ML19294A576
| ML19294A576 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 12/19/1978 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Wachter L NORTHERN STATES POWER CO. |
| References | |
| NUDOCS 7812280062 | |
| Download: ML19294A576 (1) | |
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NUCLEAR REGULATORY COMMISSION f j.gZi - j REGION til gm!
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fuu.L J i d / d Docket No. 50-282 Docket No. 50-306 Northern States Power Company ATTN:
Mr. Leo Wachter Vice President Power Production and System Operation 414 Nicollet Mall Minncapolis, MN 55401 Gentlemen:
The enclosed IE Bulletin No. 78-14 is forwarded to you for infor-mation. No written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, AkA KepNr%
James G.
Director
Enclosures:
1.
List of IE Bulletins Issued in 1978 cc w/encls:
Mr. F. P. Tierney, Jr.,
Plant Manager John W. Fernan, Ph.D.,
Nuclear Engineer, MPCA Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC 78122800(01.
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U.S. NUCLEAR REGULATORY CO'NISSIO:1 0FFICE OF INSPECTION AND ENFORCEMENT REGION III December 19, 1975 IE Eu11etin No. 75-14 DE7ERIORATION 07 BUNA-N COMPONENTS IN ASCO SOLENDIDS Description of Circu= stances:
Tc41oving a reactor scra: at the Monticelle Nuclear Power Statier er July 27, 1975, one control rod was deterrined te have a slov scra:
insertion tice.
k* nile r:easuring the average control red scra: insertier ti:'es (as required by Technical Specifications), the sa e control rod failed to strat.
Subsequent investigatier revealed that a Euna-N disc in the scra: pilet valve solenoid core asse=bly had fractured. Stall picces of the Buna-N sterial vedged between the core asser.bly and the valve pilot body. This prevented proper covecent cf the ccre asse:bly (p3 unger), anc thus prevented the valve fro: preperly venting centrol air fre: the scra: valves. A sirilar event occurred during scra testing on June 5, 1975. On both occasions the control red failed te scra during control rod surveillance testing. In these instances, had a scrar occurred during nor:a1 operation of the reacter, the affected rods would have inserted by action of the backup scrat selenedd valves.
The reactor was placed in cold shutdom on July 25, 1976. All of the scrat pflet selenoid valves and scra: backup valves were disasse bled and inspected.
Siy additional fractured Buna-N discs were found, all in scra pilot sc2enoid valves. Northern States Fever Cc:pany replaced the plunter Buna-N discs in all 21.2 scrar pilot valves and the 2 backup scra: valves.
In addition to the Montice31o failures, sief3ar events were recently reported fror the EiE Rock Point and Pilgric facilities. At Eig Rock Point, two failures were experienced in October while a-Pi3grir one faf3ure was found in July and two in Dece ber. All of these failures were encountered during survefIlance testing.
General E3ectric had previously issued Service Informatier Letters, SIL 326 (March 31, 1975) and SIL 125 Revision 1 (January 32, 1976),
addressing the deterioration through natural aging of Buna-N co:penents im CRD scr
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, meintenance progra be in scra:
pilot.valv
. tuna-N discs DUPLICATE DOCUMENT p
Entire document previously entered into system under:
ANO 71/2240230 No. of ages:
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