本研究採用MX-80膨潤土進行沖蝕試驗，試驗裝置主要以兩塊透明壓克力板模擬人工裂隙，以去離子水及不同離子濃度的溶液流過，由出水口量測液體濁度以推估沖蝕質量，再以逐日攝得之圖像，量測平均徑向膨脹距離及副礦物面積，分析不同的裂隙內寬、水化學以及水流量對於膨潤土沖蝕的影響。

在本研究所設計之參數下，觀察到最嚴重的沖蝕，是使用去離子水在較大的裂隙內寬(2.0 mm)、較高的水流量(1.0 mL/min)環境中，93天時已經損失原始試體重的30.8%，而離子強度2.54 mM與4.00 mM NaCl溶液條件下，63天內量測到的沖蝕量不足原始試體重的1.0%，可見地下水中的離子強度是影響膨潤土沖蝕的關鍵。在流量1.0 mL/min裂隙內寬0.2 mm去離子水條件下的試驗，93天內量測到的沖蝕量相當於損失原始試體重的3.68%，故膨潤土沖蝕量將隨著裂隙內寬縮小而降低。而流量0.2 mL/min裂隙內寬2.0 mm去離子水條件下的試驗，104天內量測到的沖蝕量相當於損失原始試體重的8.84%，當採用較低水流量時，膨潤土之沖蝕量也有明顯的下降。

藉由觀察及分析膨潤土圖像，再透過分析沖蝕試驗結束後之膨潤土試體，認為副礦物環形成最直接的原因為沖蝕是否發生，膨潤土沖蝕後若有大量蒙脫石流失，於原地停留之較粗顆粒將阻攔中型顆粒，接著較細小的顆粒也受到阻攔，這些顆粒因架橋現象(bridging)將彼此卡在適當的位置，最終形成明顯之深色副礦物環。

由結果得知越大的水流量以及裂隙內寬，將導致更嚴重的沖蝕。而水化學環境的影響則是最關鍵的，在4.00 mM的NaCl溶液的試驗中，緩衝材料將穩定維持障壁功能。

MX-80 bentonite was used for the erosion test. The turbidity of the liquid was measured from the water outlet of the device to estimate the erosion quality. The average radial expansion distance and the area of accessory minerals were measured by the image, analyze the influence of different aperture, water chemistry and water flow on the erosion of bentonite.

The most serious erosion was observed using deionized water in a large aperture (2.0 mm) and a high flow rate (1.0 mL/min) environment. 30.8% of the original weight has been lost at 93 days , And the ionic strength of 2.54 mM and 4.00 mM NaCl solution, the eroded mass measured in 63 days is less than 1.0% of the original weight. The ionic strength of groundwater is the key to the erosion of bentonite. In the test of deionized water with a flow rate 1.0 mL/min and a 0.2 mm aperture, the eroded mass measured at 93 days is equivalent to the loss of 3.68% of the original weight, so the eroded mass will decrease with the aperture. In the test of deionized water with a flow rate 0.2 mL/min and a 2.0 mm aperture, the eroded mass measured at 104 days is equivalent to the loss of 8.84% of the original weight. When a lower water flow rate is used, the eroded mass will reduce significantly.

Observe and analyze the image and the bentonite sample after the erosion test. It is believed that the formation of the accessory mineral ring is whether erosion occurs. If a large amount of montmorillonite is lost after bentonite erosion, the coarser particles staying in place will block the medium-sized and fine particles, These particles will be blocked by bridging. The bridging will jam each other in place, and eventually form a accessory mineral ring.

From the results, it is known that the large water flow and aperture will cause severe erosion. The impact of water chemistry is the most critical. In the test of 4.00 mM NaCl solution, buffer will maintain barrier function.

王欣婷，（2003），「緩衝材料在深層處置場模擬近場環境下回脹行為基礎研究」，國立中央大學土木工程研究所碩士論文，中壢。

台灣電力公司，(2017)，「我國用過核子燃料最終處置技術可行性評估報告」，台北。(TPC-SNFD2017-V1)

日本原子能研究開發機構(JAEA)，(2008)，「緩衝材の浸食現象評価－ベントナイトコロイドの生成挙動」，茨城縣。(JAEA-Research 2008-097)

莊文壽、洪錦雄、董家寶，（2000），「深層地質處置技術之研究」，核研季刊，第三十七期、第44-54頁。

陳文泉，(2004)，「高放射性廢棄物深層地質處置緩衝材料之回脹行為研究」，國立中央大學土木工程研究所博士論文，中壢。

鄭百宏，(2014)，「緩以膨潤土製作緩衝回填材料之性能評估」，國立台灣大學土木工程學系研究所碩士論文，台北。

Birgersson, M., Hedström, M., and Karnland, O. (2011) “Sol formation ability of Ca/Na-montmorillonite at low ionic strength.” Physics and Chemistry of the Earth, 36 (2011) 1572–1579

Huang, W.H., and Chen, W.C. (2004) “Swelling behavior of a buffer material under simulated near field environment.” Journal of Nuclear Science and Technology, 41(12), 1271-1279.

Hedström, M., Birgersson, M., Nilsson, U., and Karnland, O., (2011) “Role of cation mixing in the sol formation of Ca/Na-montmorillonite. ” Physics and Chemistry of the Earth, 36 (2011) 1564–1571

Juvankoski, M., Ikonen, K., and Jalonen, T. (2012) Buffer production line 2012: Design, production and initial state of the buffer. Posiva Oy, Eurajoki. (Posiva 2012-17)

Kiviranta, L. and Kumpulainen, S. (2011) Quality control and characterisation of bentonite materials. Posiva Oy, Eurajoki. (Working Report 2011-84)

Mitchell, J.K. (1993) Fundamentals of Soil Behavior, 2nd ed, Wiley, New York.

NWMO. (2010), Laboratory Bentonite Erosion Experiments in a Synthetic and a Natural Fracture, Nuclear Waste Management Organization(Canada), Toronto. (NWMO TR-2010-16)

Reid, C., Lunn, R., Mountassir, G.E., and Tarantino, A. (2015) “A mechanism for bentonite buffer erosion in a fracture with a naturally varying aperture.” Mineralogical Magazine, The Mineralogical Society of Great Britain & Ireland, Vol. 79(6), pp. 1485–1494.

SKB. (1983), Final Storage of Spent Nuclear Fuel – KBS-3, Swedish Nuclear Fuel and Waste Management Co. Stockholm, Sweden.

SKB. (2002), The buffer and backfill handbook part 2: materials and techniques, Swedish Nuclear Fuel and Waste Management Co. Stockholm, Sweden. (SKB TR-02-12)

SKB. (2006a), Montmorillonite stability with special respect to KBS-3 conditions, Swedish Nuclear Fuel and Waste Management Co. Stockholm, Sweden. (SKB TR-06-11)

SKB. (2006b), Physical and chemical stability of the bentonite buffer, Swedish Nuclear Fuel and Waste Management Co. Stockholm, Sweden. (SKB R-06-103)

SKB. (2009a), Bentonite erosion Laboratory studies, Swedish Nuclear Fuel and Waste Management Co. Stockholm,Sweden.(SKB TR-09-33)

SKB. (2009b), Bentonite erosion Final report, Swedish Nuclear Fuel and Waste Management Co. Stockholm, Sweden. (SKB TR-09-34)

SKB. (2009c), Mechanisms and models for bentonite erosion, Swedish Nuclear Fuel and Waste Management Co. Stockholm, Sweden. (SKB TR-09-35)

SKB. (2011a), Environmental Impact Statement, Interim storage, encapsulation and final disposal of spent nuclear fuel, March 2011, ISBN 978-91-978702-5-2.

SKB. (2011b), Long-term safety for the final repository for spent nuclear fuel at Forsmark, Swedish Nuclear Fuel and Waste Management Co. Stockholm, Sweden. (SKB TR-11-01)

SKB. (2019), Bentonite expansion, sedimentation and erosion in artificial fractures, Swedish Nuclear Fuel and Waste Management Co. Stockholm, Sweden. (SKB TR-19-08)