EUROTRANS WP 1.5 Meeting FZK – Karlsruhe, November 27-28, 2008 FPN-FISNUC / Bologna EUROTRANS – DM1 EFIT Transients Analysis with RELAP5, SIMMER-III and RELAP/PARCS Codes G. Bandini, P. Meloni, M. Polidori

EUROTRANS WP 1.5 Meeting, Karlsruhe, November 27-28, 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

EUROTRANS WP 1.5 Meeting, Karlsruhe, November 27-28, Analyzed Transients TransientBU stateBeam TripCODETransient time (s) PLOFBOCAfter 3 sRELAP5100 PLOHBOCT lead out > 525 CRELAP55000 PLOF + PLOHBOCAfter 3 sRELAP55000 SG tube rupture--SIMMER-III30 Spurious beam tripBOC1 s, 10 s (interval)RELAP/PARCS- PROTECTED TRANSIENTS TransientBU stateBeam PowerCODE ULOFBOC100%RELAP/PARCS ULOHBOC100%RELAP/PARCS ULOF + ULOHBOC100%RELAP/PARCS Beam overpowerBOC120% at HFPRELAP/PARCS UNPROTECTED TRANSIENTS

EUROTRANS WP 1.5 Meeting, Karlsruhe, November 27-28, RELAP5 Model of EFIT RELAP5 Nodalization Scheme EFIT Reactor Block

EUROTRANS WP 1.5 Meeting, Karlsruhe, November 27-28, Core Power Distribution Axial power profile in hot SAs Axial power profile in average SAs MCNP Calculations (ENEA) Total reactor power = MW Active core power = 375 MW Inner = 94 MW Middle = 140 MW Outer = 141 MW Reflector power = 10 MW Target power = 11.2 MW Radial power form factor (BOC)

EUROTRANS WP 1.5 Meeting, Karlsruhe, November 27-28, 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

EUROTRANS WP 1.5 Meeting, Karlsruhe, November 27-28, PLOF Transient Results  Reactor trip at 3 s  Core flowrate undershoot  Max clad temperature = 609 C  No significant fuel temperature increase SG primary side temperatures Core temperatures Core power and flowrate

EUROTRANS WP 1.5 Meeting, Karlsruhe, November 27-28, PLOH Transient Results (1)  Reactor trip at 55 s (T lead > 525 C)  Max clad temperature = 546 C  Max fuel temperature = 1356 C Core Temperatures

EUROTRANS WP 1.5 Meeting, Karlsruhe, November 27-28, PLOH Transient Results (2)  Max vessel temperature is below the safety limit of 450 C Core and Vessel Temperatures

EUROTRANS WP 1.5 Meeting, Karlsruhe, November 27-28, 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 DHR Temperatures Core power and flowrate Core and DHR Powers

EUROTRANS WP 1.5 Meeting, Karlsruhe, November 27-28, PLOF + PLOH Transient Results (1)  Reactor trip at 3 s  Max clad temperature = 613 C  No significant fuel temperature increase Core Temperatures

EUROTRANS WP 1.5 Meeting, Karlsruhe, November 27-28, PLOF + PLOH Transient Results (2)  Max vessel temperature is below the safety limit of 450 C Core and Vessel Temperatures

EUROTRANS WP 1.5 Meeting, Karlsruhe, November 27-28, PLOF + PLOH Transient Results (3) Core power and flowrate Core and DHR Powers DHR Temperatures

EUROTRANS WP 1.5 Meeting, Karlsruhe, November 27-28, SGTR: SIMMER-III Analysis SIMMER-III Model of EFIT Preliminary Design SCENARIO: 1 and 5 tubes rupture at SG bottom

EUROTRANS WP 1.5 Meeting, Karlsruhe, November 27-28, SGTR: SIMMER-III Results

EUROTRANS WP 1.5 Meeting, Karlsruhe, November 27-28, SGTR: SIMMER-III Results Break mass flowrate Cover gas pressure SG secondary side pressure SG primary side pressure (5 tubes)

EUROTRANS WP 1.5 Meeting, Karlsruhe, November 27-28, 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