EFIT-Pb Transient Analysis M. Schikorr, E. Bubelis EUROTRANS: DM1 WP1.5 : “Safety”

1. EFIT-Pb Transient Analysis M. Schikorr, E. Bubelis • EUROTRANS: DM1 WP1.5 : “Safety” • Karlsruhe , 27-28 November 2008 EUROTRANS WP1.5 Safety Meeting : Karlsruhe, Nov 27-28, 2008

2. Topics: 1. Reactivity Coefficients for EFIT-Pb • SIM-ADS Transient Results for EFIT-Pb • Status D1.43 Deliverable : Transient Analysis of EFIT-Pb EUROTRANS WP1.5 Safety Meeting : Karlsruhe, Nov 27-28, 2008

3. EFIT-Pb Reactivity Coefficient Calculations: Basic Data Source : G.Glinatsis, „EFIT-MgO/Pb Core Design Reactivity Coefficients” Genova, April Meeting 2008, and D-1.36 1.) 400 °C Isothermal Conditions: K_eff_ref = 0.96654 +/- 0.00019 2.) Fuel Temperature Effect: HFP Conditions: T_fuel = 910 °C, T_cool = 440 °C T nom_fuel =1800 K BoL: Keff = 0.96123  0.00027 (0.96147  0.00025); BoC: Keff = 0.96183  0.00025 (0.96207  0.00025) EoC: Keff = 0.96227  0.00026; (0.96227  0.00026). 3.) Coolant density Effect:  1% dens whole Active Core zones: (DK/K )/  1% dens = 0.00058  0.00002 4.) (ΔKeff/Keff) due to all „Thermal Expansions“: from 400°C to HFP = − 0.00549 ± 0.00034. EUROTRANS WP1.5 Safety Meeting : Karlsruhe, Nov 27-28, 2008

4. Calculated k_eff for different EFIT-Pb core states using MCNPX : Basic Data Source : D1.36 (Glinatsis data) Note : For the Safety Calculations the value of k_eff = 0.97403 at HFP and BOC is adopted. Value taken from Table 5.3, Ref [D-1.36] EUROTRANS WP1.5 Safety Meeting : Karlsruhe, Nov 27-28, 2008

5. Reactivities changes Dr [pcm] for different EFIT-Pb core states using previous k_eff data from Glinatsis: EUROTRANS WP1.5 Safety Meeting : Karlsruhe, Nov 27-28, 2008

6. Calculated EFIT-Pb Reactivity Temperature Coefficients using prevoius Glinatsis k_eff data : 1.) Diagrid expansion coefficient could not be extracted from the Glinatsis data as coolant inlet temperature remained at 400 °C for all different k_eff calculations. Thus assumed radial expansion coefficient = - 1.5[pcm/°C], similiar to what is being observed in SPX1. 2.) To calculate Coolant temperature reactivity coefficient need Pb coolant density. Used : density lead = 11042 – 1.194*T_cool [°C] [kg/m^3] EUROTRANS WP1.5 Safety Meeting : Karlsruhe, Nov 27-28, 2008

7. Reactivity Balance going 1.) fromHFP to CZP (T=380°C), and 2.) from HFP toAmbient (T= 30°C) for EFIT-Pb for various Core states (BOL, BOC; EOC) using the various EFIT-Pb reactivity coefficients from previous slide EUROTRANS WP1.5 Safety Meeting : Karlsruhe, Nov 27-28, 2008

8. 1. EFIT Pressure Drops: as proposed by Ansaldo after SA redesign leading to lower SA inlet and outlet pressure drops. EUROTRANS WP1.5 Safety Meeting : Karlsruhe, Nov 27-28, 2008

9. Proton Beam The EFIT Reactor Design: • EFIT is a pool-type reactor of about 400 MW power • Sub-critical reactor (Keff = 0.97) sustained by a spallation neutron source (beam proton energy 800 MeV and beam current 20 mA) • Reactor core with 3 U-free fuel zone with (Pu,MA)O2 in MgO matrix to improve the burning efficiency • Pure melt lead as primary coolant (lower cost and less activation products such as Polonium than LBE) • Core power is removed by forced circulation (4 pumps placed in the hot collector) through 8 steam generators with helical-coil tube bundle • 4 DHR heat exchangers are immersed in the annular cold pool between the inner vessel and the reactor vessel Pump Inner vessel Target Core heat exchanger Reactor vessel Figure Source: G. Bandini, P. Meloni, M. Polidori (ENEA - Bologna) EFIT Reactor Block EUROTRANS WP1.5 Safety Meeting : Karlsruhe, Nov 27-28, 2008 4

10. The In-vessel Flow Paths during normal Heat Removal mode: Figure Source: G. Bandini, P. Meloni, M. Polidori (ENEA - Bologna) EUROTRANS WP1.5 Safety Meeting : Karlsruhe, Nov 27-28, 2008

11. Nitrogen Header Cooling air Chimney Air Vapour Condenser Oil Vapour Separator Condensed Oil Drum Condensed Oil EFIT Reactor Safety-Related DHR Loop Boiling Oil Inner vessel Reactor vessel DHR Dip Cooler The Decay Heat Removal (DHR) System of EFIT-Pb • The DHR system is conceived for inherently safe decay heat removal and passive mode actuation • 4 independent loops partially filled with organic oil, that dissipate the decay heat to the atmosphere by natural convection circulation • Each loop consists of a dip cooler immersed in the cold pool where the oil partially vaporize and an air-vapor condenser with stack chimney and interconnecting piping • Oil boiling point is determined by superimposed pressure of an inert gas • In normal operation the oil is below its boiling point and the DHR removes only heat losses from SGs and inner vessel (few 100 kW) to keep cold the upper part of the reactor vessel Figure Source: G. Bandini, P. Meloni, M. Polidori (ENEA - Bologna) EUROTRANS WP1.5 Safety Meeting : Karlsruhe, Nov 27-28, 2008

12. The In-vessel Flow Paths during the Decay Heat Removal mode: Figure Source: G. Bandini, P. Meloni, M. Polidori (ENEA - Bologna) EUROTRANS WP1.5 Safety Meeting : Karlsruhe, Nov 27-28, 2008

13. EFIT-Pb Transient Cases Analysed using SIM-ADS EUROTRANS WP1.5 Safety Meeting : Karlsruhe, Nov 27-28, 2008

14. 1. Some sections are already finished. 2. Each of us needs to write a short text for each transient describing briefly what you did and what you found. Not more than about 1 page per transient by middle of December (15. 12.2008). 3. I will supply to you for each transient the typical frame of the chapter. In your section of that chapter, please insert your text. If you want, you can also insert your figures and tables in the provided format. Important: retain format otherwise we will have chaos in formatting final report. 4. Evaldas and I will collate the various contributions into final chapters for each transient. 5. Evaldas and myself will then finally collate the entire report for your inspection middle of January 2009 . Conclusions: Status of Deliverable D1.43 How to continue and finalize our EFIT-PB transient anlysis: EUROTRANS WP1.5 Safety Meeting : Karlsruhe, Nov 27-28, 2008