基于SCIENCE程序包的IFBA组件模型的可行性研究

Feasibility Study of IFBA Assembly Model Based on SCIENCE Code Package

  • 摘要: 表面涂有一薄层硼化锆的一体化燃料可燃吸收体(IFBA)被用作轻水堆UO2燃料组件的反应性控制。法国AREVA公司开发的SCIENCE程序包具有模拟IFBA组件的能力,但其模拟精度需经标定。本文利用APOLLO2-F程序建立IFBA组件模型和不含IFBA组件模型,研究了组件的无限增殖因数k及IFBA价值,并与西屋公司结果进行比较。分析了燃料和包壳温度的处理方法以及数据库的差异对结果的影响。利用硼化锆密度修正因子评估IFBA价值偏差对堆芯参数和功率分布等的影响。结果表明:SCIENCE计算的k及IFBA价值与西屋公司的结果符合较好,低燃耗区SCIENCE计算的价值偏小2%。装载8个104根IFBA棒组件的堆芯,组件相对功率最大偏差约为1%;硼浓度、功率峰因子FQ和焓升因子FΔH的变化均不到0.1%,可忽略。先导组件采用28根或更少的IFBA棒时,可直接采用SCIENCE程序进行计算。

     

    Abstract: The integral fuel burnable absorber (IFBA) coated with zirconium diboride (ZrB2) on the surface of UO2 pellets is used for the reactivity control of fuel assemblies in light water reactors. The SCIENCE code package developed by AREVA has the capability of simulating IFBA assembly. However, the simulation accuracy requires calibration. The Westinghouse RFA-2 assemblies with and without IFBA rods were modeled by APOLLO2-F code. The infinite multiplication factor k and IFBA value were studied and the corresponding results with Westinghouse were compared and analyzed. The different treatment methods of the fuel and cladding temperature and differences in the database were also studied. The deviation of IFBA value may affect reactor core parameters and power distribution, and its impact was assessed by analyzing the ZrB2 density correction factor. The preliminary results show that k and IFBA value calculated by SCIENCE code agree well with Westinghouse results and the former is about 2% lower than the latter at low burnup zone. The maximum of assembly relative power deviation is about 1% in the core loaded with 8 assemblies with 104 IFBA rods. The changes of boron concentration, power peak factor FQ and enthalpy rise factor FΔH can be ignored. The lead using assembly with 28 or fewer IFBA fuel rods can be directly calculated using the SCIENCE code.

     

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