Conceptual Design Development for a Demonstration Fusion ...

Conceptual Design Development for a

Demonstration Fusion Power Reactor

Ronald Wenninger, Gianfranco Federici, PPPT PMU Team, PPPT Project Leaders, WPPMI Physics Contributors

Power Plant Physics and Technology

R. Wenninger | ICFRM 2015 |Aachen (Germany)| 11/10/2015| Page 2

Outline

• Background

• DEMO Design

• Selected DEMO Design and Physics Integration Studies

• Highlights of Selected Projects

• DEMO Physics Integration Challenges Beyond ITER

• Development of the DEMO Wall Load Specification

• Summary

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


Outline

• Background

• DEMO Design





• Summary



What is different in DEMO compared to ITER

• DEMO needs to produce net electricity

• DEMO needs be Tritium self-sufficient

• Fusion power increases by a factor >4

• Discharge duration: 6min → 2h or more

• DEMO needs to be controlled with a reduced set of sensors

• Neutron fluence: <3dpa → ∼20dpa

• ...


Emphasis on: Central role of ITER

DEMO as a single step to commercial FPPs

Demonstrating production of electricity early 2050

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

• 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 Roadmap to Fusion Electricity


PPPT Development of DEMO Concept Design

6

• EU Fusion Roadmap: The development of a conceptual design for DEMO is one of the main priorities in this decade

• The development of machine components and overarching concepts is implemented in 11 projects

• Activities of especially integrative nature are implemented in the work package PMI


Pre-concept

• Engage DEMO SHG 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 / fill database gaps

• Identify DEMO pre-requisites • Identify main design and

technical challenges Preliminary assessment technical solutions

• Prioritization of R&D for the Roadmap

• Select design options from leading technologies

• Select divertor concept • Select breeding blanket

concept and BoP/ H&CD • Finalise Plant Architecture • Safety Analysis report

EUROfusion PPPT 2014-2018 ~220 ppy/year (no ENS) ~5 M€/year

>2020

Conceptual Study/ Design Phase Preparatory Phase

Concept Design Approach

DEMO Concept Design Scope

CDA EDA Construction

Commissioning/ Operation

ITER pre-concept (INTOR) ~10 years, ~150 ppy/year

ITER concept (NET/ITER) ~10 years, ~360 ppy/year ~15 M€/year

ITER EDA >10 years

EFDA PPPT 2011-2013

• Because of limitations of T-supplies there is enough T after ITER for only one DEMO reactor in the world that must operate and produce its own tritium not much later than 2050!!

2018


Organisation of Design and R&D Activities

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

MAG

SAE

MAT TFV

D&C

BOP

PMU

ENS

DIV

PMI

H&CD

RM

BB

A project-oriented structure with a central Project Control and Design/ Physics Integration Unit and distributed Project Teams aiming at the design and R&D of components



Systems Engineering Approach

Basic Process Flow for Conceptual Design Work


Outline

• Background

• DEMO Design

• DEMO Engineering Principles





• Summary



DEMO Design

Design features (near-term DEMO):

• 2000 MWth~500 MWe

• Pulses > 2 hrs

• SN water cooled divertor

• PFC armour: W

• LTSC magnets Nb3Sn

• Bmax conductor ~12 T (depends on A)

• EUROFER as blanket structure

• VV made of AISI 316 (stainless steel)

• 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

• …


DEMO Design Point Development I

Sytem codes are used to develop

many conceptual designs with a

range of materials and technology

assumptions

Every major plant system is

modelled:

•Site and buildings

•Heat and power systems

•Magnets (TF and PF)

•Shield and vessel

•Blanket

•Divertor

•Plasma –Fusion power

–Confinement

–Pressure and density limit

–Radiation

–Bootstrap current

–Etc. etc.

R. Kemp (IAEA 2012)


DEMO Design Point Development II

System Code: • Fast execution • Max 1D • All aspects relevant for

the feasibility and the performance of the device

State-of-the-art investigation: • Slower execution • Up to 6D • Only selected aspects

Design point: System Code Solution

Modification to parameters or modules in the system code


DEMO Design Options

EU DEMO design options

• DEMO1

• Pulsed operation,

conservative

assumptions

• DEMO2

• Steady state operation,

more optimistic

assumptions ITER DEMO1

(2015) A=3.1

DEMO2

(2015) A=2.6

R0 / a (m) 6.2 / 2.0 9.1 / 2.9 7.5 / 2.9

Κ95 / δ95 1.7 / 0.33 1.6 / 0.33 1.8 / 0.33

A (m2)/ Vol (m3) 683 / 831 1428 / 2502 1253 / 2217

H non-rad-corr / βN (%) 1.0 / 2.0 1.0 / 2.6 1.2 / 3.8

Psep (MW) 104 154 150

PF (MW) / PNET (MW) 500 / 0 2037 / 500 3255 / 953

Ip (MA) / fbs 15 / 0.24 20 / 0.35 22 / 0.61

B at R0 (T) 5.3 5.7 5.6

Bmax,conductor (T) 11.8 12.3 15.6

BB i/b / o/b (m) 0.45 / 0.45 1.1 / 2.1 1.0 / 1.9

Av NWL MW/m2 0.5 1.1 1.9



DEMO Physics Basis / Operating Point

Readiness of underlying physics assumptions makes the difference.


Outline

• Background

• DEMO Design





• Summary



Design and physics integration challenges

Results of Selected Studies

• Investigate impact of Aspect Ratio, A

• Sensitivity to plasma physics uncertainties

• TBR sensitivity analysis

• Optimisation of the upper null and investigation of alternative architectures

• Strike point sweeping parametric scan

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

as a more favourable compromise between pumping and power exhaust for DEMO.

• Explore advanced divertors including DN Configuration: higher plasma performance with

improved vertical position control, and an accompanying reduced machine size.

• 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.

A number of studies that have strong implications on machine parameter selection and architectural layout have been initiated. They include:


-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

Topic A 2.6

A 3.1

A 3.6

Vertical stability ↑ → ↓

Fast disruption loads on blanket and divertor

↑ → ↓

Toroidal field ripple ↑ → ↓

Tritium breeding ↑ → ↓

Physics basis established

→ ↑ →

Remote maintenance

↓? →? ↑?

Cost of device / electricity

? ? ?

Sensitivity studies are not only computer runs, but time consuming engineering assessments requiring some level of design detail.



DEMO physics basis uncertainties

Pel

tburn

1.53

0.33 17 MW/m

1.2 2.1

1

0.2

7 1

02

0 A

/W m

2

0.35

R. Kemp (CCFE) System Code: PROCESS


Results of selected studies

TBR sensitivity analysis

Neutron wall load: Blanket design: •Breeder/multiplier materials are within a box and covered by a FW.

•Box is reinforced by stiffening grids

n-absorption by steel

Blanket size (radial thickness): • Inb: ~80 cm / Out: ~130 cm

Requirement: TBR ≥ 1.05

(after integration of diagn/ H&CD)

Configuration: About 85% of the plasma must be covered by the breeding blanket.

Integration issue: Space for divertor, limiters, and auxiliary systems is limited.

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


Outline

• Background

• DEMO Design





• Summary



WPBB: Breeding Blanket

Concept Breeder/ Multiplier

Coolant T-Extraction

HCPB Ceramic Breeder / Beryllium

Helium He low pressure purging

HCLL PbLi Helium PbLi slow recirculation

WCLL PbLi Water PbLi slow recirculation

DCLL PbLi Helium PbLi

PbLi fast recirculation

Helium Cooled Pebble Bed (HCPB)

Dual Coolant Lithium Lead (DCLL)

Helium Cooled Lithium Lead (HCLL)

Water Coolant Lithium Lead (WCLL)

Be Li4SiO4

ITER TBM important: qualify fabrication technologies/validate tools and predictive capabilities


WPDIV: Divertor Design/Technology

Cassette Design & Integration

CAD models

Cooling schemes/cooling condition

Loads specification (thermal, hydraulic, EM, neutronic, static)

System/interface/functional requirements

Target Development

Analysis guidelines & design rules

1 baseline & 7 advanced design concepts

Novel materials for heat sink & interlayer (e.g. Wf/Cu composite, W/Cu laminate)

Mock-up fabrication

High heat flux tests & evaluation

Initial model (2014)

Revised model (2015)

Single circuit Dual circuit

W/Cu laminate tube Thermal break layer


WPMAG: Magnets System

- TF magnet design investigated and 3 winding pack (WP) options

- Thermohydraulic and mechanical studies conducted on the 3 WP options

- R&D on HTS is progressing well with tests of irradiated tapes and medium-current cables

The 3 TF conductor options WP#2 (ENEA)

WP#1 (CRPP)

WP#3 (CEA)


WPRMS: In-vessel maintenance

• Remote handling is a key driver for the overall architecture

• Recently a vertical maintence concept is applied

• Situation would be significantly more complex for a stellarator

Removal of the outer blanket banana

M. Coleman (FED 2014)


WPSAE: Safety and Environment

• Plant Safety Requirements outlined

• Basic safety approach and principles

set

• Likely future regulatory regime

considered

• Radioactive source terms

preliminary assessment on going

• Selected codes and models for safety

analysis

• Safety analyses to establish effects of

design choices/needs of protection /

mitigation

• Selection of accident scenarios for

detailed analyses (FFMEA)

• Models developed and validation

needs assessed

• Experimental studies on critical topics

• Studies of radioactive waste

management

• In particular, detritiation techniques to

remove tritium from bulk of structure

etc.

• All radioactive inventories contained in the

primary or secondary confinement in case of

accident

• Negative pressure cascade versus external

atmosphere maintained by the air detritiation

system in accident conditions


WPTFV: Innovative concept for the DEMO inner fuel cycle


WPENS: Early (Fusion) Neutron Source

Objective: Develop a facility to perform material irradiation test with DEMO-relevant parameters

IFMIF IFMIF-DONES

Beam current 2 x 125 mA

(Li target)

1 x 125 mA

(Li target)

Beam energy 40 MeV 40 MeV

Neutron

production 1018 n/s 5 x 1017 n/s

Typical

Damage Rate

40 dpa/fpy

@>60cm³

+

20 dpa/fpy

@>400cm³

20 dpa/fpy

@>60 cm³

+

10 dpa/fpy

@>400 cm³

10-3

10-2

10-1

100

101

100

101

102

103

104

105

106

107

CDA Design (1996)

Present Design (2003)

DEMO fusion reactor

High Flux Volume

n-f

lux d

ensity [10

10 s

-1 c

m-2M

eV

-1]

Neutron energy [MeV]

Also DEMO relevant He production


Outline

• Background

• DEMO Design





• Summary



Key areas of DEMO Physics Challenges beyond ITER

• First Wall Loads

• Divertor Loads

• Edge Localized Modes

• Vertical stability

• Disruptions

• Confinement

• Impurity transport

• LH threshold

• Toroidal field ripple

• Pedestal transport

• Fast particles

• …


Divertor Strategy

• Baseline Strategy

• Lower Single Null Configuration

• Detached divertor operation

• Psep/R≈17MW/m similar as in ITER

• Prad,main/Pheat significantly higher

ITER DEMO1

Pα+Paux [MW] 130 460

R [m] 6.2 9.0

AUG: A. Kallenbach IAEA 2014

• Alternative Strategies

✴ Advanced magnetic configurations (Double Null, Snow Flake,…)

✴ Liquid metal plasma facing components

• Central problem

✴ Capability to reliably predict divertor operation has not been

attained


Main size drivers: Divertor protection and H-mode operation

PROCESS / DEMO1: R. Kemp • Main objectives:

• Protect divertor • Psep/R=17MW/m

• H-mode operation • fLH=Psep/PLH,scal →

confinement quality and controllability

• Analysis with system code PROCESS: • Pel,net=500MW • 𝜏burn=2h • minimize R

TF coil technology limit (≈13T)

PLH uncertainty implications 95% confidence interval of the ITPA threshold scaling for ITER ≈ from

50% to 200% of PLH,scal In DEMO (Pel,net=500MW, 𝜏burn=2h): PLH=2 PLH,scal roughly corresponds to

doubling the major radius


Edge Localized Modes (ELMs)

Typical numbers for DEMO: Plasma energy content: 1-2GJ

Relative ELM loss: 10%

Fraction to the divertor: 75%-90%

A. Kirk PPCF 2007


ELMs - Mitigation Needs

• Considered limit: Divertor energy

impact

• Assume ΔtDEMO=ΔtITER

⇒ ΔW/A≤0.5MJ/m2

Typ

e I E

LM

s

Limit

b~∆W/W

• Pessimistic assumption:

Broadening b=1 for ΔW/W<1%

⇒ DEMO1 limit: ΔW/W≤0.14%

• Optimistic assumption: b=6

⇒ DEMO1 limit ΔW/W≤0.84%

• Natural ELMs for this 𝜈*: ΔW/W≈10%

• Mitigation of ΔW/W by a factor 15-90

required for DEMO1 (DEMO2: 25-150)

• Not considered limits: Main chamber

heat loads and ELM flushing


Strategies to deal with ELMs in DEMO

• Small/no ELM regimes

• No present machine can sim-

ultaneously match n/nGW and 𝜈*

• If pedestal physics dominates,

need methods for low 𝜈*

• So far demonstrated for rel. 𝜈*:

• QH-mode

• Resonant Magnetic

Perturbations

• I-mode (marginal)

• Alternatives: ELM pacing by

pellets / vertical kicks, relying on

fELM×ΔW≈const

ITER: P. Lang, NF 2013

DEMO

RMPs I-mode

• For all candidate mitigation methods important R&D has to be

carried out

• Solving the ELM problem for ITER ⇏ Solving the ELM problem

for DEMO


Disruptions

• Disruptivity (disruptions per operation duration)

• Extrapolated from existing devices to DEMO not possible

• Probabilistic engineering approach: Assume that disruptions are only caused by component failures

• Damage

• The crack limit of W is exceeded even in the case of perfectly mitigated disruptions

• How many events with a certain heat impact factor are acceptable before the first wall has to be exchanged?

• Additional challenge

• Progress in the understanding and simulation of disruptions are crucial to make robust DEMO predictions

Example (DEMO1):

• Wkin≈1GJ

• Thermal quench wall

load during a perfectly

mitigated disruption:

0.5Wkin in 1−3ms

Melt limit

Crack limit

ηaverage


Energy confinement time

• Challenge

• Prediction of 𝜏E is of key importance for

DEMO Design Point Studies

• IPB98(y,2) scaling: Typical DEMO design

points lies outside the region of confidence in

input parameters for at least β, n/nGW, Prad/Ptot

• Strategies

• Develop a more DEMO relevant scaling of 𝜏E

based on a new database

– From various devices including JET

– In DEMO relevant conditions including

the identified DEMO gaps (high beta,

low torque and highly radiative

conditions)

• Use prediction of the pedestal height and

width (e.g. EPED) in combination with state-

of-the-art core transport simulations

PROCESS / DEMO1: R. Kemp

Pel,net=500MW, 𝜏burn=2h

ΔPel,net

Δ𝜏burn


Impurity transport

DEMO1: E. Fable

• DEMO will have a higher level of impurities

• Zeff,DEMO1≈2.6

• Intrinsic impurities: He, W

• Candidates for seeding: Ne,Ar,Kr,Xe

• More core radiation necessitates more seeding

• Key uncertainties

• How does the effective He confinement 𝜏*He/𝜏E extrapolate for DEMO-like pumping

• It is even unclear, if DEMO will have peaked or hollow impurity profiles

• Also the ratio of impurity concentrations in confined plasma and SOL is highly uncertain


Outline

• Background

• DEMO Design





• Summary



Breeding Blanket Wall Load Limits

• Design assumptions

• Armour material: W

• Structural material: EUROFER

• Coolant / Heat Exchange: H2O at high temperature or He

• No high heat flux components outside the divertor

• Wall clearance >22cm

• Expected wall load limits based on engineering constraints ∼ 1MW/m2

• Comparison:

• A large fraction of ITER’s main chamber wall is specified for 3.6MW/m2 or more

• DEMO Wall Load Specification needs to be developed now

• Based on this a DEMO first wall concept can be developed

W (2mm) EUROFER H2O LiPb

J. Aubert: WCLL Blanket

ITER: Mitteau (JNM 2011)


Load Types

• Relevant Heat Load Types

• Stationary loads

• Thermal charged particles (majority/impurities) including blob

effects

• Radiation / MARFEs

• Neutrals

• Fast particles

• Dynamic loads

• Limiter configuration during ramp-up/down

• ELM filaments

• Confinement transients (e.g. H-L-transition)

• Vertical displacement events / disruptions

• Particle Loads

• Steady state and dynamic first wall erosion yield


Charged Thermals - Example

• Assumptions (DEMO1):

• Psep=150MW 50%↑,50%↓ transferred by charged thermals

• 100% into the long-λq-channel

• qpeak≈0.6MW/m2

• ITER experienced an increases of the peak loads of more than 10 when going to more realistic designs in 3D!

𝑞∥ = 𝑞0 ∙ 𝑒−

𝑑𝜆𝑞

𝑞0

Portion intersecting

upper FW

FL intersecting

divertor

λq=17cm Mitteau (JNM 2011)


Charged Thermals - λq Scan

6.16 6.18 6.2 6.22 6.24 6.26

5.94

5.95

5.96

5.97

5.98

5.99

6

6.01

6.02

6.03

q = 60mm , P

SOL = 150/2[MW/m2]

0.0

9 M

W/m

2

0.0

9 M

W/m

2

0.0

9 M

W/m

2

0.1

0 M

W/m

2

0.1

1 M

W/m

2

0.1

1 M

W/m

2

0.1

2 M

W/m

2

0.1

2 M

W/m

2

0.1

2 M

W/m

2

0.1

3 M

W/m

2

0.1

3 M

W/m

2

0.1

3 M

W/m

2

0.1

3 M

W/m

2

0.1

4 M

W/m

2

0.1

4 M

W/m

2

0.1

4 M

W/m

2

0.1

5 M

W/m

2

0.1

4 M

W/m

2

0.1

5 M

W/m

2

0.1

5 M

W/m

2

0.1

6 M

W/m

2

0.1

6 M

W/m

2

0.1

6 M

W/m

2

0.1

7 M

W/m

2

0.1

7 M

W/m

2

0.1

7 M

W/m

2

0.1

7 M

W/m

2

0.1

8 M

W/m

2

0.1

8 M

W/m

2

0.1

9 M

W/m

2

0.2

0 M

W/m

2

0.2

2 M

W/m

2

0.2

2 M

W/m

2

0.2

3 M

W/m

2

0.2

4 M

W/m

2

0.2

4 M

W/m

2

0.2

5 M

W/m

2

0.2

5 M

W/m

2

0.2

5 M

W/m

2

0.2

5 M

W/m

2

0.2

6 M

W/m

2

0.2

7 M

W/m

2

0.2

7 M

W/m

2

0.2

8 M

W/m

2

0.2

8 M

W/m

2

0.2

9 M

W/m

2

0.2

9 M

W/m

2

0.3

0 M

W/m

2

0.3

1 M

W/m

2

0.3

2 M

W/m

2

0.3

2 M

W/m

2

0.3

2 M

W/m

2

0.3

3 M

W/m

2

0.3

3 M

W/m

2

0.3

4 M

W/m

2

0.3

5 M

W/m

2

0.3

6 M

W/m

2

0.3

7 M

W/m

2

0.4

0 M

W/m

2

0.4

1 M

W/m

2

0.4

2 M

W/m

2

0.4

3 M

W/m

2

0.4

4 M

W/m

2

0.4

5 M

W/m

2

0.4

5 M

W/m

2

0.4

6 M

W/m

2

0.4

7 M

W/m

2

0.4

8 M

W/m

2

0.4

9 M

W/m

2

0.5

0 M

W/m

2

0.5

1 M

W/m

2

0.4

9 M

W/m

2

0.4

9 M

W/m

2

0.5

0 M

W/m

2

0.5

1 M

W/m

2

0.5

2 M

W/m

2

0.5

3 M

W/m

2

0.5

4 M

W/m

2

0.5

5 M

W/m

2

0.5

7 M

W/m

2

0.5

8 M

W/m

2

0.5

9 M

W/m

2

0.6

0 M

W/m

2

0.6

2 M

W/m

2

0.6

3 M

W/m

2

0.6

4 M

W/m

2

0.6

5 M

W/m

2

0.6

7 M

W/m

2

0.6

8 M

W/m

2

0.7

0 M

W/m

2

0.7

0 M

W/m

2

0.6

8 M

W/m

2

0.7

0 M

W/m

2

0.7

1 M

W/m

2

0.7

2 M

W/m

2

0.7

4 M

W/m

2

0.7

3 M

W/m

2

0.7

2 M

W/m

2

0.7

3 M

W/m

2

0.7

5 M

W/m

2

0.7

6 M

W/m

2

0.7

8 M

W/m

2

0.7

9 M

W/m

2

0.8

1 M

W/m

2

0.7

3 M

W/m

2

0.7

2 M

W/m

2

0.7

3 M

W/m

2

0.7

4 M

W/m

2

0.7

6 M

W/m

2

0.7

7 M

W/m

2

0.7

8 M

W/m

2

0.7

9 M

W/m

2

0.7

5 M

W/m

2

0.7

6 M

W/m

2

0.7

7 M

W/m

2

0.7

9 M

W/m

2

0.8

1 M

W/m

2

0.8

2 M

W/m

2

0.8

4 M

W/m

2

0.8

5 M

W/m

2

0.8

6 M

W/m

2

0.8

8 M

W/m

2

0.8

9 M

W/m

2

0.9

1 M

W/m

2

0.7

3 M

W/m

2

0.6

7 M

W/m

2

0.6

7 M

W/m

2

0.6

8 M

W/m

2

0.6

9 M

W/m

2

0.7

3 M

W/m

2

0.7

4 M

W/m

2

0.7

5 M

W/m

2

0.7

6 M

W/m

2

0.7

5 M

W/m

2

0.6

8 M

W/m

2

0.6

9 M

W/m

2

0.7

0 M

W/m

2

0.7

1 M

W/m

2

0.7

1 M

W/m

2

0.7

2 M

W/m

2

0.7

3 M

W/m

2

0.5

9 M

W/m

2

0.5

1 M

W/m

2

0.5

2 M

W/m

2

0.5

2 M

W/m

2

0.5

3 M

W/m

2

0.5

3 M

W/m

2

0.5

3 M

W/m

2

0.5

3 M

W/m

2

0.3

5 M

W/m

2

0.3

5 M

W/m

2

0.3

5 M

W/m

2

0.3

5 M

W/m

2

0.3

6 M

W/m

2

0.3

2 M

W/m

2

0.1

6 M

W/m

2

0.1

6 M

W/m

2

0.1

6 M

W/m

2

0.1

6 M

W/m

2

0.1

7 M

W/m

2

0.1

4 M

W/m

2

0.0

6 M

W/m

2

0.0

6 M

W/m

2

0.0

6 M

W/m

2

0.0

6 M

W/m

2

0.0

6 M

W/m

2

0.0

7 M

W/m

2

0.0

7 M

W/m

2

0.0

7 M

W/m

2

0.0

7 M

W/m

2

0.0

7 M

W/m

2

0.0

7 M

W/m

2

0.0

7 M

W/m

2

0.0

6 M

W/m

2

0.5

MW

/m2

0.5

MW

/m2

0.5

MW

/m2

0.5

MW

/m2

0.5

MW

/m2

0.5

MW

/m2

0.5

MW

/m2

0.5

MW

/m2

0.6

MW

/m2

0.6

MW

/m2

0.6

MW

/m2

0.6

MW

/m2

0.6

MW

/m2

0.6

MW

/m2

0.6

MW

/m2

0.7

MW

/m2

0.7

MW

/m2

0.7

MW

/m2

0.7

MW

/m2

0.7

MW

/m2

0.7

MW

/m2

0.8

MW

/m2

0.8

MW

/m2

0.8

MW

/m2

0.8

MW

/m2

0.8

MW

/m2

0.8

MW

/m2

0.9

MW

/m2

0.9

MW

/m2

0.9

MW

/m2

0.9

MW

/m2

1.0

MW

/m2

1.0

MW

/m2

1.0

MW

/m2

1.0

MW

/m2

1.0

MW

/m2

1.1

MW

/m2

1.1

MW

/m2

1.1

MW

/m2

1.2

MW

/m2

1.2

MW

/m2

1.2

MW

/m2

1.2

MW

/m2

1.3

MW

/m2

1.3

MW

/m2

1.3

MW

/m2

1.4

MW

/m2

1.4

MW

/m2

1.4

MW

/m2

1.5

MW

/m2

1.5

MW

/m2

1.5

MW

/m2

1.6

MW

/m2

1.6

MW

/m2

1.6

MW

/m2

1.7

MW

/m2

1.7

MW

/m2

1.7

MW

/m2

1.8

MW

/m2

1.8

MW

/m2

1.9

MW

/m2

1.9

MW

/m2

2.0

MW

/m2

2.0

MW

/m2

2.1

MW

/m2

2.1

MW

/m2

2.1

MW

/m2

2.2

MW

/m2

2.2

MW

/m2

2.3

MW

/m2

2.3

MW

/m2

2.4

MW

/m2

2.4

MW

/m2

2.5

MW

/m2

2.5

MW

/m2

2.6

MW

/m2

2.7

MW

/m2

2.7

MW

/m2

2.8

MW

/m2

2.8

MW

/m2

2.9

MW

/m2

2.9

MW

/m2

3.0

MW

/m2

3.1

MW

/m2

3.1

MW

/m2

3.2

MW

/m2

3.3

MW

/m2

3.3

MW

/m2

3.4

MW

/m2

3.5

MW

/m2

3.5

MW

/m2

3.6

MW

/m2

3.7

MW

/m2

3.7

MW

/m2

3.8

MW

/m2

3.9

MW

/m2

4.0

MW

/m2

4.0

MW

/m2

4.1

MW

/m2

4.2

MW

/m2

4.3

MW

/m2

4.3

MW

/m2

4.4

MW

/m2

4.5

MW

/m2

4.6

MW

/m2

4.6

MW

/m2

4.7

MW

/m2

4.8

MW

/m2

4.8

MW

/m2

4.9

MW

/m2

5.0

MW

/m2

5.1

MW

/m2

5.1

MW

/m2

5.2

MW

/m2

5.3

MW

/m2

5.4

MW

/m2

5.5

MW

/m2

5.5

MW

/m2

5.6

MW

/m2

5.7

MW

/m2

5.8

MW

/m2

5.9

MW

/m2

5.9

MW

/m2

6.0

MW

/m2

6.1

MW

/m2

6.2

MW

/m2

6.3

MW

/m2

6.3

MW

/m2

6.4

MW

/m2

6.5

MW

/m2

6.5

MW

/m2

6.6

MW

/m2

6.7

MW

/m2

6.7

MW

/m2

6.8

MW

/m2

6.9

MW

/m2

6.9

MW

/m2

7.0

MW

/m2

7.1

MW

/m2

7.1

MW

/m2

7.2

MW

/m2

7.3

MW

/m2

7.3

MW

/m2

7.4

MW

/m2

7.5

MW

/m2

7.6

MW

/m2

7.6

MW

/m2

7.7

MW

/m2

7.7

MW

/m2

7.8

MW

/m2

7.8

MW

/m2

7.9

MW

/m2

7.9

MW

/m2

8.0

MW

/m2

8.0

MW

/m2

8.0

MW

/m2

8.1

MW

/m2

8.1

MW

/m2

8.1

MW

/m2

8.2

MW

/m2

8.2

MW

/m2

8.2

MW

/m2

8.2

MW

/m2

8.2

MW

/m2

8.2

MW

/m2

8.3

MW

/m2

8.3

MW

/m2

8.3

MW

/m2

8.3

MW

/m2

8.3

MW

/m2

8.3

MW

/m2

8.3

MW

/m2

8.3

MW

/m2

8.3

MW

/m2

8.3

MW

/m2

8.3

MW

/m2

8.3

MW

/m2

8.3

MW

/m2

8.3

MW

/m2

Results: λq far-SOL scan 1cm to 17cm

* *

• Maximum qsurf = 0.91MW/m2 found for λq = 6cm (far-SOL) • The peak heat load is not a monotonic function of λq


Charged Thermals - Upper Null optimisation

• There is potential to reduce the charged particle heat loads by adjusting the equilibria and possibly the first wall contour

• Possible side effects • Reduction of the triangularity

• Reduction of the TBR

qsurf,max=1.83 0.58 0.31 MW/m2

δ= 0.53 0.45 0.38 λq= 0.02 0.11 0.17 m

qsurf,max=0.58 0.42 0.35 MW/m2

δ= 0.45 0.41 0.37 λq= 0.11 0.14 0.17 m


Charged Thermals - Effect of Blobs

Open question: fraction of Psep that comes out in ‚blobs‘

• Blobby SOL transport may dominate in DEMO

• Due to the very long connection length, power will end up on first wall

• Exact distribution depends on localisation of blob birth zone

Guiding parameter Λ

DEMO

Recent devices

M. Siccinio: Preliminary

D. Carralero: PRL 2015


Charged Thermals - Towards more realistic designs

• DEMO charged thermal particle load assessments done for idealised plasma and idealised wall in 2D

• Best approach to determine the wall contour is under discussion

• ITER experienced significant increases of the peak loads when going to more realistic designs in 3D

• Severe penalties on inaccuracies of the device or plasma inhomogeneities are suggested

• We expect clear problems to keep charged particle loads within the limits

• This might necessitate significant design changes (e.g. high heatflux limiters protecting the breeding areas)

Mitteau (JNM 2015)


Radiation

• Sustainable operation in DEMO requires that a high fraction of the power is exhausted via radiation.

• 3D Calculation of the radiation distribution on the wall using Monte Carlo approach :

• Two regions are defined: • Core radiation: Radiation from within the confined plasma

• SOL radiation: Radiation from unconfined plasma

• Core radiation: • Limited by LH power threshold 𝑃𝐿𝐻

• Sources: Bremsstrahlung, Impurities (Ar, Xe, W, …)

• SOL radiation: • Sources: Impurities and main species

B. Sieglin: EFPW2014


Radiation - DEMO 1 Plasma

• Core radiation with

Tungsten and Xenon as

impurities

• Main contributors Xenon

and Bremsstrahlung

• Assumption for SOL

• All power radiated

• Constant power density

on field line

• Exponential decay

R. Wenninger, IAEA 2014


Radiation – Tungsten & Bremsstrahlung


Radiation – Xenon & SOL


Radiation - Total Heat Load

• Total Power: ~ 500 MW

• Peak Heat Load:

𝑞𝑚𝑎𝑥 ≈ 0.64 MW

m2

• Peaking factor around 2

• Highest load on top and bottom of machine

• Divertor targets well shadowed

Core W

Core BS

Core Xe

SOL

Ptot [MW] 11 53 290 150

qpeak [MW/m2] 0.013 0.065 0.33 0.25


Effects of radiation clustering

It has been observed that radiation can have a significant poloidal peaking • Seeded scenarios • MARFEs

M. Bernert: EPS 2015

Radiation in Kr seeded detached plasma

Example:

• 150MW radiating from x-point

• Peak radiation 1.9MW/m2 on the

dome

• Divertor baffle: <0.6MW/m2


Fast Particles

First result from ASCOT with a 2D first wall:

A. Snicker: Preliminary

• Recent assumption: Same power load limits as for thermals apply for fast particles

• Including ferritic inserts (δTF≈0.3%) reduces the peak loads and moves them to the divertor

• Investigations with engineering design of the first wall are carried out at the moment

TF – No Ferritic Inserts

TF – With Ferritic Inserts


Summary I

• 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)

• 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 uncertainties

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

• Keep reasonable flexibility at the beginning. Trade-off studies with multi-criteria optimisations, including engineering assessments are underway.


Summary II

• Significant limitation of first wall power flux densities necessitates early development of the DEMO Wall Load Specification

• The DEMO divertor design needs to be based on a new set of guidelines

• It is not clear, if the same ELM control methods as in ITER can be applied in DEMO

• Prediction of frequency and availability impact of disruptions for DEMO are among the ultimate challenges

• Progress in the prediction of transport of heat and particles are essential for the DEMO Design Point Development

• Uncertainty of LH threshold power has significant impact in dimensioning DEMO




Systems Engineering Approach

• SE approach is viewed as essential from the early concept design stage to:

understand the problems and evaluate technical risks of foreseeable technical solutions;

identify design trade-offs/constraints to address urgent issues in phys., technology /integration.

prioritize the R&D needs.

• Ensuring that R&D is focussed on resolving critical uncertainties in a timely manner and that learning from R&D is used to responsively adapt the technology strategy is crucial.

[M. Coleman, P1.126, Tue]

[T. Barrett, O5A.3, Thu]

• Design dealing with uncertainties (physics and technology) e.g., FW heat loads significant impact on the architecture of the plant as a whole Alternatives being compared for a range of e aspects (e.g, T- breeding , availability, maintenance,

integration issues, etc.)


Lessons learned from Gen-IV as part of SHG Engagement

• Fission projects follow pattern of evolution in each successive plant, ASTRID drawing from SuperPhenix, MYRRHA maturing from extensive test bed development.

• Design should drive R&D and not other way around.

• Fusion is a nuclear technology and as such will be assessed with full nuclear scrutiny by a regulator.

• Traceable design process with rigorous SE approach.

• Emphasis should be on maintaining proven design features (e.g., use mature technology) to minimize risks.

• Safety, reliability and maintainability should be key drivers: allow for design margins as well as redundancy within systems to ensure more fault tolerant design.

• Gen IV has leveraged impressive industry support.

MYRRHA: Acceleration Driven System

Flexible irradiation facility

ASTRID :SFR Prototype GEN-IV

F. Gauche (CEA)

H. Aït Abderrahim (SCK-CEN)

Meetings held with GENIV Fission projects to gain insight into Project Execution strategies

Integrated Technology

Demostrator 600 MWe

Accelerator: 600 MeV - 4 mA p

Reactor: Subcritical/ critical modes – 65 to 100 MWth

1st SHG Meeting held in Garching, 18/03/15 Engage experts (e.g., industry, utilities, grids, safety, licensing) to establish realistic HLRs for DEMO plant to embark on coherent conceptual design approach -> Main outcomes: Safety, Performance and Economic viability missions.


Charged Thermals - 2D Flux Mapping

4 6 8 10 12 14

-6

-4

-2

0

2

4

6

12.25 12.3 12.35 12.4 12.45 12.5

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

Magnetic Flux mapping: • Line from plasma outer boundary at z= centroid → first wall (in green*) • To: whole fist wall curve (black solid-dotted**) • Considering one source at z = plasma centroid and r = outer boundary.

*

**

0 45 90 135 180 225 270 315 360

-44

-42

-40

-38

-36

-34

-32

angle [deg]

psi [V

s]

0 0.05 0.1 0.15 0.2

-35

-34

-33

position on segment (r=0 at bounbary) [m]

psi [V

s]

angle 0°

angl

e 90

° psi boundary

psi w

all

psi b

ound

ary

psi w

all


DEMO Conventional Divertor Design Studies

• Reduce divertor area to the minimum

• Minimum divertor target length

• Estimate poloidal target length based on heat flux profile and maximum plasma displacement: 70cm (to be further analysed)

• Radiation heat loads need to be checked

Additional breeding areas

?

• Breeding sufficient Tritium is a key engineering challenge

• Use all available low heat flux first wall areas


Divertor Dome Studies

Reducing the size or eliminating the divertor dome:

• Pros:

• Simplification of the design

• Plasma might touch the dome during a vertical displacement event

• Cons:

• Neutral particle transport from the private flux region to the x-point region might be to extensive [C. Day et al: To be pub]

• Pumping efficiency could be reduced

Date post:	16-Jan-2022
Category:	Documents
Upload:	others
View:	0 times
Download:	0 times

Conceptual Design Development for a Demonstration Fusion ...

Documents