ML17256A484
| ML17256A484 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 02/01/1983 |
| From: | Bruce M, Marlone Davis Neely Research Reactor, ATLANTA, GA |
| To: | |
| Shared Package | |
| ML17256A483 | List: |
| References | |
| EPRI-RP-1707-3, IEB-79-01B, IEB-79-1B, NUDOCS 8302140122 | |
| Download: ML17256A484 (10) | |
Text
RADIATION EFFECTS ON ORGANIC MATERIALS IN NUCLEAR -PLANTS EPRI RP 1707-3 by N.B;- Bruce 5 M.V. Davis of Georgia Institute of Technology Nuclear Engineering Department Neely Nuclear Research Center 900 Atlantic Drive, N.W.
Atlanta, Georgia 30332 Final Report for Electric Power Research Institute 3412 Hill Avenue Palo Alto, California 94304 Project Manager G. Sliter 8302i40122 83020i PDR ADQCK 05000244 P
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/r rads with rapid degradatiabove threshold.
The value % x 100 rads was 50% of the original.
Tensile and shear strength was affected at 1 x 106 rads, but these properties were not degraded quickly.
At 2'x 107 rads, tensile and shear strength were 75% of original values and 50K at 3 x 107 rads.
Large quantities of gas are evolved.
Cellulose Pro ionate/threshold
- 3 x 105 rads/impact resistance.
Impact resis-tance of Forticel samples was affected above 3 x 105 rads,36 but was still 75K of the initial value after 4.4 x 106 rads and 50% at 1.5 x 107 rads.
Tensile strength was reduced 25K at 5 x 106 rads and 50K at 1.5 x 107 rads.
Elongation 1
was reduced 25K at 3.5 x 106 rads
-and 50K at 1.5 x 107 rads.
Shear strength was affected. by 4 x 105 rads, but was still 50K of the original value at 3 x 106 rads.
Higher values are observed for thick samples48 and Ggas
= 1.5 with 35 ml/gm evolved at 10g rads.
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~Eth11111
/th hid-12 idd d/id t it Eth 122 h
,initial reduction in impact resistance at 1.5 x 106 rads, 25'X reduction at 5 x 106
- rads, and 505 loss at 1 x 107 rads.36 Elongation and shear strength are affected
- at 2 x 106 rads.
Elongation is.reduced 25K at 4 x 106 and 505 at 4 x 107 rads.
Tensile strength is affected above 3 x 106 and reduced to 50% at 2 x 107 rads.
,Tests reported were for static irradiations in air at ambient temperature.
Refer-
.ence 48 gives Ggas approximately 4.6 with 105 ml/gm evolved at 10g rads.
Halo enated Pol ers Many of the commercial halogenated polymers are chloride or fluoride substituted vinyls; others are substituted polyolefins.
Pol vin 1 Chloride Ri id/threshold - greater than 106 rads.
Reference 48 reports 80~>- or better retention of tensile and notch impact strength of a 0.17-inch thick
. sample irradiated in air at 2 x 105 rads/hour and ambient temperature to a total dose of approximately 10g rads.
Reference 33 reports very serious degradation at 1.3 x'10g rads for rigid PVC irradiated at 60oC. with 1 MeV electrons.
Radiation resistance is undoubtedly dependent on thermal'and oxidizing conditions, as is the resistance of plasticized PVC.
~
~
Pdl vin 1 Chloride, P'lasOized/threshold
- 5 x 105 rads%emperature at break.
Reference 8 reports that DC resistivity of one PVC cable insulation was affected after 5 x 106 rads and sensitivity to hot water and steam was'ncreased above this value; Large decreases in oxidation resistance were noted above 5 x 106.
Scission or crosslinking may predominate, depending on temperature and oxidizing
. conditions.
Plasticizers and additives are not generally known, for commercial materials, but a fairly large range of radiation resistances occur for different materials (Figure 3-1).
Reference 48 reports results for 4 and 20-mil samples of Geon 8630 irradiated in air at room temperature.
The 4-mil sample lost approxi-mately 20K of original tensile strength after 7 x 106 rads, but retained less than 505 after 1 x 108 rads.
The 20-mil sample lost less than 20K of original tensile strength at 1 x 108 rads.
Elongation of the 4-mil sample was reduced 20K by 1 x 10 rads.
7 x 10 rads were required for the'same change in elongation of the 20-107 m
1 sample.
Similar indications of extensive oxidation effects were observed with 4-mi'I samples of Geon 8640 irradiated in air and vacuum.
In air, tensile strength was decreased approximately 20K by 7 x 106 rads and 50K by 1 x 108 rads.
Elongation decreased 205 at 2 x 107 rads and 50% at 8 x 107 rads.
In vacuum, tensile strength was reduced 20K by 7 x 107 rads and elongation was reduced 20% by 6 x 107 rads.
References 21 and 39 note marked differences in thermal properties
'of irradiated PVC.
A reduction in the melting temperature of the polymer occurs
..in air (but not in vacuum).
Reduction of the temperature at break of samples
.heated under constant stress was noted for samples after 5 x 105 rads.
After 1.1 x 107 rads, a 30-40oC reduction in temperature at break was achieved.
The rate of HCL evolution is affected by the temperature during and subsequgt to irradiation.
GHCL =, 5.41 (-90 C), =.13 (30oC),
= 23 (70oC) after 2 x 107'. Diffusion and permeability constant are increased by irradiation but may decrease again, at higher doses.
Crosslinking is inhibited in air, but may be enhanced by inclusion of polyfunc-tional materials, such as polyethylene glycol dimethacrylate.
The temperature-oxidation resistance of commercial materials will vary with the effectiveness of free radical scavengers and antioxidants.
Pol vin 1 Fluoride/threshold approximately 107.rads/elongation.
DuPont R-20 exhi-bits approximately 20% loss of elongation at 2 x 107 rads and 50K loss at. 5 x 107.
rads.
Tensile strength was not appreciably affected below 1 x 108 rads.
Sample thickness and dose rate were not given.48 Polyvinyl fluoride is also marketed as Tedlar..Radiation. resistance is probably less at elevated temperatures.
Qne electron irradiation at 60oC to 1.8 x 109 rads resulted in severe physical
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Figure 3-1 "SIMILAR" PYC CABLES IRRADIATED AT 20-40 C
300 L 250 0
N G
200 I
0 N
150 100 50 0
5 x 10 10 ABSORBED DOSE (RAD) 5x10 Data for cables from 38 manufacturers (From Reference 50)
C'
~
o '~tlegradation but unchangedaviation resistance and a 7Ãtrease in dielectric constant.
Dissipation factor increased one decade.33 Pol tetrafluoroeth lene/threshold - 1.5 x 104 rads/elongation.
Reference 47 reports a threshold change of elongation at 1.5 x 104 rads for Teflon (TFE) in air, of tensile strength at'.1 x 104 rads, of shear and impact strength and 1
. elastic modulus at 1.8 x 105 rads.
A 25K decrease was noted at 3.4 x 104 rads for
~.
elongation, 1.2 x 105 rads for tensile strength, and 4 x 105 rads for shear strength.
impact strength increased 25K at 3.6 x 105 rads.
Oxidation effects are quite large.
Radiation resistance is approximately ten times greater in vacuum or fluid.
Teflon hoses tested under simulated operating conditions failed, by leakage, at 1 x 105 rads when exposed to intermittent fluid pressure of 1,000 psig and at approximately 1 x 106 rads when subjected to 1,200 psig static pressure:
The radiation exposure-damage relation was relatively insensitive to temperature in the range of 100 to 350oF. in that test.
Teflon back-up rings (in.
fluid) have been found serviceable in some appl.ications to approximately 4 x 107
- rads, although physical degradation occurs.><.
Sharp decreases in melting temperature wer e noted for irradiati ons above 330oC.
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,n Teflon-FEP (copolymer of fluoroethylene and perfluoropropylene) is more resistant that Teflon-TFE.
Teflon-FEP shows ten times greater radiation resistance in vacuum and sixteen times greater resistance in air for 10-mil films.46 Temperature effects have been noted.
Damaqe at cryotemperatures was negligible for a dose that produced 40K loss.of tensile strength at 73oF and 60K damage at 350oF.
Electrical properties are affected differently for irradiation in air and vacuum..
TFE volume resistivity.has been observed to drop'y a factor.of 102-103 in vacuum radiation 'and to drop an additional factor of 10-102 after irradiation (gradual recovery may occur).
One Teflon-insulated wire is reported to show s/ightly reduced flexibilityat 103 rads in a 5 psia 02 atmosphere at 90oC.
A similar Teflon wire lacking a polyimide coating present on the first wire did not show reduced flexibility under the same conditions.33 This indicates that the materials were incompatible, not that the radiation level was significant.
- Tetran, Fluorlon, and Hostaf ion FT are a few of the other commercial names for polytetrafluoroethylene.'ain chain scission is dominant and there is little evi-dence of any crosslinking during irradiation.
3-13
(,", >..:i; )
EC/CP (81) -086
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Westinghouse Electric Corporation Water Reactor Divisions Strategic Operations Oivision Box 598 Pittsburgh Pennsyhrania 15230 August 13, 1981 Mr. George lrrrobel Rochester Gas g Electric Corp.
89 East Avenue Rochester, NY 14649
Subject:
ENVIRONMENTAL UALIFICATION Ref:
EQ/CP(81)-035
Dear Mr. Nrobel:
The following responses are p'rovided to the N action items in the refer-enced letter:
a)
As discussed in both 1<CAP-7829. and 1<CAP-9003, the complete motor was qualified.
The motor-lead splices are considered part of the therma-lastic epoxy insulation system and are the same for all these motors.
The lead-cable splice qualification should be verified by RGE.