Izvestiya vuzov. Yadernaya Energetika

The peer-reviewed scientific and technology journal. ISSN: 0204-3327

Study of the dependence of the cladding – fuel pellet gap conductance coefficient on the fuel burn-up and the effects on the neutronic characteristics of the reactor core

11/15/2018 2018 - #04 Physics and technology of nuclear reactors

Vygovskiy S.B. Gruzdov F.V. Al Malkawi R.T.

DOI: https://doi.org/10.26583/npe.2018.4.02

UDC: 621.039.50

This paper presents the results of the research to study the dependence of the VVER-1000 (1200) reactor core neutronic characteristics on the cladding – fuel pellet gap conductance coefficient in the process of the fuel burn-up. The purpose of the study was to determine more accurately the dependence of the cladding – fuel pellet gap conductance coefficient on the fuel burn-up as shown in the Final Safety Report for the Bushehr NPP and to determine the extent of the effects this dependence had on the spatial distribution of the neutron field, on the xenon accumulation rate, and on the kinetic and dynamic behavior of the reactor facility. The paper presents the results of calculating the parameters using which the heat engineering safety of the reactor core is monitored in the process of the fuel burn-up (for a generalized fuel load of a VVER-1000 reactor) during the transition to an 18-month nuclear fuel cycle. This paper also includes the results of a numerical research to determine the cladding – fuel gap conductance coefficient depending on the fuel burn-up. These results have shown that, in reality, the gap conductance coefficient dependence on the burn-up does not affect greatly the steady-state characteristics. At the same time, it affects to rather a great extent the xenon accumulation rate, specifically in the event of an extended fuel life. In conditions of maneuvering (load following) modes accompanied by the xenon processes in the reactor core, it proves to be very important and timely to take into account this dependence in the engineering codes used to support the operation of the VVER-1000 (1200) NPP equipment and full-scale simulator.


  1. Evolutionary and innovative development of WWER facilities. Report of Director – General Designer of OKB «Gidropress» S.B. Ryzhov. International forum «ATOMEXPO 2010». Available at: http://2010.atomexpo.ru/mediafiles/u/files/Present/7.5_ryzhov.pdf (accessed Apr 04, 2018) (in Russian).
  2. Artemov V.G., Artemova L.M., Shemaev Yu.P. The influence of the dependence of burn-up for thermophysical properties of a fuel element in thermal-hydraulic and neutron-physical models. Sosnovy Bor. FGUP NITI n.a. A.P. Alexandrov Publ., 2007, 10 p. (in Russian).
  3. Ainscough J.B. Gap conduction in Zircaloy)Clad LWR fuel rods. Paris. Committee of the Safety of Nuclear Installations OECD Nuclear Energy Agency, 1982, 52 p.
  4. Dean R.A. Thermal contact conductance between UO and zircaloy)2. Westinghouse Electric Corporation, 1962, 127 p.
  5. Ainscough J.B., Hobbs W.R. The effects of gas composition and pressure on the thermal conductance of UO)Zircaloy interfaces under irradiation. IAEA, Vienna, 1979, pp. 23-36.
  6. Rahgoshay M., Rahmani Y. Study of the Effects of Changing Burn)up and Gap Gaseous Compound on the Gap Convection Coefficient (in a Hot Fuel Pin) in WWER)1000 reactor. Tehran. Islamic Azad University, 2007, pp. 93-95.
  7. Rahgoshay M., Rahmani Y. Study of the Role of Gap Conductance Coefficient of Fuel on Increasing Safety in WWER)1000 Reactors. Tehran. Islamic Azad University, 2011, 12 p.
  8. Vygovskiy S.B., Zimin V.G., Chernov E.V. Program Complex PROSTOR (ver. 1). Application to the Attestation Manual No 182 (Oct 28, 2004). Moscow. National Research Nuclear University «MEPhI», 2004, 8 p. (in Russian).
  9. Lucuta P.G., Matzke Hj, Hastings I.J. A pragmatic approach to modelling thermal conductivity of irradiated UO2 fuel: Review and recommendations. J. Nucl. Mater. 1996, v. 232, pp. 166-180.
  10. Wiesenack W. Separate Effect Studies at the Halden Reactor Project to Fuel Thermal Performance Modeling. Proc. of the Seminar on Thermal Performance of High Burn-up LWR Fuel, 3 – 6 March 1998. Cadarache, France, NEA, 1998, pp. 197-208. Available at: https://www.oecd-nea.org/science/pubs/1998/1247-thermal-cadarache-1998.pdf (accessed Apr 04, 2018).
  11. Tong L.S., Weisman J. Thermal Analysis of Pressurized Water Reactors. Illinois, USA, American Nuclear Society, 1996, 748 p.
  12. Mesquita Amir Z., Rezende Hugo C., Costa Antonio Carlos L. da. Experimental determination of heat transfer coefficients in uranium zirconium hydride fuel rod. Reactor and Irradiation Service, Centre of Nuclear Technology Development, Brazil, 2007, 9 p.
  13. Medvedev A., Bogatyr S., Kouznetsov V., Khvostov G., Lagovsky V., Korystin L., Poudov V. Fuel Rod Behaviour at High Burnup WWER Fuel Cycles. Moscow. FSUE VNIINM Publ., 2003, 11 p.
  14. Yousef I., Al Zabena A., Villarino E. Development of fuel rod thermal-hydraulic model for the thermal-hydraulic feedback in condor code. Mecanica Computacional. 2014, v. XXXIII, pp. 2969-2982.
  15. Geelhood K.J., Luscher W.G. FRAPCON)3,5: A Computer Code for the Calculation of Steady)State Thermal)Mechanical Behavior of Oxide Fuel Rods for High Burnup. Richland, USA, Pacific Northwest National Laboratory, 2014, 152 p.
  16. Kudrov A., Kuz’min A., Rakov Y. Effective Fuel Temperature of WWER)1000. Tomsk, Russia. National Research Tomsk Polytechnic University Publ., 2017, 4 p. Available at: http://earchive.tpu.ru/bitstream/11683/46017/1/doi.org-10.1051-matecconf-201714101030.pdf (accessed Apr 04,2018).
  17. Vygovskiy S.B, Gruzdov F.V., Al Malkawi R.T. Computational study of the dependence on the neutron-physical characteristics of the WWER core on the temperature distribution in the fuel and its influence on the parameters of the xenon processes in the core. Yadernaya Fizika i Inzhiniring. 2016, no. 1, pp. 225-235 (in Russian).
  18. Weinberg A.M., Wigner E.P. Physical theory of nuclear reactors. Moscow. Izdatel’stvo Inostrannoj Literatury Publ., 1961, 733 p. (in Russian).
  19. Bartolomey G.G., Bat’ F.A., Bajbakov V.D., Alkhutov M.S. Fundamentals of the Theory and Calculation Methods in Nuclear Power Reactors. Moscow. Energoizdat Publ., 1982, 510 p. (in Russian).

VVER-1000 gap conductance coefficient burn-up xenon oscillations reactivity Doppler effect