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EU DEMO Conceptual Design Work Status

Gianfranco Federici

Power Plant Physics and Technology

G. Federici & PPPT Team | 3rd IAEA DEMO Progr. Workshop|HEFEI| 11-14/05/2015| Page 2

Outline

• Background

• Organisation of design and R&D activities

• Definition of plant requirements

Lesson learned from GEN-IV

DEMO Stakeholder meetings

• Concept design approach

Physics basis and design drivers

Preliminary design choices under evaluation

• DEMO Design and physics integration challenges

Key interdependencies and trade-off studies

Results of selected studies no results of R&D reported in this talk

• Conclusions

See talk M. Shannon given by C. Waldon

http://www.google.co.uk/imgres?imgurl=https://www.executiveboard.com/blogs/files/2013/06/Driving-Rep-Performance-300x224.jpg&imgrefurl=https://www.executiveboard.com/blogs/are-your-rep-metrics-driving-performance/&h=224&w=300&tbnid=Qyb2Ti4UoIA6_M:&zoom=1&docid=CxyiQYZzeTBXHM&ei=ioWyVP73CMjUaoixgbAI&tbm=isch&ved=0CIsBEDMoWTBZ&iact=rc&uact=3&dur=19571&page=7&start=86&ndsp=14


Background

Outstanding Technical Challenges with Gaps beyond ITER

Tritium breeding blanket Exhaust

Remote Maintenance

Structural and HHF Materials

• For any further fusion step, safety, breeding, power exhaust, RH, component lifetime

and plant availability, are important design driver and CANNOT be compromised

- most important/novel parts of

DEMO

-

TBR >1 marginally achievable

but with thin PFCs/few

penetrations

- Feasibility concerns/

performance uncertainties with

all concepts

- Selection now is premature

- Peak heat fluxes near

technological limits (5-10 MW/m2)

- ITER solution may be marginal for

DEMO

-

Advanced divertor solutions may

be needed but integration is very

challenging

- Also exploring DN as a serious

option

- Strong impact on IVC design

-

Significant differences with ITER

RM approach for blanket

- RH schemes affects plant design

and layout

- Large size Hot Cell required

-

Service Joining Technology R&D is

needed.

- Embrittlement of EUROFER and Cu-alloys at low temp.

and loss of mechanical strength at ~ high temp. are

important design issues.

- Development needs of design rules for structural

materials

- Progressive blanket operation strategy (1st blanket 20

dpa; 2nd blanket 50 dpa).

- Technical down selection of options for DT n-sources

has been made in Europe M. Mittwollen (KIT)

L. Boccaccini (KIT)/ Y. Poitevin (F4E) R. Albanese (CREATE), H. Reimerdes (CRPP),

C. Linsmeier (FZJ), I. Mazul (Efremov)

J. Aktaa (KIT)

H. Tanigawa (JAEA)

S. O’hira (JAEA)


Emphasis on: Central role of ITER

assu ptio i ‘oad ap ITE‘ co es i operatio i early 2020 s

DEMO as a single step to commercial fusion power plants

DEMO construction starting early in the 2030s

• An ambitious roadmap implemented by a Consortium of Fusion Labs (EUROfusion)

• Distribution of resources based on priorities and on the quality of deliverables.

• Support to facilities based on the joint exploitation.

• Focus around 8 Missions

DEMO

IPH

IPH

1. Plasma Operation

2. Heat Exhaust

3. Neutron resistant Materials

4. Tritium-self sufficiency

5. Safety

6. Integrated DEMO Design

7. Competitive Cost of Electricity

8. Stellarator

Background

EU Fusion Roadmap to Fusion Electricity

See talk M. Gasparotto


Organisation of Design and R&D Activities

Each WP has a Project Board

Safety PMU & PMI

Activities

Materials

Remote

Maintenance

Diagnostics and

Control

Breeding

Blanket Magnets Divertor

H & CD

Systems

Tritium

Fuelling &

Vacuum

PHTS &

BoP

Contain

Structures

• A project-oriented

structure set-up

• Distributed Project

Teams aiming at the

design and R&D of

components

• Project Control and

Design Integration Unit

• Project coord. and

control

• Physics & Design

Integration

General Assembly ( GA )

Programme Management Unit

PPPT

Programme Manager

IPH / JET Admin Communications

PPPT Expert

Group

DEMO

Stakeholder

Group

STAC

Bureau


Organisation of Design and R&D Activities


Concept Design Approach

Time Plan and Scope

new

• EU Roadmap to fusion electricity

• Work-Plan 2014-18, AWPs

• List of Grant deliverables

• Scope, Schedule and Resource-

loaded Projects

• Project Management Plans

EFDA PPPT

2011-2013

EUROFusion

PPPT

2014-2017

EUROFusion

PPPT

2018-2022

• Identify DEMO pre-requisites

• Identify main design and technical challenges

(physics/ technology)

• Preliminary assessment technical solutions

• Prioritization of R&D to be included in the

Roadmap

new

• PRDs, SRDs, OCD, PBS,

Interface Process

• Trade-Off studies

• States & Modes Diagrams

• Functional Flow Block

Diagrams (FFBD)

• Design Description Docs

• 3D CAD model of Plant

• Cost Analysis

• Preliminary Safety Analysis

Report

• Plant RAMI Report

• Prel. Manufacturing Plans

• Preliminary Assembly &

Maintenance Plan

• Programme Management

Plan (for EDA phase)

• Select design options from leading technologies

• Select coolants

• Select divertor layout concept

• Finalise Plant System Architecture / down-select

variants in: BoP, BB, H&CD e.t.c.

• Safety Analysis report

• Engage DEMO Stakeholders and define DEMO HLRs

• Study machine configurations and key parameters.

• Optimisation / trade-off studies

• SE approach to solve design integration issues

• Resolve Plant System Architecture with variants

• Address key technology R&D needs (mainly PoP,

fabrication feasibility, performance tests)

• Develop and qualify materials and fill database gaps

Pre

pa

rato

ry P

ha

se

Pre

-Co

nce

ptu

al D

esi

gn

Ph

ase

C

on

cep

tua

l De

sig

n

Documents Scope


• In 2014 a traceable design process with SE approach was started to explore available

design/ operation space for DEMO to understand implications on technology requirements

Main challenges

• Integration of

design drivers

across different

projects.


Basic Process Flow for Conceptual Design Work

Typical example is the selection of coolants. Technical issues include:

thermal power conversion efficiency;

pumping power requirements;

power handling requirements;

inner blanket thickness (n-shielding and streaming);

achievable tritium breeding ratio;

breeder tritium extraction;

T permeation/ coolant T purification & control;

chemical reactivity, coolant leakage;

design integration and feasibility of BoP.

• Design dealing with uncertainties

(physics and technology)

• High degree of system integration/

complexity/ system Interdependencies

• Trade-off studies/ sensitivity studies

with multi-criteria optimisations,

including engineering assessments.



DEMO physics basis / uncertainties



DEMO physics basis / uncertainties

Pel

tburn



Main size drivers: Divertor and H-mode

• Power transported by electrons and

ions across separatrix:

Psep=Pα+Padd-Prad,core

• Physics/ Material limit condition for

divertor

Psep/‘ 20MW/m

• Boundary condition to access and

operate in H-mode with good

confinement:

Psep fLH PLH

Results of PROCESS Analysis:

• For low Psep/PLH major radius is

determined by the divertor protection

constraint (Psep/R)

• From a certain Psep/PLH onwards this in

combination with Psep/R is driving the

major radius

Main problem: • Extreme uncertainty on PLH is passed on to the major radius

Objective: Protect divertor and operate in H-mode



Preliminary DEMO design features

• 2000 MWth~500 Mwe

• Pulses > 2 hrs

• SN water cooled divertor

• PFC armour: W

• LTSC magnets Nb3Sn (grading)

• Bmax conductor ~12 T (depends on A)

• RAFM (EUROFER) as blanket structure

• VV made of AISI 316

• Blanket vertical RH / divertor cassettes

• Lifetime: starter blanket: 20 dpa (200 appm

He); 2nd blanket 50 dpa; divertor: 5 dpa (Cu)

Open Choices:

• Operating scenario

• Breeding blanket design concept selection

• Primary Blanket Coolant/ BoP

• Protection strategy first wall (e.g., limiters)

• Advanced divertor configurations

• Number of coils


ITER

DEMO1

(2015)

A=2.6

DEMO1

(2015)

A=3.1

DEMO2

(2015)

A (m2) 680 1428 1428 1253

Volume (m3) 830 2502 2502 2217

Pfus (MW) 400 2037 2037 3255

tburn (hrs) 0.1 2 2 ss

IP (MW) 15 19.6 20 22

BT (T) 5.3 5.7 5.7 5.6

βN,total 1.8 2.6 2.6 3.8

βα/βth 8% 14% 14% 17%

βf/βth 12% 16% 16% 25%

Te0 (keV) 11.5 27.4 25.9 34.7

ne0 (1020 m-3) 1.25 1.0 1.7 1.2

Prad,core (MW) 47 303 306 634

Prad,core/Pheat 40% 66% 67% 81%

PCD (MW) 70 50 50 s 133

-6

-4

-2

0

2

4

6

3 5 7 9 11 13

Z (

m)

R (m)

ITERDEMO1 (A=2.6)DEMO1 2015 (A=3.1)DEMO2 2015


Sensitivity study: Aspect Ratio

Courtesy R. Kemp (CCFE)


DEMO design and physics integration challenges

• Investigate impact of increasing plasma elongation, k, constrained by vertical stability,

through optimising for example PF coils layouts and current distributions (see next slide).

• Investigate divertor configurations with a lower X-point height and larger flux

expansion as they may provide a more favourable compromise between pumping and

power exhaust for DEMO than the vertical target divertor chosen for ITER.

• Improve power handling capabilities near the upper secondary null point in a SN

DEMO and assess impact of design and maintainability of the solutions proposed.

• Explore a Double Null (DN) Configuration: higher plasma performance with improved

vertical position control, and an accompanying reduced machine size. The impact on

blanket vertical RH should be investigated together with impact on T- breeding.

• Investigate divertor strike point sweeping, including technology issues such as thermal

fatigue of the HHFCs, AC losses of the adjacent PF coils, etc.

• Investigate magnetic field ripple: trade-off between RH access, coil size, and NBI

access.

• Estimate dwell time and evaluate impact of trade-offs on CS, BoP, pumping, etc.


Design and physics integration challenges

Optimisation of baseline divertor configuration

Options 1) SN deep divertor (ITER) 2) Shallow SN divertor 3) Shallow DN divertor

Advantages Compatible with BB vertical RH Compatible with BB vert. RH

improved T breeding

higher plasma performance

with improved vertical

position control

Shortcomings Elongation constrained by VS

Marginal T breeding

Limited power handling near

upper secondary null

Elong. constrained by VS

Problems of heat loads near

upper secondary null?

T breeding to be assessed

compatibility with BB vertical

maintenance scheme

questionable. Requires study.

Plasma VS is an

important design driver.

A variation of Beta or li

(e.g., due to loss of NBI,

RF, or impurity influx) or

loss of H-mode would

lead to a V moment that

in the case of an

asymmetric

configuration (SN)

would challenge control

requirements.



Results of Selected Studies

• Sensitivity to plasma elongation

• Optimisation of the Upper Null

• Divertor Geometry optimisation studies

• Neutronic / TBR sensitivity analysis divertor size

• Strike point sweeping parametric scan (not shown

here)



Increasing k,d (~20%) has large impact on machine layout

7

7,5

8

8,5

9

9,5

10

1,6 1,8 2 2,2

R0

(m

)

Elongation (k)

d = 0.5, q95 = 3.0

d = 0.75, q95 = 3.0

Single null baseline

19,5

20

20,5

21

21,5

22

22,5

1,6 1,8 2 2,2

Ip (

MA

)

Elongation (k)

d = 0.5, q95 = 3.0

d = 0.75, q95 = 3.0


0

1

2

3

4

5

6

7

1,6 1,8 2 2,2

Bt

(T)

Elongation (k)

d = 0.5, q95 = 3.0

d = 0.75, q95 = 3.0


0

0,05

0,1

0,15

0,2

0,25

0,3

0,35

0,4

0,45

0,5

1,6 1,8 2 2,2

f_b

s

Elongation (k)

d = 0.5, q95 = 3.0

d = 0.75, q95 = 3.0




Results of selected analysis: Optimisation of upper null Upper null position optimization

x

Inward-outward upper null position movement, while

preserving plasma shape

Intersection of upper-null isoflux curve with first wall larger

with null outward: less peaked heat loads expected (TBC)

Ongoing evaluation of q|| portion incident on upper wall

Upper null closer

to plasma

Upper null farther

from plasma

x

x

x upper null

— isoflux upper null

— plasma boundary

—FW-isoflux upper null

intersection x

�∥ = �0 ∙ �− ��

�0

Portion intersecting

upper FW

Courtesy R. Ambrosino (CREATE))


Results of selected studies

Optimisation of divertor geometry

Comparison previous (red) & new (dashed

blue) geometry with increased B.B. area

(dashed green)

• Exlcude divertor dome as the necessity is

not obvious —> Effect of the dome will be

investigated with SOLPS.

• Divertor area decreased and breeding area

increased in favour of meeting the DEMO

unique tritium breeding requirement.

Investigation on moving strike-

point closer to x-point: I estigatio o shallo divertor:

Wetted area increases linearly

with flux expansion fexp,t

However: Higher flux fexp,t also reduces the grazing angles g between

the field lines and the target plate, which cannot be arbitrarily small

Toroidal incidence angle

Connection length


Results of selected studies

TBR sensitivity analysis

Neutron wall load: Potential Tritium breeding contributions: Total TBR:

• Significant improvement of TBR due to reduction of divertor size.

• DN configuration with two small divertors seems possible regarding TBR.

P. Pereslavtsev, U. Fischer (KIT)


Conclusions

• The demonstration of electricity production ~2050 in a DEMO Fusion Power Plant is

a priority for the EU fusion program

• ITER is the key facility in this strategy and the DEMO design/R&D will benefit largely

from the experience gained with ITER construction

• There are outstanding gaps requiring a vigorous integrated design and technology

R&D (e.g., breeding blanket, divertor, Remote Handling, materials)

• DEMO reactor design suffers from high degree of system integration/ complexity/

system Interdependencies. Trade-off studies/ sensitivity studies with multi-criteria

optimisations, including engineering assessments

• In 2014 a traceable design process with SE approach was started to explore DEMO

design/ operation space to understand implications on technology requirements

• Main difficulty with designing is dealing with uncertainty.

• One of the greatest difficulties is the definition of a sufficiently flexible design /

analysis framework and approach to start a coherent iterative design process and

technology development in the projects.

• We are also keeping some flexibility in exploring options in parallel.

See talk M. Gasparotto


Highlights of Achievements

• WPBB: 4 designs studied: HCPB. HCLL, WCLL, DCLL. Key technology R&D work in progress.

• WPBOP: modelling work is underway for systems using water and He as coolant. Feasibility

issues are being identified and proposals for solutions examined.

• WPDIV: several target candidate concepts developed and fabrication trials performed. Design

integration of several divertor layout configurations are analysed.

• WPHCD: systems studies are exploring options for NBs, EC and IC Heating. System efficiencies

and feasible launch positions for these technologies are investigated.

• WPMAG Basic coil layouts defined. Samples of optimised design of LTSCs with improved

performance were manufactured and will be tested in 2015. HTSC samples fabricated /tested.

• WPMAT: two 80 kg batches of low temp. optimised EUROFER material were produced, + nine

80 kg of high temp optimised material. 23 lab-scale batches (250 – 550 g each) of ODS steel

were produced. Development of Codes and Design Criteria has been started.

• WPRM: consolidate the requirements for RH systems. Blanket extraction and installation

processes have been developed.

• WPSAE: S&E philosophies and approaches have been prepared, together with the high-level

principles, requirements. Initial safety studies are in progress.

• WPTFV: define system block diagrams and requirements for Tritium, Fuelling and Vacuum

systems. Direct Pumping concept further developed.

• WPDC/ WPENS: Being implemented. Definition of activities and establish working teams.


Acknowledgements

The PPPT PMU Team:

M. Shannon, C. Morlock, R. Wenninger, F. Maviglia, C. Bachmann, M. Coleman, B.

Meszaros, T. Franke, S. Ciattaglia, E. Diegele, F. Cismondi, H. Hurzlmeyer.

PPPT Project leaders:

L. Boccaccini (KIT), M. Rieth (KIT), C. Day (KIT), W. Biel (FZJ), J-H. You (IPP), N. Taylor

(CCFE), T. Loving (CCFE), L. Zani (CEA), A. Ibarra (CIEMAT), M.Q. Tran (CRPP), M.

Grattarola (ENEA).

PPPT Work Programme Collaborators on this talk

(in particular): R. Kemp (CCFE), G. Giruzzi (CEA), M. Gilbert (CCFE), U. Fischer (KIT),

P. Pereslavtsev (KIT), R. Albanese (ENEA/Create), R. Ambrosino (ENEA/Create)

PPPT Expert Group:

H. Zohm, W. Morris, B. Saoutic, C. Waldon, P. Sonato, T. Mull, K. Hesch, S.

Chiocchio, P. Barabaschi.