在全UOX(铀氧化物)堆芯平衡循环的基础上,研究了UOX/PuThOX(钚钍混合氧化物)混合堆芯和UOX/U3ThOX(工业级233 U-钍混合氧化物)混合堆芯的燃料管理方案设计,实现了钍-铀增殖循环.U3ThOX燃料组件在堆内停留6个燃料循环,平均循环长度较参考的全UOX堆芯增加5 EFPD;U3ThOX燃料组件卸料后冷却1年时易裂变核素存量较装料时增加了7％.为比较分析,设计了UOX/MOX(钚铀混合氧化物)混合堆芯的燃料管理方案.核特性分析结果表明:1)装载PuThOX燃料对堆芯核特性产生的影响与装载MOX燃料类似,硼微分价值和控制棒价值减小、临界硼浓度变大、慢化剂温度系数更负、停堆裕量减小、多普勒亏损更大；2)UOX/U3ThOX混合堆芯和参考的全UOX堆芯具备相似的核特性.%Two kinds of mixed core designs were investigated in this study respectively with partially PuThOX (plutonium-thorium mixed oxide) and U3ThOX (reactor grade 233U-thorium mixed oxide) loading on the basis of reference full UOX (uranium-oxide) equilibrium-cycle core design. In UOX/U3ThOX mixed core, U3ThOX fuel assemblies stay in-core for 6 cycles of which average cycle length is 5 EFPD longer than that of reference full UOX core. Compared with initial load, the fissile material inventory in U3ThOX fuel increased by 7% via 1 year cooling after discharge. Furthermore, the fuel management scheme of UOX/MOX (plutonium-uranium mixed oxide) mixed core was designed for comparison. The results show that: 1) Mixed core with PuThOX loading has similar impacts as MOX on several neutronic characteristics, such as reduced differential boron worth, reduced control rod worth, higher critical boron concentration, more negative moderator temperature coefficient, reduced shutdown margin and larger Doppler power defects; 2) mixed core with U3ThOX loading has no distinct impacts on neutronic characteristics compared with reference full UOX core.
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