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Research Papers

An Finite Element Method Study of the Thermal Conductivity of Polycrystalline UO2

[+] Author and Article Information
Enze Jin

State Power Investment Central
Research Institute,
Beijing 102209, China

Chen Liu

Beijing Research Institute of Chemical
Engineering and Metallurgy,
Beijing 102209, China

Heming He

State Power Investment Central
Research Institute,
Beijing 102209, China
e-mail: heheming@snptc.com.cn

1Corresponding author.

Manuscript received September 8, 2016; final manuscript received June 17, 2017; published online July 31, 2017. Assoc. Editor: Guoqiang Wang.

ASME J of Nuclear Rad Sci 3(4), 041006 (Jul 31, 2017) (10 pages) Paper No: NERS-16-1099; doi: 10.1115/1.4037189 History: Received September 08, 2016; Revised June 17, 2017

A finite element method (FEM) is applied to investigate the thermal conductivity of polycrystalline UO2. The influences of microstructure are especially important for UO2 due to the severe structural changes under irradiation conditions. In this study, we have investigated the influences of microstructures on the thermal conductivity of polycrystalline UO2 using FEM. The temperature profile of fuel pellet with different microstructures during service is also investigated. The thermal conductivity increases with increasing grain size. The grain size distribution has obvious influence on the thermal conductivity especially when there are pores in the polycrystal. The influences of porosity and pore size are very sensitive to the position of the pores. The results obtained in this study are useful for the prediction of property changes of UO2 fuel in pile and important to gain some design guidance to tune the properties through the control of the microstructure.

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References

Albarhoum, M. , 2011, “ Performance of UO2 Ceramic Fuel in Low-Power Research Reactors,” Prog. Nucl. Energy, 53(1), pp. 73–75. [CrossRef]
Lucuta, P. G. , Matzke, H. , and Hastings, I. J. , 1996, “ A Pragmatic Approach to Modelling Thermal Conductivity of Irradiated UO2 Fuel: Review and Recommendations,” J. Nucl. Mater., 232(2–3), pp. 166–180. [CrossRef]
An, C. , Moreira, F. C. , and Su, J. , 2014, “ Thermal Analysis of the Melting Process in a Nuclear Fuel Rod,” Appl. Therm. Eng., 68(1–2), pp. 133–143. [CrossRef]
Soba, A. , Lemes, M. , González, M. E. , Denis, M. , and Romero., L. , 2014, “ Simulation of the Behaviour of Nuclear Fuel Under High Burnup Conditions,” Ann. Nucl. Energy, 70, pp. 147–156. [CrossRef]
Hyland, G. J. , 1983, “ Thermal Conductivity of Solid UO2: Critique and Recommendation,” J. Nucl. Mater., 113(2–3), pp. 125–132. [CrossRef]
Higuch, S. , 1998, “ A Molecular Dynamics Study of Thermal Conductivity of UO2 with Imupurities,” J. Nucl. Sci. Technol., 35(11), pp. 833–835.
Millett, P. C. , Tonks, M. R. , Chockalingam, K. , Zhang, Y. , and Biner, S. B. , 2013, “ Three Dimensional Calculations of the Effective Kapitza Resistance of UO2 Grain Boundaries Containing Intergranular Bubbles,” J. Nucl. Mater., 439(1–3), pp. 117–122. [CrossRef]
Harding, J. H. , and Martin, D. G. , 1989, “ A Recommendation for the Thermal Conductivity of UO2,” J. Nucl. Mater., 166(3), pp. 223–226. [CrossRef]
Konings, R. G. M. , Wiss, T. , and Beneš, O. , 2015, “ Predicting Material Release During a Nuclear Reactor Accident,” Nat. Mater., 14(3), pp. 247–252. [CrossRef] [PubMed]
Yang, H. S. , Bai, G. R. , Thompson, L. J. , and Eastman, J. A. , 2002, “ Interfacial Thermal Resistance in Nanocrystalline Yttria-Stabilized Zirconia,” Acta Mater., 50(9), pp. 2309–2317. [CrossRef]
Nikolopoulos, P. , and Ondracek, G. , 1983, “ Conductivity Bounds for Porous Nuclear Fuels,” J. Nucl. Mater., 114(2–3), pp. 231–233. [CrossRef]
Albrecht, J. D. , Knipp, P. A. , and, Reinecke, T. L. , 2001, “ Thermal Conductivity of Opals and Related Composites,” Phys. Rev. B, 63(13), p. 134303. [CrossRef]
Loeb, A. L. , 1954, “ Thermal Conductivity 8. A Theory of Thermal Conductivity of Porous Materials,” J. Am. Ceram. Soc., 37(2), pp. 96–99. [CrossRef]
Bakker, K. , Kwast, H. , and Cordfunke, E. H. P. , 1995, “ Determination of a Porosity Correction Factor for the Thermal Conductivity of Irradiated UO2 Fuel by Means of the Finite Element Method,” J. Nucl. Mater., 226(1–2), pp. 128–143. [CrossRef]
Nichenko, S. , and Staicu, D. , 2014, “ Thermal Conductivity of Porous UO2: Molecular Dynamics Study,” J. Nucl. Mater., 454(1–3), pp. 315–322. [CrossRef]
Millett, P. C. , and Tonks, M. , 2011, “ Meso-Scale Modeling of the Influence of Intergranular Gas Bubbles on Effective Thermal Conductivity,” J. Nucl. Mater., 412(3), pp. 281–286. [CrossRef]
Chockalingam, K. , Millett, P. C. , and Tonks, M. , 2012, “ Effects of Intergranular Gas Bubbles on Thermal Conductivity,” J. Nucl. Mater., 430(166–170), pp. 166–170. [CrossRef]
Kim, H. , Kim, M. H. , and Kaviany, M. , 2014, “ Lattice Thermal Conductivity of UO2 Using Ab-Initio and Classical Molecular Dynamics,” J. Appl. Phys., 115(12), p. 123510. [CrossRef]
Chen, T. , Chen, D. , Sencer, B. H. , and Shao, L. , 2014, “ Molecular Dynamics Simulations of Grain Boundary Thermal Resistance in UO2,” J. Nucl. Mater., 452(1–3), pp. 364–369. [CrossRef]
Williams, N. R. , Molinari, M. , Parker, S. C. , and Storr, M. T. , 2015, “ Atomistic Investigation of the Structure and Transport Properties of Tilt Grain Boundaries of UO2,” J. Nucl. Mater., 458, pp. 45–55. [CrossRef]
Kang, K. W. , Yang, J. H. , Kim, J. H. , Rhee, Y. W. , Kim, D. J. , Kim, K. S. , and Song, K. W. , 2010, “ Effects of MnO-Al2O3 on the Grain Growth and High-Temperature Deformation Strain of UO2 Fuel Pellets,” J. Nucl. Sci. Technol., 47(3), pp. 304–307. [CrossRef]
Schelling, P. K. , Phillpot, S. R. , and Keblinski, P. , 2002, “ Phonon Wave-Packet Dynamics at Semiconductor Interfaces by Molecular-Dynamics Simulation,” Appl. Phys. Lett., 80(14), p. 2484. [CrossRef]
Smith, D. S. , Fayette, S. , Grandjean, S. , Martin, C. , Telle, R. , and Tonnessen, T. , 2003, “ Thermal Resistance of Grain Boundaries in Alumina Ceramics and Refractories,” J. Am. Ceram. Soc., 86(1), pp. 105–111. [CrossRef]
Amrit, J. , 2006, “ Grain Boundary Kapitza Resistance and Grain-Arrangement Induced Anisotropy in the Thermal Conductivity of Polycrystalline Niobium at Low Temperatures,” J. Phys. D: Appl. Phys., 39(20), pp. 4472–4477. [CrossRef]
Manzel, R. , and Walker, C. T. , 2002, “ Epma and Sem of Fuel Samples From Pwr Rods With an Average Burn-up of Around 100 MWd/kgHM,” J. Nucl. Mater., 301(2–3), pp. 170–182. [CrossRef]
Sasahara, A. , and Matsumura, T. , 2008, “ Post-Irradiation Examinations Focused on Fuel Integrity of Spent Bwr-Mox and Pwr-UO2 Fuels Stored for 20 Years,” Nucl. Eng. Des., 238(5), pp. 1250–1259. [CrossRef]
Arborelius, J. , Backman, K. , Hallstadius, L. , Limbaeck, M. , Nilsson, J. , Rebensdorff, B. , Zhou, G. , Kitano, K. , Loefstroem, R. , and Roennberg, G. , 2006, “ Advanced Doped UO2 Pellets in LWR Applications,” J. Nucl. Sci. Technol., 43(9), pp. 967–976. [CrossRef]
Harada, Y. , 1997, “ UO2 Sintering in Controlled Oxygen Atmospheres of Three-Stage Process,” J. Nucl. Mater., 245(2), pp. 217–223. [CrossRef]
Song, K. W. , Kim, K. S. , Kang, K. W. , and Jung, Y. H. , 2003, “ Grain Size Control of UO2 Pellets by Adding Heat-Treated U3O8 Particles to UO2 Powder,” J. Nucl. Mater., 317(2–3), pp. 204–211. [CrossRef]
Une, K. , Hirai, M. , Nogita, K. , Hosokawa, T. , Suzawa, Y. , Shimizu, S. , and Etoh, Y. , 2000, “ Rim Structure Formation and High Burnup Fuel Behavior of Large-Grained UO2 Fuels,” J. Nucl. Mater., 278(1), pp. 54–63. [CrossRef]
Noirot, J. , Lamontagne, J. , Nakae, N. , Kitagawa, T. , Kosaka, Y. , and Tverberg, T. , 2013, “ Heterogeneous UO2 Fuel Irradiated up to a High Burn-Up: Investigation of the HBS and of Fission Product Releases,” J. Nucl. Mater., 442(1–3), pp. 309–319. [CrossRef]
Yi, J. , Argon, A. S. , and Sayir, A. , 2005, “ Creep Resistance of the Directionally Solidified Ceramic Eutectic of Al2O3/C-ZrO2(Y2O3): Experiments and Models,” J. Eur. Ceram. Soc., 25(8), pp. 1201–1214. [CrossRef]
Zhang, J. , Su, H. , Song, K. , Liu, L. , and Fu, H. , 2011, “ Microstructure, Growth Mechanism and Mechanical Property of Al2O3-Based Eutectic Ceramic in Situ Composites,” J. Eur. Ceram. Soc., 31(7), pp. 1191–1198. [CrossRef]
Spino, J. , Cruz., H. S. , Jovani-Abril, R. , Birtcher, R. , and Ferrero, C. , 2012, “ Bulk-Nanocrystalline Oxide Nuclear Fuels—An Innovative Material Option for Increasing Fission Gas Retention, Plasticity and Radiation-Tolerance,” J. Nucl. Mater., 422(1–3), pp. 27–44. [CrossRef]
Lösönen, P. ,2000, “ On the Behaviour of Intragranular Fission Gas in UO2 Fuel,” J. Nucl. Mater., 280(1), pp. 56–72. [CrossRef]
Kashibe, S. , Une, K. , and Nogita, K. , 1993, “ Formation and Growth of Intragranular Fission Gas Bubbles in UO2 Fuels With Burnup of 6-83 GWd/T,” J. Nucl. Mater., 206(1), pp. 22–34. [CrossRef]
Song, K. W. , Young, W. L. , Myung, S. Y. , Sohn, D. , and Kang, Y. H. , 1994, “ Pore Growth in Sintered UO2,” J. Nucl. Mater., 209(3), pp. 263–269. [CrossRef]

Figures

Grahic Jump Location
Fig. 1

(a) The finite element model of polycrystalline UO2 used in the present study. The circular holes in the model represent pores. (b) In the 2D finite element model, grains are set to connect with each other via a narrow gap. (c) Simple illustration of the computational procedure to calculate temperature profiles of UO2 pellet during service.

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Fig. 2

(a) Polycrystal simulation model with different grain size: 5 μm, 10 μm, 20 μm, and 40 μm. (b) The effective thermal conductivity κeff with different grain size. (c) Effective thermal conductivity of polycrystalline UO2 at 1000 K with different grain size. The solid line represents the effective thermal conductivity calculated by Eq.(7), where the value of κ0 is 3.94 W/m·K, and Rk is 1.14 × 10−7 m2 K/W.

Grahic Jump Location
Fig. 3

(a) Radial temperature profile of UO2 pellets (radium = 0.4 cm) with different grain sizes and (b) temperature distribution inside the UO2 pellet

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Fig. 4

(a) Polycrystalline UO2 models with different topological entropies:3.5, 2.96, and 2.31. The grain size is 5 μm, and the porosity is zero. (b) Thermal conductivity of polycrystalline UO2 with different topological entropies. (c) Enlarged view of thermal conductivity of polycrystalline UO2 with different topological entropies.

Grahic Jump Location
Fig. 5

(a) Polycrystalline UO2 models with grain growth directions of 0 deg, 30 deg, 60 deg, and 90 deg. The dimension of each grain is approximately 40 μm × 10 μm. (b) Thermal conductivities of polycrystalline UO2 models with grain growth directions of 0 deg, 30 deg, 60 deg, and 90 deg. The thermal conductivity of polycrystal with no certain grain growth direction (d = 20 μm) is also shown for comparison.

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Fig. 6

(a) Polycrystalline UO2 models with porosity of 3%, 5%, and 7%. Pores are distributed randomly in the polycrystals. (b) Thermal conductivities of polycrystalline UO2 with different porosities. (c) Comparison of thermal conductivity curves of polycrystalline UO2 with 5% porosity computed in this study (solid line) and Eq. (8) (the shaded region). (d) The differences of thermal conductivity between polycrystals with grain size of 40 μm and 5 μm.

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Fig. 7

(a) Polycrystalline UO2 models pores with in different locations and (b) thermal conductivities of polycrystalline UO2 with different pore locations

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Fig. 8

(a) Polycrystalline UO2 models pores with in different pore sizes. Pores are distributed randomly in the polycrystals. (b) Thermal conductivities of polycrystalline UO2 with different pore sizes. The solid lines represent the polycrystals that all pores are randomly distributed, and the dashed lines represent the polycrystals that all pores are along GBs. (c) Radial temperature profile of UO2 pellets with different pore sizes. Pores are along the GBs. (d) Temperature distribution inside the UO2 pellet.

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Fig. 9

Thermal conductivities of polycrystals with different topological entropies under the condition of pore existence. The dashed lines represent the polycrystals that all pores are randomly distributed, and the solid lines represent the polycrystals that all pores are along GBs.

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