Determining time of the complete relaxation of contact interaction between the fuel clad and the elastic spacer grid cell in WWER fuel assembly

Fuel rods and spacer grids are the main elements of the power reactor fuel assembly. The fuel rods are fixed inside the spacer grid cells with negative allowance. Negative allowance produces contact forces between the fuel rod and the spacer grid cell. Contact forces are reduced to zero during the fuel assembly’s operating because there are high temperature and intense neutron fields in the power reactor core. Reducing contact forces is the relaxation of contact interaction. The relaxation of contact interaction only due to temperature effects is considered. The relaxation causes slippage between the fuel rod and the spacer grid cell. Slippage time determination and and finding solution to the problem of relaxation are urgent because slippage of the fuel rods causes the intensive process of fuel clad fretting wear, as well as the reduction of fuel assembly stiffness.

References

[1] Zinkevich О. Metod konechnykh elementov v tekhnike [Finite-element method in engineering]. Moscow, Mir Publ., 1975. 343 p.

[2] Golan O., Arbel A., Eliezer D., Moreno D. The applicability of Norton’s creep power law and its modified version to a single-crystal superalloy type CMSX-2. Materials Science and Engineering, 1996, A216, pp. 125-130.

[3] Troyanov V.M. Raschetno-eksperimental’noe obosnovanie termomekhaniki aktivnykh zon reaktorov tipa VVER. Diss. dokt. tekhn. nauk [Calculated experimental justification of thermomechanics of the nuclear reactor core in terms of pressurized water type reactor. Dr. tehn. sci. diss.]. Obninsk, 2003. 237 p.

[4] Dragunov Yu.G., Ryzhov S.B., Vasil’chenko I.N., Kobelev S.N. [Development and application of TVC-2M for future fuel cycles]. Atomnaya energiya, 2005, vol. 99, pp. 432-437 (in Russ.).

[5] Gusev M.P., Danilov V.L. Experimental study of contact interaction relaxation of a fuel element and a spacer grid cell. Izv. Vyssh. Uchebn. Zaved., Mashinostr. [Proc. Univ., Mech. Eng.], 2014, no. 10, pp. 64-69 (in Russ.).

[6] Puzanov D.N. Satin A.A. Data analysis and collation according to zirconium alloy properties being used as engineering structural materials. Sci. and Tech. Conf. of Young Professionals: Conf. Proc. OKB "Gidropress", March 16-17, 2011. URL: http://www.gidropress.podolsk.ru/files/proceedings/kms2011/documents/kms2011-013.pdf (accessed 20.05.2014).

[7] Semishkin V.P. Raschetno-eksperimental’nye metody obosnovaniya povedeniya tvelov i TVS VVER v avariynykh rezhimakh s bol’shoy tech’yu iz pervogo kontura RU. Diss. dokt. tekhn. nauk [Calculated experimental methods for validating the behavior of nuclear fuel elements and a fuel-rod array of the pressurized water type reactor in emergency operations with a large break in the primary coolant circuit of the reactor unit equipment. Dr. tehn. sci. diss.]. Podol’sk, 2007. 360 p.

[8] Gusev M.P., Danilov V.L. Creep inverse problem of the power reactor fuel assembly elements contact interaction. Applied Mechanics and Materials, 2015, vol. 698, pp. 643-648. doi: 10.4028/www.scientific.net/AMM.698.643