高放玻璃固化体深地质处置过程中溶解机理分析与计算
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摘要
对高放玻璃固化体在地质处置过程中由于地下水的侵蚀而导致玻璃体溶解的溶解机理进行了分析,利用水解反应动力学模型对不同温度、不同p H条件下的玻璃固化体溶解速率进行了计算。计算结果表明:玻璃在酸性或高温情况下溶解速率较大,60℃、p H值6时平均溶解速率在0.35 g/a左右,120℃、p H值8.5时平均溶解速率在0.8 g/a左右;在100万年这个时间尺度上,120℃、p H值8.5时玻璃的最大溶解量是80%。考虑到地下处置库中温度一般要低于60℃,地下水的p H值范围在6~10,所以最保守估计100万年玻璃固化体的溶解侵蚀分数不大于50%。
The mechanism of vitrified HLW dissolution due to ground water erosion in the process of geological disposal is analyzed. Through hydrolysis reaction kinetics,dissolution rate of vitrified HLW is calculated with different temperatures and p H values,which comes out that dissolution rate is about 0. 35 g / a with 60 ℃ and p H 6,while dissolution rate is about 0. 8 g / a with 120 ℃ and p H 8. 5; and it can be concluded that there may be a trend for dissolution rate of vitrified HLW that increases with temperatures and acidity. Among the dimension of 1 million years,the maximum dissolution load of HLW vitrified waste is 80% with 120 ℃ and p H 8. 5. When considering that the disposal temperature at 60 ℃ and the range of ground water p H is 6—10,the most conservative estimated dissolution load of vitrified HLW is less than 50% over the dimension of 1 million years.
The mechanism of vitrified HLW dissolution due to ground water erosion in the process of geological disposal is analyzed. Through hydrolysis reaction kinetics,dissolution rate of vitrified HLW is calculated with different temperatures and p H values,which comes out that dissolution rate is about 0. 35 g / a with 60 ℃ and p H 6,while dissolution rate is about 0. 8 g / a with 120 ℃ and p H 8. 5; and it can be concluded that there may be a trend for dissolution rate of vitrified HLW that increases with temperatures and acidity. Among the dimension of 1 million years,the maximum dissolution load of HLW vitrified waste is 80% with 120 ℃ and p H 8. 5. When considering that the disposal temperature at 60 ℃ and the range of ground water p H is 6—10,the most conservative estimated dissolution load of vitrified HLW is less than 50% over the dimension of 1 million years.
引文
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[2]Hellmann R,Cotte S,Cadel E.Nanometre-scale evidence for interfacial dissolution reprecipitation control of silicate glass corrosion[J].Nature Materials,2015,14:306-311.
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[4]Gin S,Jollivet P,Fournier M.The fate of silicon during glass corrosion under alkaline conditions:A mechanistic and kinetic study with the International Simple Glass[J].Geochimica et Cosmochimica Acta,2015,151:68-85.
[5]Frugier P,Gin S,Minet Y,et al.SON68 nuclear glass dissolution kinetics:Current state of knowledge and basis of the new GRAAL model[J].Journal of Nuclear Materials,2008,380:8-21.
[6]Quaranta A,Cattaruzza E,Gonella F.Modelling the ion exchange process in glass:Phenomenological approaches and perspectives[J].Materials Science&Engineering B,2008,149:133-139.
[7]Ojovan M,Pankov A,Lee W.The ion exchange phase in corrosion of nuclear waste glasses[J].Journal of Nuclear Materials,2006,358:57-68.
[8]Gin S,Jegou C,Frugier P.Theoretical consideration on the application of the AagaardHelgeson rate law to the dissolution of silicate minerals and glasses[J].Chemical Geology,2008,255:14-24.
[9]Ferrand K,Abdelouas A,Grambow B.Water diffusion in the simulated French nuclear waste glass SON68 contacting silica rich solutions:Experimental and modeling[J].Journal of Nuclear Materials,2006,355:54-67.
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[11]Munier I,Crovisier J,Grambow B.Modelling the alteration gel composition of simplified borosilicate glasses by precipitation of an ideal solid solution in equilibrium with the leachant[J].Journal of Nuclear Materials,2004,324:97-115.
[12]Strachan D,Neeway J.Effects of alteration product precipitation on glass dissolution[J].Applied Geochemistry,2014,45:144-157.
[13]Nicole Godon.Simulations experimentales des interactions verres/materiaux d’environnement des essais en laboratoire aux tests in-situ[C]//Le Verre Recherche Scientifique pour un Confinement de Haute Performance,1997.
[14]Nicole Godon,Yves MINET,Isabelle RIBET.Leaching of full-scale fractured glass blocks[R].International Topical Workshop on glass in its disposal environment.Bruges,2000.
[15]Ray B,Stout,Herman R,Leider R.Waste form characteristics report[R].Revision 1.UCRLID-108314.Version 1.3.1998.
[16]George G,Wicks.US field testing programs and results[J].Journal of Nuclear Materials,2001,298:78-85.
[17]US Department of Energy.Defense HLW glass degradation Model[R].ANL-EBS-MD-000016 REV 02.2004.