重水堆核电厂典型严重事故氢气风险分析  

Analysis on Hydrogen Risk of Typical Severe Accident for the Pressurized Heavy Water Reactor

作　　者：宫海光 郭丁情[1] 佟立丽[1] 曹学武[1] 

机构地区：[1]上海交通大学机械与动力工程学院,上海200240

出　　处：《核科学与工程》2015年第3期525-531,共7页Nuclear Science and Engineering

基　　金：国家自然科学基金项目资助(11205099)

摘　　要：核电厂严重事故下的氢气控制一直是核电厂关注的热点问题之一。本文采用重水堆一体化事故分析程序建立了主热传输系统(PHTS)模型、排管容器及端屏蔽系统、堆腔以及安全壳模型。分别选取代表高压熔堆和低压熔堆的全厂断电及出口集管大破口失水事故始发严重事故序列,从堆芯氧化产氢以及系统热工水力行为出发,对重水堆产氢特性及点火器的消氢效果进行了研究。分析表明:严重事故下随着堆芯冷却恶化,排管容器内发生锆水反应而产生氢气,排管容器和堆腔内的水对氢气产生有较长时间的抑止作用,随着排管容器和堆腔内水的逐渐烧干,排管容器蠕变失效,熔融堆芯落入堆腔发生堆芯熔融物与混凝土的相互作用而产生大量氢气。当氢气点火器失效时,安全壳隔间内氢气体积份额持续增加,存在燃爆风险;点火器开启时,隔间中的氢气混合气体在较低浓度下点燃,氢气燃烧模式处于慢速燃烧区。Hydrogen control under severe accidents is a key issue for nuclear power plant. Based on integral systems analysis code of heavy water reactor, the model including primary heat transfer system （PHTS）, calandria, end shield system, reactor cavity and containment has been instituted. And two accidents sequences, i. e. station blackout which represents high-pressure core melt accident and outlet header LLOCA which represents low-pressure core melt, have been selected to study the hydrogen generation characteristic and the effectiveness of hydrogen mitigation with igniter in terms of hydrogen generation under core oxidation condition and systematic thermal-hydraulic responsiveness. The analysis results indicate that under severe accident, zirconium-water reaction will produce hydrogen with deterioration of core cooling. The water in calandria and reactor cavity can inhibits hydrogen generation for a long time, but as thewater dries out, creep failure happens on calandria and molten core falls into the cavity, resulting in interaction between core debris and concrete and much hydrogen generating. When hydrogen igniter fails, volume fraction of hydrogen will continue rising in containment, leaving an explosion risk. When igniters start, hydrogen mixture ignites at low concentration in compartment and this combustion mode locates in slow-burning zone.

关 键 词：重水堆 堆芯氧化 点火器 慢速燃烧 

分 类 号：TL364.4[核科学技术—核技术及应用]