本研究主軸為進行六角柱型高溫氣冷式反應器全爐心的有效增殖因數、熱中子通率分佈及功率分佈計算，並藉由功率分佈探討燃料組件之設計。所探討的目標以日本原子能委員會（JAEA）設計的高溫工學試驗研究爐（HTTR）為主要對象，並進一步分析同樣由JAEA設計的高溫氣冷式反應器原型機（GTHTR300）兩者設計的不同及造成的影響。
全爐心的臨界計算使用蒙地卡羅方法。由於爐心會因為燃料的位置以及冷卻劑的流動方向在內部產生溫度分佈，因此本研究以中子截面處理程式產生溫度相依的連續點能量截面資料庫。發現若使用均勻溫度的HTTR模型代替具有詳細溫度分佈的模型對於有效增殖因數計算會有大約2 mk的高估，而在熱中子通率分佈及功率分佈上面也會造成最大13%~14%的誤差。
在HTTR的原始設計中，為了達到良好的功率分佈，採用12種不同的鈾濃縮度，並按照特定排列方式擺放，但是在原型機GTHTR300中卻沒有這樣的設計。若將HTTR詳細溫度分佈模型改成使用均勻鈾濃縮度燃料，會發現有效增殖因數增加約24 mk。而徑向功率分佈在原始設計中較為平緩，軸向功率分佈在均勻鈾濃縮度燃料的模型中會使得底層燃料出力增加為2.5倍，造成底部燃料最高溫度超過限值1400℃。
在原型機GTHTR300的設計中，燃料束擺放於爐心外圈，使得熱中子通率分佈及功率分佈變得較為平坦，徑向功率分佈最大值與平均值之比值約為1.2，略比HTTR的1.04高一些。此外，HTTR燃料棒與護套間有一層不流通的氦氣縫隙，由於氦氣的熱導率低，因此對底部燃料塊的燃料表層溫度造成88 K的升高。GTHTR300取消了燃料護套的設計，沒有氦氣縫隙降低了燃料棒的溫度，因而不會超過燃料最高溫限值。
本研究初步奠定高溫氣冷式反應器爐心中子物理計算與熱流計算相互影響之計算模式，一窺爐心設計的堂奧。

The purpose of this study is to investigate core design of high-temperature gas-cooled reactor by calculating the effective multiplication factor, thermal neutron flux distribution, and power distribution. The prismatic-type high-temperature gas-cooled reactor chosen is the High Temperature Test Reactor (HTTR) designed by Japan Atomic Energy Agency (JAEA). The prototype design of Gas Turbine High Temperature Reactor of 300MWe nominal capacity (GTHTR300) is also investigated.
Reactor core may have certain temperature distribution due to fuel position and helium flow direction. By using cross-section generation code, temperature-dependent cross sections can be generated for the criticality calculation for effective multiplication factor, thermal neutron flux distribution, and power distribution of the core. Using uniform temperature HTTR model may cause ~2 mk overestimate of effective multiplication factor, 13% difference in thermal neutron flux distribution and 14% difference in power distribution, compared with the detailed temperature model.
In the original HTTR core design, there are 12 different fuel enrichments used in the core for better power distribution. However, in GTHTR300, there is only one enrichment. Replacing HTTR detailed temperature model by uniform enrichment model will result in 24 mk increase of effective multiplication factor. The radial power distribution in the original design is flatter. The power generated from the bottom fuel in the uniform enrichment model will be 2.5 times of the original one, and the bottom fuel temperature will exceed the design criteria.
In the GTHTR300 core design, fuel columns are arranged in outer region of the core, which will result in smoother thermal flux and power distribution. The maximum- to-average ratio of radial power distribution is 1.2, slightly higher than 1.04 of HTTR. In HTTR calculation, it is found that the helium gap between the fuel rod and the cladding will result in increasing of fuel temperature by 88 K. In the GTHTR300 design, by eliminating cladding and the helium gap, the temperature of fuel rod can remain under the design limit.
This study established the preliminary coupling of reactor neutron physics and thermal hydraulic calculation, and therefore was able to look into the key issues of the core design of the high temperature gas-cooled reactor.

第一章 緒論
第二章 計算工具介紹
第三章 HTTR爐心模型建立與驗證計算
第四章 HTTR 30MW爐心熱中子通率及功率分佈計算
4.1 HTTR 30MW運轉燃料簡易溫度分佈模型
4.2 HTTR 30MW運轉詳細溫度分佈模型
4.3 HTTR 30MW運轉詳細溫度分佈部分溫度改變對於臨界計算的影響
4.4 HTTR 30MW運轉簡化溫度分佈模型
4.5 HTTR的鈾濃縮度分佈對於爐心的影響
4.6燃料最高溫度計算
第五章 GTHTR300爐心模型建立與計算
5.1 GTHTR300爐心介紹
5.2 GTHTR300爐心初始狀態計算
第六章 結論與未來工作建議
參考文獻

1. J.D. Bes, N. Fujimoto, B.H. Dolphin, L. Snoj, and A. Zukeran, Evaluation of the Start-Up Core Physics Tests at Japan’s High Temperature Engineering Test Reactor (Fully-Loaded Core), INL/EXT-08-14767 Rev. 2, Idaho National Laboratory (INL), 2010.
2. N. Nojiri, S. Shimakawa, K. Takamatu, Y. Ishii, S. Kouno, S. Kobayashi,
T. Kawamoto, and T.Iyoku, “Power Distributions in the High Temperature Engineering Test Reactor (HTTR) by Measuring Gross Gamma Ray from the Fuel Assembles”, JAERI-Tech 2003-086, Japan Atomic Energy Research Institute, Nov. 2003.
3. K. Kunitomi, S.Katanishi, S. Takada, X. Yan, and N. Tsuji, “Reactor core design of Gas Turbine High Temperature Reactor 300”, Nuclear Engineering and Design 230, 349–366, 2004.
4. K. Kunitomi, S.Katanishi, S. Takada, T. Takizuka, and X. Yan, “Japan’s future HTR—the GTHTR300”, Nuclear Engineering and Design 233, 309–327, 2004.
5. T. Nakata, S.Katanishi, S. Takada, X. Yan, and K. Kunitomi, “Detailed Analysis for a Control Rod Worth of The Gas Turbine High Temperature Reactor (GTHTR300)”, JAERI-Tech 2002-087, Japan Atomic Energy Research Institute, Nov. 2002.
6. T. Shibata, M. Eto, E. Kunimoto, S Shiozawa, K. Sawa, T. Oku, T. Maruyama, “Draft of Standard for Graphite Core Components in High Temperature Gas-cooled Reactor”, JAEA-Research 2009-042, Japan Atomic Energy Agency, Jan. 2010.
7. S. Katanishi and K. Kunitomi, “Safety Evaluation on the Depressurization Accident in the Gas Turbine High Temperature Reactor (GTHTR300) ”, Nuclear Engineering and Design 237, 1372–1380, 2007.