Evaluation of Radiation Resistance for Organic Materials Used in Atomic Energy-related Facilities Japan Atomic Energy Agency Quantum Beam Science Directorate Advanced Ceramic Group Akira Idesaki , Akihiko Shimada, Norio Morishita, Masaki Sugimoto, Masahito Yoshikawa
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Evaluation of Radiation Resistancefor Organic MaterialsUsed in Atomic Energy-related Facilities
Japan Atomic Energy AgencyQuantum Beam Science Directorate
■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
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.
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
■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.