Fusion Test FacilitiesCatalyzed D-D with T-removal

John SheffieldISSE - University of Tennessee

ReNeW MeetingUCLA March 3, 2009

With thanks to Mohamed Abdou, Don Batchelor, Vincent Chan, Steve Obenschain, Martin Peng, Mohamed Sawan,

Tom Simonen, Ron Stambaugh, Steve Zinkle et al.

Introduction

I will discuss two topics:

• The need for Fusion Test Facilities, both MFE and IFE: we’ll benefit from any of them!

• A solution to alleviate the 14 MeV neutron problem – but with much tougher plasma performance requirements.

Destructive Testing

• It is common practice to test engineered components to destruction prior to deployment of a system e.g.,

- Automobile crash tests

- Airplane wing flexing tests

- Testing nuclear fuel assemblies to

meltdown—PHEBUS reactor

Released on February 28, 2008: Boeing 787 Dreamliner Successfully Completes Fuselage Barrel Test

Boeing engineers proved the composite technology barrel design of the 787 by first taking the barrel to limit load, a test condition that simulates the most extreme conditions expected to be experienced in the life of the airplane.

Next, the test article was taken to 150 percent of limit load -- a condition called "ultimate load," the level required for certification.

Finally, the team pushed the composite section well beyond ultimate load to a destruct-condition maneuver beyond two and a half times the force of gravity.

Testers observed audible indications of damage as the test progressed but the piece did not reach the level of destruction that had been anticipated. Boeing engineers now are performing an extensive inspection of the barrel and analysis of test results.

PHEBUS REACTOR--CADARACHE

• Purpose: studies of hypothetical accidents in pressurized water reactors

• Type: pool with an open core• Power: capable of operating at between 20 and 40

MW thermal• Fuel: uranium enriched to 2.78%• The reactor was transformed into a miniature

PWR (scale 1/5000) for the program Phébus PFF, a study of the fission products released by a melting core. In ten years, six core fusion experiments were undertaken.

PHEBUS TESTS

• Tomography of damaged

fuel rod, following meltdown

in the PHEBUS reactor

A FUSION DEMO WILL REQUIRE LIFETIME & DESTRUCTIVE COMPONENT TESTING

• The Finesse study (Abdou et al, 1994) provides an analysis of the kind of nuclear testing required for in vessel components such as the first wall and blankets.

• While ITER will provide some data, it will have quite a low fluence of 14 MeV neutrons. Furthermore, its mission does not require testing components to destruction; although this may happen, it can not be considered as an adequate basis for qualifying all of the DEMO components.

• Even the Europeans are now considering this need – “R&D Needs and Required Facilities for the Development of Fusion as an Energy Source,” October 2008.– A Components Test Facility could be a desirable risk reduction for

DEMO associated to the qualification of nuclear technology components.

SIGNIFICANT FUSION DEMO COMPONENTS

• Blanket/First Wall• Divertor • Antennas or Final Focusing • Diagnostics & Controls• Remote Maintenance

SOME TESTING REQUIREMENTS

• Neutron Wall Load 1-2 MW/m2

• Plasma Mode: Steady state (>80% duty cycle) or a few times a second for IFE

• Minimum continuous operating time: 1-2 weeks

• Neutron Fluence at Test Module MW.y/m2

Stage I: Initial Fusion “Break-in” 0.3

Stage II: Concept Performance Verification 1-3

Stage III: Component Engineering Development 4-6

and Reliability Growth

Total Neutron Fluence for Test Device > 6

Hopefully, we’ll make less of a mess!

SUMMARY

• Fusion Component Test Facilities are an essential step prior to committing to a final design for a DEMO reactor.

• It is encouraging that options exist in both MFE and IFE.

• I hope that they will be built.

Catalyzed D-D Power Plants

• Deuterium is the ultimate fuel for fusion power plants because it is effectively unlimited.

• But the catalyzed D-D system requires substantially better plasma parameters than an equivalent D-T system e.g., <T> ~ 30 to 40 keV, and higher beta, say > 10%.

• Advanced tokamaks and stellarators appear to have the kind of performance that could be used to support a large D-D plant, say > 2000MWe.

Alleviation of Neutron Damage with Catalyzed D-D and removal of as much

tritium as possible.

The neutron damage, mainly from helium production, would be less than for D-T, but the heat load to the walls will be higher.

• Removal of some tritium would reduce the neutron damage. If this tritium were stored and allowed to decay to He-3, the He-3 could be recycled to enhance the reduction in the 14 MeV neutron flux.

• For the equilibrium case with 70% of the tritium removed and 70% recycled as He-3, the helium production in the wall is reduced by a factor 7.5 from the equivalent D-T case.

• If materials are developed, sufficient for the D-T case, this might allow the wall to last for at least 25 years.

Tritiumremoved fTr

Fusion powerin neutrons

Fraction of powerat 14.1 MeV

Fraction of power in neutrons

Fraction of powerat 14.1 MeV

fRec = 0 fRec = 1

0.0 0.384 0.326 0.383 0.326

0.2 0.346 0.284 0.317 0.260

0.5 0.276 0.205 0.218 0.162

0.7 0.216 0.137 0.153 0.097

0.8 0.181 0.103 0.120 0.064

0.9 0.141 0.052 0.088 0.032

1.0 0.096 0.000 0.056 0.000

0

10

20

30

40

50

0 100 200 300 400 500

D-D SystemD-T System

dpa/

FPY

He appm/FPY

D-T

D-D

No T removed

50% T removed

90% T removed

70% T removed

Ferritic Steel

Fission Reactors

Conclusions for D-D with tritium removal

• I believe that this approach is the ultimate solution for fusion energy because deuterium is, in effect, unlimited.

• What is needed in the next 5 -10 years is more work—experiment and theory—on using RF to remove tritium. Also a study of how magnetic ripple might enhance tritium removal.