LOW TEMPERATURE PHYSICS
The effect of neutron and gamma radiation on magnet
components
Michael Eisterer, Rainer Prokopec, Reinhard K. Maix, H. Fillunger, Thomas Baumgartner,
Harald W. Weber
Vienna University of TechnologyAtominstitut, Vienna, Austria
RESMM Workshop, Fermilab, 14 February 2012
LOW TEMPERATURE PHYSICS
ACKNOWLEDGEMENTS
Work on the superconductors started at ATI in 1977 and was done partly at Argonne, Oak Ridge and Lawrence Livermore National Laboratories as well as at FRM Garching.
Work on the insulators started in 1983 and in systematic form in 1990.
Many graduate students and post-doctoral fellows have been involved.
Substantial support by the European Fusion Programme (EFDA) and by the ITER Organization (IO) is acknowledged.
The contributions of the ATI crew are gratefully acknowledged.
Senior scientists: H. Fillunger, K. Humer, R.K. Maix, F.M. Sauerzopf
Post-docs: K. Bittner-Rohrhofer, R. Fuger, F. Hengstberger, R. Prokopec, M. Zehetmayer
PhD students: T. Baumgartner, M. Chudy, J. Emhofer
LOW TEMPERATURE PHYSICS
Outlook
• Radiation environment in a fission reactor– Neutron and - spectrum
• Damage production– neutrons, - radiation
• Scaling: Prediction of behavior in other radiation environments
• Superconductors: NbTi, Nb3Sn, MgB2, cuprates– Transition temperature, critical current
• Insulators: epoxy resin, cyanate ester, bismaleimides– Dielectric strength– Mechanical properties
• Ultimate tensile strength, iterlaminar shear strength, fatigue behavior
– Gas evolution
• Conclusions
LOW TEMPERATURE PHYSICS
Fission of 235U
+ ~200 MeV
kinetic energy of fission products: ~165 MeVprompt gamma rays: ~7 MeV kinetic energy of the neutrons: ~6 MeVenergy from fission products (-decay): ~7 MeVgamma rays from fission products : ~6 MeV anti-neutrinos from fission products : ~9 MeV
http://www.atomicarchive.com/Fission/Fission1.shtml
LOW TEMPERATURE PHYSICS
Neutron Energy Distribution
Intense Pulsed Neutron Source, Argonne National Laboratory
Atominstitut, Vienna
Rotating Target Neutron SourceLawrence Livermore National Laboratory
LOW TEMPERATURE PHYSICS
Fission: prompt emission
F.C. MaienscheinR.W. PeelleW. ZobelT. A. Love
Second United Nations International Conference on the Peaceful Uses of Atomic Energy 1958
7 photons/fission, 7 MeV/fission, ~100 keV to ~8 MeV, peak at 300 keVIn addition: radioactive decay, e--e+ annihilation (511 keV), n-capture, Bremsstrahlung
Total: 1 MGy/h
LOW TEMPERATURE PHYSICS
Damage Production: Neutrons
“Elastic” collision with lattice atoms:
n
nL
nLp E
mm
mmE 2
4
11
4
LnL
n
mEm
E (Hydrogen)
Minimum energy to displace one atom: (epithermal and fast neutrons)
Bp EE ~4 eV C-H~few eV in metals~5-40 eV in ionic crystals Stable?
pE 1 keV: Displacement cascades
Stable in HTSDisintegrate at room temperature to small clouds of point defects in LTS
LOW TEMPERATURE PHYSICS
Damage Production: Neutrons
Nuclear reactions: (n,), (n,), (n,) ,fission
Example: 10B + n → 7Li (1 MeV) + 4He (1.7 MeV)
Neutron caption cross sections are most often largest at low neutron energies.
(n,), (n,): point defects
LOW TEMPERATURE PHYSICS
Damage Production: Gamma rays
Interaction via electronic system:
Compton scattering:
Photoelectric effect:
Pair production:
Emc
EEp 2
42
2
EEe
MeV 1.022E
Ionization!
• Breaks chemical bonds in organic molecules. (plastic deteriorates in sunlight.)
• Little effect in crystalline materials (superconductors).
LOW TEMPERATURE PHYSICS
Damage Calculation: Neutrons
Superconductors:
Insulators:
Fast neutron fluence: 4×1022 m−2 (E > 0.1 MeV)
LOW TEMPERATURE PHYSICS
Other Radiation Environments?
(E) neutron cross sectionT(E) primary recoil energy distribution(E) neutron flux density distributiont irradiation time in the neutron spectrum (E)
tTE
dEdEd
dEdEd
ETET
D
)()(displacement energy cross section
damage enegy
Superconductors:
Insulators:
Dose (total absorbed energy) [Gy]=[J/kg]
Scaling
Prediction of property changes in other radiation environments (?)
LOW TEMPERATURE PHYSICS
Transition Temperature Tc
- through disorder
Normal state resistivity n
- through the introduction of additional scattering centers
Upper critical field Hc2
- through the same mechanism: n 1/l Hc2
Critical current density Jc
- through the production of pinning centers
Changes of Superconducting Properties
LOW TEMPERATURE PHYSICS
Changes in Transition Temperature
maximum fluence around 7-10 x 1023 m-2 (E>0.1 MeV)
Decrease at a fast fluence of1022 m-2: • NbTi: ~ 0.015 K• A-15: ~ 0.3 K• Cuprates: ~ 2 K• MgB2: ~ 4 K (n,)!
LOW TEMPERATURE PHYSICS
Changes of the Critical Current
H.W. Weber, Int. J. Mod. Phys. E 20 (2011) 1325
NbTi, 4.2 K
RTNS (14 MeV)IPNS (distr.)
Damage energy scaling:
LOW TEMPERATURE PHYSICS
Changes of the Critical Current
H.W. Weber, Int. J. Mod. Phys. E 20 (2011) 1325
NbTi, 4.2 K
Irradiation temperature is rather unimportant! (intermediate warm-up)
LOW TEMPERATURE PHYSICS
Changes of the Critical Current
H.W. Weber, Adv. Cryog. Eng. 32 (1986) 853
Nb3Sn, 4.2 K
I C /
I C0
EM Nb3Sn at µ0H = 12 T RHQT Nb3Al at µ0H = 16 T
fast neutron fluence (m-2)
6 T
LOW TEMPERATURE PHYSICS
J
T
H
TCHC2(T)
JC
LOW TEMPERATURE PHYSICS
J
T
H
TC
JC
HC2(T)
LOW TEMPERATURE PHYSICS
4 6 8 10 12 14
107
108
109
unirradiated
1022 m-2
J c(A/m
2 )
B (T)
MgB2 4.2 K
fast neutron fluence: 1022 m-2
Changes of the Critical Current
Maximum at around 1-2×1022 m-2 depending on Tcunirr.
MgB2, 4.2 K
LOW TEMPERATURE PHYSICS
• Decrease of JC at low fields• Increase of JC at higher field• Start of (overall) degradation
depends on temperature (1-2×1022 m-2 at 77 K)
Crossover field (mT) 2x1021 m-2 4x1021 m-2 1x1022 m-2
77 K 244 382 630
64 K 114 219 440
50 K 130 195 334
Changes of the Critical Current
Y-123
LOW TEMPERATURE PHYSICS
14 mConductor (35
tons)
Coil Case(200 tons)
Winding(7 double pancakes)
Radial Plate (RP)(60 tons)
9 m
Structures
Insulation (glass and resin) ∼ 5 tons
7 RP
ITER TF coil design
TF Coil (300 tons) Boeing 747: ~185 tA380: ~280 t
LOW TEMPERATURE PHYSICS
Impregnation of TF Model Coil
LOW TEMPERATURE PHYSICS
Dielectric strength at 77 K after reactor irradiation
1021
1022
0
20
40
60
80
100
120
0
Laminate
Sandwich
Die
lect
ric
Str
eng
th (
kV
mm
-1)
Neutron Fluence (m-2
, E>0.1MeV)ITER
LOW TEMPERATURE PHYSICS
Radiation effects on insulators
Neutrons directly deposited energy by the entire neutron spectrum
(via computer codes and damage parameters foreach constituent of resin, i.e. H, C, O, N, ...)production of H, He → gas production
-rays Dose rate (Gy/h) times irradiation time (h)
Total absorbed energy (Gy)
Scaling quantity ?
LOW TEMPERATURE PHYSICS
Damage calculations
Examples: ZI-003 (Epoxy Resin) ZI-005 (Bismaleimide Triazine) 15 wt% H, 75 wt% C, 3 wt% N, 7 wt% O 5 wt% H, 73 wt% C, 10 wt% N, 12 wt% O
irradiated to 5x1022 m-2 (E>0.1 MeV) in: irradiated to 7.8x1021 m-2 (E>0.1 MeV)
TRIGA Vienna: IPNS Argonne:
ZI-003: from neutrons: 186 MGy (50 %) 16.3 MGy (39 %) from gamma rays: 182 MGy (50 %) 25.9 MGy (61 %) ------------------------ ------------------------- 368 MGy (100%) 42.2 MGy (100%)
ZI-005: from neutrons: 76 MGy (30 %) 6.5 MGy (20 %) from gamma rays: 182 MGy (70 %) 25.9 MGy (80 %) ------------------------ ------------------------- 258 MGy (100%) 32.4 MGy (100%)
LOW TEMPERATURE PHYSICS
Mechanical Tests
MTS 810 test facility Tensile test specimen geometries
0,00 0,05 0,10 0,15 0,200,00
0,25
0,50
0,75
1,00 = 0.8 max
u
l=
u*0.1
R=0.1
/
max
Time (s)
Fatigue measurements
LOW TEMPERATURE PHYSICS
TRIGA Vienna
2 MeV electrons
60-Co -rays
IPNS Argonne
Influence of radiation environment and resin composition
Irradiation at ~340 KTests at 77 K
Epoxy
Bismaleimide
Epoxy
Scaling works well!
LOW TEMPERATURE PHYSICS
Garching ~ 5 KEkaterinburg 77 KATI ~340 K
Tests at 77 K
Influence of irradiation temperature and of annealing to RT
Epoxy
Bismaleimide
Epoxy
LOW TEMPERATURE PHYSICS
0 1x1021
1x1022
0
10
20
30
40
50
60
70
80
90
100
110
Cyanate ester Cyanate ester/epoxy (40:60) Epoxy
Mec
hani
cal s
tren
gth
(%)
Neutron fluence (E>0.1 MeV)
Radiation Effects on Different Resins Tested for ITER
• Costs of CE up to 10 times higher than for epoxies
• CE can be mixed with epoxies for reducing costs
CE/epoxy blends
O
O
O
O
H
H
epoxy
O
O
CH3
H
CN
C
N
cyanate ester
LOW TEMPERATURE PHYSICS
T1 (100) (90°)
T2 (40) (90°)
T8 (30) (90°)
T10 (20) (90°)
Alstom (90°)
Ansaldo (90°)
0 10 20 30 40 50 60 70 80 90 100
UTSirr/UTS
unirr (%)
1*1022m-2
2*1022m-2
ultimate tensile strength after irradiation @ 77 K
DGEBF
20 % CE
DGEBA
30 % CE
40 % CE
100 % CE
0°
90°
286 MPa
265 MPa
387 MPa
269 MPa
313 MPa
250 MPa
Influence of CE content
LOW TEMPERATURE PHYSICS
DGEBF
DGEBA
20 % CE
30 % CE
40 % CE
100 % CET1 (100) (0°)
T1 (100) (90°)
T2 (40) (0°)
T2 (40) (90°)
T8 (30) (0°)
T8 (30) (90°)
T10 (20) (0°)
T10 (20) (90°)
Alstom (0°)
Alstom (90°)
Ansaldo (0°)
Ansaldo (90°)
0 10 20 30 40 50 60 70 80 90 100
ILSSirr
/ILSSunirr
(%)
1*1022
m-2
2*1022
m-2
4*1022
m-2
Interlaminar shear strength after irradiation @ 77 K
59 MPa
42 MPa
77 MPa
57 MPa
74 MPa
63 MPa
62 MPa
48 MPa
0°
90°
81 MPa
75 MPa
45 MPa
41 MPa
Influence of CE content
LOW TEMPERATURE PHYSICS
No significant influence of the irradiation!
Fatigue measurements @ 77 K
LOW TEMPERATURE PHYSICS
Bonded Glass/Polyimide tapes
Radiation resistant bonding agent necessary!
Delamination caused by weak bonding between resin and polyimide
LOW TEMPERATURE PHYSICS
Material
Chemistry Neutron Fluence
(E>0.1 MeV)(1021 m-2)
Total absorbed
Dose (MGy)
Gas Evolution Mean ±
Sdev(mm3)
Gas Evolution Rate
Mean ± Sdev(mm3g-1MGy-
1)CTD-422
Cyanate Ester/Epoxy
1 4.19 105 ± 0 68.9 ± 2.4
CTD-10x
Cyanate Ester/Epoxy/BMI
1 4.05 83 ± 11 57.1 ± 6.8
CTD-101K
Epoxy/Anhydride
1 4.14 165 ± 0 108.4 ± 1.9
CTD-7x Cyanate Ester/Epoxy/PI
1 3.90 75 ± 0 48.2 ± 0.4
CTD-15x
Cyanate Ester/BMI
1 4.46 60 ± 0 38.9 ± 0.3
CTD-101
Epoxy/Anhydride
1 4.11 165 ± 21 114.3 ± 10.3
CTD-HR3
Cyanate Ester/PI
1 4.31 60 ± 0 33.9 ± 0.5
CTD-404CTD-404
Cyanate Ester 15
4.0420.18
68 ± 11200 ± 9
47.0 ± 7.430.4 ± 1.1
ER Baselin
e
Epoxy/Anhydride
1 4.15 263 ± 11 176.2 ± 10.3
Gas Evolution Rates
LOW TEMPERATURE PHYSICS
Conclusions• Minor influence of irradiation temperature• Superconductors
– Defects mainly caused by high energy neutrons (except MgB2)
– Decrease of transition temperature– Critical current initially increases (except NbTi) then
decreases (1-2x1022 m-2)– Scaling by damage energy
• Insulators– Defects caused by (nearly) all neutrons and rays– Degradation of mechanical properties– Gas evolution– Scaling by total absorbed energy (dose)
Top Related