池式钠冷快堆双环路12%差异非对称功率运行及流量调节缓解工况的三维数值模拟

Three-dimensional Numerical Simulation on 12%Differentiated Asymmetric Cooling Power Operation and Flow Regulation Mitigation Condition of Two-loop Pool-type Sodium-cooled Fast Reactor

双环路池式钠冷快堆在部分事故运行工况下,堆本体内一回路的两组环路可能出现非对称功率运行工况,使得钠池内出现特殊的非对称三维热工分布特征,对核电厂的正常运行产生一定影响。基于三维数值模拟方法,对池式钠冷快堆进行全尺寸一体化计算,模拟当一回路两个环路的冷却功率不相等时,一回路主热传输系统的三维热工水力变化。并分析流量分配调节措施对池内非对称运行现象的缓解效果,获取钠池内整体三维温度、流动分布特性。计算结果表明,两环路在12%冷却功率差异的非对称运行条件下,两环路中间热交换器(intermediate heat exchanger,IHX)出口温差可达20℃,经适当的流量分配调节后,可补偿冷却功率差异造成的非对称现象,在较高运行功率下两个环路的温度场可以形成基本稳定的对称分布,两环路IHX出口温差仅约3℃,双环路非对称效应得到有效缓解,关键区域和部件的热工参数可以满足安全要求。三维计算结果是对现有一维、二维计算程序的有力补充,可为核电厂设计、运行提供三维数值参考。

Under some operating conditions,the two sets of loops of the primary circuit will operate in asymmetrical state for the pool-type sodium-cooled fast reactor.It leads to special asymmetric three-dimensional thermal distribution characteristics and has certain influence on the normal operation of the nuclear power plant.Based on the three-dimensional numerical simulation method,a full-scale integrated model and calculation for the pool-type sodium-cooled fast reactor were built and carried out,and the three-dimensional thermal hydraulic behavior of the primary heat transfer system was simulated when the cooling power of the two loops of the primary circuit was not equal.Meanwhile,the mitigation effect of flow distribution regulation measures on asymmetric operation in the pool was analyzed,and the overall three-dimensional temperature and flow distribution characteristics in the sodium pool were obtained.The results show that,under the asymmetric operation condition of 12%power difference,the temperature difference of intermediate heat exchanger(IHX)outlet between the two loops can reach 20℃.After proper flow distribution adjustment,the asymmetrical phenomena caused by cooling power difference can be compensated.A basically stable symmetrical distribution of temperature field of two loops in the primary circuit develop under high operating power,and the temperature difference of IHX outlet between the two loops is only about 3℃.The asymmetric effect of two loops is alleviated effectively.By this means,the thermal parameters of the key areas and components can meet requirements.The three-dimensional results make a powerful supplement to the existing one-dimensional and two-dimensional calculation codes,which also provide a three-dimensional numerical reference for the design and operation of nuclear power plants.