【作者】 李宁；

【导师】 薛雨；

【作者基本信息】 大连理工大学 ， 土木工程（专业学位）， 2023， 硕士

【摘要】 中国核电站发展成熟稳定,2021年累计发电量和上网电量同比增长超过11%。与燃煤发电相比,核能发电排放少污染小。我国在运核电机组51台,全球第三,并且在建核电站15台,全球第一。虽然核电技术发展有进步,但仍需解决技术和安全问题。安全壳泄漏率指的是24小时内安全壳泄漏气体质量占总气体质量的百分比。为避免外界环境对反应堆造成影响和维护壳体的完整性和密封性,需要对安全壳泄漏率进行准确计算和控制。在基准事故工况下,通常需要将安全壳整体泄漏率控制在一定水平以满足特定指标要求。对于核电站安全壳泄漏率的计算,通常采用基于理想气体状态方程的方法。核电站反应堆启机阶段的泄漏率计算比较困难,因为在启机阶段,安全壳内部的压力、温度、湿度等参数时刻变化,同时启机阶段通常持续时间较短,因此现有核电站安全壳泄漏率计算方法无法计算启机阶段安全壳泄漏率。鉴于此,本课题采用理论推导、CFD数值模拟方法及遗传算法提出核反应堆启机阶段安全壳泄漏率计算方法及针对温度传感器布置的热贡献率计算方法。主要研究内容包括:(1)本方案基于Fluent仿真计算平台,通过模拟核反应堆的运行情况,了解安全壳内部的热环境分布规律,并判断是否适用于正常功率运行阶段的传感器体积权重仍能用于核反应堆启机阶段。模拟对象为辽宁省红沿河核电站3号机组,分别模拟核反应堆正常功率运行阶段和启机阶段,判断机组启机阶段和正常功率运行阶段安全壳内热量分布存在的差异。(2)应用遗传算法开发一套基于优化温度传感器体积权重的安全壳泄漏率计算方法,以使其可以应用于核反应堆启机阶段,本课题结合辽宁省红沿河四类机组二十余次大修数据提出了一种核反应堆启机阶段泄漏率快速计算方法,并经过验证,方法可行。(3)在伴随概率方法的基础上,通过使用CFD的逆向方法,推导不同热源热贡献率计算方法。以三通管道及居住房间为研究区域,将正向模拟结果作为房间温度的“真实数据”,分别在管道及建筑房间两种情况下对热贡献率计算方法进行阐述和验证,并将上述方法应用于辽宁省红沿河3号机组判断部分传感器布置位置是否正确及核岛通风空调系统是否对相应空间起到了通风降温作用。更多还原

【Abstract】 The development of nuclear power plants in China is mature and stable,with cumulative electricity generation and feed-in tariffs increasing by more than 11% year-on-year in 2021.Compared to coal-fired power generation,nuclear power generation has fewer emissions and is less polluting.China has 51 nuclear power units in operation,the third largest in the world,and has 15 nuclear power plants under construction,the largest in the world.Although there has been progress in the development of nuclear power technology,technical and safety issues still need to be addressed.The containment leak rate refers to the percentage of the mass of gas leaking from the containment to the total mass of gas within 24 hours.The containment leakage rate needs to be accurately calculated and controlled in order to avoid the impact of the external environment on the reactor and to maintain the integrity and hermeticity of the shell.Under baseline accident conditions,it is often necessary to control the overall containment leakage rate to a certain level to meet specific targets.The calculation of containment leakage rates for nuclear power plants is usually based on the ideal gas equation of state method.It is difficult to calculate the leakage rate during the start-up phase of a nuclear power plant reactor because the pressure,temperature,humidity and other parameters inside the containment are constantly changing during the start-up phase,and the duration of the start-up phase is usually short.In view of this,this project proposes a theoretical derivation,CFD numerical simulation method and genetic algorithm to calculate the containment leakage rate during the start-up phase of a nuclear reactor and a thermal contribution rate calculation method for the temperature sensor arrangement.The main research elements include:(1)The scheme is based on the Fluent simulation and calculation platform to understand the thermal environment distribution pattern inside the containment by simulating the operation of the nuclear reactor and to determine whether the sensor volume weights applicable to the normal power operation stage can still be used in the nuclear reactor start-up stage.Unit 3 of the Hongyanhe Nuclear Power Plant in Liaoning Province was simulated in the normal power operation phase and the start-up phase of the nuclear reactor to determine the differences in the heat distribution inside the containment during the start-up phase and the normal power operation phase.(2)A genetic algorithm is applied to develop a set of calculation methods for containment leakage rate based on optimised temperature sensor volume weights so that they can be applied to the nuclear reactor start-up phase.A fast calculation method for nuclear reactor start-up phase leakage rate is proposed and verified to be feasible by combining data from more than twenty overhauls of the four types of units at Hongyanhe in Liaoning Province.(3)Based on the accompanying probabilistic method,a method for calculating the thermal contribution rate of different heat sources is derived by using the inverse method of CFD.The forward simulation results were used as the "real data" of room temperature,and the thermal contribution rate calculation method was elaborated and verified in two cases: ducts and building rooms,respectively.The method was also applied to the Hong Yanhe Unit 3 in Liaoning Province to determine whether some of the sensors were correctly positioned and whether the ventilation and air conditioning system of the nuclear island had provided ventilation and cooling to the corresponding space.更多还原