Multiple effects for HT DCLL - PowerPoint Presentation

Slide1

Multiple effects for HT DCLL

Presented by Neil Morley

University of California, Los Angeles

US-EU DCLL Workshop

November 14-15, 2014

Slides from my colleagues S.

Smolentsev

and M.

Abdou

gratefully acknowledged

Next 10 Years

We are now in mostly “Separate Effects” stage. We need to move to “multiple effects/multiple interactions” to discover new phenomena and enable future integrated tests in ITER TBM and FNSF

Now

TBMs in ITER & FNSF

in FNSF

Property Measurement

Phenomena

Exploration

Model Validation

Non-Fusion Facilities:

2

Theory/Modeling

Basic

Separate

Effects

Multiple Effect/

Interactions

Partially

Integrated

Integrated

Design Codes/Data

Component

Multiple Effects / Multiple Interactions

– bringing together different combinations of multiple physical loads, multiple materials and complex configurations that can drive new interacting and synergistic phenomena

Testing in Fusion Facilities

Consider a representative FW/blanket system:“Dual Coolant Lead Lithium” - DCLL

3

FW Armor

RAFS Structure

SiC Flow Channel

Inserts

Shield

He Flow

ARIES-ST DCLL

blanket

This is considered as a leading FW/Blanket system in the US

EU and China have similar version

Features and R&D issues are typical

of a family of

PbLi

and/or helium cooled FW/blankets

M

olten

PbLi

and helium coolants / breeders and circulation systems

Thermomechanical

response of helium cooled RAFS structures

Tritium transport and control

Corrosion and activation

Reliability over long operation and transient events

Features of the High Temperature DCLL

Allow high temperature PbLi flow inside FCI while keeping the RAFM steel operating in acceptable range for both structural and PbLi compatibilityKeep MHD pressure drop under control in a practical way that results in acceptable inboard dP and overall flow distribution

 High temperature condition can be intentional for better power conversion or as a safety margin for temperature excursion protection

4

FCI

PbLi

He

5

What do we think we need to know about DCLL MHD

thermofluid

multiple

e

ffects / multiple

i

nteractions

Combined MHD/heat/mass transfer behavior in a DCLL unit cell

Given a inflow conditions, non-uniform B-field and heating in typical DCLL unit cells, what will be the:Material interface temperatures, temperature gradients, thermal stressesMass loss rates and corrosion product concentrationsTritium transport rates and tritium concentrationsFCI performance and MHD Pressure dropWhat science needs to be studiedWhat combination of phenomena controls flow regime / stability of the channel. What is the sensitivity?How does the flow regime impact the heat and scalar transportE.g. Hot spots, corrosion product source terms, tritium leakage to helium, How does the FCI material properties and component integrity evolve over time due to interfacial effects

6

FCI

PbLi

He

Spatial Gradients in Nuclear Heating and Temperature in LM Blanket Lead to New Phenomena that fundamentally alter our understanding of the behavior of the blanket in the fusion nuclear environment

7

B

g

V

UPWARD FLOW

DOWNWARD FLOW

Vorticity Field

shows unstable velocity affecting all transport

phenomena

Base flow

strongly altered possibly leading to stagnant zones and “flow reversal”

Buoyant MHD interactions result in “Mixed Convection” flow regime

with substantial impact on flow dynamics, heat transfer, corrosion/tritium transport

The mixed-convection flow requires new rules for predicting transition.

Bottom: Flow map showing stable laminar (

s) and two turbulent regimes (wt and st) in the Ha – Re plane for Gr = 5x107.Top: Predictions of the critical Ha number with the linear theory.

Linear stability analysis

DNS

UCLA (

Smolentsev

) built

flow maps (Ha-Re-Gr) and

determined critical

Ha number to predict transitions and specify turbulence mode. These results suggest that in DCLL blanket (DEMO, Gr~1012) poloidal flows are turbulent.These predictions are so far limited to computations and analytical studies. Experiments are needed. We are planning such experiments. Pre-experimental analysis has been completed showing that anticipated flow regimes can be reproduced in the MTOR Lab.

Flow distribution in a complex, multi-material configuration of parallel channels

What design, flow conditions, and FCI behavior leads to highly unbalanced flow and channel overheating?Complex conducting structures, manifold designs and partial FCI insulation Magnetic fields not aligned with walls and will vary front-to-back, side-to-side and over time in large modulesHeating varies strongly back to front and vary over timeFCIs motion and property changes over timeUnsteady flows that may cause pressure oscillations

9

DCLL blankets modules have 4-8 multiple channels fed from common supply and return pipes

FW Armor

RAFS Structure

SiC Flow Channel

Inserts

Shield

He Flow

The current paths in complex flow elements are difficult to understand and predict, and will strongly impact flow distribution

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In MHD one must always always be prepared to consider the complete electromagnetic field. The current and magnetic fluxes must have complete paths which may extend outside the region of fluid-mechanical interest into locations whose exact position may be crucial -- J A

Shercliff

UCLA current flow simulation in a 3 channel manifold, cut along symmetry plane down middle channel

PbLi ingress in SiC FCI can dramatically change conductivity, increase drag in that channel and lead to severe flow redardation

15

vol

% dense, 85% porosity filled with aerogel

12

What do we think we need to know about DCLL

t

hermofluid

multiple effects / multiple interactions

Next 10 Years

So how do we explore, discover, understand and accurately model multiple effect multiple interactions phenomena?

Now

TBMs in ITER & FNSF

in FNSF

Property Measurement

Phenomena

Exploration

Model Validation

Non-Fusion Facilities:

13

Theory/Modeling

Basic

Separate

Effects

Multiple Effect/

Interactions

Partially

Integrated

Integrated

Design Codes/Data

Component

Testing in Fusion Facilities

Use real materials, prototypic temperatures

Simulate surface and bulk heating and gradients

Provide large volume and use multiple channels

Have

more prototypic

Ha,

Gr, N, Re, etc.

A

handful of upgraded/new experimental facilities will be needed that:

We envision two thermofluid MHD facilities beyond near term upgrades of existing facilities

Multiple Effect/Multiple Interactions Blanket Facility Role: Address near full size DCLL unit cell thermofluid flow and transport issues and reduced scale multi-channel flow controlPartially Integrated Blanket FacilityRole: bring together all simulated conditions affecting thermofluid/thermomechanical blanket/FW performance to the maximal practical degree prior to FNSF

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These are both non-nuclear facilities that can be flexibly operated and instrumented to investigate both prompt and long time scale DCLL blanket phenomena in a controlled and well characterized fashion

Blanket MHD thermofluid test facilities

Multiple Effect/Multiple Interactions Blanket Facility. Role: Address near full size DCLL unit cell thermofluid flow and transport issues and reduced scale multi-channel flow controlstrong magnetic field, ~5T Magnetic volume capable to accommodate full single channel size, ~0.3 x 1.5 m)controlled orientation with respect to gravity and channel wallssimulated volumetric heating and gradients PbLi and He flow loops at prototypic temperatures (~1/2 TBM scale)

15

$20M class facility, can be a gradual extension of MTOR/

MaPLE

facilities at UCLA

Possible upgrades for MaPLE and BOB magnet

Flexible B orientationHigher flowrate and temperature PbLiSimulated volumetricheatingOnline PbLi purificationInstrumentation

System to switch from Horizontal to Vertical oriented “BOB” magnet gap

Possible upgrades for MaPLE and BOB magnet

Flexible B orientationHigher flowrate and temperature PbLiSimulated volumetricheatingOnline PbLi purificationInstrumentationSecondary He coolantHigher magnetic fieldLarger magnetic volume

System to switch from Horizontal to Vertical oriented “BOB” magnet gap

Evolve into the Multiple Effect Multiple Interaction facility just described

Blanket MHD thermofluid test facilities

Partially Integrated Blanket Facility. Role: bring together all simulated conditions affecting thermofluid/thermomechanical blanket/FW performance to the maximal practical degree prior to FNSFSimulated toroidal and poloidal magnetic fieldUp to full size FW/blanket test modules in multiple poloidal orientations with respect to gravitySimulated surface and volumetric heating and gradients PbLi and He flow loop of ~full DEMO module sizePrototypic temperatures, pressures, materials

18

$50-80M class National Laboratory facility to really prepare for FNSF – requires significant design and construction effort

What are the principal challenges in simulating the fusion nuclear environment?

Nuclear heating in a large volume with strong gradients, not possible to reproduce in simulation facility. Use various techniquesEmbedded heaters in LM, on walls or in flow channel inserts. Must be careful about changing the flow, FCI behavior, etc. Integration into multiple experiments requiredInlet temperature control (e.g. flow in hot, let cool)Complex magnetic field with toroidal field / poloidal field fidelity or transient fields during disruptionsRequires complex magnet systems, very important for LM blanketsOr utilization of modules in long pulse confinement devicesComplex mockup configuration with prototypic size and scale Not possible in fission reactors

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Can not bring together all conditions in one test or adequately simulate nuclear heating

Study on Blanket/FW Multiple Effect/Multiple Interaction and Partially Integrated Test Strategy and Facilities

20

Why the Study is Needed

The subject of multiple effect/multiple interactions is very complex and requires experienced blanket R&D experts

But the cost of the facility for full simulation can be very expensive

Therefore, tradeoffs between the capabilities incorporated in the facility and COST are needed. Developing cost estimates require mechanical design for a given set of specified parameters

Requires Blanket R&D experts as well as mechanical engineers and magnet designers and cost professionals. There are several US institutions interested in developing proposals to construct blanket facilities

The study could be “international” and a good mechanism for collaboration