IAEA DEMO Workshop

KIT – The Research University in the Helmholtz Association

www.kit.edu

IAEA DEMO Workshop

November 15th - 18th, 2016 at KIT

Klaus Hesch, Head of Programme

KIT R&D Work for DEMO – Recent Highlights

Klaus Hesch November 18th, 2016

The KIT Nuclear Fusion Programme

Objective:

Development of key technologies for fusion energy

Focus on three lines of fusion experiments:

Design, engineering, realisation and testing of components and systems for ITER

Key developments towards DEMO and Fusion Power Plant (inter alia: Broader Approach, IFMIF)

Contributions to Wendelstein 7-X

Staff:

~ 220 scientists, engineers and support staff

From 9 KIT institutes

Budget:

~ 32 M€


Remote

Maintenance

Neutronics

Balance of Plant

Systems Integration Safety

Logistics

Requirements Management

Barriers

Magneto-

Hydrodynamics

Breeder

Materials

Functional Materials

Cryo-Materials Testing

HTS Cabling

Components

Fusion Magnets

T Pumping

T Processing

Fuel Cycle

Plant System & Dynamics

Gyrotrons

Microwave

Antennas

Microwave

Plasma Heating

W Materials

Design

Rules

Manufacturing

Technologies

Irradiations

/ IFMIF

Red. Activ. Steels

Structural Materials

In-Vessel Components

Breeding Blanket Divertor

High-Temperature

Cooling

KIT Fusion Programme - Structure

Shield

Materials

Corrosion


Outline – Recent Highlights

Fusions Magnets & Magnet Components

High-Temperature Superconductor Cross Conductor (HTS CroCo)

Microwave Plasma Heating & Current Drive

Advanced Gyrotrons

Fusion Fuel Cycle

KALPUREX Process


Blanket Design

Blanket Manufacturing


Breeder Ceramics

Magneto-Hydrodynamic Effects in Liquid Metal Blankets


Tungsten Materials Engineering





Advanced Gyrotrons

Fusion Fuel Cycle

KALPUREX Process


Blanket Design



Breeder Ceramics






High Temperature Superconductor REBa2Cu3O7-d (REBCO) with RE = Rare Earth atom e.g. Y, Gd, Nd or other

For high field REBCO is superior

compared to Low Temperature

Superconductors

but anisotropic with respect to field

orientation

0 5 10 15 20 25 3010

1

102

103

104

Je /

(A

/mm

2)

B / T

NbTi (1.9 K)

Nb3Sn internal tin

Nb3Sn bronze

REBCO ||

REBCO _|_

CuO2

planes

Grain orientation is

mandatory

Preparation as thin films,

only


Proposals to Form Cables from thin REBCO Tapes

Makoto Takayasu et al.,

Supercond. Sci. Technol. 25 (2012) 014011

A twisted stacked-tape cable

demonstrator made by MIT

measured at KIT in the FBI facility

and carried a current of

(C. Barth et al., SUST 28 (2015)

045015)

5.4 kA at 4.2 K and 12 T

D. van der Laan, (Advanced

Conductor Technologies LLC)

HTS4Fusion workshop Pieve

S. Stefano, Sept. 11-12, 2015

6.5 kA @ 4.2 K & 20 T

Conductor On Round Core Cables

(CORC)

Round strands by enclosing HTS in Cu half

shells D. Uglietti et al. demonstrated a

Rutherford cable with round

strands (ENEA) Supercond. Sci. Technol. 28 (2015)

124005

60 kA at 4.2 K & 12 T

Twisted stacked-tape cables

CRPP / SPC


For economical fabrication

of long lengths:

all these steps

in one continuous process

HTS CrossConductor (CroCo)

Arrange the tapes

Pre-tin the tapes

Twist the stack

Solder all individual tapes

Form the stack

Apply a jacket or former

Awarded the EURATOM

Innovation Prize in

Fusion Research 2016,

together with SPC


IAEA DEMO Workshop


HTS CroCo Application

to be used

for large high field magnets or for low loss power transmission

Design concept of a 100 kA DC cable,

cooled with sub-cooled LN2 at T = 68 K

Design concept of a compact Rutherford cable

for a DEMO TF coil with Iop(4.5 K, 13 T) = 50 kA

with a temperature margin of 12 K.

HTS CroCo is a base element with simple fabrication and great performance

with simple long length manufacturing incl. twist

• „all-in-one“ fabrication of core (3 m/min)

• no degradation caused by fabrication

• good mechanical and electrical stabilization


HTS CroCo for Large High-Field Magnets

e.g. Fusion Magnets

Cross section of a DEMO TF magnet winding pack

Design concept of a

compact Rutherford cable

for a DEMO TF coil

with Iop(4.5 K, 13 T) = 50 kA

with a temperature margin

of 12 K.






Advanced Gyrotrons

Fusion Fuel Cycle

KALPUREX Process


Blanket Design



Breeder Ceramics





Targets for Future DEMO Gyrotrons

Operate at optimum current drive frequencies

CD frequency: > 200 GHz (up to 240 GHz)

Keep the total number of gyrotrons low

Output power: ≥ 2 MW

Achieve a high energy gain for the power plant

Total efficiency: > 60 %

Provide multi-purpose operation capability

Multi-purpose at n·l/2 of window resonances

Steps of about ~34 GHz (136/170/204/238 GHz)

Achieve a fast frequency step-tunability

±10 GHz in steps of 2-3 GHz, step-to-step in

seconds

Optimized designs + broadband window

technologies

SN5i 2 MW

Short-pulse

Coaxial-cavity

prototype

W7-X 140 GHz

1 MW CW

series gyrotron

ITER 170 GHz

1 MW SP

prototype

Towards DEMO: The EU gyrotron family


Physical Designs for Frequencies ≥ 200 GHz

Conventional cavity Simple and robust design

Dense spectrum of competing

modes => stable operation limited

=>Operation ≥ 1 MW

Coaxial cavity Reduced mode competition

Reduced voltage depression

Inner conductor: Risk of

misalignment + thermal loading

=>Operation ≥ 2 MW

ITER 170 GHz 1 MW CW

conventional-cavity gyrotron

ITER 170 GHz 2 MW CW

coaxial-cavity gyrotron

Starting point:

ITER Gyrotrons


Broadband Brewster-Angle Window Design

67.2°

140 mm 50 mm

New joining technologies for diamond discs under consideration.

today

Today: A 140 mm large axis

corresponding to 50 mm

waveguide is the upper limit for a

Brewster diamond window and the

corresponding waveguide.

Target: At minimum a 180 mm large

axis corresponding to an 63.5 mm

waveguide has to be achieved for

future designs if considering same

waveguide diameter as for ITER.


FULGOR –

Fusion Long-Pulse Gyrotron Laboratory

HVDCPS:

• EPSM module technology

• Support of multi-stage

depressed collectors

• Low-noise operation

-> Company Ampegon

High performance cooling:

• 10 MW, CW

SC Magnet:

• 10 T (up to 240 GHz)

• L-He-free

RF Diagnostics

• 2 MW CW load

Control system:

• Siemens S7

Gyrotron:

• ≤ 2 (4) MW CW

• ≤ 240 GHz

under construction (HVDCPS by end of 2017)






Advanced Gyrotrons

Fusion Fuel Cycle

KALPUREX Process


Blanket Design



Breeder Ceramics





KALPUREX Process

= Karlsruhe liquid metal based pumping

process for fusion reactor exhaust gases

The KALPUREX direct internal recycling process

… is continuous

… is the EUROfusion reference solution…

to minimize radioactive inventories in the fuel cycle below the

legal limit

to reduce the tritium start-up inventory to the absolute minimum

to enable sufficiently high plasma densities

to limit the use of cryogenic power for operation and increase the

balance of plant and hence the attractiveness of fusion


KALPUREX Process

Awarded the

EURATOM innovation

prize in fusion

research 2014

Mercury based diffusion

pump + mercury based

liquid ring pump =

Continuous exhaust

pumping

MFP = Metal Foil

Pump

LDP = Lin. Diff.

Pump

LRP = Liquid Ring

Pump

Torus


Mercury rough pump train tested in JET DTE2

Fully tritium compatible mercury based roughing pump unit under

manufacturing,

To be characterized and exploited in JET during TT and DTE2

(2018/19)

Acceptance tests of the ring pumps at

the manufacturer site Turn-key pump unit for JET






Advanced Gyrotrons

Fusion Fuel Cycle

KALPUREX Process


Blanket Design



Breeder Ceramics





EUROfusion HCPB Reference Design

Large design revision in 2015

Blanket internals largely simplified:

Better use of blanket radial thickness,

(breeding zone, BSS, manifold, neutron

shield)

Steel amount reduction, improved

neutron economy

Simplified, fully counter-flow coolant

scheme

Reduced coolant pressure drops

Simplified manufacturing route, relying

on ITER HCPB TBM experience

BSS = Back Supporting Structure


Flexible Design & Impact on TBR

TBR can be easily modelled for

different approaches in the

EUROfusion DEMO baseline:

v0: Blanket with thin caps

(representative for Single Module

Segment „banana“), TBR

maximisation.

v1: Blanket with thick caps

(representative for Multi Module

Segment)

v2: Blanket with shorter breeder

zone (larger BSS, increased

shielding capability)

v0 v1 v2

v1 v0 v2

CAD models

Neutronics (MCNP) model construction

TBR = 1.37 TBR = 1.30 TBR = 1.20


Blanket Integration in Vacuum Vessel

Development of a RH-compatible attachment system:

HCPB blanket segments and attachment system structural

integrity verified for an accidental scenario of central disruption

event (collaboration with WPRH / CCFE)

von Mises stress (left) and displacement (right) distributions of a DEMO HCPB

blanket sector after a central disruption event

HCPB DEMO sector + CCFE‘s

blanket transporter

CCFE‘s blanket

transporter

Port shield

RH compatible

attachment

system

RH interface






Advanced Gyrotrons

Fusion Fuel Cycle

KALPUREX Process


Blanket Design



Breeder Ceramics





Device with external dimensions ~ meters

RAFM steel (EUROFER)

To be assembled mainly from various plate

segments, e.g.:

First Wall (plasma facing)

Side Caps (transparent)

Breeder Zones

All parts penetrated by complex cooling

channel structures

Example for fabrication strategy of a typical HCPB TBM relevant

structural part:

Stiffening Plate (SP)

The TBM / DEMO Breeding Blanket from

Fabrication Point of View:


?

EB-welding

Stiffening Plate (SP): Assembly of 3 Segments

Rear part: Coolant manifolds with changing geometry => EDM (Electrical

Discharge Machining)

Middle part: Straight and parallel channels => EDM

Front part: Segments with complex channels e.g. turnarounds and in case 3D

flow-paths; requires complex manufacturing routines, therefore:

Is Additive Manufacturing (SLS) an option?

28

SLS an Option for ITER / DEMO Components?

• Layer of metal powder

• Orientation directions!

• Next layer placed on top,

• Repeated…

• Laser operated in sequences,

• Areas of powder remain

• Cavities created after powder removed

X

Y

Z

X

X

X

Y

Y

Y

Z

Z

Z

Huge flexibility for creation of parts with internal cavities

Additive Manufacturing (AM) processes: Selective Laser Sintering (SLS)

=> Process scheme… • Layer sintered/melted

by laser in lines


TBM Stiffening Plate Demonstrator

200 mm

100 m

m

Hybrid component from AM-EUROFER + EUROFER-97 (remaining test parts)

6 independent pressure chambers

Electron Beam welding


Promising results

Start material qualification of AM-EUROFER

TBM Stiffening Plate Demonstrator


Micro-structure of AM-EUROFER

Qualification of AM-EUROFER

BEFORE HT: Generation in columns traceable

AFTER HT: No more traces of SLS process EUROFER-97,

heat 993402

HV30 ~ 220

IAM AWP

IAM AWP

50 µm

No artefacts of layered generation of the material

after HIP

For comparison: “classical”

EUOFER


Not pressurized

AM Technology for Shell Structures

Ductile behavior during fracture demonstrated

Comparison of cylindrical sections of capsule, plastic deformation visible

No splintering of capsules observed, crack in expected direction






Advanced Gyrotrons

Fusion Fuel Cycle

KALPUREX Process


Blanket Design



Breeder Ceramics





Development of Advanced Ceramic Breeders

Ø 250 – 1250 µm

Advanced tritium breeding ceramics by melt-

based process

Li4SiO4 based ceramics with up to 35 mol% Li2TiO3

Investigations are focused on

Process development

Material evaluation and qualification for DEMO

Reprocessing studies and activation calculations


Processing of Advanced Ceramic Breeders

A controlled pressure is applied to the melt in a

crucible to form a laminar jet from a nozzle

The jet decays into small droplets as described

by the Plateau-Rayleigh instability

The droplets are solidified using a spray system

Optical process control by high-speed camera

and image processing of footage

Process is also suitable for reprocessing –

no wet chemistry

The KALOS Process (Karlsruhe Lithium Orthosilicate) was developed

in order to offer better process control (w.r.t. existing industrial process)


Qualification of Advanced Ceramic Breeders

Evaluation of optimum composition

Long-term stability

Thermal conductivity of pebble beds

Tritium loading / release behavior

Behavior under e- and γ-irradiation

Compatibility of CB and EUROFER

Reprocessing studies

Mechanical Properties

Long-term Annealing

Pupeschi et al., under review for FED

Thermal Conductivity

Kolb et al., under review for FED

Tritium Release

Mechanism

Zarins et al., JNM 470 (2016)

Radiolysis

Leys et al., FED 107 (2016)

Remelting

Mukai et al., FED 100 (2015)

Activation Characteristics

Mukai et al., SOFT 2016

Corrosion






Advanced Gyrotrons

Fusion Fuel Cycle

KALPUREX Process


Blanket Design



Breeder Ceramics





MHD Effects in Liquid Metal Blankets for DEMO

PbLi is one option as breeder material and

coolant for a DEMO reactor

Movement of the electrically conducting fluid

within the magnetic field induces currents and

generates strong electromagnetic forces => Magnetohydrodynamics dominates the flow

Fundamental and applied MHD research to

support design activities by

Asymptotic analysis using simplifications for very

strong B-fields

Numerical simulations using finite volume technique

Experimental work in the MEKKA laboratory for

Code validation

Engineering correlations, e.g. for pressure drop

HCLL (CEA)

WCLL (ENEA)

DCLL (CIEMAT)


WCLL Blanket: MHD Modelling

MHD flows in model geometries

Flows in rectangular ducts with internal

coaxial cooling pipe

Non uniform thermal conditions caused by

internal heat source and cooling at the pipe

Various magnetic fields and internal heat

sources are considered

g

B

cooling

pipes

breeding

zone (BZ)

PbLi inlet BZ water

inlet

BZ water

outlet

g

B

rad

tor

pol

g

B

tor

pol

v

Convective flow is slowed down by EM

forces even with intense thermal sources

Resulting flow path is pretty complex

Temperature contours and v

streamlines. Flow at Ha =1000


DCLL Blanket: Electric Potential and

Velocity Profiles with Flow Channel Insert

Gap between 2 FCI

Insulating FCIs decouple induced electric currents from well

conducting walls => smaller currents, smaller pressure drop

Leakage currents at junctions of FCIs generate local 3D effects => locally increased pressure drop, 3D distortion of velocity profiles


DCLL Blanket: FCI Experiments

Next step: Investigate local 3D effects

Fabrication of sandwich-type FCSs, insulating

coating made by plasma chemical vapor

deposition between two steel sheets

Fabrication of a test section for MHD

experiments in the MEKKA laboratory Laser-welded FCI sheets

Pressure taps

B FCI

Gap between two FCIs

Design of a test section for experiments in MEKKA






Advanced Gyrotrons

Fusion Fuel Cycle

KALPUREX Process


Blanket Design



Breeder Ceramics





By cold rolling it is possible to achieve room-temperature tensile ductility of pure W

The ductile–brittle transition temperature (DBTT) can be decreased through cold rolling

Ductilisation of W through Cold-Rolling

Hot-rolled, coarse-grained W

Test temperature: RT Severely cold-rolled, ultrafine-grained W

Test temperature: RT

10 mm 10 mm

3PB Tests


The higher the degree of cold-rolling, the lower the DBTT temperature

Ductilisation of W through Cold-Rolling

0 100 200 300 400 500 600 700 800 900 1000

0.0

0.5

1.0

1.5

300 400 500 600 700 800 900 1000 1100 1200

Ch

arp

y E

ne

rgy [

J]

Temperature [°C]

Temperature [K]

L-S T-S

L-S

T-S

L-S T-S

Cold-rolled Hot-rolled Recrystallized

The results show that the DBTT scales with the grain size, 𝑑, of the tungsten sheets:

the smaller the grain size, the lower the DBTT. By severely cold rolling KIT succeeded

in producing a tungsten sheet with a DBTT of -100°C (not shown in the diagram).

The cold-rolled sheets from this diagram are about to enter an irradiation campaign

organized by EUROfusion.

J. Reiser, J. Hoffmann et al. (2016)

Temperature [K]

Temperature [°C]

Ch

arp

y

En

erg

y [

J]

LS = in rolling direction

TS = perpendicular to rolling direction


Cold-Rolled W Sheets - Application in DEMO

Divertor Mock-up

Low brittle-to-ductile transition

temperature and high fracture

toughness, 𝑲𝑰𝑪

Interesting candidate for plasma facing

components.

The problem of “main crack” may be

overcome by using cold-rolled sheets

(under investigation).

Detail A

H. Greuner, IPP,

Garching

Detail A: Main crack

H. Greuner, IPP, Garching

10 mm

RD

“hot-rolled“ plates “severely cold-rolled” /

“cold rolled” plates

RD

W-laminate pipe and W monoblocks


Mass production of components

Material development

Time & cost effective

near-net-shape forming process

Shape complexity &

high final density

Tailoring new materials

&

Investigation of properties

Tungsten Powder Injection Molding


Mass Fabrication of Tungsten Parts

…The PIM Process Sequence (1)

Material development

Design & engineering of a tool

Powder Binder

Mixing /

kneading /

extrusion

Filling

Simulation

PIM tool

Feedstock



…The PIM Process Sequence (2)

Injection molding

of green parts

Debinding,

heat treatment


23.11.2

016


with shaping various Ø

…W monoblocks –

various sizes and shapes –

assembly to a component…


A series of 60 Langmuir probes produced at KIT and delivered to CEA in spring 2016.

Langmuir probes to determine the

electron temperature, electron

density, and electric potential of a

plasma

Mass fabrication of tungsten parts …W PIM samples for WEST…

Water-cooled CuCrZr PFU


W (PIM) W PLANSEE (rolled)

400 °C

High strength in rolling direction only Same strength in all directions

Fully ductile @ 200 °C Fracture already

at 3% strain

Development of New Materials …Mechanical testing via 4-PB tests from 20 °C to 400 °C…

Sample geometry: (12 x 1 x 1) mm

Constant strain rate: 0.0330 mm/min


Development of new materials … Mechanical testing via 4-PB tests from 20 °C to 400 °C …

ductile @ 200 °C

Transgranular crack @ RT

EBSD of the notch

Grain sizes:

Pure W: 50 – 100 µm

W-1TiC: 4 – 6 µm

W-2Y2O3: 4 – 8 µm

Sample geometry: (12 x 1 x 1) mm

Constant strain rate: 0.0330 mm/min

AES: Microstructure & element allocation

yield at 400 MPa

ductile at 400 °C

yield at 1000 MPa

ductile at 300 °C

yield at 1100 MPa






Advanced Gyrotrons

Fusion Fuel Cycle

KALPUREX Process


Blanket Design



Breeder Ceramics





KIT Contributions to DEMO – Summary

Competent in technology and materials development for fusion

Bring ideas to maturity

Committed to fusion energy

Many collaborative approaches

Open to further collaboration within and beyond Europe

Documents

IAEA DEMO Workshop