alfred system configuration luigi mansani [email protected]
TRANSCRIPT
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
ALFRED Main Parameters
Parameter Value
Thermal Power, MWth 300
Electric Power, MWe 124.5
Primary Coolant Flow rate, kg/s 3247.5
Primary Pressure Loss, kPa < 150
Core Inlet Temperature, °C 400
Average Core Outlet Temperature, °C 480
Max. Fuel Cladding Temperature, °C 550
Secondary System Flow rate, kg/s 193
Secondary System Pressure, MPa 18.2
Feed water Temperature, °C 335
Superheated Steam Temperature, °C 450
Steam Cycle Efficiency, % 44.7
Net Cycle Efficiency 41.5
Fuel Assembly and Fuel Pin
MaterialClad & spacers 15-15/TiWrapper T91
Core Configuration4 Safety Rods
12 Control/shutdown Rods
57 Fuel Assembly %(Pu+Am)=21.7%
114 Fuel Assembly %(Pu+Am)=27.8%)
171 Fuel Assembly
12 ControlShutdown Rods
4 Safety Rods
108 Dummy Element
Safety rod
Control/Shutdown rod
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
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
Inner Vessel
Material AISI 316LN
Inner Vessel Assembly
Upper grid
Cylinder
Lower grid
Pin
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
Steam Generator Bayonet Tube Geometry
Steam Generator Geometry
Bayonet tube
Number of coaxial tubes 4
Slave tube O.D 9.52 mm
Slave tube thickness 1.07 mm
Inner tube O.D 19.05 mm
Inner tube thickness 1.88 mm
Outer tube O.D 25.4 mm
Outer tube thickness 1.88 mm
Outermost tube O.D 31.75 mm
Outermost tube thickness 2.11 mm
Length of exchange 6 m
Number of tubes 510
Steam Generator Details
Material:
X10CrMoVNb9-1, RCC-MRx
(T91 ASME)
Steam Generator Details
Steam Generator Performances
First tubesheet
Second tubesheet
Third tubesheet
Steam outlet
Water Inlet
Pump casing
Tubes
Steam Generator Performance
Removed Power [MW] 37.5
Core outlet Lead Temperature [°C]
480.0
Core inlet Lead Temperature [°C]
401.5
Feedwater Temperature [°C] 335.0
Immersed bayonet steam outlet T [°C]
451.5
Steam Plenum Temperature [°C]
450.1
SG steam/water side global ∆p [bar]
3.3
Reactor Vessel
Main Dimensions
Height, m 10.13Inner diameter, m 8Wall thickness, mm 50 Design temperature, °C 400Vessel material AISI 316L
MAIN COOLANT PUMP
REACTOR VESSEL
SAFETY VESSEL
FUEL ASSEMBLIES
STEAM
GENERATOR
STEAM
GENERATORMAIN COOLANT PUMP
REACTOR CORE
Reactor Block Configuration
Reactor Block Configuration
Item Denomination N°
01 Fuel Assembly positions 295
02 Inner Vessel 1
03 Core Lower Support Plate 1
04 Core Upper Support Plate 1
05 Reactor Vessel 1
06 Reactor Cover 1
07 Steam Generator 8
08 Vessel Support 1
09 Primary Pump 8
10 Reactor FAs Cover 1
Decay Heat Removal Systems
• Several systems for the decay heat removal function have been conceived and designed for ALFRED– One non safety-grade system, the secondary system, used for the normal decay
heat removal following the reactor shutdown– Two independent, passive, high reliable and redundant safety-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
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)
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
DHR System Performances
300
320
340
360
380
400
420
440
460
480
500
0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 16,000
°C
s
Core inlet temp
Core outlet temp
300
350
400
450
500
550
0 5,000 10,000 15,000 20,000 25,000°C
s
Core inlet temp
Core outlet temp
3 Loops in operation (Minimum performances)Lead Peak Temperature 500°C
Time to freeze > 8 hours
4 Loops in operation (Maximum performances)Lead temperature < nominal
Time to freeze 4 hours
Freezing temperatureFreezing temperature
Secondary System
Selected materials
for the main components of ALFRED and ELFR Components
Material
ALFRED ELFRReactor Vessel AISI316L AISI316L
Vessel Support P295GH P295GH
Safety Vessel (Cavity Liner) AISI316L AISI316L
Reactor Cover AISI316L AISI316L
Inner Vessel AISI316LN AISI316LN
Core Lower Grid AISI316LN AISI316LN
Core Upper Grid AISI316LN AISI316LN
Steam Generator T91 T91
Primary Pump: Duct and Shaft AISI316LN AISI316LN
Primary Pump: Impeller tbd (Maxtal ?) tbd (Maxtal ?)
Deep Cooler na AISI316LN
Fuel Assembly: Cladding 15-15/Ti T91
Fuel Assembly: Grids 15-15/Ti T91
Fuel Assembly: Wrapper T91 T91
Main Components Operating Conditions*
Components Min./Max Temp. Normal
Operation(°C)
Max Temp. Accident
Conditions(°C)
Max. Lead velocity
(m/s)
Max. Radiation damage(dpa/y)
Max. Radiation damage
(dpa)
Reactor Vessel 380÷430 440 0.1 < 10-5 0.0002
Inner Vessel 380÷480 470 0.2 0.1 2.1
Steam Generator 380÷480 470 0.6 < 10-5 0.0001
Primary Pumps 380÷480 470 10 < 10-5 0.0001
Fuel Assembly FA 380÷550 480 2 - (100)
Dummy Assemblies 380÷480 470 0.01 - (100)
DHR Heat Exchanger 380÷430 440 0.2 < 10-5 0.0001
*Operating Conditions from ELSY project
ALFRED and ELFR Design Options (Differences)
Items ALFRED Option ELFR OptionElectrical Power (MWe) 120 MWe (300 MWth) 600 MWe (1500 MWth)
Fuel Clad Material 15-15Ti (coated) 15-15Ti or T91 (coated)
Fuel type MOX (max Pu enrich. 30%) MOX for first loadMAs bearing fuel .....
Max discharged burnup (MWd/kg-HM) 90÷100 100
Steam generatorsBayonet type with double walls, Integrated in the reactor vessel, Removable
Spiral type or alternate solution, Integrated in the reactor vessel, Removable
DHR System 2 diverse and redundant systems (actively actuated, Passively operated)
2 diverse and redundant systems (actively actuated, Passively operated)
DHR1 Isolation Condenser connected to Steam Generators: 4 units provided on 4 out of 8 SGs
Isolation Condenser connected to Steam Generator: 4 units provided on 4 out of 8 SGs
DHR2 Duplication of DHR1260% total power removal
Alternate solution to ELSY W-DHR under investigation
ALFRED and ELFR Design Options (Similarities)
Primary Coolant Pure Lead
Primary System Pool type, Compact
Primary Coolant Circulation: Normal operationEmergency
conditions
ForcedNatural
Allowed maximum Lead velocity (m/s) 2
Core Inlet Temperature (°C) 400
Steam Generator Inlet Temperature (°C) 480
Secondary Coolant Cycle Water-Superheated Steam
Feed-water Temperature (°C) 335
Steam Pressure (MPa) 18
Secondary system efficiency (%) 41
Reactor vessel Austenitic SS, Hung
Safety Vessel Anchored to reactor pit
Inner Vessel (Core Barrel) Cylindrical, Integral with the core support grid, Removable
Primary pumps Mechanical in the hot collector, Removable
ALFRED and ELFR Design Options (Similarities)
Fuel AssemblyClosed (with wrapper), Hexagonal, Weighted down when primary pumps are off, Forced in position by springs when primary pumps are on
Maximum Clad Temperature in Normal Operation (°C)
550
Maximum core pressure drop (MPa) 0.1 (30 min grace time for ULOF)
Control/Shutdown System 2 diverse and redundant systems of the same concept derived from CDT
1st System for Shutdown Buoyancy Absorbers Rods: control/shutdown system passively inserted by buoyancy from bottom of core
2nd System for Shutdown Pneumatic Inserted Absorber Rods: shutdown system passively inserted by pneumatic (by depressurization) from the top of core
Refuelling System No refuelling machine inside the Reactor Vessel
Seismic Dumping Devices 2D isolator below reactor building