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应用FG2DB两维两群扩散燃耗程序和带69群中子截面库的CELL栅元少群参数计算程序,对高功率研究堆低浓化堆芯进行了物理计算。LEU燃料元件的铀密度为3.6～7.2g/cm~3,包壳厚度为0.38～0.56 mm。结果表明:改变燃料芯体铀密度或厚度在物理上相当;各堆芯方案的控制棒价值等运行安全有关参数都可以接受,部分计算结果被拟合成线性或二次关系式以便于应用。给出了各堆芯的最小临界值、剩余反应性、运行寿期、快热中子通量和积分通量等物理参数。分析这些参数后指出,当~(235)U含量提高20％或更多时,LEU堆芯与HEU堆芯的主要物理性能相近,这时快中子通量几乎不受影响,热中子通量的下降率近似正比于元件~(235)U含量增加率,但由于LEU堆芯运行寿期的延长,对一般同位素生产与燃料元件辐照考验不会有太大影响。
By using FG2DB two-dimensional two-group diffusion burn-in program and CELL cell-less group parameter calculation program with 69 neutron cross-section banks, physical calculations were carried out on the low-concentration core of high-power research reactor. LEU fuel element uranium density of 3.6 ~ 7.2g / cm ~ 3, cladding thickness of 0.38 ~ 0.56 mm. The results show that it is physically equivalent to change the density or thickness of uranium in the fuel core. Parameters such as the control rod value of each core scheme are acceptable for operation safety. Some of the calculated results are fitted to a linear or quadratic relationship for ease of application. The minimum critical values, residual reactivity, operating lifetime, fast thermal neutron flux and integral flux of each core are given. After analyzing these parameters, it is pointed out that when the content of 235 U is increased by 20% or more, the main physical properties of LEU core and HEU core are similar, and the fast neutron flux is hardly affected. The thermal neutron pass The rate of decrease of the amount is approximately proportional to the rate of increase of elemental U content, but due to the prolongation of the lifetime of the LEU core, it will not have much impact on the general isotope production and fuel element radiation test.