使用离散钍铀燃料组件的CANDU6堆物理特性初步研究

Preliminary Study on Physical Characteristics of CANDU6 Reactor Using Discrete Thorium-Uranium Fuel Pins

为研究钍铀燃料在CANDU6堆中的应用,采用DRAGON/DONJON程序,对使用离散型钍铀燃料37棒束组件的CANDU6堆进行时均堆芯分析。结果表明,组件采用235U富集度为2.5%的铀棒以及第1、2、3圈布置钍棒的37棒束组件,堆芯在8棒束换料、3个燃耗分区的方案下,组件的冷却剂空泡反应性较使用天然铀的37棒束组件(NU-37组件)与采用混合钍铀元件棒的37棒束组件更负;堆芯最大时均通道/棒束功率满足小于6700 kW/860 kW的限值;燃料转化能力比采用NU-37组件时更高;卸料燃耗可到达13400MW·d/t(U)。研究表明,所设计的离散型钍铀燃料37棒束组件可用于现有CANDU6堆芯,且无需对堆芯结构及控制机构作重大改造;燃料组件和堆芯设计方案可为钍铀燃料在CANDU6堆芯的应用提供参考。

In order to study the application of thorium uranium fuel in the CANDU6 reactor, the code DRAGON/DONJON is adopted to study the time-averaged equilibrium core of CANDU 6 with37-element bundle assembly of discrete thorium uranium fuel rods. The results show that, when the assembly is the uranium rods with 2.5% enrichment of 235 U and the 37-element bundle assembly of thorium rods arranged in the 1, 2 and 3 layers, and under the refueling scheme of 8 bundles with 3 burnup partition, the coolant void reactivity of the assembly is lower than that of the 37-element bundle assembly（NU-37 assembly） with natural uranium and the assemblies containing mixed thorium uranium pins; that the max time-averaged channel/bundle power of the core respects the limits（less than 6700 kW/860 kW）; that the fuel conversion ratio is higher than the CANDU6 reactor with natural uranium; and that the discharge burnup is up to 13400 MW·d/t（U）. Therefore, the 37-element bundle using discrete thorium uranium fuel is applicable in the CANDU6 reactor, without major modification of the structure of the core and operation modes, and the design of fuel assembly and core provides a reference for the thorium uranium fuel in CANDU6.