1. Preparation of activation experiments for ITER material characterization and data validation in the Deuterium–Tritium JET campaign
T. Vasilopoulou & I.E. Stamatelatos, NCSRD, Greece
L. W. Packer & S. Lilley, CCFE, UK
P. Batistoni, ENEA, Italy

2. Roadmap towards fusion
Not in scale
2-4 GW
38 MW
500 MW
JET
(in operation)
ITER
(under construction)
DEMO
(under design)
Fusion power: a safe, clean, and limitless energy source for the future
A fusion reactor builds in the main on three devices: JET, ITER and DEMO
JET is considered as the test bed for ITER technologies
HNPS 2016, NCSRD, Athens, 3-4 June 2016

3. ITER material characterization
ITER materials
structural materials used in the manufacturing of the main in-vessel components
functional materials used in diagnostics and heating systems
Why?
ITER materials need to satisfy a range of requirements:
their mechanical properties must be maintained in an environment of
severe mechanical, electro-mechanical and thermal stresses
high radiation field, including neutrons with energies up to 14 MeV
an intense flux of charged particles, photons and other radiation
low activity levels, since neutron activation of the structure can lead to
medium-term radiation complicating the handling of components in maintenance or decommissioning operations
long-term activation which requires special treatment, storage or disposal as waste at end of the plant life
HNPS 2016, NCSRD, Athens, 3-4 June 2016

4. ACT Project Preparation of ITER materials irradiation experiment
Activation experiments project (ACT):
Nuclear analysis and characterization of real ITER materials
Experiments and simulations performed at JET
Scope of the present work
Preparation of ITER materials irradiation experiment
to be performed during the JET Deuterium–Tritium campaign
Updated JET schedule
HNPS 2016, NCSRD, Athens, 3-4 June 2016

5. Long Term Irradiation System (LTIS)
Neutron spectra at LTIS
Installed before the 2015 D-D campaign, filled with activation foils in order to characterize the local neutron field
Will be used in the forthcoming T-T and D-T JET campaigns, carrying dosimetry foils and samples of ITER materials
HNPS 2016, NCSRD, Athens, 3-4 June 2016

6. ITER materials 23 ITER materials studied
No.
Component
Material
Supplier
Type 1
Vacuum Vessel
SS316L(N)-IG
Outokumpu
Plate
Industeel
Kind
Forging
Thyssen 2
In-wall shield
SS304 (borated) -
Borated steel
Alloy 660 3
First Wall
316L(N)
CuCrZr 6
Divertor W
Bar, plates
OF-Cu
Plates 7
XM-19
Plate forgings
Al-bronze
Forgings 9
Toroidal Field Coils
SS316L(N)
Radial plates
Nb3Sn
BEAS
Mixture
SS316L
Cover plates
NbTi 9a
Hyundai
TF coil case
Daido steel
23 ITER materials studied
Both structural and functional components
Material composition data provided by manufacturers and ITER basic model literature [1]
[1] V. Barabash (2013) ITER IDM:HTN8X3
HNPS 2016, NCSRD, Athens, 3-4 June 2016

7. Dosimetry Foils To monitor neutron fluence
data from FENDL-3.0
To monitor neutron fluence
Discs D=18 mm, thickness=1 mm
Selection based on
Response on neutron energy
Half-lives
Material properties (i.e. melting point)
Threshold reactions
Ti, Mn, Co, Ni, Fe, Y
Neutron capture reactions
Co, Sc, Ta, Fe
HNPS 2016, NCSRD, Athens, 3-4 June 2016

8. Calculations European Activation System (EASY-II)
EAF-2010 nuclear data library
D-T plasma source neutron spectrum at LTIS
Detailed MCNP model of JET (tokamak and hall)
Total neutron fluence of 1.06×1016 cm-2 (4 months)
Fluence rate of 1.02×109 cm-2·s-1 (continuous scheme)
Output
Specific activity (Bq/g)
Dose rate at 1 m (Sv/h)
Detector count rate (cps)
Cooling times ranging from 1 d to 600 d
Model of JET tokamak
HNPS 2016, NCSRD, Athens, 3-4 June 2016

9. Results: Specific activity (1)
Vacuum Vessel
Toroidal Field Coils
In-wall shield
HNPS 2016, NCSRD, Athens, 3-4 June 2016

10. Results: Specific activity (2)
First Wall
TFC conductors
Divertor materials
HNPS 2016, NCSRD, Athens, 3-4 June 2016

11. Results: Dose rate Dose rate per gr at 1m
200 d post-irradiation dose rates per gr at 1m distance are bellow 1 Sv/h for all materials
The dose rate calculated for material Nb3Sn is attributed to the different impurity content and in particular to the high level of Ta resulting in significant 182Ta production
200 d post-irradiation the dose rate at 5 cm distance from Nb3Sn material is ≈ 40 μSv/h
HNPS 2016, NCSRD, Athens, 3-4 June 2016

12. Concluding remarks
The preparation for D-T irradiation experiment has been completed
ITER samples will be installed in LTIS in 2018 for the T-T campaign and in for the D-T campaign
Manageable activities and dose rates are expected to be acquired after irradiation
For accurate prediction of activity levels and dose rates, exact knowledge of impurity levels is of outmost importance
Unique opportunity to study ITER materials under real fusion conditions
HNPS 2016, NCSRD, Athens, 3-4 June 2016

13. Thank you for your attention!
JET tokamak