本論文旨在探討添加可燃毒物 (burnable poison) 於球床型高溫氣冷式反應器 HTR-10 之可行性。HTR-10 為北京清華研究院建造的第四代反應器，係世界第三座模組式球床型高溫氣冷式反應器。球床型反應器擁有不停爐裝卸燃料 (online-refueling) 的特點，能大幅減少停爐時間，並藉由多次通過 (multi-pass) 燃料營運模式獲得高燃耗的用過燃料。然而，此營運方式需偵測卸載燃料球之燃耗值，以做為燃料球回填爐心的基準，為降低此程序之複雜性，因此，本論文改以一次通過 (Once Through Then Out, OTTO) 作為燃料營運，並試圖在爐心中添加可燃毒物以抑制新加入燃料的過溢反應度 (excess reactivity)。本論文使用 MCNP6.1 以及 ENDF/B-VII 截面資料庫進行計算，爐心溫度定為 900 K，並為均勻分佈。
可燃毒物添加方式使用三種幾何模型進行探討，分別為：可燃毒物放置於燃料球中心、於 TRISO (TRIstructural ISOtropic) 顆粒中加入一層可燃毒物殼層、以及將可燃毒物均勻混入內核。後續針對軸向功率分佈、軸向中子增殖因數與各項燃耗特性進行分析，結果顯示，可燃毒物的加入對爐心燃料區頂層增殖因數具有良好的抑制效果，其中，可燃毒物放置於燃料球中心模型的抑制效果相較其餘兩種模型差。根據計算結果並考量到燃料球在工程上的製造，將可燃毒物混入內核為較建議的方式。同時，本論文亦針對不同種類的可燃毒物以及混合式可燃毒物進行爐心與燃耗特性的分析與探討，根據燃耗及中子增殖因數分析，以 B 與 Gd2O3 混合之可燃毒物為最佳的可燃毒物組合。最後，本研究嘗試以 U-233 與 Th-232 替換 U-235 及 U-238 進行計算分析，其中，U-235 與 Th-232 燃料組成的燃料與緩速劑溫度係數皆為負值，此組合為安全上可行之燃料組成；而 U-233 與 Th-232 燃料組成其緩速劑溫度係數為正，在加入可燃毒物後由正值轉負值，運轉上更加安全。以 U-233 與 Th-232 做為燃料可有效降低錒系元素的產生，在後續用過燃料處理上具有相當大的優勢，為可發展之燃料選擇，期待後人對 U-233 與 Th-232 燃料組成有更詳細的研究探討。

The object of this study is to investigate the feasibility of the addition of burnable poison in pebble bed high temperature gas-cooled reactor (HTR-10). HTR-10, the third modular pebble-bed reactor (PBR) in the world, is constructed by Tsing Hua University, China. The features of PBR is online-refueling, which can drastically decrease the reactor shutdown time and achieve high-burn-up spent fuel through multi-pass fuel loading scenario. However, this fuel loading scenario requires to detect the burnup value of the unloading fuel pebble and use it as the standard for the backfilling of the fuel pebble. In order to reduce the complicity of the procedure, this study adopted the once through then out (OTTO) fuel loading scenario, and attempts to put the burnable poison into the core to suppress the excess reactivity of the upper layer of the fuel. Furthermore, all the calculations were performed using MCNP6.1 and ENDF/B-VII cross-section library. The core temperature was assumed to be 900K and uniformly distributed.
Three geometrical models were established to examine the influence of burnable poison on the effective neutron multiplication factor of the core, including addition of burnable poison in the center of fuel particles, insertion of a layer of burnable poison in TRISO (TRIstructural ISOtropic) particles, and mix of burnable poison with fuel in the kernels. The axial power distribution, axial multiplication factor and burnup characteristics were studied. The results revealed that burnable poison effectively suppressed the effective multiplication factor in the upper layer of the fuel. Besides, comparing with the three geometrical models, the efficiency of burnable poison in the center of fuel particles holds the worst. According to calculation results and the consideration of the fuel particle fabrication, it is suggested that mixing burnable poison with fuel in the kernels is the best model to use. Meanwhile, this study investigated the core and burnup characteristics for different types of burnable poison as well as the combination of the burnable poison. The combination of B and Gd2O3 is the best burnable poison considering power fraction and effective neutron multiplication factor. Finally, this study tried to use U-233 and Th-232 are fuel instead of U-235 and U-238 for calculation and analysis. The fuel and moderator temperature coefficients of U-235 and Th-232 fuel are both negative. As a result, the combination is a secure and feasible fuel composition considering the security reasons. In addition, the moderator temperature coefficients of U-233 and Th-232 fuel change from positive to negative after adding burnable poisons. Moreover, the fuel composition of U-233 and Th-232 can effectively reduce the production of actinides, which could greatly reduce the radiotoxicity of spent the nuclear fuel. The combination of U-233 and Th-232 fuel is a promising fuel option and is worth having more detailed research.

摘要 i
ABSTRACT ii
致謝 iv
目錄 v
表目錄 viii
圖目錄 ix
第一章 緒論 1
1.1 前言 1
1.2. HTR-10 反應器 2
第二章 文獻回顧 3
2.1 反應器設計參數 5
2.2 球床式反應器燃料元件設計 6
2.3 反應器材料與模型建立 7
2.4 燃料營運模式 11
2.5 爐心燃料球軸向動態模型 12
2.6 使用可燃毒物的一次通過燃料營運模式 15
2.7 可燃毒物 16
2.8 可孕核種釷 18
2.9 研究動機 22
第三章 計算方法與程式介紹 23
3.1 MCNP介紹 23
3.2 截面資料庫介紹 24
3.3 夏農熵介紹 24
3.4 臨界計算 24
3.5 燃耗計算 26
第四章 可燃毒物模型建立 27
4.1 HTR-10原始模型建立 27
4.1.1 TRISO顆粒模型 27
4.1.2 燃料球單位晶格建立 28
4.1.3 爐心燃料排列方式 29
4.1.4 燃料裝卸過程 30
4.2 一次通過燃料營運模式之模型建立 31
4.2.1 可燃毒物燃料球模型設計 32
4.2.2 靈敏度測試 34
第五章 反應器燃耗特性分析 37
5.1 改變可燃毒物總量 37
5.2 可燃毒物燃料球之軸向功率分佈與燃耗分析 40
5.3 可燃毒物分析 46
5.4 混合式可燃毒物分析 48
第六章 可燃毒物添加量與燃耗特性分析 51
6.1 可燃毒物重量調整根據 51
6.1.1 HTR-10停爐設定 51
6.1.2 SDM 定義 51
6.1.3 控制棒反應度 51
6.1.4 可燃毒物添加重量設定 52
6.2 燃耗特性分析 54
第七章 HTR-10 中可孕核種的替換 59
7.1 釷鈾氧化物比例 59
7.2 中子增殖因數 60
7.3 燃料與緩速劑之溫度係數分析 61
7.4 可燃毒物加入對釷燃料溫度係數之影響 64
第八章 結論與未來建議 67
8.1 結論 67
8.2 未來建議 68
參考文獻 69

[1] “BP Statistical Review of World Energy 2019”, BP p.l.c. 2019
[2] “A Technology Roadmap for Generation IV Nuclear Energy Systems,” Generation IV International Forum, 2002.
[3] 吴宗鑫，张作义，「先进核能系统和高温气冷堆」，第一版，清华大学出版社，北京，西元2004年。
[4] K. Kunitomi, X. Yan, T. Nishihara, N. Sakaba, T. Mouri, “JAEA’S VHTR for hydrogen and electricity cogeneration: GTHTR300C”, Nuclear Engineering and Technology, Vol. 39, No. 1, pp. 9-20, 2007.
[5] 百度科技HTR-PM頁面，http://baike.baidu.com。
[6] G. Ilas, D. Ilas, R.P. Kelly, E.E. Sunny, “Validation of SCALE for High Temperature
Gas- Cooled Reactor Analysis”, ORNL/TM-2011/161, Oak Ridge National Labotory
(2012).
[7] K. Kunitomi, Y. Sun, S. Ball, H.L. Brey, M. Methnani, “Evaluation of High Temperature Gas Cooled Reactor Performance: Benchmark Analysis Related to Initial Testing of the HTTR and HTR-10”, IAEA-TEDOC-1382, International Atomic Energy Agency, 2007.
[8] Y. Yang, Z. Luo, X. Jing, Z. Wu, “Fuel Management of the HTR-10 including the Equilibrium state and Running-in Phase”, Nuclear Engineering and Design, Vol. 218, pp. 33-41, 2002.
[9] W.K. Terry, S.S. Kim, L.M. Montierth, J.J. Cogliati, A.M. Ougouag, “Evaluation of HTR-10 Reactor as a Benchmark for Physics Code QA”, PHYSOR-2006, Vol. 39, No. 4, ANS Topical Meeting on Reactor Physics, 2006.
[10] 吳尚謙，「高溫氣冷式反應器HTR-10之模擬計算與燃耗特性分析」，國立清華大學核子工程與科學研究所，碩士論文，西元2013年。
[11] D. She., J. Zhang, B. Xia, C. Wei, L Fu, J. Xingqing, “Study on OTTO fueling schemes of the HTR-PM with boron burnable particles”, Nuclear Engineering and Design, Vol. 329, pp 198-203, 2018.
[12] T. Obara, T. Onoe, “Flattening of burnup reactivity in long-life prismatic HTGR by particle type burnable poisons”, Annals of Nuclear Energy, Vol. 57, pp 216-220, 2013
[13] Nuclear Energy Agency, “Uranium 2011: Resources, Production and Demand”, OECD 2012 NEA No. 7059; 2012.
[14] J. Chernick, S.O. Moore, “Breeding Potential of Thermal Reactors”, Nuclear Science and Engineering, 1959.
[15] D. Irwanto, T. Obara, “Burnup characteristics and fuel cycle economic of mixed uranium-thorium fuel in a simplified small pebble bed reactor”, Journal of Nuclear Science and Technology, Vol. 49, pp 222–229, 2012.
[16] T. Piyatida, O. Toru, “Particle-type Burnable Poisons for Thorium-based Fuel in HTGR”, INES-4, 2015.
[17] X-5 Monte Carlo Team, “MCNP-A General Monte Carlo N-Particle Transport Code. Version 5 Volume I: Overview and Theory”, LA-UR-03-1987, Los Alamos National Laboratory, 2003.
[18] J.S. Hendricks, G.W. McKinney, M.L. Fensin, M.R. James, J.W. Durkee, J.P. Finch, D.B. Pelowitz, L.S. Waters, M.W. Johnson, “MCNPX 2.6.0 Extensions”, LA-UR-08-2216, Los Alamos National Laboratory, 2008.
[19] T. Goorley, M. James, T. Booth, F. Brown, J. Bull, L.J. Cox, J. Durkee, J. Elson, M. Fensin, R.A. Forster, J. Hendricks, H.G. Hughes,1 R. Johns, B. Kiedrowski, R. Martz, S. Mashnik, G. Mckinney, D. Pelowitz, R. Prael, J. Sweezy, L. Waters, T. Wilcox, T. Zukaitis, “Initial MCNP6 Release Overview – MCNP6 version 1.0”, LA-UR-13-22934, Los Alamos National Laboratory, 2013.
[20] F. B. Brown, “On the Use of Shannon Entropy of the Fission Distribution for Assessing Convergence of Monte Carlo Criticality Calculations”, PHYSOR-2006, Los Alamos National Laboratory, 2006.
[21] 张竞宇，李富，魏春琳，孙玉良，「基于蒙特卡罗方法对VSOP模型的keff验证」，原子能科学技术，第47卷第3期，第350-354頁，西元2013年。
[22] 吳炘融, 「球床型高溫氣冷式反應器不停爐裝卸燃料之臨界及燃耗分析」，國立清華大學核子工程與科學研究所，碩士論文，西元2011年。
[23] ENDF/B-VII.1 Incident-Neutron Data, https://t2.lanl.gov/nis/data/endf/endfvii.1-n.html, 2011.
[24] N. Jakiyah, Suharyana, Riyatun, A Khakim, “The dependency of shutdown margin values of the HTR-10 on packing fraction absorber”, AIP Conference Proceedings, 2018.
[25] Glasstone, Sesonske, “Nuclear Reactor Engineering: Reactor Systems Engineering”, Springer; 4th edition, ISBN: 978-0412985317, 1994.
[26] W. M. Stacey, “Nuclear Reactor Physics”, John Wiley & Sons, ISBN: 0- 471-39127-1, 2001.
[27] J. R. Smith, S. D. Reeder, R.G. Fluharty, “MEASUREMENT OF THE ABSOLUTE VALUE OF ETA FOR U-233, U-235 and Pu-239 USING MONOCHROMATIC NEUTRONS”, National Technical Information Service, IDO-17083, 1966.
[28] V. V. Naicker, “Analysis of specific design aspects of a thorium-uranium fuelled European Pressurised Reactor”, Potchefstroom Campus of the North-West University, doctoral dissertation, 2017.