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Recent design developments in the EU HCPB TBM F. Cismondi 1 , S. Kecskes 1 , B. Kiss 2 , F. Hernandez 1 , L.V. Boccaccini 1 1 Karlsruhe Institute of Technology, Germany, 3 Budapest University of Technology and Economic, Hungary. Presented by: Dr Fabio CISMONDI - PowerPoint PPT Presentation
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www.kit.edu
Presented by:Dr Fabio CISMONDI
Karlsruher Institut für Technologie (KIT)Institut für Neutronenphysik und Reaktortechnik
e-mail: [email protected]
Recent design developments in the EU HCPB TBM
F. Cismondi1, S. Kecskes1, B. Kiss2, F. Hernandez1, L.V. Boccaccini1
1Karlsruhe Institute of Technology, Germany, 3Budapest University of Technology and Economic, Hungary
• Helium Cooled Pebble Beds (HCPB) and Helium Cooled Lithium Lead (HCLL) Test Blanket Modules (TBMs) are the two DEMO blankets concepts selected by EU to be tested in ITER.
• The Test Blanket Systems (TBS) are developed by different Associations throughout EU.
• The European Joint Undertaking “Fusion for Energy” is in charge of delivering the Test Blanket Modules System (TBS) to ITER.
• The European partners developing the TBS are joint together into a Consortium Agreement (TBM-CA).
• The TBM CA works under contracts with F4E
• KIT and CEA develop within TBM CA the design of the HCLL and HCPB TBMs.
Contest of the study
ITER section
2 | Recent developments in the design of the EU HCPB –TBM, Fabio Cismondi
DEMO relevancy for the TBMs:• Maximum geometrical similarity between the design of the TBM and the corresponding DEMO blanket modules;• Active cooling of the structure by Helium at 8 MPa with 300°C/500°C inlet/outlet temperatures,• Same structural materials;• Maximum structural temperature limited to 550°C;• Same manufacturing and assembly techniques.• Same functional materials and relevant Be and OSI temperatures.
Structural material HCPB and HCLL TBMs structural material is the Reduced Activation Ferritic-Martensitic (RAFM) steel EUROFER97.
RAFM steels derive from the conventional modified 9Cr-1Mo steel eliminating the high activation elements (Mo, Nb, Ni, Cu and N).
Main advantages: excellent dimensional stability (low creep and swelling) under neutron irradiation. Drawback: ductility characteristics considerably lower than austenitic steels and severely reduced following irradiation .
Contest of the study
TBM test programme main objectives in ITER• Demonstrate tritium breeding capability and verify on-line tritium recovery and control systems;• Ensure high grade heat production and removal; • Demonstrate the integral performance of the blanket systems in a fusion relevant environment;• Validate and calibrate design tools and database used in the blanket design process.
3 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
HCPB TBM design description
First Wall
Vertical SGs
Breeder Units
Horizontal SGs
Caps
Plas
ma
side
1660
mm
710mm
Manifold plates
Back plate
He outlet
He inlet
Purge gas in/outlet
By pass Helium at 80bar cools the TBM box components and the BUs CPs. Helium at 4bar purges the Breeder Zone for tritium removal
1660 mm (poloidal) × 484 mm (toroidal) × 710 mm (radial)• Robust box (First Wall and Caps) • Internal structure of Stiffening Grids (SGs) • 5 backplates (BP) constitute the coolant manifolds• Horizontal SGs crossing the TBM box to ensure the box stiffness
Breeder Units (BUs):• Arranged in the space defined by the SGs. • Filled by ceramic breeder pebbles (Li4SiO4) and Beryllium neutron multiplier pebbles• Based on U-shaped Cooling Plates (CPs) extracting the heat
4 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
Design development strategy
Objective: develop a design of the TBM boxes maximizing the similarities.
Strategy: synergies are maximized but differences are kept in the most critical points to investigate different design options and minimize the risk.
Critical points:• FW, fabrication issues• Manifold, design different for the different internal engineering of the 2 TBMs
FW: larger bending radius (150mm) in HCPB TBM
Manifolds: Horizontal SGs crossing the TBM box (HCPB), Stiffening rods (HCLL)
5 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
6 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
Detailed view of BU design
Purge gas MFsB
ack
plat
e
MF.1
MF.4
MF.3 MF.2
Li4SiO4Be
Radial-poloidal cut and BU detail
He at 8 MPa, T 300 to 500 °C
7 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
Detailed view of BU design
Be pebble bed
Be pebble bed
Be pebble bed
Li pebble bed
Li pebble bed
PLASMA
First Wall
n
14,08 MeV
Cooling/stiffening grid
Purge gas MFsB
ack
plat
e
MF.1
MF.4
MF.3 MF.2
8 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
HCPB TBM design life cycleStart
Structural concept
Material selection
Neutronic
Tritium breeding
Ratio
Nuclear heating
rate
Thermal-hydraulics
Temperature of structural,
functional materials
Coolant velocity and
pressure loss
Thermo-mechanics
Stress evaluation
Overall performance evaluation
End
Tritium recovery
FabricabilitySupport concept,
manteinance
9 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
3D CFD model of the TBM box
300
350
400
450
500
550
600
0 100 200 300 400 500 600 700 800Time [s]
Tem
pera
ture
[°C
]
Tmax FW
Tmax vSGs
Tmax hSGs
Tmax Caps
Tmax BP
t1=40s t1=500s
Primary + secondary stress field on the TBM at t2=500s
MPa
0 120 240 360 450
Temperature distribution at t1=40s.
Design Description Document (DDD) of the TBM box released (complete set of Build To Print CAD drawings performed)
10 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
3D CFD model of the BU
First Wall
Vertical SGs
Breeder Unit CFD model
Horizontal SGs
Cooling Plates
Goal: determine helium coolant mass flow rate in the different subcomponents and heat fluxes generated in BU and deposed on the subcomponents.
Improved modeling of pebble beds region: •thermal conductivity temperature and strain (for Be) dependent•thermal contact resistance temperature dependent.
Thermal contact resistance Thermal contact resistance between pebble beds and structural material: correlations from Yagi & Kuni Yagi & Kuni used to define the HTC between pebble beds and structural material:
4424
2 1091.8327.42577 SiOLiforCTCTKmWh
11 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
3D CFD model of the BU
∆x ≈ - 0,5mm
∆x ≈ - 0,31mm
∆x ≈ + 0,09mm∆x ≈ + 0,17mm
∆sbed ≈ 0,4mm
∆y ≈ + 2,09mm
∆y ≈ + 1,96mm
Structural analyses: secondary stresses and structural deformation
y
x
z
12 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
3D CFD model of the BU
Beryllium:Beryllium:k as a function of the temperature T and the pebble bed strain ε:
39263
27
101,2106,710386,103,9
1050012,081,1
TTT
TTmKWk
values of ε=0.2%, 0,32% and 0,5% (corresponding respectively to a pressure of 2.0, 1.0 and 0.5MPa) have been considered as being characteristic for the three zones
OSI:OSI:variation of the OSi thermal conductivity with the temperature :
TmKWk
310496,0768,0
The OSi thermal conductivity has the same order of magnitude than the purge gas one and its variation with the temperature is limited.
13 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
3D CFD model of the BU
Transient analyses performed (typical ITER pulse).Transient analyses performed (typical ITER pulse).Maximal temperatures:Maximal temperatures:•Low strain region in Be 760˚C. •OSi pebbles 870˚C.•Helium outlet stable at 490˚C by the end of the pulse.
14 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
3D CFD model of the BU
Transient analyses performed (typical ITER pulse).Transient analyses performed (typical ITER pulse).Maximal temperatures:Maximal temperatures:•Low strain region in Be 760˚C. •OSi pebbles 870˚C.•Helium outlet stable at 490˚C by the end of the pulse.
15 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
3D CFD model of the BU
First Wall
Vertical SGs
Breeder Unit CFD model
Horizontal SGs
Cooling Plates
Transient analyses performed (typical ITER pulse).Transient analyses performed (typical ITER pulse).Temperatures in Be and OSI at the end of the plasma pulse
16 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
Transient thermo mechanical analyses of the BU
Primary stress in base design. Equivalent Von Mises
SM1
SM2
Goal: Evaluate thermo-mechanical performance of the BU. Design changes implemented to fulfill the design criteria. The selected design C&S is RCC-MR 2007 completed by SDC-IC ITER rules (adressing irradiation damages).
17 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
Transient thermo mechanical analyses of the BU
BU base designBU base design
Design improvement: 20mm thick BU backplate and Design improvement: 20mm thick BU backplate and stiffenersstiffeners
Submodel 2: BU manifold center region
18 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
Transient thermo mechanical analyses of the BU
M-Tpe damages assessment
3 4 9 10
19 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
Transient thermo mechanical analyses of the BU
M-Tipe damages assessment
3 10
C-Tipe damage assessment
20 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
Progress in fabrication
• 4x Cooling plates (CPs)• 2x U-shaped CPs• 4x Lateral Wraps• 2x U-shaped Lateral Wraps
• Complexity of the BU manufacturing is mainly in the CPs: manufacturing test mock-ups are addressed to study the CPs fabrication techniques.
• Complex mounting sequence: TIG orbital welding adressed.
• 1 BU Backplate• 1x Inlet + 1x Outlet pipes• 2x Ditributor Frontplate • 2x Distributor Backplate • 2x Grill plate
21 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
Progress in fabrication
Complete set of Build To Print CAD drawings performed and Design Description Document (DDD) of the BU released :Complete set of Build To Print CAD drawings performed and Design Description Document (DDD) of the BU released :
22 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
Progress in fabrication
Qualification of fabrication techniquesQualification of fabrication techniques
• BU bending radius (Uni Stuttgart)BU bending radius (Uni Stuttgart)
• Cooling channels with Spark Erosion Cooling channels with Spark Erosion (industry)(industry)
Slight bump, poor torch orientation
Qualification in welding laboratories of CEA Saclay to Qualification in welding laboratories of CEA Saclay to obtain welding parameters for BU TIG2 (purge gas obtain welding parameters for BU TIG2 (purge gas pipe with backplate manifold, RCC-MR and ISO pipe with backplate manifold, RCC-MR and ISO starndards)starndards)
Manufacturing of CP mock-ups Qualification of TIG orbital welding
23 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
BU mock-up testing program in EU
BU cell, 1 to 1 BU dimensions
BU container, optimal shape for:– the interface with Heblo facility– leak tightness– instrumentation– access to the testing zone– experimental plan flexibility
Instrumentation access from the mock up side: high testing possibilities and flexibility
Possible access for the instrumentation from the
back side
Goal: Design and Procurement of a BU Mock-up
24 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
TBM design requirements
Several functional requirements for the HCPB Blanket are related to the Solid Breeder performances. They concern:•Neutronic performances for T self-sufficiency (TBR, Tritium Breeding Ratio);Neutronic performances for T self-sufficiency (TBR, Tritium Breeding Ratio);•Temperature control;Temperature control;•Long Blanket lifetime;Long Blanket lifetime;•Tritium extraction;Tritium extraction;•Material compatibility;Material compatibility;•Low tritium inventory in materials;Low tritium inventory in materials;•Low activation (for waste management and recycling).Low activation (for waste management and recycling).
Most of these requirements have been quantified for the design of DEMO and FPP, e.g. a calculated TBR not lower than 1.12 is requested for DEMO and FPP or a blanket lifetime compatible with a neutron fluence of ~15 MWa/m 2 is assumed in the FPP. These requirements are the basis on which sets of specification for the pebble production have been generated.These requirements are the basis on which sets of specification for the pebble production have been generated.The connection among these general functional requirements and specification of the pebble (e.g. density, Li-6 enrichment, etc.) and pebble beds (e.g. effective thermal conductivity, packing factor, etc.) can be reconstructed for some of them, but can be very complicated in other case.E.g. the nuclear analyses can correlate well properties like material density, pebble bed packing, ceramic composition with the TBR, allowing to determine the required properties for the pebble production. More complicated is to state the impact that e.g. the crash load value has on functional requirements like the T extraction or lifetime; fragmentation of pebble (that can impact the purging functionality) should be minimised, but a quantification of an upper limit necessitate further R&D.Then ITER TBM has specific functional requirement. Then ITER TBM has specific functional requirement. The specifications of the pebbles for TBM are oriented to the specification generated for DEMO/FPP. I.e. in TBM relevant reactor pebble beds will be tested trying to reproduce the most relevant reactor conditions. Deviations are introduced to cope with specific ITER relevant requirement; e.g. Li-6 enrichment in the ceramic is used at the “maximum” enrichment level of 90 in order to compensate the lower T and heat production related to lower neutron wall load in ITER (0.78 vs. 2.5 MW/m2 in a FPP).
25 | Recent developments in the design of the EU HCPB-TBM, Fabio Cismondi
Conclusions
Main results achieved:• Definition of C&S for TBM design and analyses• Definition and analyses of main TBM specific loading conditions • Transient thermo mechanical analyses of a standard ITER pulse.• Release of DDD for TBM box and Bus.
Important outcomes of the TBM transient analyses:• Several junctions present peak stresses : design optimization is on-going.
Open issues:• Design rules developed mainly for austenitic-type steels (i.e. 316L(N)-IG ITER shielding steel)• Limited experience with martensitic-type steel in a fusion relevant environment, • Concerns regarding the validity/degree of conservatism of the C&S rules when taking into account Eurofer97 mechanical properties.
Next priorities:• Develop dedicated models and studies addressing design issues• Assess possible requirements and operating scenarios limiting the margins under which the design can evolve.• Experiments validating FE modeling: pebble beds thermo mechanics, fluid dynamic, structural material behavior
26 | Thermo-mechanical performance of the EU TBMs under a typical ITER transient; Fabio Cismondi