ML17296A264
| ML17296A264 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 12/19/1978 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Van Brunt E ARKANSAS POWER & LIGHT CO. |
| References | |
| NUDOCS 7812290036 | |
| Download: ML17296A264 (4) | |
Text
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UNITED STATES NUCLEAR REGULATORY COMIVIISSION REGION V I
I SUITE 202, WALNUTCREEd PLAZA 1990 N. CALIFORNIA BOULEVARD WALNUTCREEKe CALIFORNIA 94596 December 19,,1978 Docket Nos.
50-528 50-529 50-530 Arizona Public Service Company P. 0.
Box 21666 Phoenix, Arizona 83036 Attention:
Mr.
E.
E.
Van Brunt, Jr.
Vice President, Construction Projects Gentlemen:
The enclosed Bulletin 78-14 is forwarded to you for information.
No written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, R.
H. Engelken Director
Enclosures:
l.
List of IE Bulletins Issued in 1978 cc w/enclosures:
'..ll. Hartley, APS
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~~/vc. Q 812260 230 A(02
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UNITED STATES NUCLEAR REGULATORY COMMISS IOl'l OFFICE OF INSPECTION AND ENFORCEMENT l/ASHINGTON, D.C.
20555 December 19, 1978 IE Bulletin Ho. 78-14 DETERIORATION OF BUNA-H COMPONENTS IN ASCO SOLENOIDS Description of Circumstances:
Following a reactor scram at the Monticello Nuclear Power Station on July 27,
- 1978, one control rod was determined to have a slow scram insertion time.
While measuring the average control rod scram insertion times (as required by Technical Specifications),
the same control rod failed to scram.
Subsequent investigation revealed that a Buna-N disc in the scram pilot valve solenoid core assembly had fractured.
Small pieces of the Buna-N material wedged between the core assembly and the valve pilot body.
This prevented proper movement of the core assembly (plunger),
and thus prevented the valve from properly venting control air from the scram valves.
A similar event occurred during scram testing on June 5, 1978.
On both occasions the control rod failed to scram during control rod surveillance testing.
In these instances, had a scram occurred during normal operation of the reactor, the affected rods would have inserted by action of the backup scram solenoid valves.
The reactor was placed in cold shutdown on July 28, 1978.
All of the.
scram pilot solenoid valves and scram backup valves were disassembled and inspected.
Six additional fractured Buna-N discs were found, all in scram pilot solenoid valves.
Northern States Power Company replaced the plunger Buna-H discs in all 242 scram pilot valves and the 2 backup scram valves.
In addition to the Monticello failures, similar events were recently reported from the Big Rock Point and Pilgrim facilities.
At Big Rock
- Point, two.failures v(ere experienced in October while at Pilgrim one failure was found in July and two in December.
All of these failures were encountered during surveillance testing.
General Electric had previously issued Service Information Letters, SIL 128 (March 31, 1975) and SIL 128. Revision 1 (January 30, 1976),
addressing the deterioration through natural aging of Buna-N components in CRD scram pilot valves.
These letters recommended that a maintenance program be adopted which replaced certain Buna-N components in scram pilot valves on a regularly scheduled basis.
However, the Buna-H discs 1of 3