ML20077S327
| ML20077S327 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Crane |
| Issue date: | 03/11/1977 |
| From: | Stewart Bailey, Klingaman R, Lefin R METROPOLITAN EDISON CO. |
| To: | Colitz J METROPOLITAN EDISON CO. |
| Shared Package | |
| ML20077S281 | List: |
| References | |
| FOIA-83-349 GEM-0715, GEM-715, NUDOCS 8309220022 | |
| Download: ML20077S327 (4) | |
Text
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bTROPOLITAN EDISON COMPdNY s.S,for ch eMum 'c,
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Subject CONTIUUED OPERATIONS OF DEV-1 UTILIZING FURMANITE !.ocation Reading
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Date March 11,19TT' "
~J. J. COLITZ
. GEM 0715 To.,
Background:
The purpose of this memorandu:s is to document Generation Engineering's.'
decision to 'not disassemble this Decay Heat valve DHV-1 during the 1977 Refueling Outage..This is the valve.which was injected with the nuclear
. grade Furmanite' compound. during November,1976 to successfully stop....,-
leakage past the pressure ' seal gasket.,
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Discussion:
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Change Modification 81h presented and discussed the reasons for acceptance
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of the Furmanite compound that was injected. Nov vith the leakage succes:
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l'ully stopped, Generation. Engineering was requested to provide the basis a evaluation by which this compound may. be' left in the valve for an extendet period of, time.
The areas of concern to be considered are cutlined in thi following categories:.
1.
Valve Stress and Fatigue
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- 2.. Reactor Coolant Chemistry
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Radiction Environment 5
Thermal cycling
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Boric Acid Corrosion
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l-Valve Stress and Fatigue
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9 A detailed' stress analysis of.the valve b.edy was performed prior to il-l drilling the injection holes.
This analysis is.avellable and shows that the location and small,ize of the holes vill not effect the gross s
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stresses in the valve body.
In addition to this, a fatigue analysis also shows that the fatigue life of the valve body vill not be affected. '
This conservative analysis allows for more than 30,000 full pressure (0 - 2500 psi) operating cycles over a 40 year plant life. ' Therefore,,
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the valve modifications required to inject Furmanite do not. effect the Service Life of the valve.'
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March 11,19TT..
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Reactor Coolant Chemistry
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As previously stated in GEM 3317, the Furmanite compound was tested and approved for contact with the Reactor Coolant System.
This analysis was.
based upon th'e amount of compound to be injected and the specific total and leachable quantities of particular elements of. coni:ern. As a resulti j,.
continued operation of the system with the Furmanite compound in the valyc will in no var violate the required" primary coolant limits.,
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F Although the Furmanite is in direct contact with the stainlees steel val e body, this is not. considered to, cr'eate the problem of chloride induced; f.
s, tress corrosion cracking for the following reasons:
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The absence of oxygen essentially inhibits the* occurrence of ' ",
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chlo. ride stress corrosion.
.The. areas of the val,ve in conf.act. ~. '.
with Furmanite vould 'he exposed to reactor coolant, whose' f
' oxygen content is essentially zero. With the leakage stopped,,'
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there' is only a very s= nan surface area of the Furmanite being.
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Without leakage, there is no evaporative mechanism for concentrat:,
ing any chloride that may leach from the Furmanite. '*
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The temperatuie a,t the seal location on DRV-1 is, low, abkut 1(O F.
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Chloride stress corrosion is.strongly temperature dependent and i.
,140 F is near the lower end of the temperature range where it could
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occur.
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The Furmanite has a Nitrile rubber' base' with a measu' red quantity of 1eachable chlorides being 8 pps.
Typical Nitrile rubbers containing )
50 ppm leachable chlorides have been videly an1 successfully used in contact with stainless steels at temperatures exceeding those!
of DKY-1..
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The valve body is made of cast 316 stainless steel.
It is well'known
.that the duplex austenitic-ferritic structures typically obtained
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~ stress corrosion.
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t As a result, based upon the type of valve material, environment, and '
l chemical composition'of Furmanite, stress corrosion cracking of the valve is not 'conside' red to be a concern in this ' application. ',.-
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March 11,1977 '
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Radiation Environment
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...-v Samples of the Furmanite vere exposed to gn=na radiation to provide a -
basis for the detemination of whether the material could withstand
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the environment within containment.
The sa=ples were placed i 3
field at an air equivalent dose rate of 5 x 10g a. rad.s '.'
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5 rads while another received per hour.
One sample.vas exposed to 10 rads.
Neither of the. samples. showed any apparent. physical degradation '.'
or embrittlement and subsequent tests showed that, no increase in
, leachable chlorides resulted from such radiation exposure. Based upon gn
- and neutron dose rates of 6 and.5 rads per hog respectively duriz power operations, the Furenite sample exposure of 10 rads represents.
17 years.of inservice plant time at DHV-1..
- .f Thermal Cycling.:...
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it Thermal cycling' is very lov at DH.V-1 and it. is expected tbst the tem _Eerai variations.at this valve vill have a very minimM effeict' on the Furmanith
, Measured temperature changes of the valve between operating and decay hed modes has been approximately 50 F.
This is due to the fact that DHV-1 id en c. dead leg pipe run frc= the reacter coolant loop during power operatil and reduced reactor ' coolant temperatures prior to establishing' deca'y ' heat flow..Furmanite, Inc. has previously only experienced leakage due to the cycling 'vhen' temperature variations have been in the range of 200 to 3C
- The lov temperature (140 F) of the injected area'is anticipated'to helg keen the 7urmanite compound more pliable, since high temperatures (300 t 500 F) tend to make,the material more brittle and therefore, more suscept to the thermal' expansions and contractions of the metal components. "Have if such cycling 'does result in leakage, then reinjection of Furmanite car be used to stop all leakage.
Boric Acid Corrosion After injection of the Furmanite, the valve components vere given a very
. thorough visual examination for corrosion.
The retaining ring'vas examir in particular.
This is a lov alloy steel component *Lnd.has a protective chrome plating on the threads.
The exposed threads shoved no sign of l
corrosion or pitting whatsoever,. indicating that there has been no,degra'd tion at all.
This area of the threads vould be the most susceptible. to such phenomenon since they were exposed to the highest ' levels of oxygen.
The valve body which interfaces.this area is type 316 stainless steel and therefore, has not undergone any corrosion. As a result, this threaded retaining ring is considered to be fully functionel to provide a pressure retaining bouridary at the seal interface.
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..1 The bonnet studs and nuts 'did exhibit some c'orrosion shich is considered.
not to be significant.. These ' parts serve no function during operation
. of the valve' and are used only for' assembly purposes when performing.. r' maintenance on the valve. No other parts of the valve exposed to the'.
l boric acid solution showed any 'significant corrosion which could.in'any
' vay affect their structural integrity.
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Conclusion:==
.u Generation Engineering has thoroughly reviewed the continued operation
'of-DRV-1 with the. injected Furmanite compound and sees no reason why such operations cannot be continued.at least until the'1978 retw h_...
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outage. During this time, the. potential longer tern effects created by ;
.a use of Furmanite vill 'be reviewed to verify our initial determination -
.of its acceptability.
To reflect iaur current evaluation 'of the accept
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ability of Furnanite.. Generation Engineering recommends the following J.
modification to the surveillance procedure of DHV-1 previous 13 establisha
.by Change Modification 81h, GEM 331T.. Specifically, that the visual per month to, once a month following the 19T[ Refueling Outage. s
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Subnitted:.
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Reviewed:
R. R. Lefin '
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Approved:
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Approved:
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L. L. Lawye.r
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cc:. R. C. Arnold
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'J. JJ Colitz
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.W. W. Cotter R. M.~Lefin
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P. S. Stoner (GPU)
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