OVERALL POWER CORE

CONFIGURATION AND SYSTEM

INTEGRATION FOR ARIES-ACT1

FUSION POWER PLANT

X.R. Wang, M. S. Tillack, S. Malang,

F. Najmabadi and the ARIES Team

20th TOFE

Nashville, TN

August 26-31, 2012

MAJOR PARAMETERS OF THE ARIES-ACT1

POWER PLANT

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Parameter Value

Major radius R 6.25 m

Aspect ratio A 4

Elongation k 2.1

Toroidal field on axis Bo 6 T

Plasma Current Ip 10.93 MA

Fusion power Pf 1813 MW

Thermal power Pth 2016 MW

Recirculating power Precirc 154 MW

Net electric power Pe 1006 MW

Average wall load at FW Pn 2.3 MW/m2

Maximum wall load at FW 3.6 MW/m2

Power conversion efficiency ᵑth 57.9 %

ARIES-ACT1 Power Core

A COMPARISON OF THE ARIES-AT AND

ARIES-ACT1 POWER CORE

ARIES-AT ARIES-ACT1

Major radius 5.5 m 6.25 m

IB Blanket LiPb cooled SiC/SiC structure LiPb cooled SiC/SiC structure

1st OB Blanket LiPb cooled SiC/SiC structure LiPb cooled SiC/SiC structure

2nd OB Blanket LiPb cooled SiC/SiC structure LiPb cooled SiC/SiC structure

HT Shield LiPb cooled SiC/SiC structure and B-

FS filler

He-cooled ODS steel structure

Upper/Lower Divertors LiPb cooled SiC/SiC structure He-cooled W-based divertor and

ODS steel cartridge

Vacuum vessel Water-cooled FS structure and WC He-cooled Bainitic FS

(3Cr-3WV)

LT shield Water-cooled Bainitic FS and WC

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REPLACEMENT UNITS FOR THE QUICK SECTOR

MAINTENANCE

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All the in-vessel components have a limited lifetime and

require replacement. Our design approach is to integrate

all the in-vessel components into replacement units to

minimize the number of the coolant access pipe

connections and time–consuming handling inside the

plasma chamber.

The integrated replacement unit must maintain a

constant distance in radial direction, and no welds are

used for the connections between the different

components of the replacement units and between the

units and the VV.

The replacement units are supported at the bottom only

through the VV by external vertical pillars, and can

expand freely in all directions without interaction with

the VV.

The unit can be inserted and withdrawn by straight

movement in radial direction during installation and

maintenance.

Replacement unit (1/16)

OVERALL LAYOUT OF THE ARIES-ACT1

POWER CORE

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All the coolant access pipes to the sector are

connected to the structural ring close to its

bottom plate.

Cutting/Reconnection of all the access pipes

is located in the port, and all the pipes and

shield blocks would be removed for sector

maintenance.

Control coils are supported by the structural

ring and be removed to the upper corner of

the VV for the sector removal.

Shield blocks are arranged in the VV port to

protect the coils, and they would be cooled by

helium.

The saddle coil can be attached to the upper

shield block and removed together during

maintenance.

Maintenance ports are arranged between the

TF coils, and there is only one vacuum door

located at the end of the port for each sector.

Cross section of the ACT1 power core

(1/16 sector)

T-SHAPED ATTACHMENT AND RAIL SYSTEM

UTILIZED FOR SECTOR ALIGNMENT

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During the installation, a rail system with 2 or

3 vertical pistons would be inserted and the

sector will be supported by the rail system for

the vertical and horizontal alignment.

There are wide gaps in the wedge allowing the

precise alignment of the sector in all

directions.

After the alignment, the grooves of the

attachment have to be filled with a suitable

liquid metal (possibly a Cu-alloy) and fixed in

the position by freezing the liquid metal the

attachment grooves. Then, the rail system will

be withdrawn.

T-shaped attachment for sector support

Cross-section of T-shaped attachment

and rail system

MAIN FEATURES OF THE SECTOR

MAINTENANCE

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A transfer flask with the rail system and fresh

sector can be docked to the port to avoid any spread

of radioactivity during maintenance.

After all access pipes disconnected, and the shield

blocks, saddle coil, control coils and access pipes

removed, the rail system would be inserted into the

space between the structural ring and the VV.

Using the rail system, the sector is supported by

pressurizing the pistons and separated from the

VV by melting the metal inside the T-shaped

attachment grooves.

Then, the sector can be pulled in straight way out

the plasma chamber into the transfer flask. After

that, the new sector can be installed in reverse

order without moving the flask away from the port.

Design and Optimization of the First Wall and

Blanket Modules

Major objective of the blanket design is

to achieve high performance while

keeping attractive features, feasible

fabrication, credible maintenance

schemes and reasonable design margin

on the operating temperature and stress

limits.

Design iterations were made to

determine and optimize all the

parameters of all the blanket segments,

including:

curvature of the FW/BW,

thickness of the FW/SW/BW,

width and depth of FW cooling

channels,

number of the ribs per duct,

number of modules per sector.

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ARIES-AT-type SiC/SiC blanket modules

Cross-section of one OB-I module

Outer

duct

FW Center duct

with ribs

Scope Structural Analyses for Optimizing the

Geometry and Reducing SiC Volume Fraction

Stress limits for using in FEM analysis: Conventional stress limits (3 Sm) can not be directly applied to ceramics.

In our design, we try to maintain the primary stress to <~100 MPa and limit the total combined stress to ~190 MPa.

Assumed the MHD pressure drop through

the FW and blanket ∆P MHD=~0.2 MPa

ARIES-AT blanket

ARIES-ACT1 blanket

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(Inboard blanket of the ARIES-ACT1)

Phydrostatic=~0.8 MPa

(Inboard blanket)

Example of Definition, Dimensions of the OB

Blanket Modules

Total number of the module for each blanket sector=16, 14

inner modules with pressure balance on side walls and 2

outer modules without pressure balance on the outer side

wall. (same number for OB-II)

The FW/SW/BW thickness of the outer/inner ducts =5 mm

(7 mm for OB-II)

The fluid thickness of the annular gap=10 mm

(same for OB-II)

Rib thickness at 4 corners=6 mm (same for OB-II)

Rib thickness on both sides=2 mm (same for OB-II)

Diameter of the curvature for the FW and back wall=30 cm

(45 cm for OB-II)

Inner modules of the OB-I and OB-II

Outer module of the OB-I and OB-II

Inner and Outer Modules of OB Blanket

45 cm

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Increase the thickness of the outer SW from 5 mm to 15 mm

(22 mm for OB-II)

Increase the thickness of the rib at the outer SW from 2 to 5 mm

(6 mm for OB-II)

Increase the numbers of the rib at the outer SW from 2 to 5

(9 for OB-II)

Inner

modules

Outer module

30 cm

Thermal Stress Results indicate the Design Limits

Are Satisfied

B.C. and loads: Free expansion, and allowing for free bending Pressure load at the bottom: 1.95 MPa at annular ducts and 1.65 MPa at the center duct Pressure load at the top: 0.95 MPa at the annular ducts and 0.85 MPa at the center duct

Thermal stress distribution of the inboard blanket module

Max. thermal stress =~91 MPa

Pressure stress<~50 MPa

Total stresses=~141 MPa

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Max. combined primary and thermal stresses are ~141 MPa at the bottom (higher primary stress, lower thermal stresses) and ~142 MPa at the top (higher thermal stresses, lower primary stress)

INTEGRATION OF THE HE-COOLED W-BASED

DIVERTOR IN THE ACT1 POWER CORE Fingers arranged over the entire plate Imping-jet cooling, Tin/Texit=700/800 ᵒC Allowable heat flux up to~14 MW/m2

Avoiding joints between W and ODS steel at the high heat flux region

~550,000 units for a power plant

T-Tube divertor: ~1.5 cm dia. X 10 cm long Impinging-jet cooling, Tin/Texit=700/800 ᵒC Allowable heat flux up to~11 MW/m2

~110,000 units for a power plant

Plate divertor: 20 cm x 100 cm Impinging-jet cooling, Tin/Texit=700/800 ᵒC

Allowable heat flux up to~9 MW/m2

~750 units for a power plant

Two zone divertor (any combination of the plate and finger and T-tube)

Fingers for q>~8 MW/m2, plate for q<~8 MW/m2

Decreased number of finger units

The selection of the divertor

depends on the peak heat flux

and heat flux profile of the

ACT1.

Plate-type divertor concept is

selected for the ARIES-ACT1

based on the peak-time average

heat flux of 10.6 MW/m2.

Tubular or T-Tube He-cooled SiC/SiC divertor

Impinging-jet cooling, Tin/Texit=600/700 ᵒC Allowable heat flux up to~5 MW/m2

Divertor region of the ARIES-ACT1

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SUMMARY The power core configuration, system integration and maintenance scheme of the

ARIES-ACT1 have been re-examined, and major new design features are discussed

and highlighted.

The Pb-17Li SiC/SiC blankets including the IB, OB-I and OB-II segments have been

re-designed and optimized with the objective of achieving high performance (~58%

power conversion efficiency) while maintaining attractive safety features, feasible

fabrication process, credible maintenance scheme and reasonable design margin on

the temperature and stresses.

Design issues, uncertainties and R&D needs are discussed in separate presentation..

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