Status of Material R&D Activities Relevant for Fusion Power Reactors

Rajamannar Swamy*1, Alpesh Patel1, Shailesh Kanpara1, S. Khirwadkar1, Kedar Bhope1,

Mayur Mehta1, Sejal Shah2, P.N. Maya1, P. Sharma2, C. S. Sasmal1, P. Chaudhuri1

1Institute for Plasma Research, Bhat, Gandhinagar, Gujarat, 382428, India2ITER-India, Institute for Plasma Research, Gandhinagar, Gujarat, 382428, India

E-mail: rajamannar@ipr.res.in

Institute for Plasma Research (IPR)

P13

Material Development for Blanket and Divertor

GLEEBLE 3800 System

Type of heating system Direct resistance with closed-loop

control

Temperature range 30°C to 2300°C

Maximum heating rate 10,000°C/sec

Maximum force 196 kN (Compression), 98 kN (Tension)Sample

Graphite

plunger

TC

[1] Tungsten-Fiber Reinforced Tungsten Composites

Optical images of Wf/W cross section (a) parallel

(b) perpendicular to the pressing direction

(a) (b)

Micromechanical model of RDSM

• The maximum relative density achieved is 96% for Vf: 70% sample

• The avg. hardness of fibers in composites is 485 ±9 HV0.4 for Vf: 70%

To improve fracture toughness and crack propagation

Radiation Damage Studies

Neutron spectra for ITER-like divertor

•W foil of 100 µm thick

• 80 MeV Au7+, 10 MeVB3+

• 1.3 x1018 ions/m2

TEM micrographs

1 100 10000E

PKA (keV)

10-4

10-3

10-2

10-1

100

101

102

103

PK

A/p

arti

cle

10 MeV Li10 MeV B80 MeV W2.3 MeV Cu20 MeV W6 MeV Feneutron

EFragment

[4] India specific Reduced Activation Ferritic

Martensitic (IN-RAFM) Steel for Breeding

Blanket Module

[1] Radiation damage in Tungsten Foils [2] Radiation damage in Insulator

•Alumina

•300 keV Ar6+ (range ~ 180nm)

•Fluence: 5x1011 to 1x1016 ions/cm2

•DPA ~3×10-4 for lowest fluence

To investigate the ion irradiation impact on the structural and electrical properties of alumina

Ref: Sunil kumar et.al. Ceramics International 45 (2019) 20346-20353Ref: P.N.Maya et.al. Nucl.Fusion 59 (2019) 076034 (14pp)

[5] Lithium Titanate (Li2TiO3)

W-fiber

Ф: 0.25-0.1mm, L: 3-5mm

W-Powder

Size: 0.5-1µm

Powder Metallurgy Route

Temperature (ºC) 1900

Pressure (MPa) 40

Holding time (min.) 4

%Vf 10, 30, 50, 70

Powder Metallurgy Route

Temperature (ºC) 1000 & 1030

Pressure (MPa) 5, 20, 40

Holding time (min.) 10

Cu (Wt. %) 20, 30, 50

High Temperature Bonding

Temperature (ºC) 1100 -1500

Pressure (MPa) 60

Holding time (min.) 15

Diffusion Bonding

To improve toughness, creep and tensile strength at high

temperature with lower shift DBTT after irradiation

Vacuum Induction Melting & Vacuum Arc Refining

Hot working

Forging Temperature (ºC) 1140 -1600

Rolling Temperature (ºC) 1100-1120

Heat Treatment

Normalizing (ºC) for 30min 980-1000

Tempering (ºC) for 90min 760-765

9Cr–1.4W–0.06Ta–0.22V-0.1C

Ф:10mm, t:4mm

To investigate the neutron induced radiation damage and its effect in fuel retention in divertor armor material using surrogate ion irradiation

80 MeV Au produces

vacancy clusters

10 MeV B irradiated

produces dislocations

Clusters

Clusters

Dislocation

To develop materials and to assess its performance under reactor-relevant conditions such as high heat and particle loads, radiation and tritium environment

0.85-1.18

mm

Dried Powder

Un

der

/ov

er

Siz

e

Pebble Fabrication

Calcined at 1000°C,5 hr.

Ball mill grinded for 6 hr.

Li2CO3

Isopropanol

TiO2

Sintered at 1100°C, 5hr

Grinding

Green Pebble

15mm Ф, 6mm to 2.5mm (t)

Surface morphology of Pebbles

prepared by FGM

100 µm 10 µm

10 µm 2 µm

Li2T

iO

3P

ow

de

r P

re

pa

ratio

nP

eb

ble

Fa

bric

atio

n

ESM FGM

Au-ion produces defects

structures at room

temperature similar to

those produced by neutron

at high temperature.• Raman and XRD analysis show defect density increased by irradiation for lower fluence whereas

defect annealing observed at higher fluence.

• Insulation resistance is observed to be changed in presence of radiation environment.

Peak intensity variation with

irradiation fluence (XRD Analysis)RAMAN Spectroscopy

PKA spectrum of ions and neutrons

B-ion produced PKA

spectrum similar to

neutron

• Li2TiO3 powder is synthesis by solid state reaction method &

solution combustion method.

• Pebbles of ~ 1.00 mm is fabricated by Extrusion-

Spheronization (ESM) & Freeze Granulation-freeze drying

method (FGM).

Li2TiO3 is developed as a Tritium Breeder Material for the

Fusion Blanket

Database generation of physical, thermal, thermo-physical,

Mechanical properties of Li2TiO3 are being evaluated

Ref: A. Shrivastava et.al. Fusion Sci. Tech. 65 (2014) 319-324

Evaluation of Material properties

• Variation of volume fraction

• Variation of fiber aspect ratio

Martensitic structure

Coarse

Cr rich carbides

V, Ta rich carbides

Fine GlobularTempered

Mechanical & Thermo-physical properties ,i.e. Thermal

diffusivity, Thermal Conductivity and Specific Heat of

commercial grade IN-RAFM steel w.r.t variation of temperature

are being evaluated

Optical image of W-laminate sample

Applications of ceramic in ITER NBIs

[3] Tungsten Laminates

100 µm thick W foils

B- scanC- scan

Ultrasonic Testing (UT), microstructure characterization and electrical

resistivity measurement show flaw less (defect free) and good interfacial

bonding of laminates

UT inspection result

To improve toughness and lower DBTT

100XRef: A.N.Mistry et.al. FED. 125 (2017) 263-268

[2] Tungsten–Copper Functionally Graded Materials

FGM Density

(a) 80/20 Grade – 6 layers – 94.5 %

(b) 70/30 Grade – 4 layers – 89.6 %

(c) 50/50 Grade – 3 layers – 88.8%

W-Powder: 0.5 - 1µm

Cu-Powder: 20-25µm

To improve chemical and thermo-mechanical compatibility at W-Cu interface

(a) SEM image (b) Elemental mapping of W/Cu FGM 70/30 grade

Microstructure characterization, thermal conductivity

measurement and mechanical properties evaluation

show good interface bonding with thermo-mechanical

compatibility of developed FGM

Layer-1 Layer-2

Layer-3 Layer-4

(a)

(b)

30 mm x 10 mm x 3mm