ML20049J360
| ML20049J360 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 02/26/1982 |
| From: | Robert E. Uhrig FLORIDA POWER & LIGHT CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, L-82-70, NUDOCS 8203170534 | |
| Download: ML20049J360 (2) | |
Text
P.O. BOM 5291CD MI AMI, F L 33152 O
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.m km FLORIDA POWER & LIGHT COMPANY February 26, 1982 L-82-70 Mr. James P. O'Reilly, Regional Administrator, Region II U. S. Nuclear Regulatory Commission 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 4
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Dear Mr. O'Reilly:
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Broken Studs on Relay Mechanical
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Florida Power & Light Company, on November 24, 1981, notifie 'the,0ff
- 0 of Inspection and Enforcement :. a potential 10CFR50.55(e) (incident - -
regarding Broken Studs on Relay Mechanical Interlock Arms used in' va'rious safety and non-safety Motor Control Centers. An interim report was submitted on December 23, 1981 (L-81-538). We have evaluated the situation and deem that this incident is non-reportable. This letter consitutes our final report.
FPL start-up personnel, while testing breakers in the 480V motor control centers, found that the mechanical interlock arm on a 42 closing relay (starter) would hang up. Upon closer inspection, it was found that the top mechanical arm guide stud was broken off. With this stud broken off, the mechanical ann could nct return to the open position, thus prohibiting starter operability. A nonconformance report was generated and an extensive investigation was performed.
The broken mechanical arm guide stud problem was found on two Class IE motor control centers, MCC 2A5 and 2B5. These breakers feed valves MV-07-1A, MV-07-1B, 2I-MV-14-11 and 21-MV-14-16. The first two valves (MV-07-1A and MV-07-18) are the isolation valves for the ESF pump suction lines from the refueling water tank. These valves are nonnally open and close on a RAS signal. Failure of the valve to close (due to interlock arm being broken) would not have any consequence.
If these valves failed to close the water seal created by the difference in elevation between the containment sump water level and RWT would prevent air from being drawn into the systam. Valves 21-MV-14-11 and 21-MV-14-16 are the isolation valves on the component cooling water lines for containment cooling units 2B and 2D. These are normally locked open and are not required to be j
closed during nonnal operation or accident conditions. Thus, the failure has no consequence to the safe operation of the plant.
General Electric (GE), the MCC vendor was contacted. GE removed several interlock arms from the motor control centers and subjected them to six 4W.
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Mr. James P. O'Reilly Regional Administrator, Region II U. S. Nuclear Regulatory Commission Page 2 times the rated application operations for this device.
Both forward and reverse operations were performed, with no arm failure. A group of interlock arms from GE's own production line was also included in this test.
X-ray inspection performed by FPL on a random sample also could not detect any defect. These test results indicate that the problem is not generic in nature but could most likely be attributed to some damage in assembly, shipping or installatioh.
Presently, tne FPL start-up group is checking all starters that have these mechanical interlock arms to determine if any others are broken.
Any interlock arm found defective will be replaced according to a site procedure.
We consider this situation to involve a deviation from performance specifi-cation. The defective relays found have no adverse consequence on plant safety. The situation does not require any extensive evaluation, extensive repair or extensive redesign to establish adequacy of the components.
Hence, we deem this situation as non-reportable.
All pertinent documentation regarding this concern will be maintained at the site and will be available for your inspection.
Very truly yours, l
Robert E. Uhrig Vice President Advanced Systems & Technology REU:RAK:cf cc: Harold F. Reis, Esquire i
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