Experimental study of the contact interaction relaxation between fuel elements and spacer grid cells

Fuel elements and spacer grids are parts of the fuel assembly in nuclear reactors. The fuel elements are inserted in spacer grid cells with interference. During the operation of a nuclear reactor, the contact forces between the fuel rods and spacer grid cells decrease, which leads to the slippage of fuel rods in the cells, and this in turn reduces the rigidity of the fuel assembly. Since the contact interaction relaxation process is not currently fully understood, the assembly deformation cannot be adequately analyzed during the reactor operation. This article presents the results of experimental studies of the contact interaction relaxation of the fuel elements in spacer grid cells. The experiments showed that the contact force relaxation in a fuel element – spacer grid cell pair is significant and depends on its temperature and initial interference.

References

[1] Dragunov Iu.G., Ryzhov S.B., Vasil’chenko I.N., Kobelev S.N. Razrabotka i vnedrenie TVS-2M dlia perspektivnykh toplivnykh tsiklov [Elaboration and Implementation of TBC-2M Designs with Increased Fuel Loading for Perspective Fuel Cycles with the Extended Operating Periods]. Atomnaia energiia [Atomic Energy]. 2005, vol. 99, no. 6, pp. 432–437.

[2] Semishkin V.P. Raschetno-eksperimental’nye metody obosnovaniia povedeniia TVELov i TVS VVER v avariinykh rezhimakh s bol’shoi tech’iu iz pervogo kontura RU. Diss. dokt. tekh. nauk [Calculation and experimental methods and study the behavior of VVER fuel rods in emergency mode with the big leak from the primary circuit of the reactor facility. Dr. tech. sci. diss.]. Podol’sk, 2007. 360 p.

[3] Troianov V.M. Raschetno-eksperimental’noe obosnovanie termomekhaniki aktivnykh zon reaktorov tipa VVER. Diss. dokt. tekh. nauk [Numerical and experimental study of active zones thermomechanics VVER reactors. Dr. tech. sci. diss.]. Obninsk, 2003. 237 p.

[4] Wang Z.G., Yoshikawa Y., Suzuki T., Osakada K. Determination of friction law in dry metal forming with DLC coated tool. CIRP Annals — Manufacturing Technology, 2014, vol. 63, issue 1, pp. 277–280. Available at: http://dx.doi.org/10.1016/j.cirp.2014.03.050 (accessed 2 June 2014).

[5] Puzanov D.N., Satin A.A. Analiz i obobshchenie dannykh po svoistvam tsirkonievykh splavov, primeniaiushchikhsia v kachestve konstruktsionnykh materialov [Analysis and synthesis of data on the properties of zirconium alloys are used as structural materials]. Nauchno-tekhnicheskaia konferentsiia molodykh spetsialistov: Materialy konferentsii OKB «Gidropress», 16–17 marta 2011 g. [Scientific and technical conference of young specialists: Conference OKB «Hydraulic», 16–17 March 2011]. Available at: http://www.gidropress.podolsk.ru/files/proceedings/kms2011/documents/kms2011-013.pdf (accessed 20 May 2014).

[6] Danilov V.L., Dobrov M.V., Semishkin V.P., Vasilchenko I.N. Analysis of Dismantling Possibility and Unloading Efforts of Fuel Assemblies from Core of WWER. Proceedings of the 6th International Conference WWER FUEL Performance, Modelling and Experiment Support, 19–23 September 2005, Albena, Bulgaria, pp. 319–327.