ALFRED

1. ALFRED System Configuration Luigi Mansani Luigi.mansani@ann.ansaldo.it

2. ALFRED Status Design changes of the ELSY configuration identified ALFRED configuration (300 MWth) defined DHR System conceptual design performed (DEL10 issued) Secondary System conceptual design performed (DEL09 issued) The following Mechanical Drawings have been issued: LEADER 33 DMBX 013 Rev 0 Reactor Block General Assembly LEADER 33 DMMX 014 Rev 0 Fuel assembly outline LEADER 33 DMMX 015 Rev 0 I nner vessel outline LEADER 33 DMMX 016 Rev 0 Core lower grid outline LEADER 33 DMMX 017 Rev 0 Core upper grid outline LEADER 33 DMMX 018 Rev 0 Reactor vessel outline LEADER 33 DMMX 019 Rev 0 Reactor cover outline LEADER 33 DMMX 020_001 Rev 0 Steam generator outline LEADER 33 DMMX 020_002 Rev 0 Steam generator outline LEADER 33 DMMX 021 Rev 0 Vessel support outline LEADER 35 DMBX 036 Rev 0 Isolation Condenser outline

3. ALFRED Main Parameters

4. Fuel Assembly and Fuel Pin Material Clad & spacers 15-15/Ti Wrapper T91

5. 4 Safety Rods 12 Control/shutdown Rods 57 Fuel Assembly %(Pu+Am)=21.7% 114 Fuel Assembly %(Pu+Am)=27.8%) 171 Fuel Assembly 4 Safety Rods 12 ControlShutdown Rods 108 Dummy Element Core Configuration Control/Shutdown rod Safety rod

6. Lower Core Support Plates Box structure with two horizontal perforated plates connected by vertical plates. Plates holes are the housing of FAs foots. The plates distance assures the verticality of FAs Material AISI 316LN

7. Upper Core Support Plates Box structure as lower grid but more stiff It has the function to push down the FAs during the reactor operation A series of preloaded disk springs presses each FA on its lower housing Material AISI 316LN

8. Inner Vessel Material AISI 316LN

9. Inner Vessel Assembly Upper grid Cylinder Pin Lower grid

10. Steam Generator Bayonet Tube Concept • Bayonet vertical tube with external safety tube and internal insulating layer • The internal insulating layer (delimited by the Slave tube) has been introduced to ensure the production of superheated dry steam • The gap between the outermost and the outer bayonet tube is filled with pressurized helium to permit continuous monitoring of the tube bundle integrity • High thermal conductivities particles in the gap to enhance the heat exchange capability • In case of tube leak this arrangement guarantees that primary lead does not interact with the secondary water

11. Steam Generator Bayonet Tube Geometry

12. Steam Generator Details

13. Steam Generator Details Material: X10CrMoVNb9-1, RCC-MRx (T91 ASME)

14. Steam Generator Performances Pump casing Water Inlet Third tubesheet Steam outlet Tubes Second tubesheet First tubesheet

15. Reactor Vessel Main Dimensions Height, m 10.13 Inner diameter, m 8 Wall thickness, mm 50 Design temperature, °C 400 Vessel material AISI 316L

16. Reactor Block Configuration MAIN COOLANT PUMP REACTOR VESSEL SAFETY VESSEL FUEL ASSEMBLIES STEAM GENERATOR STEAM GENERATOR MAIN COOLANT PUMP REACTOR CORE

17. Reactor Block Configuration

18. Several systems for the decay heat removal function have been conceived and designed for ALFRED Onenon safety-grade system, the secondary system, used for the normal decay heat removal following the reactor shutdown Twoindependent, passive, high reliable and redundantsafety-related Decay Heat Removal systems (DHR N1 and DHR N2): in case of unavailability of the secondary system, the DHR N1 system is called upon and in the unlike event of unavailability of the first two systems the DHR N2 starts to evacuate the DHR DHR N1: Rrelay on the Isolation Condenser system connected to four out of eight SGs DHR N2: Other four Isolation Condenser to the other four SGs have been added Considering that, each SG is continuously monitored, ALFRED is a demonstrator and a redundancy of 266% is maintained, the Diversity concept could be relaxed DHR Systems features: Independence obtained by means of two different systems with nothing in common Redundancy is obtained by means of three out of four loops (of each system) sufficient to fulfil the DHR safety function even if a single failure occurs Decay Heat Removal Systems

19. DHR Systems (Isolation Condenser) • 8 Independent loops • DHR N1 4 loops • DHR N2 the other 4 loops • Each Isolation Condenser loop is comprehensive of: • One heat exchanger (Isolation Condenser), constituted by a vertical tube bundle with an upper and lower header • One water pool, where the isolation condenser is immersed (the amount of water contained in the pool is sufficient to guarantee 3 days of operation) • One condensate isolation valve (to meet the single failure criteria this function shall be performed at least by two parallel valves) 1 loop (typical)

20. Isolation Condenser Heat Exchanger • Upper and lower spherical header diameter 560 mm • Tube /T 38.1x3 mm • Number of tubes 16 • Average tube length 2 m • Material AISI 316LN

21. DHR System Performances Freezing temperature Freezing temperature 4 Loops in operation (Maximum performances) Lead temperature < nominal Time to freeze  4 hours 3 Loops in operation (Minimum performances) Lead Peak Temperature  500°C Time to freeze > 8 hours

22. Secondary System

23. Selected materialsfor the main components of ALFRED and ELFR

24. Main Components Operating Conditions* *Operating Conditions from ELSY project

25. ALFRED and ELFR Design Options (Differences)

26. ALFRED and ELFR Design Options (Similarities)

27. ALFRED and ELFR Design Options (Similarities)