Evaluation of Radiation Resistance for Organic Materials ...Electron beam irradiation facility Co-60 gamma-ray irradiation facility ... Mechanical properties Electrical insulator :

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)


■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.


■Radiation resistance of organic materials : Effect of irradiation atmosphere


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)


Radiation oxidation is accelerated in the case of low dose rate.


■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


■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


■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.


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


■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)


■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


■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)


■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.


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.

Documents

Evaluation of Radiation Resistance for Organic Materials ...Electron beam irradiation facility Co-60 gamma-ray irradiation facility ... Mechanical properties Electrical insulator :