Transient EM Analysis of ITER Plasma-facing ComponentsTimothy Burke, Thomas Holschuh

SAND2010-7328C

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.

The Fusion Reaction•The peak DT reactivity is about 200 keV but a plasma temperature of about 20 keV (~100 MK) has a sufficient reaction rate•The reaction products are a 3.5 MeV alpha and a 14 MeV neutron•Deuterium is found in all water•Tritium is bred from lithium using fusion neutrons

Deuterium-Tritium Fusion Reaction

Stars are confined by gravity.Terrestrial plasmas are

confined by either magnetic fields (many configurations) or inertially (inward momentum confines the plasma long enough for reactions to take place)The most common

magnetic scheme is the tokamak (bottom figure).

Plasma Confinement

ITER

Largest tokomak device to be built

“The way” Prove the feasibility of fusion

technology, not produce power

First plasma to ignite in 2018 Collaboration of 7 National

Entities• United States, Russian

Federation, China, South Korea, Japan, European Union, India

Central Solenoid

Outer Inter-coil Structure

Toroidal Field Coil

Poloidal Field Coil

Machine Gravity Support

Blanket Module

Vacuum Vessel

Cryostat

Port Plug

(IC Heating)

Divertor

Torus Cryopumping

ITER – The Device

Total fusion power 500 MW

Additional heating power 50 MW

Q - fusion power/ additional heating power ≥ 10

Average 14MeV neutron wall loading ≥ 0.5 MW/m2

Plasma inductive burn time 300-500 s *

Plasma major radius (R) 6.2 m

Plasma minor radius (a) 2.0 m

Plasma current (Ip) 15 MA

Toroidal field at 6.2 m radius (BT) 5.3 T

Characteristics of ITER

ITER - Blanket

Covers the interior of the vacuum vessel and magnets Modular - 440 individual segments, 1x1.5 m Thermal shielding, Nuclear Shielding weighing up to 4.6 tons

Courtesy of J. Kotulski

First Wall and Shield

Blanket comprised of thin PFC First Wall and thicker Shield Block

First Wall serves as heat sink

Shield Block serves as neutron shield

Shield Block

First Wall

Slits in shield block to mitigate currents

Pivot Point

First Wall and Shield - Continued

Courtesy of J. Kotulski

Slits in shield block to mitigate eddy currents

First wall comprised of “fingers” to mitigate currents

Plasma Disruptions

Normal Plasma Plasma at end of Disruption, t = 50 ms

Dots represent plasma shape

Outline of First Wall

•Plasma dissipates in milliseconds

•Numerous causes

•Loss of Temperature

•Loss of Control

•Change in plasma current or magnetic fields causes plasma to move, eventually hitting the walls of the vessel

Plasma Disruptions

•Rapid loss of current in plasma induces current in other structures

•Induced current in a magnetic field creates JxB forces and torques on objects

•Extreme current magnitudes mean extreme forces are possible 0.0E+00

5.0E+06

1.0E+07

1.5E+07

2.0E+07

0 0.02 0.04 0.06

Plas

ma

Cur

rent

(Am

ps)

Time (Seconds)

Plasma Current During Disruption

Electromagnetic Analysis of Current Induced in ITER Blanket Modules

Tim Burke

Blanket Module – Vacuum Vessel Interface

Different configurationsCenter/off center Hydraulic ConnectorDifferent Mount shorting scenariosDifferent impedances/conductivityDifferent Strip countsDifferent Strip positions

All of these have the potential to carry current to and from the vacuum vessel

Goal is to minimize current path through vacuum vessel as well as current magnitude

Mounts

Conducting Strips

Hydraulic Connector

The Model

•Simple, imperfect model in design and properties

•Designed for time efficiency

•4 hours of run-time compared to days or weeks of run-time

•Designed to see if the problem warrants further investigation

BM 6

BM 12

Pink = 450 A/mm²

Blue = 0 to 50 A/mm²

•Disruptions cause current to flow through blanket module

•Currents can impart JxB forces on module

•Currents become un-balanced due to connections between shield block and vacuum vessel

Note: size and direction of arrows indicate direction and magnitude of current.

Currents in Blanket Module 12

Circulating Current

Vacuum vessel interface

Currents in Blanket Module 12Interface between shield block and vacuum vessel

Blue areas are conducting strips

(Not shown)

Arrows indicate magnitude and

direction of current

Currents in Blanket Module 6

Interface between shield block 6 and Vacuum Vessel

Blue areas are conducting strips (Not shown)

Currents in Blanket Module 6 Components

•Major currents flowing from vessel, to strips, through shield block, through strips, then back to vessel

•Unexpected current flow

•Merits further investigation

•Current density of 150 A/mm² in strips•Minimal current in hydraulic connector

Vacuum Vessel Interfacing

Shield block interfacing

Current with one conducting strip

Shield-block interfacing side

•Current flowing in to and out of the same conducting strip from shield block

•Unexpected results

•Merits further investigation

•Minimal current flowing through hydraulic connector

BM6 Strip Current

0

2000000

4000000

6000000

8000000

10000000

12000000

0 1 2 3Time (ms)

Cur

rent

(A)

Current ramps up to 11MA in milliseconds

Potential to generate massive forces

Current in BM 6 Conducting Strips

BM6 Force

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

2.5E+06

3.0E+06

0 0.5 1 1.5 2 2.5 3time (ms)

Forc

e(N

)

BM6 Torque

0.0E+00

1.0E+04

2.0E+04

3.0E+04

4.0E+04

5.0E+04

0 0.5 1 1.5 2 2.5 3time (ms)

Torq

ue(N

-m)

Conclusion

Interesting results

Problem warrants further investigation

Next steps• Properly model B-field inside vacuum vessel• Analyze different current paths thoroughly • Include components with more intricate design

Electromagnetic Analysis of Test Blanket Module

Tommy Holschuh

Test Blanket Module

The Test Blanket Module is designed to produce tritium.

Deuterium is easy to get.

Tritium is needed for the fusion reaction, but harder to find.

Plasma-Facing Side

Back

Test Blanket Module

The TBM contains PbLi as a liquid metal.

Neutrons interact with Lithium, produce tritium.

Elaborate system behind module to extract tritium.

Front

(Plasma-Facing Side)

BackLead-Lithium

Test Blanket Module

During a disruption, the change in current produces forces on pieces of tokamak.

Need to model forces and torque on TBM

Use OPERA-3D to do Elektra E&M Transient Analysis

Toroidal Filament

Poloidal Coils

Conductors to simulate

Plasma

TBM

Elektra AnalysisSum of Forces on Pieces of TBM

-40

-20

0

20

40

60

80

100

120

140

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05

Time (s)

Forc

e (k

N)

Force - XForce - YForce - Z

Elektra AnalysisSum of Torque on TBM

-200

-150

-100

-50

0

50

100

150

200

250

300

0 0.01 0.02 0.03 0.04 0.05

Time (s)

Torq

ue (k

N-m

)

Torque - X

Torque - Y

Torque - Z

Elektra Analysis

Sum is a little high, but near expected values.

This is the sum of Force and Torque on every piece of the Test Blanket Modules (blue-colored).

These do not include frame (light green) and SS plate (green).

Frame

SS316

Elektra Analysis – Frame and PlateSum of Forces on TBM

-400

-300

-200

-100

0

100

200

300

400

500

0 0.01 0.02 0.03 0.04 0.05

Time (s)

Forc

e (k

N)

Force - XForce - YForce - ZForce - SS316 - XForce - SS316 - YForce - SS316 - ZForce - Frame - XForce - Frame - YForce - Frame - Z

Elektra Analysis – Frame and PlateSum of Torque on TBM

-6000

-4000

-2000

0

2000

4000

6000

8000

0 0.01 0.02 0.03 0.04 0.05

Time (s)

Torq

ue (k

N-m

)

Torque - XTorque - YTorque - ZTorque - SS316 - XTorque - SS316 - YTorque - SS316 - ZTorque - Frame - XTorque - Frame - YTorque - Frame - Z

Elektra Analysis

Plasma-Facing Side

Back

Future

Since then, conductor properties were checked. It was found that initial current densities were incorrect. Toroidal filament was several orders of magnitude larger than

correct value. Solenoid coils were several orders of magnitude smaller than

correct value. This was adjusted. OPERA is currently re-running analysis

Correct simulations, pictures, and data will be finished by end of this week.