Water uptake-induced pressure development by French bituminized radioactive waste products under nearly constant volume conditions

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Water uptake-induced pressure development by French bituminized radioactive waste products under nearly constant volume conditions. / Bleyen, Nele; Smets, Steven; Verwimp, Wim; Van Gompel, Veerle; Valcke, Elie; Lautru, Joseph; Poulesquen, A.; Leclerc, A.; Champenois, J.B.

In: Journal of Nuclear Materials, Vol. 561, 153569, 01.04.2022, p. 1-14.

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@article{dcf918b8e0194933b08b6411840729f5,
title = "Water uptake-induced pressure development by French bituminized radioactive waste products under nearly constant volume conditions",
abstract = "Water uptake and salt leaching of two simulated French Bituminized Waste Products (BWP) have been investigated under nearly constant volume conditions. The resulting pressure development was monitored during 5 to 6 years for two simulated BWP samples, varying one from the other by their inorganic load and composition. Pressure development induced by water uptake is mainly the result of two processes: (1) an osmotic phenomenon due to the presence of soluble and hygroscopic salts (NaNO 3 and Na 2 SO 4 ) embedded in the bitumen matrix and (2) recrystallization of anhydrous Na 2 SO 4 into its decahydrate form, leading to an important volumetric expansion. After a certain hydration period, the pressure exerted by the hydrating BWP stabilizes when the pressure generating phenomena are fully counteracted by the leaching of soluble salts via out-diffusion, reconsolidation of pores in highly leached parts of the BWP, and/or some creep of the BWP into the technical voids of the water uptake cells. For one of the French BWP, this already occurred after 1 year of hydration. Differences are found in the pressure evolution and increase rate of the two studied BWP, though a much larger difference is observed when comparing the results of the French BWP to a Belgian BWP, i.e. Eurobitum. The faster pressure development observed for the French BWPs can be attributed to the differences in the soluble salt content, the inorganic load, the content of recrystallizing salts, but also to the presence of insoluble salts such as BaSO 4 , which seems to facilitate the water uptake rate in the French BWP. The faster hydration in French BWP results in a larger fraction of salts becoming available for osmosis and recrystallization within a relatively short time frame, thereby explaining the faster pressure build-up. On the other hand, BaSO 4 does not seem to affect the leaching of soluble salts from BWP directly.",
keywords = "Bituminized waste products, Osmosis, Recrystallization, Leaching, Pressure build-up",
author = "Nele Bleyen and Steven Smets and Wim Verwimp and {Van Gompel}, Veerle and Elie Valcke and Joseph Lautru and A. Poulesquen and A. Leclerc and J.B. Champenois",
note = "Score=10",
year = "2022",
month = apr,
day = "1",
doi = "10.1016/j.jnucmat.2022.153569",
language = "English",
volume = "561",
pages = "1--14",
journal = "Journal of Nuclear Materials",
issn = "0022-3115",
publisher = "Elsevier",

}

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TY - JOUR

T1 - Water uptake-induced pressure development by French bituminized radioactive waste products under nearly constant volume conditions

AU - Bleyen, Nele

AU - Smets, Steven

AU - Verwimp, Wim

AU - Van Gompel, Veerle

AU - Valcke, Elie

AU - Lautru, Joseph

AU - Poulesquen, A.

AU - Leclerc, A.

AU - Champenois, J.B.

N1 - Score=10

PY - 2022/4/1

Y1 - 2022/4/1

N2 - Water uptake and salt leaching of two simulated French Bituminized Waste Products (BWP) have been investigated under nearly constant volume conditions. The resulting pressure development was monitored during 5 to 6 years for two simulated BWP samples, varying one from the other by their inorganic load and composition. Pressure development induced by water uptake is mainly the result of two processes: (1) an osmotic phenomenon due to the presence of soluble and hygroscopic salts (NaNO 3 and Na 2 SO 4 ) embedded in the bitumen matrix and (2) recrystallization of anhydrous Na 2 SO 4 into its decahydrate form, leading to an important volumetric expansion. After a certain hydration period, the pressure exerted by the hydrating BWP stabilizes when the pressure generating phenomena are fully counteracted by the leaching of soluble salts via out-diffusion, reconsolidation of pores in highly leached parts of the BWP, and/or some creep of the BWP into the technical voids of the water uptake cells. For one of the French BWP, this already occurred after 1 year of hydration. Differences are found in the pressure evolution and increase rate of the two studied BWP, though a much larger difference is observed when comparing the results of the French BWP to a Belgian BWP, i.e. Eurobitum. The faster pressure development observed for the French BWPs can be attributed to the differences in the soluble salt content, the inorganic load, the content of recrystallizing salts, but also to the presence of insoluble salts such as BaSO 4 , which seems to facilitate the water uptake rate in the French BWP. The faster hydration in French BWP results in a larger fraction of salts becoming available for osmosis and recrystallization within a relatively short time frame, thereby explaining the faster pressure build-up. On the other hand, BaSO 4 does not seem to affect the leaching of soluble salts from BWP directly.

AB - Water uptake and salt leaching of two simulated French Bituminized Waste Products (BWP) have been investigated under nearly constant volume conditions. The resulting pressure development was monitored during 5 to 6 years for two simulated BWP samples, varying one from the other by their inorganic load and composition. Pressure development induced by water uptake is mainly the result of two processes: (1) an osmotic phenomenon due to the presence of soluble and hygroscopic salts (NaNO 3 and Na 2 SO 4 ) embedded in the bitumen matrix and (2) recrystallization of anhydrous Na 2 SO 4 into its decahydrate form, leading to an important volumetric expansion. After a certain hydration period, the pressure exerted by the hydrating BWP stabilizes when the pressure generating phenomena are fully counteracted by the leaching of soluble salts via out-diffusion, reconsolidation of pores in highly leached parts of the BWP, and/or some creep of the BWP into the technical voids of the water uptake cells. For one of the French BWP, this already occurred after 1 year of hydration. Differences are found in the pressure evolution and increase rate of the two studied BWP, though a much larger difference is observed when comparing the results of the French BWP to a Belgian BWP, i.e. Eurobitum. The faster pressure development observed for the French BWPs can be attributed to the differences in the soluble salt content, the inorganic load, the content of recrystallizing salts, but also to the presence of insoluble salts such as BaSO 4 , which seems to facilitate the water uptake rate in the French BWP. The faster hydration in French BWP results in a larger fraction of salts becoming available for osmosis and recrystallization within a relatively short time frame, thereby explaining the faster pressure build-up. On the other hand, BaSO 4 does not seem to affect the leaching of soluble salts from BWP directly.

KW - Bituminized waste products

KW - Osmosis

KW - Recrystallization

KW - Leaching

KW - Pressure build-up

UR - https://ecm.sckcen.be/OTCS/llisapi.dll/open/47970908

U2 - 10.1016/j.jnucmat.2022.153569

DO - 10.1016/j.jnucmat.2022.153569

M3 - Article

VL - 561

SP - 1

EP - 14

JO - Journal of Nuclear Materials

JF - Journal of Nuclear Materials

SN - 0022-3115

M1 - 153569

ER -

ID: 7397282