ML20077S324
| ML20077S324 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Crane |
| Issue date: | 03/01/1977 |
| From: | Mitchell D, Stoner P GENERAL PUBLIC UTILITIES CORP. |
| To: | Stewart Bailey GENERAL PUBLIC UTILITIES CORP. |
| Shared Package | |
| ML20077S281 | List: |
| References | |
| FOIA-83-349 NUDOCS 8309220019 | |
| Download: ML20077S324 (2) | |
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',-j"~.9 Location READING Subject Considerations Relating to the Extended
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Use of Furmanite In DEV-1 at TMI 1
. Date. March 1,1977.:
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'. ' - One consideration in'the use of Turmanit'e in the subject,applice.t[ ion is the potential for chloride stress corrosion cracki'ng of the cast 316 stainless steel valve.
The engineering ' evaluation regarding "tliis.first usage ' * -
is wel'1 documented. It is the understanding of the. System Laboratory that that evaluation considered the short-term use of Furmanito as'a stop gap measure to c
preclude an unscheduled plant ' shut down.
Since that time, nuclear
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Iurcanite has' proven extremely successful in stopping the original leak. ' Based l.'
on this success, Met-Ed is considering Turnanite as a long-tern solution to the It is the' udderstanding of the writers that it wo'uld be V
'eaking valve problem.
desirable to delay the inspection and possible replacement of the DEV-1 ince'rnalsI l
i or the entire valve until the; first.Three Mile Island Unit.1 in-service inspec tion in 1985..This memorandum is to recoccaud that the previous 'Furmanite istjection be considered an adequate' valve repair for operation until the 1978 -
During this next year of 'operatio.n, the opera' ting conditions.' <
refueling outage.
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and known chloride content of Furmanite should be considered in the light of advances in stress corrosion cracking technology to assess the potential' for cracking-durin's the following seven (7) years of expected operation.
There are rany.. variables' which control the potential for s' tress corrosion cracking as it affects this valve.
These include time, temperature, E
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stress,. chloride level, oxygen level, heat-treated condition, and amount of
- ' d delta ferrite present in the cast 316 stainless steel valve body. ? System Laboratory tests have shown that the nuclear grade Furmanite used to repair DHV-1 has approximately 8 ppu leachable chloride and a t'otal chloride content of nominally 100 ppa as found using an ashed sample.
The most pertinent stress I
corrosion cracking study that the writers are aware-of may be summarized as'
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follows:.
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.. 1., Decreasing chloride level greatly. increases the threshold. ', '
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stress for cracking to occur.
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Specimens immersed in liquid require considerably longer "l-3m to crack. than those in. vapor..
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, The. presence of air accelerates cracking 1n liquid and
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The presence of molybdenun in the stdel lowers the ' # -
J; tf.reshold stress for the onset of cracking.
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for oli: hor en 8 ppa chlorida lavsi or the 100 ppa total chlorida contrat tho **-
thrakhold strass for cracking of DRV-1 undar expacted, environmental condi-.
J tiens would greatly excesd tha yield stress of the material. 4 Basad en thi.a ~...
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data and the inability to. find a. documented case of cracking under conditions..
similar to 'the seivice environment of DEV-1, it is recommended that the
- . e Furmanitie be considered a suitable repair for operation through at least 1978.,.'.
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There are several on-going stress corrosiati ' tudie's' which may provida.'
s information pertinent to this' problem. ' The boundary conditions wherein chl'orida stress corrosion cracking may occur are continually being redefined. On this-basis', it is recommended that a more thorough literature. search be. conducted of*]
recent' co,rrosion information in order to make. the best judgement concerning the The writers are awara.of at least two (.%
long-term nature of the DEV-1 r'epair.
(2) current programs which may provide information en better assess conditions.-
Presently, work by R. W. Staehle at Ohio, University, sponsored by EPRI, is providing basic information regatding the stress corrosion crac. king phenomena.l-Curreht progress reports of his work are ob'tainable from EPRI.. Addicit.o,nally, with the cracking of 4-inch recirculation bypass lines and other austenitic
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stainless steel piping.in the BUR plants, work is be'ing undertaken to understa'n
.other environmental aspects of stress, corrosion cracking.
- Some of t.he'alternat
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materials recommended for. this. application includs cast austenitic stainless
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steel; therefore, progress reports,from this work should provide ~ additional
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~ On th'e' basis of the literature presently available, it appears that unless leaking should occur in DRV-1 and cause a concentra. tion effect of..
the chloride content, as previously described, there should be no concern'.'.. '
for cracking"under p' resent ' conditions.
However, as it i's underdtood that ': 2.
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.2dditional information regarding cracking.will be available in t.ha near futurs #
it.would be prudent to consider all of the available stess cor':osion cracking -
data.
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J. L'.
C. Bachofer, Jr.
R. O. Earley
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J. J. Colitz
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'J. C. Herbein ',
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R. D. Hopkins
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R. H. Klinga.can T!!I 1 & Furmanite Files s
. Sh i sose, er. al.- Proceedings of Conference Trom the IIetal Aspects of Stress Corrosion Cracking, edited by R. W. Stachle, Page 239,. published -
by NACE, Copyright 1969.
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