FNSF Testing Strategy Discussions for PFC – PFC/FNSF Joint Session

Chairs: Maingi, Menard, Morley

Session Objectives and First Wall Testing Description

Neil Morley, UCLA8/4/2010

Starting Point for this session, a Fusion Nuclear Science Facility – FNSF (CTF, VNS, etc)…

An FNSF facility is proposed as an test facility in which the impact of the integrated fusion environment – Combined plasma particle and heat flux; nuclear heating, damage,

activation; magnetic field and forces; vacuum; and high temperature operation, …

on the operation, performance, and reliability of in-vessel components and systems– Divertor, firstwall/blanket, shields, plasma facing features of

fueling/heating/diagnostic systems, …

can be tested, studied, improved and validated

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Linkages of Main Thrust 13 Elements (Theme IV)

Slide 3

Basic Properties / Separate Effects Testing

Multiple / Partially-Integrated Effects Testing

Integrated Fusion Mockup/Comp Testing

Demo ReadinessDatabase, Design Tools, Qualification / Licensing

Increasing time, complexity, integration, cost

Models and Theory

Simulation Codes

Integration, Benchmarking

The multiple Theme III thrusts also had a similar progression -- ending with testing in a integrated fusion environment

Test Facility Planning & Preparation

ITER-TBM / FNSF Facility and Test Article

Planning, Preparation, Qualification

Decreasing number of concepts and options

The classical fusion “bootstrap” problem…

• To test in a fusion environment, one must be able to create and sustain a fusion environment

• FNSF will to some/large degree require the successful operation of the very components it is supposed to test– How should the basic machine be built?

• How to scale, design, instrument and perform relevant experiments in a reduced scale FNSF that tell us something/everything about DEMO and power plant conditions?

• These questions have led to, in the FNST community meetings over the past 2 years, a discussion of a strategy for first wall / blanket components. We would like to broaden this discussion to include the divertor as well.

Agenda of this joint session

• What divertor material, cooling and configuration options should be considered for FNSF?

• What FNSF parameters and features are required for divertor/PMI testing? What is the PFC/PMI testing strategy in FNSF?

• What R&D is required for the FNSF divertor?

“Base” vs. “Test” First Wall/Blanket

• First wall is integrated into blanket – development, design, analysis and testing must be considered together

• A functioning breeding blanket will be needed to breed tritium during DT operation– no practical or affordable external source is likely available

(~1.6 kg/year burned per 100 MW at 30% availability)

• Consider deployment of a base FW/blanket whose main mission is supply tritium, and port based test FW/blankets that are more easily removable and replaceable and instrumentable

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A FW/Breeding Blanket Testing Strategy

Both port-based and base blanket have a testing mission

Base blanket – Are made largely using the same materials and designs as desired test

blankets, optimized for reliability • Interaction with plasma and neutron field similar to testing blankets

– Should be operated with more conservative temperature margins and smaller temperature gradients

– Can still provide important statistical data on operations and failure modes/effects/rates in all phases DD thru DT operation

Port-based blankets – Are more highly instrumented and designed for specific scientific purposes

and experimental missions– Can be operated with more aggressive and prototypic temperatures and

gradients– Should be designed for fast replacement

What Material Options Exist to Use For Base First Wall / Breeding Blanket

FW and Structural Material: Ferritic/Martensitic steel– Austenitic steel is less suitable because of low thermal stress

factor, high activation, and high swelling. It does not extrapolate to reactor. No reasons found to think that austenitic steel reduces risk.

– Issue of FW armors have not yet been discussed in detail, need PFC/PMI input

Primary Coolant should be Helium, even for base blanket– Most generically reactor relevant, both for ceramic breeder and

dual coolant blanket options– Keep operating temperature of the ferritic structure above 300°C

to minimize the impact of neutron-induced damage.– Potential for chemical reactions between the coolant and the

beryllium or liquid metal breeders can be avoided

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A breeding blanket w/ integrated First Wall should be installed as a BASE Blanket on a FNSF from the beginning

Switching from non-breeding to breeding blanket involves complexity and long downtime, especially if coolant changes from water to helium

There is no non-breeding blanket for which there is more confidence than a breeding blanket (all involve risks, all will require development).

The actual wall conditions and materials used during the DT testing phase – e.g. high temperature and ferritic steel, should also be used during the HH/DD early operation phase in order to:– correctly optimize the plasma performance and pulse length and – obtain actual information on plasma-blanket interactions prior to

DT operations (PMI, first wall heat flux, off-normal events…)Such information is needed for safety/licensing/availability of the DT phase

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Fundamental FNST Research

An intensive program of laboratory scale experiments and model development addressing gaps in understanding and database

Example areas:– PbLi alloy tritium chemistry, transport

characteristics, isotope / impurity control– PbLi compatibility with SiC flow channel

insert material and ferritic/martensitic steel– Liquid metal MHD interactions that

dominate liquid metal blankets and free surface divertors flow and transport

– Heat transfer and enhancement in high-temperature helium-cooled divertor concepts.

– Tritium chemistry, transport and removal techniques from high temperature helium

– Ceramic-breeder pebble-bed response to thermomechanical load and cycling

– Interaction database of beryllium and liquid metal alloys with water and air

Slide 10

An example -- 3D MHD simulation of LM coolant streamlines in a pipe disturbed by a magnetic field gradient

Formation of instabilities and recirculating regions can strongly influence both heat and tritium transport behavior and generate strong flow resistance.

MHD forces generally exceed viscous and inertial forces by 5 orders of magnitude in fusion blankets.

Gradient region

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Fundamental FNST Research (2)

Scope– Functions and Elements of the Blanket,

FW, Divertor, heat transport and tritium systems (mainline and alternates)

– Database, basic phenomena exploration, model development in:

• Thermofluid/Heat transfer properties• Chemistry and reaction rates• Thermomechanical properties• Diagnostic capabilities

– Multiple university/lab research programs

Time scale– Consistent 10 year effort

Other Benefits– Innovation, invention, discovery– Basic validation of existing designs and

models– Reinvigoration of FNST in the US

Slide 11

heater

86mm

86mm

87mm

43mm

64mm

TC

TCLiPb (1 Š 1000 g)In alumina crucible

Alumina crucible

Heat block

Past tritium solubility measurements in PbLi have a wide discrepancy, by orders of magnitude. New experiments must provide better accuracy and help identify sensitivities that can drastically change the results

Objectives of this PFC/FNSF session Similar to first wall/blanket, discuss FNSF objectives, strategy and requirements for testing PFC components •What type of divertors are we considering for DEMO and power plants?

– Are they good candidates for testing in FNSF– How many variations, how should they be tested?– What needs to be shown/observed/measured in divertor testing in FNSF

•What are the possible testing strategies for divertor in FNSF– Can base/test divertors be included (partial toroidal, or upper/lower splits)– Use DD phase for extensive divertor and FW testing– What PMI specific testing is envisioned (maybe independent of first wall or divertor heat

sink design)•What are the requirements on FNSF

– Heating power, access for diagnostics, replacement speed, flexibility in PF coil positioning??

– Accommodate significant quantities of lithium•For these strategies, what is the R&D required in advance of an FNSF

Keep an open mind…

• We asked some people to supply a perspective on some of these questions

• We likely won’t arrive at a definite conclusion today • Try to understand the assumptions and concerns of experts

from PFC and plasma edge• Try to understand how divertor operation and testing can be

done in FNSF• Try to identify the features or parameters of an FNSF that

might be required

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Linkages of Main Thrust 13 Elements (Theme IV)

Slide 14

Basic Properties / Separate Effects Testing

Multiple / Partially-Integrated Effects Testing

Integrated Fusion Mockup/Comp Testing

Demo ReadinessDatabase, Design Tools, Qualification / Licensing

Increasing time, complexity, integration, cost

Models and Theory

Simulation Codes

Integration, Benchmarking

The multiple Theme III thrusts also had a similar progression -- ending with testing in a integrated fusion environment

Test Facility Planning & Preparation

ITER-TBM / FNSF Facility and Test Article

Planning, Preparation, Qualification

Decreasing number of concepts and options

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Multiple-Effects, Synergistic Phenomena

Synergistic phenomena will dominate the behavior, failure modes and reliability of first designs and prototypes. Examples…

– LM Thermofluid/MHD + FCI Thermomechanics– Neutron irradiation driven heating and breeding in blanket

unit cells– Multiple effect tritium/thermal/chemical effects

Utilize test facilities to – explore multiple-effect phenomena,– investigate specific design and material combinations – uncover synergistic failure modes

Partially-integrated thermal, nuclear, electromagnetic, and plasma loading conditions

– Magnetic/Thermal, – Plasma/Thermal, Tritium/Thermal, – Neutron/Thermal/Tritium

that can accommodate prototypic sizes and materials (Be, Li, PbLi, T)

Sufficient single effects database a prerequisite

Slide 15

PMTF-1200 high heat flux facility

MTOR Thermofluid/MHD facility

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Multiple-Effects, Synergistic Phenomena (2)

Slide 16

TPE, in the STAR Tritium Lab

HFIR and ATR Test Reactors

Scope– Mockups of the Blanket, First Wall,

Divertor, heat transport and tritium systems (mainline and alternates)

– Upgrade and construction of needed user test facilities (3-4 total)

Time scale– Planning and scoping - Immediate– Operations, Consistent 10 yr effort

Additional Benefits– Model validation in more complex

operational regimes– Testing fabrication and

diagnostic capability– Initial reliability growth and

qualification information– Enabling continuous power

and tritium extraction