ML19294A577
| ML19294A577 | |
| Person / Time | |
|---|---|
| Site: | 05000484 |
| Issue date: | 12/19/1978 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Dienhart A NORTHERN STATES POWER CO. |
| References | |
| NUDOCS 7812280064 | |
| Download: ML19294A577 (1) | |
Text
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g*"""&t, UNITED STATES 4
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NUCLEAR REGULATORY COMMISSION f! /.'.;
e REGION 111
, s g 'g* j, j 799 soosevetT soAo sl g G L E N E L LY N, IL LINO tS 6013 7 o
DEC 191978 Docket No. 50-484 Northern States Power Company ATTN:
Mr. A. V. Dienhart Vice President - Tyrone Energy Park 100 North Barstow Street Eau Claire, WI 54701 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,
& g nxA__
JamesG.Kep$br Director
Enclosures:
1.
List of IE Bulletins Issued in 1978 cc w/encls:
Central Files 71 rector, NRR/DPM
78122800(o
4 A
L U.S. NUCLEAR REGULATORY C0!BilSSION OFFICE OF INSPECTION AND ENFORCEMENT REGION III December 19, 1975 IE Bulletin Nc. 75-14 DETERIORAI1ON 07 BLM-5 COMPONENTS IN ASCO SOLENDIDS Description of Circe stances:
Following a reactor scra: at the Mo,ticelle Nuclear Fever Statier er July 27, 1975, one control red was deter:1ned to have a slow scrat insertion tice. Vnile measuring the averaBe control red scra: insertien tires (as required by Technical Specificatiens), the sa:e control red failed to scrat. Subsequent investf ation revea]ed that e Buna-N disc E
in the scra pilot valve solenoid core asse bly had fra:tured. Stall pieces of the Buna-N caterial vedged between the core asse bly and the valve pilot body. This prevented proper covecent cf the cere asse:bly (p2unEer), and thus prevented the valve fro: properly verting contrcl air frc: the scra: valves. A sirdlar event occurred during scrat testing on June 5 1976. On both occasions the control rod failed te scra during cor. trol rod survefilance testing.
In these instances, had a scrar occurred during nor:a1 operation of the reactor, the affected rods would have inserted by acticn cf the backup scra selencid valves.
The reactor was p; aced in cold shutdo-T. on July 25, 1975. All cf the s:ran pilet se:encid valves and scra backup valves were disassethief and inspected.
Six additional fractured Bona-N discs were found, all in scra; pilot seIenedd valves. Northern States Fever Co:pany replaced the plunger Buna-N discs in all 21.2 scrat pilot valves and the 2 backup scra: valves.
In addition to the Monticelle failures, sief2ar events were recently reported fror the Big Rock Point and Pilgrit facilities. At Big Rock Point, two failures were experienced in October while at Pilgrir one fad 3ure was found in July and two in Dece ber. All of these failures were encountered during surveillance testing.
General E]ectric had previously issued Service Infor atien Letters, SIL 325 (March 31, 1975) and SIL 126 Revision 1 (January 30, 1976),
addressing the deterioration through natural aging of Buna-N cc:penents im CRD ser _
a.m y m h n g g m y g,g y, caintenance
,g progra be
.in scra:
pilot valv
~.
. Luna-N discs DUPLICATE DOCUMENT Entire doctunent previously entered into system under:
7f/224CZ30 anO No. of aces:
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