液态重金属反应堆燃料棒及控制棒设计

doi:10.19596/j.cnki.1001-246x.8863

摘要/Abstract

摘要：

旨在从中子学角度分析液态重金属快堆燃料棒和控制棒的物理特性, 以支撑其结构设计及材料选型。使用快中子反应堆分析程序SARAX对燃料棒的液铀比选择、径向功率分布、包壳材料选型、反射层材料选型, 控制棒径向结构设计、吸收体材料选型、慢化结构设计进行计算分析。计算结果表明: 燃料棒栅元K_inf与液铀比呈线性关系, 液铀比的选择更多需要考虑载热因素。燃料棒包壳优先选择铁素体/马氏体钢材料。活性段轴向两端反射层材料可选择钢类材料。基于Pu迁移现象分析结果, 当前物理计算程序中均未耦合Pu迁移现象, 计算得到的功率分布相对均匀, 导致燃料中心温度计算结果偏不保守。控制棒采用细棒设计能有效降低自屏效应, 但会降低空间利用率。快堆常用B₄C作为吸收体材料。控制棒吸收体外包裹慢化体能使中子能谱软化, B-10中子吸收截面大幅上升, 提高控制棒价值。同一外径下, 纯吸收体芯块的棒价值小于使用慢化体(ZrH₂)包裹的芯块。

关键词: 液态重金属反应堆, 燃料棒设计, 控制棒设计

Abstract:

The aim of the paper is to analyse the physical properties of liquid heavy metal fast reactor fuel rods and control rods from a neutronics point of view to support their structural design and material selection.In this paper, the liquid-uranium ratio selection, radial power distribution, cladding material selection, reflective layer material selection for fuel rods, radial structural design of control rods, absorber material selection, and moderated structural design are computationally analysed using the fast neutron reactor analysis program SARAX. Calculation results show that: the K_eff of the fuel rod grid element is linearly related to the liquid-uranium ratio, and the selection of the liquid-uranium ratio needs to consider the heat-carrying factor more. The fuel rod cladding is preferred to be made of ferritic/martensitic steel materials. The materials for the reflective layer at the axial ends of the fuel may be chosen to be made of steel materials.Based on the results of the analysis of the Pu migration phenomenon, none of the current physical calculation procedures are coupled with the Pu migration phenomenon, and the power distribution obtained from the calculation is relatively homogeneous, which leads to a bias of unconservative results in the calculation of the fuel centre temperature.The use of thin rod design for control rods can effectively reduce the self-screening effect, but the use of thin rod structure will lead to lower space utilisation. B₄C is commonly used as the absorber material in fast reactors.The wrapping of the control rod absorber with a moderator softens the neutron energy spectrum and increases the B-10 neutron absorption cross section significantly, increasing the value of the control rod. At the same outer diameter, the rod value of a pure absorber core block is less than that of a core block wrapped with a moderator (ZrH₂).

Key words: liquid heavy metal reactor, fuel rod design, control rod design

中图分类号:

TL32

徐昌恒, 潘晖, 何明涛, 赵常有, 蔡德昌, 许怀金. 液态重金属反应堆燃料棒及控制棒设计[J]. 计算物理, 2024, 41(5): 582-588.

Changheng XU, Hui PAN, Mingtao HE, Changyou ZHAO, Dechang CAI, Huaijin XU. Liquid Heavy Metal Reactor Fuel Rod and Control Rod Design[J]. Chinese Journal of Computational Physics, 2024, 41(5): 582-588.

图/表 13

图1 (a) 燃料棒横截面图；(b)燃料组件轴向示意图

Fig.1 (a) Fuel rod cross-sectional diagram and (b) fuel assembly axial schematic

图2 燃料棒栅元33群归一化能谱

Fig.2 Normalized energy spectrum of the 33-group of fuel rod grid element

表1 液铀比敏感性分析结果

Table 1 Analytical results of liquid-uranium ratio sensitivity

芯块半径/mm	包壳外径/mm	栅元对边距/mm	V_液/V_铀	K_inf结果
5.4	12	无冷却剂	0.000	1.434 54
5.4	12	12	0.127	1.426 19
5.4	12	13	0.363	1.412 31
5.4	12	13.6	0.514	1.404 49
5.4	12	14	0.618	1.399 01
5.4	12	15	0.892	1.386 46
5.4	12	16	1.186	1.374 27

图3 燃料棒栅元Kinf随液铀比的变化

Fig.3 Variation of Kinf with liquid-uranium ratio for fuel rod grid element

表2 不同包壳材料栅元Kinf计算结果

Table 2 Kinf calculation results for different cladding materials

芯块半径/mm	包壳内径/mm	包壳外径/mm	包壳材料	K_inf
5.4		无包壳		1.434 54
5.4	11	12	铁马钢	1.404 33
5.4	11	12	316不锈钢	1.397 82
5.4	11	12	M5锆合金	1.407 66

表3 反射层材料选型分析

Table 3 Reflection layer material selection analysis

反射层材料	316钢	BeO	MgO	ZrO₂	LBE	Al₂O₃	DU
归一化燃耗反应性速率^*	0.95	1.17	1.01	0.98	1.00	1.01	0.80
不泄漏率K_eff/K_inf	0.961	0.971	0.966	0.965	0.956	0.965	0.966
轴向功率峰因子F_z	1.211	1.172	1.159	1.183	1.205	1.17	1.25

图4 不同反射层材料选型活性段轴向功率分布

Fig.4 Axial power distribution with different reflective layer material selections

图5 Pu同位素的归一化密度随芯块半径分布

Fig.5 Normalized density of Pu isotopes according with the pellet radius

图6 Pu迁移与Pu均匀分布工况下归一化功率密度随芯块半径分布

Fig.6 Normalized power density distribution with pellet radius of Pu migration and Pu uniform distribution case

图7 控制棒径向结构示意图(a) 方案A；(b) 方案B；(c) 方案C

Fig.7 Schematic of the radial structure of control rods (a) design scheme A; (b) design scheme B; (c) design scheme C

表4 控制棒径向结构棒价值分析

Table 4 Control rod value analysis of different rod radial structure

设计方案	方案A	方案B	方案C
吸收体径向结构	7根细棒	1根实心粗棒	1根分层粗棒
归一化控制棒价值	1.00	0.92	0.94

表5 控制棒吸收体材料选型分析

Table 5 Control rod absorber material selection analysis

材料选型	B₄C(丰度85%)	B₄C(天然丰度)	EU₂O₃	Ag-In-Cd	Ta	HfB₂(丰度85%)
归一化棒价值	1.000	0.353	0.399	0.246	0.265	0.833

表6 控制棒慢化设计分析

Table 6 Control rod moderator design analysis

设计方案	方案1	方案2	方案3	方案4	方案5	方案6
吸收体芯块半径/mm	4.8	4	4	4	4	4
慢化体厚度/mm	0	0	0.4	0.5	0.8	1
归一化棒价值	1.000	0.784	0.911	0.953	1.036	1.114

参考文献 6

1	ZRODNIKOV A V , TOSHINSKY G I , KOMLEV O G , et al. SVBR-100 module-type fast reactor of the Ⅳ generation for regional power industry[J]. Journal of Nuclear Materials, 2011, 415 (3): 237- 244. DOI
2	ADAMOV E O, ORLOV V V, FILIN A I, et al. Conceptual design of BREST-300 lead-cooled fast reactor[C]//Proceedings, International Topical Meeting on Advanced Reactor Safety, ARS'94, Pittsburgh, USA. 1994: 509-516.
3	ALEMBERTI A, FROGHERI M, MANSANI L. The Lead fast reactor: Demonstrator(ALFRED) and ELFR design[C]// 21 Specific Nuclear Reactors and Associated Plants; Configuration; Design; Fast Reactors, 2013: IAEA-CN-199/024.
4	SMITH C F , HALSEY W G , BROWN N W , et al. SSTAR: The US lead-cooled fast reactor (LFR)[J]. Journal of Nuclear Materials, 2008, 376 (3): 255- 259. DOI
5	郑友琦, 吴宏春, 杜夏楠, 等. 快堆中子学计算程序NECP-SARAX的改进与验证[J]. 强激光与粒子束, 2017, 29 (5): 112- 117.
6	谢光善. 快中子堆燃料元件[M]. 北京: 化学工业出版社, 2007.

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