1. FEDERAL STATE UNITARY ENTERPRISE Alexandrov Research Institute of Technology SOSNOVY BOR, RUSSIA FEDERAL STATE UNITARY ENTERPRISE Alexandrov Research Institute of Technology SOSNOVY BOR, RUSSIA

2. SENSITIVITY ANALYSIS AND VERIFICATION OF FUEL ROD MODEL USED IN COUPLED NEUTRONIC AND THERMAL-HYDRAULIC CODES L.M. Artemova, V.G. Artemov, Y.P. Shemaev Alexandrov Research Institute of Technology Sosnovy Bor, Russia

3. Alexandrov Research Institute of Technoloqy 3 SAPFIR_95&RC_VVER program package Fuel rod model considers:  ― thermal expansion  ― fuel swelling and cladding creep  ― degradation of fuel thermal conduction  ― change of gap conductance  ― asymmetric disposition of pellets in fuel rod

4. Alexandrov Research Institute of Technoloqy 4 Fuel diameter variation with burnup (VVER-1000)

5. Alexandrov Research Institute of Technoloqy 5 Fuel rod diameter variation with burnup (VVER-1000)

6. Alexandrov Research Institute of Technoloqy 6 Variation of fuel rod geometry with burnup (RC models)

7. Alexandrov Research Institute of Technoloqy 7 Experiments at different burnup depth

8. Alexandrov Research Institute of Technoloqy 8 Axial xenon oscillations (Rostov NPP, unit #1, 30 FPD)

9. Alexandrov Research Institute of Technoloqy 9 Axial xenon oscillations (Rostov NPP, unit #1, 60 FPD)

10. Alexandrov Research Institute of Technoloqy 10 Spontaneous power reduction (Rostov NPP, unit #1, 80 FPD)

11. Alexandrov Research Institute of Technoloqy 11 Axial xenon oscillations (Rostov NPP, unit #1, 80 FPD)

12. Alexandrov Research Institute of Technoloqy 12 Axial xenon oscillations (Zaporozhye NPP, unit #1, 175 FPD)

13. Alexandrov Research Institute of Technoloqy 13 Weight function for calculation of fuel effective temperature

14. Alexandrov Research Institute of Technoloqy 14 Dependence of modeling results on pellets disposition

15. Alexandrov Research Institute of Technoloqy 15 Fresh fuel conduction

16. Alexandrov Research Institute of Technoloqy 16 Spontaneous power reduction (Rostov NPP, unit #1, 80 FPD)

17. Alexandrov Research Institute of Technoloqy 17 Conclusions:  Realistic evaluation of fuel temperature is needed for transients modeling  Best agreement of modeling results with experiment is provided with: —model 3 (TRANSURANUS) of fuel swelling and cladding creep — fuel thermal conduction from VNIINM data base

18. Alexandrov Research Institute of Technoloqy 18 Contacts: Ludmila Artemova Alexandrov Research Institute of Technology Sosnovy Bor, Leningrad region, Russia Tel. +7(81369) 60-619 e-mail:elchine@niti.ru THANK YOU !