ML19263D060
| ML19263D060 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 02/02/1979 |
| From: | Bixel D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| NUDOCS 7903200598 | |
| Download: ML19263D060 (5) | |
Text
- w i Consumels o Power
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cene ai on.ce.: 2i2 west u.cnigan Avenue. a.ca.on. u.cnigan 920s. Area Code S$ 7 788-0550 February 2, 1979 Mr James G Keppler Office of Inspection and Enforcement Region III US Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137 DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT - RESPON9E TO IE BULLETIN 78-14:
DETERIORATION OF BUNA-N COM1'ONENTS IN ASCO SOLEN 0 IDS The subject bulletin addressed failure of Buna-N components in ASCO solenoid valves.
Consumers Power Company's response to the subject bulletin's request for information is delineated below:
Item Review Buna-N material applications in your control rod scram systems and determine the time since installation and, for installed material, the time since packaging.
Response 1 Our records indicate that the subject scram solenoid valves were shipped from General Electric in 1966 and installed in 1966 and 1967.
There is no data available concerning the length of package or storage time prior to shipment.
Item Report the results of the review set forth in Item 1 above and describe your schedule for replacement, both in response to this bulletin and for periodic maintenance.
Response 2 The scram solenoid valves will be rebuilt with the kits specified in General Electric's Service Information Letter (SIL) 128, Rev 1, Supp 1, during the D
7 1979 7903200 W $
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2 next refueling outage scheduled to begin in February 1979. A preventive maintenance program has been established to replace the affected solenoid valve parts on a five-year frequency.
Item Describe the bases for your schedule of replacement identified in response to Item 2 above. Justify any proposed replacement time in excess of three years.
Response 3 General Electric's letter dated January 30, 1979 (copy attached) reported that a combination of shelf and in-service life of seven years for the subject components is conservative based on industry experiences with failure of Buna-N components in scram pilot valves. Records at Big Rock Point reinforce GE's recommendation as the Big Rock Point failures discussed in the subject bulletin involved valves which had been installed for approximately twelve years before the first failure of this type occurred. As a result, a scheduled preventive maintenance kit replacement program bas been established with a replacement frequency of five years. This is conservative and justifiable based on both industry and BRP's past experiences.
David A Bixel (Signed)
David A Bixel Nuclear Licensing Administrator CC Director, Office of Nuclear Reactor Regulation Director, Office of Inspection and Enforcement
i GENERAL @ ELECTRFC nocteaa esen.
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GENER AL f" ELECTRIC noctera enen DUSINeSS GRO GENERAL ELECTWC COMPANY,175 CURTMeR Ave SAN JcSe. CAur-CENU,95125 G-EJ-9-10 cc:
F. Turski C. Hinton January 30, 1979 Mr. J. Rang Consumers Power Co.gany 1945 West Parnall Road-Jackson, Michigan 49201
$UBIECT:
RESPONSE T0 tiRC-IE SULLETIN 78-14
Dear Mr. Rang:
Tnis letter has been prepared by the General Electric Company to provide information to the operating BWP. cwners to assist them in responding to the !SC-IE Bulletin 78-14, and to provide a clarif f cation of the re-
. co mandations in Service Information Letter 128.
In order to establisi; a corrmn base for discussing maintenance' recom-cendations, and their bases, it is helpful to start with a few defini-tions.
1.
Cure-Date (C.D.)
This is the date on which the Buna-N elastc. eter parts are created m
in a rolding and heat curing process.
This is the true "beginning-of-life" for the material.
While the cure-date is the ideal re-ference for defining useful life of an slastomer, historically it l
has not been identified on piece parts for a variety of cunufac-turing related reasons.
2.
Pachacina Date (P.O.)
This is the date on which the various piece parts are packaged into replacenent part hits.
The tins bat:,een curing and packaging are not al;,ays known accurately; therefore, it is conservatively assu ed to be equal to or lass than t' o years (P.D. = C.D. +2 ' yrs. ).
[
GEff ER AL [j) ELECTRIC G-EJ-9-10 3.
Service Life (S.L.)
Service life is defined as the period of tire from packaging s w
during which the elasto=er retains enough of its design propercies to perfom its design function.
Service life includes shelf tire prior to installation.
' Discussion The service life of elastomer parts in a pneuratic system is affected by environmental # actors such as temperature, radiation, air quality, etc.
The initial Service Information Letter (3/31/75) recomended replacemnt of the Buna-N parts after three years of ar.tual sery;ce.
This recon-rendation was.,rade with knowledge that as much as four years could --
elapse between the cure-date and the. beginning of' actual service.
It was also rade without the benefit of a significant quantity of service i
life data.
The 1/3G/76 revision to the Service Infor ation Letter revised the expected service life based on actual in-service performance i.
data (see Figure 1).
At thac tire there were three plants that reported j
diaphragm failures.
These three plants had times to failure of 7, 7 and 10 years from the tire the valves o valve parts were shipped to the sites.
At the time of failure of ciaphragr:s of the last twa of these three plants there were eight other plants that had been in operation longer with no failures in 1252 valves.
(At another plant there were tw failures not related to aging / hardening of the elastomer raterial.
The first was at four years after valve shipping dates; the second at seven years; these are considered isolated failures not related to the subject of this letter.)
The E/78 supplement to the Service Inforration-tet$r took into xcount, for the first tire, the failure of the Buna-N disc in the solenoid valve core assembly (plunger).
Prior to this time only the dynamic (i.e.,
flexing) parts of the valves were considered to have a limited life.
The disc in the plunger is almost completely surrounded and is nechani-cally captured by the metal plunger body.
It is a passive eierent which flexes only minically when the plunger strikes the valve seat.
The
.first tir.e a failure of the Buna-N disc in the solenoid plunger was observed at a plant there were 14 other plants that had been in opera-tion longer with no similar failures in 2574 valves.
The actual tire to failure from the year the valves were built was ten years.
Fioure 1 surr.arizes the experience to date with failures of Buna-N components in scran pilot valves.
It is clear that the erobability of
' aging-type failures beginning to occur before seven years from the packaging date is low enough to be acceptable; therefore, a cor.bination of shelf and in-service life of seven years from packaging date is co..;erva tive.
Very truly yours, l
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f-Nl ME.LtlQ..l b f A*L O A.
- 11. A. Costandi Product Service Engineer EW?. Product Service M/C C31 - Ext, 5-1515-
rigure t scram Pilot Valves 30
' no accianula ted railures in operatino plants 25 acetimul ated failures in operating plartts 20 15 l
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{-]~~t ADDRESSEES - LETTER DATED A
' 3 73 M. L. Picklesimer, Chairman, NRC/RSR F. D. Coffman, Jr., NRC/ DOR G. P. Marino, NRC/RSR R. O. Meyer, NRC/ DSS J. A. Norberg, NRC/0SD L. S. Rubenstein, NRC/NRR w
____ :--., u r- ;
P. O. Strom NRC/ID R. Fra dCRS R. N. Oehlberg, EPRI g
J. T. A. Roberts, EPRI R. M. Klingensmith, BCL C. R. Hann, BNWL M. Fischer, GfK J. S. Goedkoop, ECN-Petten C. Crouthamel, Exxon A. L. Lowe, B&W D. L. Burman, W E. D. Hindle, UKAEA S. Kawasaki, JAERI E. F. Jageler, CE R. P. Tucker, GE, Vallecitos R. Van Houten, NRC/RSR H. Chung, ANL R. A. Copeland, B&W F. E. Paniski, PNL A. M. Garde, ANL T. F. Kassner, ANL D. A. Hoatson, NRC/RSR L. M. Lowry, BCL G. P. Smith, BCL A. J. Markworth, BCL D. Burman, W D. Hagrman, EG&G G. Engelman, EG&G J. Crowley, ORNL D. O. Hobson, ORNL R. H. Chapman, ORNL T. Healey, CEGB/BNL/UK C. Hartley, University of Florida D. Powers, NRC/NRR S. Dagbjartsson, KfK/INEL
.