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Evaluation of Radiation Resistancefor Organic MaterialsUsed in Atomic Energy-related Facilities
Japan Atomic Energy AgencyQuantum Beam Science Directorate
Advanced Ceramic Group
Akira Idesaki, Akihiko Shimada,Norio Morishita, Masaki Sugimoto, Masahito Yoshikawa
Electron beam irradiation facility
Co-60 gamma-ray irradiation facility
Ion beam irradiation facility
Please visit ! → http://www.taka.jaea.go.jp/
Takasaki Advanced Radiation Research Institute of JAEA
Acceleration Voltage :0.5~2.0MeVBeam Current : 0.1~30mA
Dose rate : 0.2Gy/h ~ 20kGy/h
TIARA(Takasaki Ion Accelerator for Advanced Radiation Application)
●AVF Cyclotron : H, He, Xe, Os, etc(~several hundred MV)
●3MV Tandem Accelerator : H, C, Ni, etc●3MV Single-ended Accelerator : H, He, etc●400kV Ion Implanter : H, Ar, etc
Takasaki-Daruma
Tokyo
Osaka
Takasaki(Gunma Pref.)
Tokai
Application for biotechnology and medical use
R&D for environmental preservation and resource security technology
Development of novel functional materials
Poly(lactic acid)
©JAXA
Research Activities for Quantum Beam Applications
Polymer electrolyte membrane for fuel cells
Silicon carbide fiber Evaluation of semiconductor devices for space use
Creation of carnations with variety of colors
Creation of UV-resistant plants
Fibrous adsorbent for metals Biodegradable plastics Decomposition of air pollutants
Novel DNA-repair protein
Quantum Beam Science Directorate Advanced Ceramics Group
■ Fabrication of ceramic materials from Si-polymers with radiation curing
■ Evaluation of radiation resistance for organic materials used in atomic energy-related facilities
J-PARC
ITER
Si-polymer Forming : fiber, molding, etc.
Radiation curing : EB, gamma-rays
Firing : ~1200℃ SiC fiber : φ 5μm SiC micro-products
60μm
●Power cables●Vacuum components●Sensors●Superconducting magnets
etc.
Organic materials are used as electrical insulator and structural materials.
Evaluation of radiation resistance for organic materials
Safe and stable operation of facilities
Spacecraft, Fusion reactorChemical plant, Microreactor
Change of molecular structure
Irradiation Effects on Organic Materials
Reaction of free radicals
Production of free radicals-Crosslinking-Chain scission-Formation of unsaturated bonds (C=C, etc.)-Oxidation (under presence of oxygen)-Gas evolution
Modification Degradation
■Scheme of interaction between organic materials and radiation
COOH
HOOC
Gas evolution(H2, CH4, etc)
- Irradiation temperature- Irradiation atmosphere
(presence of oxygen)- Additives
Radiation
Molecules
●Polyether-ether-ketone (PEEK)
Irradiation Effects on Organic Materials
■Radiation resistance of organic materials : Effect of irradiation temperature
Reference : “Radiation Resistivity of Polymeric Materials with Data Tables” (in Japanese)JAERI-Data/Code 2003-015
●Polytetrafluoroethylene (PTFE)
Degradation of organic materials is accelerated at high temperature.
O
O
CO
n
C CF
F
F
F nGlass transition temperature : about 140℃
0
50
100
150
0 5 10 15
50℃100℃150℃
Tens
ile s
treng
th (M
Pa)
Dose (MGy)
0
10
20
30
40
50
60
0 2 4 6 8 10
4KRT
Tens
ile s
treng
th (M
Pa)
Dose (MGy)
Radiation oxidation accelerates degradation of organic materials.
Irradiation Effects on Organic Materials
■Radiation resistance of organic materials : Effect of irradiation atmosphere
Reference : “Radiation Resistivity of Polymeric Materials with Data Tables” (in Japanese)JAERI-Data/Code 2003-015
C CH
H
H
H n
●Polyethylene (PE)
0
10
20
30
40
50
0 0.5 1 1.5 2
VacuumAir
Tens
ile s
treng
th (M
Pa)
Dose (MGy)
Reference : “Radiation Resistivity of Polymeric Materials with Data Tables” (in Japanese)JAERI-Data/Code 2003-015
Radiation oxidation is accelerated in the case of low dose rate.
Irradiation Effects on Organic Materials
■Radiation resistance of organic materials : Radiation oxidation of organic materials
CH2 CH2 CH2 CHCH3
nm
●Ethylene-propylene rubber (EPR)
KOHsolution
-COOH + K+
→ -COOK
Distribution of potassium= Oxidized region
EPR sheetirradiated in air
X-ray Micro Analyzer
100
200
300
XM
A c
ount
s of
pot
assi
um (c
ount
s/s)
0 1.0 2.0Depth (mm)
1kGy/h
0.3kGy/h
-Gamma-ray, 200kGy, RT
Irradiation Effects on Organic Materials
■Radiation resistance of organic materials :Effect of additives
Reference : T. Seguchi et al, Rad. Phy. Chem., 80(2011), pp.268-273.
●Crosslinked polyethylene (XLPE)- XLPE with (1wt%) and without antioxidant- Gamma-ray irradiation with dose rate of 1kGy/h in air at 100℃
0
20
40
60
80
100
120
1 10 100 1000
0%1%
Elon
gatio
n at
bre
ak (r
el. %
)
Aging time (h)
Even 1wt% of antioxidant is effective for suppression of degradation.
Properties should be evaluated according to the purpose for use.
●Structural materials : Mechanical properties●Electrical insulator : Electrical properties●Materials for vacuum components : Outgas, mechanical properties●Adhesives and paints : Detachment, coloring, outgas
Irradiation Effects on Organic Materials
■Measurements and analyses for evaluation of radiation resistance●Chemical properties
- Electron spin resonance (ESR) : Quantification (and qualification) of free radicals- Gas chromatography : Quantification and qualification of evolved gases- FT-IR (Fourier-transformed infrared spectroscopy) : Analysis of chemical bonds- GPC (Gel permeation chromatography) : Measurement of molecular weight- Thermal analysis : Measurement of melting point, decomposition temperature- Elasticviscosity : Measurement of glass transition temperature
●Mechanical properties- Tensile test- Bending test
●Electrical properties - Breakdown voltage- Electrical resistance
Evaluation under conditions close to practical conditions as possible
■Materials used in superconducting magnet system at J-PARC neutrino beam line
Evaluation of radiation resistance for organic materials used in J-PARC
Gamma-ray irradiation at temperature of liquid nitrogen (77K)
Plastic spacer(GFRP; Glass fiber/Phenolic resin)
Insulation of superconducting coil(Film; Polyimide/Epoxy resin)
Wedge(GFRP; Glass fiber/Epoxy resin)
●Service condition:- Temperature of liquid helium(4K)- Irradiation of γ-rays and neutron
Dose rate : 30kGy/yearOperating time : 4000h/year
Evaluation of radiation resistance- Mechanical properties- Behavior of gas evolution
Reference : A. Idesaki et al, Advances in Cryogenic Engineering, Vol. 52, 2006, pp.330-334.T. Nakamoto et al, Advances in Cryogenic Engineering, Vol. 52, 2006, pp.225-232.
Evaluation of radiation resistance for organic materials used in J-PARC
LN2 TankVacuumPump
Cryostat
Wall
Sample
■Low temperature irradiation vessel
0.25 0.5
5
10 ■ 4K▲ 77K
Evo
lved
gas
(10-5
mol
/g)
Dose (MGy)Effect of irradiation temperature on tensile property and gas evolution.(High Density Polyethylene; HDPE)
Reference : H. Kudoh et al, Rad. Phy. Chem., 48(1996), pp.89-93.
- Gamma-ray irradiation at 77K(4K is not available…)
- Dose rate : ~30kGy/h
●
●
●
●
●
●
■ 4K▲ 77K● RT
500
1000
0.4 0.8Dose (MGy)
Elo
ngat
ion
at b
reak
(%)
Difference between 4K and 77K is almost negligible.
Condition of 4K can be simulated by irradiation at 77K.
Co-60source
Irradiation room
5
5.5
6
6.5
7
7.5
8
0 2 4 6 8 10 12 14
ParallelVertical
Tear
stre
ngth
(N/m
m)
Dose (MGy)
Unirradiated
Evaluation of radiation resistance for organic materials used in J-PARC
■Mechanical tests after γ-ray irradiation at 77K
0
100
200
300
400
500
0 2 4 6 8 10 12 14
G11PM9640
Flex
ural
stre
ngth
(MPa
)
Dose (MGy)
Unirradiated
0.3MGyTotal dose after the operation for 10 years
●Tear test for film- Polyimide/Epoxy resin
●Three-point bending test for GFRP- Glass fiber/Epoxy resin (G11)- Glass fiber/Phenolic resin (PM9640)
The materials show sufficient radiation resistance.
GFRP; Epoxy resin GFRP; Phenolic resin Polyimide/Epoxy resin
0
5
10
15
20
0 3 6 9 12 15
TotalH2
Evo
lved
gas
(10-6
mol
/g)
Dose (MGy)0
10
20
30
40
0 3 6 9 12 15
TotalH2
Evo
lved
gas
(10-6
mol
/g)
Dose (MGy)0
10
20
30
40
50
60
0 3 6 9 12 15
TotalH2
Evo
lved
gas
(10-6
mol
/g)
Dose (MGy)
Evaluation of radiation resistance for organic materials used in J-PARC
■Gas analysis after γ-ray irradiation at 77K
Sufficient radiation resistance of organic materials was proved.
0.37mol/year of hydrogen (0.01L/year as liquid hydrogen)= Negligible for the capacity of hydrogen-absorber
- Hydrogen should be removed to keep stable operation of the magnet system.- Estimation of the amount of hydrogen from the whole magnet systems (28 magnets)
Beam supply has started since Jan 2010.
0
5
10
15
20
25
0
5
10
15
20
0 40 80 120 160 200 240 280
Tens
ile s
treng
th (M
Pa)
Evo
lved
gas
(10-5
mol
/g)
Dose (kGy)
Gas analysis for evaluation of radiation resistance
Reaction offree radicals
Free radicalsOOH
HOO
Gas evolution
- XLPE- Gamma-ray, RT, vacuum
Gases evolved from organic materials by irradiation can be detected with low dose where deterioration of mechanical property is negligible.
Gas analysis is a good tool for:●Selection of materials●Evaluation of radiation resistance
Change of tensile strength and the amount of evolved gases by γ-ray irradiation for XLPE.
Gas analysis system
Selection of organic materials used as electrical insulatorfor ITER superconducting coil■Fabrication of electrical insulator for ITER superconducting coil
●Candidates-Epoxy resin (DGEBF) + Cyanate ester (CE)-Epoxy resin (DGEBF) + Epoxy resin (TGDDM)
Central Solenoid (CS) Coilfor Ignition of Plasma
Toroidal Field (TF) Coilfor Confining of Plasma
Poroidal Field (PF) Coilfor Adjustment of Positionand Shape of Plasma
Glass cloth/Polyimide/Epoxy resin
●Required properties for epoxy resin- Viscosity : 200mPa・s at 60℃- Pot life time : 40h (time to increase the viscosity)- Radiation resistance : 10MGy
Vacuum infiltration of epoxy resin
Superconducting coil
Glass clothPolyimide film
●DGEBFDi-Glycidyl Ether of Bisphenol F
●TGDDMTetra-Glycidyl-Diamino-DiphenylMethane
●CECyanateEster
C O C NOCN
H
CH3
H2C CH
O
CH2 O CH2 O CH2 CHO
CH2
CH2N NCH2
CH2
CH2
CH2
CH CH2O
CH CH2
O
CHH2CO
CHH2CO
Selection of organic materials used as electrical insulatorfor ITER superconducting coil
Resin of●Sample A : DGEBF + CE●Sample B : DGEBF + TGDDM
Gamma-ray irradiationat 77K
●Selection of insulation material- Gas analysis- Interlaminer shear strength
■Candidates of electrical insulator for ITER superconducting coil
Glass cloth/Polyimide/Epoxy resin
Evolved gases from laminated materials by γ-ray irradiation at 77K
0
20
40
60
80
100
120
0 5 10 15 20 25 30 35
Sample ASample B
Evo
lved
gas
(10-6
mol
/g)
Dose (MGy)
Total
0
20
40
60
80
100
0 5 10 15 20 25 30 35
Sample ASample B
Evo
lved
gas
(10-6
mol
/g)
Dose (MGy)
H2
Sample A : DGEBF + CESample B : DGEBF + TGDDM
0
5
10
15
0 5 10 15 20 25 30 35
Sample ASample B
Evo
lved
gas
(10-6
mol
/g)
Dose (MGy)
CO
0
5
10
15
0 5 10 15 20 25 30 35
Sample ASample B
Evo
lved
gas
(10-6
mol
/g)
Dose (MGy)
CO2
Selection of organic materials used as electrical insulatorfor ITER superconducting coil
●Main components of the evolved gas : H2, CO, CO2●Radiation resistance of Sample A is superior to that of Sample B.
■Gas analysis after γ-ray irradiation at 77K
Reference : A. Idesaki et al, Advances in Cryogenic Engineering, Vol. 54, 2008, pp.169-173 .
Selection of organic materials used as electrical insulatorfor ITER superconducting coil■Mechanical tests after γ-ray irradiation at 77K
Apparent interlaminar shear strength of the irradiated Sample B (warp specimens).
Sample A (Epoxy resin + Cyanate ester) was selected as electrical insulator for ITER superconducting coil.
Reference : Y. Shindo et al, Cryogenics, 50, 2010, pp. 36-42.
Scheme of short-beam shear test.
Warp
Fill
0
10
20
30
40
50
60
0 5 10 15 20 25 30 35A
ppar
ent i
nter
lam
inar
she
ar s
treng
th (M
Pa)
Dose (MGy)
12.5mm
d=6mm
d=10mm
Load
Sample BDirection : WarpTemp. : 4K
Development of organic material with high radiation resistance
Fabrication process of epoxy resin
Epoxy resin + hardener + (catalyst) → Heat treatment- Acid anhydrides- Amines- Phenols- Cyanate esters
■Irradiation effect on epoxy resins with different hardeners
Relationship between chemical structure of hardener and radiation resistance
Epoxy/Cyanate ester resin showed high radiation resistance.・・・・・The reason has not been clarified.
(Collaboration with University of Hyogo (Prof. Kishi) and KEK)
CO
CH3
CH3
OH2C
H2C
HC CH2
HCH2C
O O
O
O
O
H2NH2C NH2
COCH3
CH3
O CC NNOH
CH2 CH2
OHOH
n
Development of organic material with high radiation resistance
■Examined materials
●Epoxy resin
DGEBADi-Glycidyl Ether of Bisphenol A
●Hardeners
-Acid anhydrideHHPA (Hexahydrophthalic anhydride)
-AminesDDM (Diaminodiphenylmethane)
-PhenolsPN (Phenolnovolac resin)
-Cyanate estersDCBA (Di-Cyanate ester of Bisphenol A)
Development of organic material with high radiation resistance
■Gas analysis after γ-ray irradiation
C
CH3
CH3
:
0
10
20
30
40
H2 N2 CH4 CO CO2 Total
HHPADDMPNDCBA
Evol
ved
gas
(10-6
mol
/g・M
Gy)
Crosslinking structure between epoxy and hardener
R
OO CH2 CH
O
CH2 O
RO
CHCH2O CH2 O
O
O
Acid anhydridesCH2 CH CH2 O
OHNRCH2 CH CH2 O
OH
Amins
R
O
H2C CH CH2
OH
OPhenols
OCH2
CHCH2
N
O O CHCH2
CH2
O
NCOCHH2C CH2 O
C OCH CH2
OO
CH2O
Cyanate esters
Bond-dissociation energy
C-HO-HC-CO-NC-N
(kJ/mol)334.7424.4599626.8745
●Crosslinking structure is collapsed by radiation.●Hardeners which include benzene ring and/or C-N bonds suppresses gas evolution.●Cyanater esters, which forms very complex crosslinking structure, leads the highest radiation resistance.
Development of organic material with high radiation resistance
Bis-A type
Bis-E type
Bis-F type
Diphenylether type
Cyanate Epoxy
CO
CH3
CH3
O CC NN
[DCBA]
CO
CH3
CH3
OH2C
H2C
HC CH2
HCH2C
O O
[DGEBA]
CO
CH3
H
O CC NN
[DCBE]
COH
H
O CC NN
[DCBF]
OO O CC NN
[DCDPE]
COCH3
H
OH2C
H2C
HC CH2
HCH2C
O O
[DGEBE]
COH
H
OH2C
H2C
HC CH2
HCH2C
O O
[DGEBF]
OO OH2C
H2C
HC CH2
HCH2C
O O
[DGEDPE]
Development of Epoxy/Cyanate ester resin with higher radiation resistance●Combination●Composition J-PARC, CERN LHC Upgrade, etc.
Summary
●The performance of instruments used in atomic energy-related facilities depends on the radiation resistance of organic materials used.
●Radiation degradation of organic materials depends on temperature, atmosphere and additives. Especially, much attention should be paid to the dose rate in case of evaluation under presence of oxygen.
●It is important to evaluate the materials under the conditions close to practical conditions as possible.
●Gas analysis can be a good tool for selection of materials.
●A novel epoxy/cyanate ester resin is under development in order to put it to practical use for J-PARC, CERN LHC Upgrade, etc.
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