Comparison of various methods for modeling uranium dioxide fuel pellet cracking

During the operation of a fuel element, a large number of complex physical processes take place within it. Existing integrated codes use numerous simplifying assumptions to describe these processes in order to reduce computational complexity. However, a more in-depth study of some individual phenomena would be of great interest. The paper presents a simulation of the uranium dioxide pellet cracking in a fuel element section when the heat dissipation power reaches its nominal value. A mathematical model based on the axisymmetric thermoelastic approximation is used. The numerical model is developed using the finite element method. Two methods were used to analyze the cracking of the material: the smeared crack model and the discrete crack method. Two calculations were performed and a comparative analysis of the stress fields obtained for the two methods was carried out. The results showed that the smeared crack model allowed to reduce the tensile stresses to a level below the ultimate strength of the material, while the discrete crack model led to a multiple decrease only in axial stresses.
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References

[1] Yagnik S. Fuel analysis and licensing code: FALCON MOD01. Vol. 1. Theoretical and numerical bases. EPRI, Palo Alto, CA. 2004. 246 p.

[2] Bolshov L.A., ed. Trudy IBRAE RAN. Vyp. 12. Razrabotka i primenenie integralnykh kodov dlya analiza bezopasnosti [Proceedings of IBRAE RAS. Iss. 12. Integral codes development and application for NPP safety analysis]. Moscow, Nauka Publ., 2011. 300 p. (In Russ.).

[3] Tarasov A.E., Chalyy R.V., Tomashchik D.Yu. et al. Investigation of thermomechanical behavior of vver fuel rod claddings with SOCRAT/B1 code. VANT. Ser. Fizika yadernykh reaktorov [Problems of Atomic Science and Engineering], 2019, no. 2, pp. 91–99. (In Russ.).

[4] Vatulin A.V., Kashirin B.A., Temis Yu.M. Accounting for asymmetric factors in the calculation of dispersion fuel rods based on half-space rod theory. Preprint VNIINM im. A.A. Bochvara, 2002, no. 2. 33 p. (In Russ.).

[5] Kuznetsov V.I., Demyanov P.G., Khankov A.A. et al. [Irradiation of uranium disilicide fuel pellets: verification of the START-4A code]. Tez. dok. XII Mezhd. konf. po reaktornomu materialovedeniyu [Abs. 12th Int. Conf. on Reactor Materials Science]. Dimitrovgrad, GNTs NIIAR Publ., 2024, pp. 126–128. (In Russ.).

[6] Frost B.R.T. Nuclear fuel elements. Pergamon press, 1982. 275 p. (Russ. ed.: TVELy yadernykh reaktorov. Moscow, Energoatomizdat Publ., 1986. 248 p.)

[7] Galanin M.P., Rodin A.S. Solution to a coupled problem of thermomechanical contact of fuel elements. Prikladnaya mekhanika i tekhnicheskaya fizika, 2024, vol. 65, no. 2, pp. 99–109, doi: https://doi.org/10.15372/PMTF202315387 (in Russ.). (Eng. version: J. Appl. Mech. Tech. Phy., 2024, vol. 65, no. 2, pp. 265–273, doi: https://doi.org/10.1134/S0021894424020081)

[8] Kachanov L.M. Osnovy mekhaniki razrusheniya [Fundamentals of fracture mechanics]. Moscow, Nauka Publ., 1974. 312 p. (In Russ.).

[9] Besson J., Cailletaud G., Chaboche J.-L. et al. Non-linear mechanics of materials. Springer, 2010. 433 p.

[10] Lemaitre J. A course on damage mechanics. Springer, 1996. 228 p.

[11] Dahlblom O., Ottosen N.S. Smeared crack analysis of concrete using a nonlinear fracture model. In: Fracture Mechanics of Concrete. Nordic Seminar Held at Division of Building Materials. Lund Institute of Materials, 1986, pp. 31–46.

[12] Hillerborg A. Application of the fictitious crack model to different types of materials. Int. J. Fract., 1991, vol. 51, no. 2, pp. 95–102, doi: https://doi.org/10.1007/BF00033972

[13] Suzuki M., Saitou H. Light water reactor fuel analysis code FEMAXI-6. Detailed structure and user’s manual. Japan Atomic Energy Agency, 2006. 415 p.

[14] Galanin M.P., Lukin V.V., Rodin A.S. et al. Fracture model for brittle material under the thermal loads. Vestn. Mosk. Gos. Tekh. Univ. im. N.E. Baumana, Estestv. Nauki [Herald of the Bauman Moscow State Tech. Univ., Nat. Sci.], 2014, no. 6, pp. 96–118. EDN: TCSEKV (In Russ.).

[15] Zarubin V.S., Kuvyrkin G.N. Matematicheskie modeli termomekhaniki [Mathematical models of thermomechanics]. Moscow, Fizmatlit Publ., 2002. 168 p. (In Russ.).

[16] SCDAP/RELAP5/MOD3.1 Code Manual. Vol. IV. MATPRO — a library of materials. Properties for light-water-reactor accident analysis. Idaho National Engineering Laboratory, 1995. 668 p.

[17] Bathe K.-J. Finite element procedures. Prentice-Hall, 1996. 1037 p.

[18] Marchal N., Campos C., Gamier S. Finite element simulation of Pellet-Cladding Interaction (PCI) in nuclear fuel rods. Comput. Mater. Sci., 2009, vol. 45, no. 3, pp. 821–826, doi: https://doi.org/10.1016/j.commatsci.2008.10.015

[19] Wriggers P. Computational contact mechanics. Springer, 2006. 518 p.

[20] Galanin M.P., Rodin A.S. Investigation and application of the domain decomposition method for simulating fuel elements. Zhurnal vychislitelnoy matematiki i matematicheskoy fiziki, 2022, vol. 62, no. 4, pp. 659–676. (In Russ.). (Eng. version: Comput. Math. and Math. Phys., 2022, vol. 62, no. 4, pp. 641–657, doi: https://doi.org/10.1134/S0965542522040078)