一、引言动力堆的性能在很大程度上受热工-水力设计的限制。为了提高堆芯的热工-水力性能,要求堆芯的热工-水力分析尽可能精确地计算出堆芯各子通道内的压力、流量和焓分布,从而使对水堆设计造成重大限制的烧毁比和出口含汽量的计算更为精确。在压水堆的早期设计中,堆芯的热工-水力设计都在名义条件下进行,并把所得到的结果再迭加上极端条件下的热管因子和累计状态下的不确定性。由于设计中重复地使用这些因 I. INTRODUCTION The performance of the power reactor is largely limited by the thermal-hydraulic design. In order to improve the thermal-hydraulic performance of the core, thermal-hydraulic analysis of the core is required to calculate as accurately as possible the pressure, flow and enthalpy distribution in each sub-channel of the core, thereby greatly restricting the design of the water reactor Burning ratio and the calculation of export steam content more accurate. In the early design of the PWR, the thermal-hydraulic design of the core was carried out under nominal conditions and the results obtained were superimposed with the heat pipe factor under extreme conditions and the uncertainty under the cumulative condition. Due to the repetitive use of these factors in the design