。PXS能有效排出堆芯衰变热,将反应堆引导到安全停堆状态,防止事故向严重事故发展。 相似文献
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采用RELAP5/MOD3.2系统程序建立一体化小型反应堆的事故分析模型,包括反应堆冷却剂系统(RCS)、简化的二回路系统和专设安全设施。一体化多用途的非能动小型压水反应堆(SIMPLE)热功率为660 MWt(电功率大于200 MWe)。针对SIMPLE的直接安注管线(DVI)双端断裂事故和DVI2英寸(50.8mm)小破口失水事故(SBLOCA)进行分析。计算结果表明:对于直接安注管线双端断裂事故,破口和自动降压系统(ADS)能有效地使反应堆冷却系统降压,安注箱(ACC)和安全壳内置换料水箱(IRWST)能实现堆芯补水,确保堆芯冷却;对于DVI的SBLOCA,非能动专设安全设施能有效对RCS进行冷却和降压,防止堆芯过热。 相似文献
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AP1000小破口叠加重力注射失效严重事故分析 总被引:1,自引:1,他引:0
应用新版MELCOR程序,建立了AP1000一二回路、非能动安全系统及安全壳隔室的热工水力模型,并以热段小破口叠加重力注射系统失效事故为例,对该严重事故进程在压力容器内阶段进行模拟计算,对缓解措施的功能进行了分析和评价。结果表明:自动卸压系统(ADS1~4)的成功实施,可使来自堆芯补水箱和安注箱的冷却水快速有效地注入堆芯,在冷却水完全耗尽前,堆芯始终处于淹没的状态。ADS4爆破阀开启后,使回路压力快速与安全壳压力平衡;非能动安全壳冷却系统对抵御严重事故下由于衰变热和非冷凝气体带来的缓慢升温升压是行之有效的措施;点火器在氢气浓度较低时点火,缓解了安全壳大空间发生全局燃爆而引发安全壳超压失效的风险,但连续点火燃烧会引起局部隔室温升远超出设计温度而危及后备缓解设施的存活。 相似文献
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Rae-Joon Sang-Baik Kim Seong-Wan Hong Hee-Dong Kim 《Nuclear Engineering and Design》2009,239(11):2484-2490
A coolant injection into the reactor vessel with depressurization of the reactor coolant system (RCS) has been evaluated as part of the evaluation for a strategy of the severe accident management guidance (SAMG). Two high pressure sequences of a small break loss of coolant accident (LOCA) without safety injection (SI) and a total loss of feedwater (LOFW) accident in Optimized Power Reactor (OPR)1000 have been analyzed by using the SCDAP/RELAP5 computer code. The SCDAP/RELAP5 results have shown that only one train operation of a high pressure safety injection at 30,000 s with indirect RCS depressurization by using one condenser dump valve (CDV) at 6 min after implementation of the SAMG prevents reactor vessel failure for the small break LOCA without SI. In this case, only one train operation of the low pressure safety injection (LPSI) without the high pressure safety injection (HPSI) does not prevent reactor vessel failure. Only one train operation of the HPSI at 20,208 s with direct RCS depressurization by using two SDS valves at 40 min after an initial opening of the safety relief valve (SRV) prevents reactor vessel failure for the total LOFW. 相似文献
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M. Taube M. Lanfranchi Th. von Weissenfluh J. Ligou G. Yadigaroglu P. Taube 《Annals of Nuclear Energy》1986,13(12):641-648
A philosophy of inherent safety is formulated and an inherently-safe thermal power reactor is presented. Solid fuel in the form of spheres a few centimetres in diameter is suspended under the hydrodynamic pressure of molten lead coolant in vertical channels within the graphite moderator. Loss of main pump pressure, or a loss-of-coolant accident (LOCA), results in immediate removal of the fuel to rigid sieves below the core, with consequent subcriticality. Residual and decay heat are carried away by thermal conduction through the coolant or, in the case of a LOCA, by a combination of radiation and natural convection of cover gas or incoming air from the fuel to the reactor vessel and convection of air between the vessel and steel containment wall. All decay heat removal systems are passive, though actively initiated external spray cooling of the containment can be used to reduce wall temperature. This, however, is only necessary in the case of a LOCA and after a period of 24 h. 相似文献
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本文采用不可压缩流体均匀流模型对华龙一号(HPR1000)的非能动安全壳冷却系统(PCS)进行数值模拟,在反应堆冷却剂系统(RCS)大破口丧失冷却剂事故(LOCA)工况下对PCS进行热工水力分析,并对PCS设计工况进行性能分析计算。结果表明:PCS的非能动运行特性与事故进程具有很好的匹配能力,能在事故早期极快启动,并在24 h内将安全壳的温度和压力稳定在安全范围内。通过PCS设计工况的换热性能分析,PCS在运行5 h后进入两相流传热阶段,当换热水箱介质达到饱和温度后仍能长期稳定运行,导出安全壳内热量。 相似文献
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基于多物理场耦合框架MOOSE,采用五方程两相流模型开发了模块化程序ZEBRA,实现了高阶时间、空间离散格式两相流动传热问题的求解。采用Bartolomei开展的垂直圆管过冷沸腾实验对ZEBRA进行验证,在不同热流密度、质量流密度、压力工况下,将程序计算值与实验值进行了数值验证和计算分析。结果表明:ZEBRA中五方程模型预测值与实验值符合良好,沸腾起始点和空泡份额的预测合理,表明ZEBRA初步具备了处理两相流问题的能力。 相似文献
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Containment depressurization has been implemented for many nuclear power plants (NPPs) to mitigate the risk of containment overpressurization induced by steam and gases released in LOCA accidents or generated in molten core concrete interaction (MCCI) during severe accidents. Two accident sequences of large break loss of coolant accident (LB-LOCA) and station blackout (SBO) are selected to evaluate the effectiveness of the containment venting strategy for a Chinese 1000 MWe NPP, including the containment pressure behaviors, which are analyzed with the integral safety analyses code for the selected sequences. Different open/close pressures for the venting system are also investigated to evaluate CsI mass fraction released to the environment for different cases with filtered venting or without filtered venting. The analytical results show that when the containment sprays can't be initiated, the depressurization strategy by using the Containment Filtered Venting System (CFVS) can prevent the containment failure and reduce the amount of CsI released to the environment, and if CFVS is closed at higher pressure, the operation interval is smaller and the radioactive released to the environment is less, and if CFVS open pressure is increased, the radioactive released to the environment can be delayed. Considering the risk of high pressure core melt sequence, RCS depressurization makes the CFVS to be initiated 7 h earlier than the base case to initiate the containment venting due to more coolant flowing into the containment. 相似文献