以膨潤土製作緩衝回填材料之性能評估

Performance Evaluation of Buffer and Backfill Material Made of Bentonite

鄭百宏(Bai-Hung Cheng)

指導教授 ： 詹穎雯

國立臺灣大學/工學院/土木工程學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.01488

摘要

近年來，核能發電與原子能的應用日益廣泛，台灣與許多國家都在享受著核能或原子能技術帶來的科技進步與便利，而如何處理這些帶有輻射汙染且會危害人類健康的放射性廢棄物問題漸漸浮上檯面，因此盡快找尋可以達到隔離效果且能夠配合長久時間存放這類放射性廢棄物之道，儼然已成為一相當重要之課題。
以目前國外放射性廢棄物最終處置場案例中皆是採用「多重障壁」的概念進行設計，乃是利用人造之工程障壁，與天然障壁所組成之多項防護措施來隔絕放射性廢棄物於人類生活環境外，以確保在足夠時間內輻射強度減弱至對生物圈無害之劑量，故研究工程障壁中之緩衝回填材在不同材料組成下之性能為相當重要一環。
本研究以美國進口之懷俄明膨潤土與台灣生產之日興膨潤土混和金門地區之花崗岩粒料與台東地區之硬頁岩粒料，並依不同配比與不同夯實壓力製作緩衝回填材料，再藉由土壤基本性質試驗、單向度膨脹率試驗、膨脹壓力試驗、水力傳導度試驗，發現相同情況下，懷俄明膨潤土組別擁有比日興膨潤土組別更佳之膨脹性能及阻水性能，此外，希望能更進一步找尋影響緩衝回填材性能之因素，並透過試驗結果建立運用懷俄明膨潤土與日興膨潤土在緩衝回填材中膨脹特性之預測方法。

關鍵字

放射性廢棄物 ； 緩衝回填材料 ； 水力傳導度 ； 膨脹壓力 ； 膨脹率

並列摘要

Applications of nuclear power and atomic energy are becoming more and more extensive all around the globe in recent years, bringing about technological advancements and conveniences that benefit Taiwan and many other countries. However, perfection is hard to attain－problems about disposal of those hazardous radioactive pollutants have begun to surface. To find a solution for radioactivity isolation and long-term storage of the waste has become a serious issue. According to some overseas cases of final radwaste disposal site, people adopt a measure designed by the concept of multiple barrier. It basically takes on multi-protection, using artificial engineering barrier and natural barrier to keep human living environments free of radioactive waste; in the meantime, it makes sure that the radioactivity reduces to an innocuous level. The performance of buffer and backfill material made of different materials plays a crucial role in research on engineering barrier.
In this research, bentonite of Wyoming imported from the US and Zhishin clay produced in Taiwan were mixed with granite from Kinmen and argillite from Taitung with different ratios and compaction energy, and were further made into buffer and backfill materials. To determine the factors that affect performance of buffer and backfill material, tests for material characteristics, swelling rate, swelling pressure and hydraulic conductivity were performed. The results of this research found out that under the same conditions, bentonite of Wyoming outperformed Zhishin clay in both swelling rate and water resistance; the results also provided a way of evaluating the swelling characteristics of buffer and backfill material made of mixture of bentonite of Wyoming and Zhishin clay.

並列關鍵字

radioactive waste ； buffer and backfill material ； hydraulic conductivity ； swelling pressure ； swelling rate

參考文獻

[1] International Atomic Energy Agency (IAEA), “Classification of radioactive waste: general safety guide, IAEA Safety Standards Series No GSG-1”, 2009.

[3] Teens網路教育園區&財團法人清華網路文教基金會-清蔚園網站，「放射性廢料的處理」，2004。

[7] Komine, H., “Predicting hydraulic conductivity of sand–bentonite mixture backfill before and after swelling deformation for underground disposal of radioactive wastes”, Engineering Geology Vol. 114, pp. 123–134, 2010.

[10] South Korea's Ministry of Education, ”Korean fourth national report under the joint convention on the safety of spent fuel management and on the safety of radioactive waste management”, Science and Technology, 2011.

[13] Komine, H., “Simplified evaluation for swelling characteristics of bentonites”, Engineering Geology, Vol. 71, pp.265–279, 2004.