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EUROTRANS – DM1

FPN-FISNUC / Bologna. EUROTRANS – DM1 RELAP5 Model Evaluation with SIMMER-III Code and Preliminary Transient Analysis for EFIT Reactor. P. Meloni, G. Bandini, M. Polidori. WP5.1 Progress Meeting KTH / Stockholm, May 22-23, 2007. EFIT Transient Analysis by ENEA.

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EUROTRANS – DM1

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  1. FPN-FISNUC / Bologna EUROTRANS – DM1 RELAP5 Model Evaluation with SIMMER-III Code and Preliminary Transient Analysis for EFIT Reactor P. Meloni, G. Bandini, M. Polidori WP5.1 Progress Meeting KTH / Stockholm, May 22-23, 2007

  2. EFIT Transient Analysis by ENEA • Use of SIMMER-III code for in-vessel natural circulation assessment and DHR performance evaluation • RELAP5 model evaluation and revision based on SIMMER-III results • Preliminary transient analysis (PLOHS and ULOF) with revised RELAP5 model KTH – Stockholm, May 22 – 23, EUROTRANS – DM1 – WP1.5 Progress Meeting

  3. EFIT Design and Parameters • Primary circuit layout from ANSALDO presentation at the last EUROTRANS - DM4 Technical Review Meeting (March 2007): • Reactor core with 3 fuel zones • 4 primary pumps, 8 IHXs, 4 secondary loops • 4 DHR units (3 out of 4 in operation in transient analysis) • Primary circuit parameters: • Active core thermal power = 379 MW (ENEA study) • Lead mass flowrate = 31850 kg/s • Core inlet / outlet temperature = 400 / 480 C • Total pressure drop = 43 kPa (core pressure drop = 36 kPa) KTH – Stockholm, May 22 – 23, EUROTRANS – DM1 – WP1.5 Progress Meeting

  4. Used Approach SIMMER-III calculation PLOHS (beam trip at t = 0 s) 3 DHR in operation Comparison Comparison with ANSALDO data Recirculation ratio at DHR outlet Additional RELAP5 pressure drop coefficients to fit core and DHR natural circulation mass flow rates (SIMMER) RELAP5 calculation PLOHS (beam trip at t = 0 s) 3 DHR in operation RELAP5 revised model Transient analysis with RELAP5 RELAP5 model evaluation and transient analysis ULOF with SIMMER-III PLOHS (beam and pump trip if aver. core out T > 500 C) Comparison ULOF KTH – Stockholm, May 22 – 23, EUROTRANS – DM1, WP1.5 Progress Meeting

  5. SIMMER-III Model of EFIT • 2-D R-Z (36 x 35) Cylindrical model • Initial condition with stagnant lead and free level DH simulation • Harmonization with RELAP5 plant data and boundary conditions • No steam generator heat losses • 3 out of 4 DHR units in operation (degraded conditions) • DHR heat removal based on constant oil temperature in secondary side (Tin = 405 C, Tout = 409 C) KTH – Stockholm, May 22 – 23, EUROTRANS – DM1, WP1.5 Progress Meeting

  6. SIMMER-III Results (Lead Temperature) KTH – Stockholm, May 22 – 23, EUROTRANS – DM1, WP1.5 Progress Meeting

  7. SIMMER-III Results (Lead Temperature) KTH – Stockholm, May 22 – 23, EUROTRANS – DM1, WP1.5 Progress Meeting

  8. SIMMER-III Results at 3600 s (Lead Velocities) Vertical velocity Horizontal velocity KTH – Stockholm, May 22 – 23, EUROTRANS – DM1, WP1.5 Progress Meeting

  9. TDi mD TCo mC TCo TDo TDi x TCo y TCi TCi TCi Recirculation Ratio at DHR Outlet for RELAP5 SIMMER-III ANSALDO Results at after 1 hour t = 3600 s: (P= 16 MW) mC = 2740 kg/s mD = 2983 kg/s 2985 Kg/s TCi = 410.5 C TCo = 449.1 C TDi = 444.6 C 444 C TDo = 407.0 C 407 C (TCi - TDo) y = mC (TDi - TDo) x = y + mD - mC y = 255 kg/s Recirculation ratio at DHR outlet: x = 498 kg/s (17% of mD) Simplified scheme of RELAP5 model KTH – Stockholm, May 22 – 23, EUROTRANS – DM1, WP1.5 Progress Meeting

  10. SIMMER and RELAP5 Comparison at t = 3600 s Additional pressure drop coefficients in RELAP5 model to fit SIMMER-III results KTH – Stockholm, May 22 – 23, EUROTRANS – DM1, WP1.5 Progress Meeting

  11. Code Result Comparison (Transient) Core inlet / outlet temperature Core mass flow rate and temperature Core mass flow rate • After the initial transient (about 2000 s) the revised RELAP5 model fit very well the SIMMER-III results KTH – Stockholm, May 22 – 23, EUROTRANS – DM1, WP1.5 Progress Meeting

  12. Code Result Comparison (Transient) DHR inlet / outlet temperature DHR mass flow rate and temperature DHR mass flow rate • After the initial transient the revised RELAP5 model fit well the SIMMER-III results, and stable DHR operation is predicted by both codes KTH – Stockholm, May 22 – 23, EUROTRANS – DM1, WP1.5 Progress Meeting

  13. Code Result Comparison (Transient) Core decay power and DHR removed power KTH – Stockholm, May 22 – 23, EUROTRANS – DM1, WP1.5 Progress Meeting

  14. Preliminary Transient Analysis with RELAP5 • Protected Loss of Heat Sink (PLOHS) at BOC with beam and pump trip when average outlet core temperature exceeds 500 C and DHR degraded conditions (3 out of 4) • Unprotected Loss of Flow (ULOF) at BOC with SGs full capacity and without reactivity feedback (constant core power) KTH – Stockholm, May 22 – 23, EUROTRANS – DM1, WP1.5 Progress Meeting

  15. Nominal Conditions (RELAP5 steady-state) (*) about 5 MW (not considered in this study) KTH – Stockholm, May 22 – 23, EUROTRANS – DM1 – WP1.5 Progress Meeting

  16. PLOHS Transient Results (Relap5) About 3 hours transient Core and DHR mass flow rate Initial transient • Proton beam and pump trip is assumed at 73 s (average lead temperature at core outlet > 500 K) • After some initial oscillations (free levels movements) both core and DHR mass flow rates became stable KTH – Stockholm, May 22 – 23, EUROTRANS – DM1 – WP1.5 Progress Meeting

  17. PLOHS Transient Results (Relap5) About 3 hours transient Core and DHR power Initial transient • The DHR system reaches full operation after about 600 s • A maximum of 20 MW power can be removed by 3 DHR units in operation) KTH – Stockholm, May 22 – 23, EUROTRANS – DM1 – WP1.5 Progress Meeting

  18. PLOHS Transient Results (Relap5) About 3 hours transient Max lead and clad temperature Initial transient • Peak clad temperature reaches 585 C in the hot channel of inner core zone • Max lead and clad temperature stabilize at about 450 C after 6000 s KTH – Stockholm, May 22 – 23, EUROTRANS – DM1 – WP1.5 Progress Meeting

  19. PLOHS Transient Results (Relap5) Max fuel temperature (hot channel) Max vessel wall temperature About 3 hours transient Initial transient • The vessel wall temperature reaches a maximum of about 460 C after 3000 s and reduces below 440 s after 10000 s KTH – Stockholm, May 22 – 23, EUROTRANS – DM1 – WP1.5 Progress Meeting

  20. ULOF Transient Results (Relap5) Core mass flow rate Core mass flow rate and power Core and SG exchanged power • All primary pumps stop at 0 s (no pump inertia), secondary loops at nominal conditions • Core mass flow rate stabilizes at about 37% of the nominal value KTH – Stockholm, May 22 – 23, EUROTRANS – DM1 – WP1.5 Progress Meeting

  21. ULOF Transient Results (Relap5) Hot channel temperature Max lead temperature (top of active zone) Average channel temperature • Peak lead temperature reaches about 850 C in the hot channel of inner core zone just after pump stop • Max lead temperature stabilizes at about 625 C in the hot channel of outer core zone KTH – Stockholm, May 22 – 23, EUROTRANS – DM1 – WP1.5 Progress Meeting

  22. ULOF Transient Results (Relap5) Hot channel temperature Max clad temperature (top of active zone) Average channel temperature • Peak clad temperature reaches about 870 C in the hot channel of inner core zone just after pump stop • Max clad temperature stabilizes at about 660 C in the hot channel of inner core zone KTH – Stockholm, May 22 – 23, EUROTRANS – DM1 – WP1.5 Progress Meeting

  23. ULOF Transient Results (Relap5) Hot channel temperature Max fuel temperature (centre of active zone) Average channel temperature • Peak fuel temperature reaches about 1525 C in the hot channel of middle core zone just after pump stop • Max fuel temperature stabilizes at about 1405 C in the hot channel of middle core zone KTH – Stockholm, May 22 – 23, EUROTRANS – DM1 – WP1.5 Progress Meeting

  24. ULOF with SIMMER-III (Lead Temperature) KTH – Stockholm, May 22 – 23, EUROTRANS – DM1 – WP1.5 Progress Meeting

  25. ULOF with SIMMER-III (Lead Temperature) KTH – Stockholm, May 22 – 23, EUROTRANS – DM1 – WP1.5 Progress Meeting

  26. ULOF with SIMMER-III at 1000 s (Lead Velocities) Vertical velocity Horizontal velocity KTH – Stockholm, May 22 – 23, EUROTRANS – DM1 – WP1.5 Progress Meeting

  27. ULOF: SIMMER-III – RELAP5 Comparison Core inlet / outlet temperature Core mass flow rate and temperature Core mass flow rate • SG tube temperature in SIMMER-III calculation is imposed according to RELAP5 results • After the initial transient (about 200 s) there is a good agreement in code results KTH – Stockholm, May 22 – 23, EUROTRANS – DM1 – WP1.5 Progress Meeting

  28. Use of SIMMER-IV (3-D Calculation) In progress (Convergence and CPU time problems still to be solved) A A B B Section B - B Section A - A KTH – Stockholm, May 22 – 23, EUROTRANS – DM1 – WP1.5 Progress Meeting

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