ML20211K843
| ML20211K843 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 06/12/1986 |
| From: | Watson R CAROLINA POWER & LIGHT CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| CON-NRC-456, REF-PT21-86, REF-PT21-86-252-000 226, NCR-86-0091, NCR-86-91, PT21-86-252, PT21-86-252-000, NUDOCS 8606300286 | |
| Download: ML20211K843 (4) | |
Text
_ _ - _ _ _ _ _ _ _ _. _ _
trV00 CD&L Carolina Power & Light Company c.,
HARRIS NUCLEAR PROJECT 5
22 P. O. Box 165 New Hill, North Carolina 27562 cl>
JUN 12 M6
]
File Number: SHF/10-13510E NRC-456 Letter Number: HO-860308 (0)
CD Dr. J. Nelson Grace United States Nuclear Regulatory Commission Region II 101 Marietta Street, Northwest (Suite 2900)
Atlanta, Georgia 30323 CAROLINA POWER & LIGHT COMPANY SHEARON HARRIS NUCLEAR POWER PLANT 1986 - 900,000 KW - UNIT 1 480V SWITCHCEAR BREAKERS, ITEM 226
Dear Dr. Grace:
Attached is a final report on the subject item, which was deemed reportable per the provisions of 10CFR50.55(e) and 10CFR, Part 21 on May 15, 1986. With this report, Carolina Power and Light Company considers this matter closed.
If you have any questions regarding this matter, please do not hesitate to contact me.
Yours very truly, R. A. Watson Vice President Harris Nuclear Project MW:cwj cc: Messrs. C. Maxwell (NRC-SHNPP)
J. M. Taylor (NRC) e? Wat WA?*e*
S MEM/HO-860308 (0)/Page 1/0S1 7g j
. ll l
CAROLINA POWER & LIGHT COMPANY SHEARON IIARRIS NUCLEAR POWER PLANT UNIT 1 FINAL REPORT 480 VOLT BREAKER FAILURE NCR 86-0091 ITEM 226 FAY 29, 1986 i
REPORTABLE UNDER 10CFR 50.55(e) AND 10CFR PART 21 IBMD-WKK010-0S4
k
SUBJECT:
Shearon Harris Nuclear Power Plant Unit Number 1 10CFR50.55(e) and 10CFR Part 21 reportable deficiency. Breaker failure on 480 Volt Switchgear.
ITEM:
480 Volt Circuit Breaker Trip Coil SUPPLIED BY:
Brown Boveri Corporation, Columbia, South Carolf.na NATURE OF DEFICIENCY:
During Hot Functional Testing of the Shearon Harris Plant, a Brown Boveri LK-16 Breaker (Serial Number 52994D-39-01041R) with 800 amp trip coil lodged internally and could not be operated electrically i
or manually. The breaker was energized at the time it failed. This is a safety related breaker which had been used to control power feeding the pressurizer heaters which were being cycled on and off to control pressure in support of hot functional testing. A failure of a non-safety 480 volt LK-16 breaker (Serial Number 52522 A-31-01020R) with an 800 amp trip coil occurred in the same general time frame. This failure was identical in nature to the safety breaker failure.
DATE PROBLEM IDENTIFIED:
Shearon Harris personnul identified this problem via NCR 86-0091 on February 8, 1986.
DATE PROBLEM REPORTED:
On February 26, 1986, CP&L (Mr. N. J. Chiangi) notified the NRC (Mr.
P. Fredrickson of a potentially reportable item under the provirions of 10 CFR 50.55(e) and 10 CFR, Part 21.
On May 15, 1986, CP&L (Mr.
K. V. Hate') notified Mr. D. Verrelli of the NRC, that this item was reportable.
SCOPE OF PROBLEM:
The failure affected two breakers as identified in " Nature of Deficiency" above. Due to the possible ranifications of these failures, it has been treated as a generic problem to the LK-16 breakers.
SAFETY IMPLICATION:
Failure of breakers to trip would result in loss of control of safety equipment fed from 480 volt switchgear, f
l IBMD-WKK010-0S4
REASON DEFICIENCY IS REPORTABLE:
Failure of the breakers to open on command would necessitate tripping of the entire switchgear bus to deenergize a feed should that breaker fail. This condition is unacceptable and results in the potential loss of safety functions.
EVALUATION BY MANUFACTURER (Brown Boveri Inc.)
The failures of the LK-16 type breakers were evaluated to be attributed to the following factors:
1.
Design change in the push rod te bridge blade pivot point which was moved two tenths of an inch resulted in a moment arm larger than the earlier design adding an additional loading of 48 pounds to push the contacts closed and to pull them open.
2.
Improper maintenance could lead to resultant accumulation of friction in the opening spring nechanism, thereby preventing the breakers from opening on command.
CORRECTIVE ACTION:
In view of the above evaluations, the following corrective actions have been recommended by Brown Boveri Inc.
1.
To oftset the force due to changes in pivot point, Brown Bover.L recommends installation of booster springs into existing tripping springs which would restore the opening force to original design level through the addition of 56 pounds of force.
2.
In order to avoid possibility of questionable maintenance procedures, Brown Boveri has issued installation bulletin IB-8604 to provide additionel detailed maintenance for LK-16 breakers.
CP&L has completed the corrective actions for booster spring installation by FCR-E-6031 under the supervision of Brown Boveri technical representatives. Upon revision and approval of procedures PM-E012 and MST-E0002, the maintenance requirements of FCR-E-6031 will be initiated.
IBMD-WKK010-OS4
.