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EUROTRANS – DM1

EUROTRANS – DM1 EFIT Transients Analysis with RELAP5, SIMMER-III and RELAP/PARCS Codes. G. Bandini, P. Meloni, M. Polidori. SUMMARY. Analyzed Transients Results from RELAP5 Calculations Steady-state Results Protected Transients: PLOF, PLOH, and PLOF + PLOH

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EUROTRANS – DM1

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  1. EUROTRANS – DM1 EFIT Transients Analysis with RELAP5, SIMMER-III and RELAP/PARCS Codes G. Bandini, P. Meloni, M. Polidori

  2. SUMMARY • Analyzed Transients • Results from RELAP5 Calculations • Steady-state Results • Protected Transients: PLOF, PLOH, and PLOF + PLOH • Results from SG Tube Rupture with SIMMER-III • Results from RELAP/PARCS Coupled Calculations (Presented by M. Polidori) • Spurious Beam Trips • Unprotected Transients: ULOF, ULOH, ULOF + ULOH, Beam Overpower • Conclusions

  3. Analyzed Transients PROTECTED TRANSIENTS UNPROTECTED TRANSIENTS

  4. RELAP5 Model of EFIT RELAP5 Nodalization Scheme EFIT Reactor Block

  5. Core Power Distribution Axial power profile in average SAs • MCNP Calculations (ENEA) • Total reactor power = 396.2 MW • Active core power = 375 MW • Inner = 94 MW • Middle = 140 MW • Outer = 141 MW • Reflector power = 10 MW • Target power = 11.2 MW Axial power profile in hot SAs Radial power form factor (BOC)

  6. RELAP5 Steady-State Calculation • GAP behavior at BOC according to FZK-SIMADS detailed analysis (114 μm) • Good agreement with SIMADS results Axial temperature profile Hot pin of hot SA of outer core zone

  7. PLOF Transient Results • Reactor trip at 3 s • Core flowrate undershoot • Max clad temperature = 609 C • No significant fuel temperature increase Core power and flowrate SG primary side temperatures Core temperatures

  8. PLOH Transient Results (1) • Reactor trip at 55 s (Tlead > 525 C) • Max clad temperature = 546 C • Max fuel temperature = 1356 C Core Temperatures

  9. PLOH Transient Results (2) • Max vessel temperature is below the safety limit of 450 C Core and Vessel Temperatures

  10. PLOH Transient Results (3) • DHR system (3 units) reaches full operation (20 MW) after about 500 s • Temperature reduces in the medium term and stabilizes below 440 C Core power and flowrate Core and DHR Powers DHR Temperatures

  11. PLOF + PLOH Transient Results (1) • Reactor trip at 3 s • Max clad temperature = 613 C • No significant fuel temperature increase Core Temperatures

  12. PLOF + PLOH Transient Results (2) • Max vessel temperature is below the safety limit of 450 C Core and Vessel Temperatures

  13. PLOF + PLOH Transient Results (3) Core power and flowrate DHR Temperatures Core power and flowrate Core and DHR Powers

  14. SGTR: SIMMER-III Analysis SIMMER-III Model of EFIT Preliminary Design SCENARIO: 1 and 5 tubes rupture at SG bottom

  15. SGTR: SIMMER-III Results

  16. SGTR: SIMMER-III Results Break mass flowrate SG secondary side pressure Cover gas pressure SG primary side pressure (5 tubes)

  17. CONCLUSIONS • Steady-state RELAP5 calculations show that in normal operation at nominal power the maximum core temperatures (lead, clad and fuel) are well within safety limits • Results from protected transient analysis with RELAP5 show that the maximum core and vessel temperatures remains below safety limits in the short and long term even in the unfavorable cases of total loss of forced circulation in the primary system and total loss of heat removal by the secondary system • Investigation of SGTR accident with SIMMER-III gives indication of: (1) no concern for cover gas pressure increase limitation by protective measures, (2) no concern for steam recirculation at core inlet with void reactivity effect, (3) pressure peaks and their mechanical effect on SG surrounding structure need more detailed analysis

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