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The effect of gamma irradiation on hardening self-compacting mortar in the Belgian Supercontainer concept for high level radioactive waste disposal

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Abstract
For the disposal of vitrified high level waste assemblies, which are highly active (high concentration of beta and gamma radiation resulting in heat emitted by this type of waste), the use of cylindrical concrete supercontainers is considered as the reference design in Belgium, based on the use of an integrated waste package composed of a carbon steel overpack surrounded by a massive concrete buffer based on Ordinary Portland Cement. Once the buffer is cast and hardened sufficiently in controlled environment, the radwaste is emplaced inside the buffer, the remaining gap is filled by casting a fresh mortar material (the filling) and the container is closed by fitting the lid. As a consequence, the concrete buffer, the filling and the lid, will be exposed to the effect of the heat-emitting radioactive waste during hardening (the filling) and in a hardened state (the buffer and the lid). The effect of gamma radiation (with a relevant dose rate) on the strength of the hardening filling is investigated in a preliminary study, by means of compressive strength tests, sample weighing, fluorescence microscopic test methods and scanning electron microscopy, to verify whether a possible strength loss can be noticed and to identify the main mechanisms behind the strength variations, e.g. by evaluating the possible changes in capillary porosity or to evaluate the drying process due to gamma irradiation. Furthermore, the simulations of the early-age behaviour of the concrete buffer of the supercontainer indicate a possible macro cracking risk of the outer concrete buffer, mainly devoted to the thermal expansive behaviour of the carbon steel overpack. The main goal is to prevent through-going concrete macro cracking of the buffer and the filler material, as it facilitates transport mechanisms of aggressive species once placed in the underground disposal galleries and this might jeopardize the durability of the radiological Second International Conference on Microstructural- elated Durability of Cementitious Composites, 11-13 April 2012, Amsterdam, The Netherlands Second International Conference on Microstructural-related Durability of Cementitious Composites, 11-13 April 2012, Amsterdam, The Netherlands protection medium. An efficient way to overcome this cracking nature can be achieved by reducing the modulus of elasticity of the filler material, which can be a consequence of irradiation by means of gamma rays during hardening of the cementitious filling.

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MLA
Craeye, Bart, Geert De Schutter, I Gerardy, et al. “The Effect of Gamma Irradiation on Hardening Self-compacting Mortar in the Belgian Supercontainer Concept for High Level Radioactive Waste Disposal.” Microstructural-related Durability of Cementitious Composites, RILEM Proceedings PRO 83. Ed. Guang Ye et al. Bagneux, France: RILEM Publications, 2012. 1–8. Print.
APA
Craeye, B., De Schutter, G., Gerardy, I., De Raemaeker, M., & Gevers, K. (2012). The effect of gamma irradiation on hardening self-compacting mortar in the Belgian Supercontainer concept for high level radioactive waste disposal. In G. Ye, K. van Breugel, W. Sun, & C. Miao (Eds.), Microstructural-related Durability of Cementitious Composites, RILEM Proceedings PRO 83 (pp. 1–8). Presented at the 2nd International Conference on Microstructural-related Durability of Cementitious Composites, Bagneux, France: RILEM Publications.
Chicago author-date
Craeye, Bart, Geert De Schutter, I Gerardy, M De Raemaeker, and K Gevers. 2012. “The Effect of Gamma Irradiation on Hardening Self-compacting Mortar in the Belgian Supercontainer Concept for High Level Radioactive Waste Disposal.” In Microstructural-related Durability of Cementitious Composites, RILEM Proceedings PRO 83, ed. Guang Ye, Klaas van Breugel, Wei Sun, and Changwen Miao, 1–8. Bagneux, France: RILEM Publications.
Chicago author-date (all authors)
Craeye, Bart, Geert De Schutter, I Gerardy, M De Raemaeker, and K Gevers. 2012. “The Effect of Gamma Irradiation on Hardening Self-compacting Mortar in the Belgian Supercontainer Concept for High Level Radioactive Waste Disposal.” In Microstructural-related Durability of Cementitious Composites, RILEM Proceedings PRO 83, ed. Guang Ye, Klaas van Breugel, Wei Sun, and Changwen Miao, 1–8. Bagneux, France: RILEM Publications.
Vancouver
1.
Craeye B, De Schutter G, Gerardy I, De Raemaeker M, Gevers K. The effect of gamma irradiation on hardening self-compacting mortar in the Belgian Supercontainer concept for high level radioactive waste disposal. In: Ye G, van Breugel K, Sun W, Miao C, editors. Microstructural-related Durability of Cementitious Composites, RILEM Proceedings PRO 83. Bagneux, France: RILEM Publications; 2012. p. 1–8.
IEEE
[1]
B. Craeye, G. De Schutter, I. Gerardy, M. De Raemaeker, and K. Gevers, “The effect of gamma irradiation on hardening self-compacting mortar in the Belgian Supercontainer concept for high level radioactive waste disposal,” in Microstructural-related Durability of Cementitious Composites, RILEM Proceedings PRO 83, Amsterdam, The Netherlands, 2012, pp. 1–8.
@inproceedings{2106103,
  abstract     = {For the disposal of vitrified high level waste assemblies, which are highly active (high concentration of beta and gamma radiation resulting in heat emitted by this type of waste), the use of cylindrical concrete supercontainers is considered as the reference design in Belgium, based on the use of an integrated waste package composed of a carbon steel overpack surrounded by a massive concrete buffer based on Ordinary Portland Cement. Once the buffer is cast and hardened sufficiently in controlled environment, the radwaste is emplaced inside the buffer, the remaining gap is filled by casting a fresh mortar material (the filling) and the container is closed by fitting the lid. As a consequence, the concrete buffer, the filling and the lid, will be exposed to the effect of the heat-emitting radioactive waste during hardening (the filling) and in a hardened state (the buffer and the lid). The effect of gamma radiation (with a relevant dose rate) on the strength of the hardening filling is investigated in a preliminary study, by means of compressive strength tests, sample weighing, fluorescence microscopic test methods and scanning electron microscopy, to verify whether a possible strength loss can be noticed and to identify the main mechanisms behind the strength variations, e.g. by evaluating the possible changes in capillary porosity or to evaluate the drying process due to gamma irradiation. Furthermore, the simulations of the early-age behaviour of the concrete buffer of the supercontainer indicate a possible macro cracking risk of the outer concrete buffer, mainly devoted to the thermal expansive behaviour of the carbon steel overpack. The main goal is to prevent through-going concrete macro cracking of the buffer and the filler material, as it facilitates transport mechanisms of aggressive species once placed in the underground disposal galleries and this might jeopardize the durability of the radiological Second International Conference on Microstructural- elated Durability of Cementitious Composites, 11-13 April 2012, Amsterdam, The Netherlands Second International Conference on Microstructural-related Durability of Cementitious Composites, 11-13 April 2012, Amsterdam, The Netherlands protection medium. An efficient way to overcome this cracking nature can be achieved by reducing the modulus of elasticity of the filler material, which can be a consequence of irradiation by means of gamma rays during hardening of the cementitious filling.},
  author       = {Craeye, Bart and De Schutter, Geert and Gerardy, I and De Raemaeker, M and Gevers, K},
  booktitle    = {Microstructural-related Durability of Cementitious Composites, RILEM Proceedings PRO 83},
  editor       = {Ye, Guang and van Breugel, Klaas and Sun, Wei and Miao, Changwen},
  isbn         = {9782351581292},
  language     = {eng},
  location     = {Amsterdam, The Netherlands},
  pages        = {1--8},
  publisher    = {RILEM Publications},
  title        = {The effect of gamma irradiation on hardening self-compacting mortar in the Belgian Supercontainer concept for high level radioactive waste disposal},
  year         = {2012},
}