ML20080M996
| ML20080M996 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 02/13/1984 |
| From: | Tucker H DUKE POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| SD-413-84-01, SD-413-84-1, NUDOCS 8402220051 | |
| Download: ML20080M996 (3) | |
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Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303 Re: Catawba Nuclear Station Unit 1 Docket No. 50-413
Dear Mr. O'Reilly:
Pursuant to 10 CFR 50.55(e), please fir.d attached Significant Deficiency Report SD 413/84-01.
Very truly yours, c
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Hal B. Tucker LTP/php Attachment cc: Director INP0 Records Center Office of Inspection and Enforcement Suite 1500 t
U. S. Nuclear Regulatory Commission 1100 Circle 75 Parkway Washington, D. C. 20555 Atlanta, Georgia 30339 NRC Resident Inspector Mr. Robert Guild, Esq.
Catawba Nuclear Station Attorney-at-Law P. 0. Box 12097 Palmetto Alliance Charleston, South Caroline 29412 21351 Devine Street Columbia, Souu; Carolina 29205 2
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CATAWBA NUCLEAR STATION REPORT NUMBER: SD 413/84-01 REPORT DATE: February 13, 1984 FACILITY: Catawba Nuclear Station - Unit #1 IDENTIFICATION OF DEFICIENCY:
During the cool-down stage of the hot functional test, Nuclear Production Department detected an incretse in the coolant makeup requirements. A search was made, and a leaking socket weld was found in the Residual Heat Removal System (ND) in the Auxiliary Building. This was identified on 01-03-84.
INITIAL REPORT:
On January 13, 1984, G. Nejfelt, NRC Region II, Atlanta, Georgia, was notified of the subject deficiency by W. O. Henry, L. M. Coggins, J. K. Berry, and R. L. Williams of Duke Power Company, Charlotte, North Carolina 28242.
DESCRIPTION OF DEFICIENCY:
Our investigation found that a 2" socket weld (IND66-35) had developed a crack in the weld metal extending approximately 300 around the circumference of the weld. This weld is a socket weld joining 2" pipe to a socket weld half coupling.
The 2" line provides water to letdown heat exchanger for cleanup during refueling.
While investigating this problem in the "A" Train, a similar problem was found in the "B" Train.
In the latter case, another 2" socket (IND66-6) had developed a crack. This weld joined 2" pipe to a socket weld valve. This crack extended approximately 70 around the circumference of the pipe and was at the juncture of the weld metal and pipe base material.
The two socket welds have been removed and a metallurigical evaluation performed.
This consisted of sectioning, polishing, and etching the cross section of the weld i
for optical microscopy. We also separated the cracked sections and examined the fracture surface using a scanning electron microscope.
l Each of the two lines in question contain a motor operated valve.
There are spring supports on the motor operators to support the weight of the valves; and on the "A" Train motor operator, there is a restraint to control seismic vibration.
The supports on the valves had been disconnected for valve maintenance. Stress Analysis reviewed the systems with and without the supports.
The conclusions of our evaluations to date are as follows:
- 1. The system is adequately supported for all normal design loads.
- 2. The socket welds met code requirements.
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Catawba Nuclear Station - Unit #1 Report Number :
SD 413/84-01 Report Date :
January 13, 1984
- 3. The possible cause of the weld failures was low cycle fatigue _ induced by vibration within the system. This condition may have been aggrevated by the absence of the valve supports mentioned above.
ANALYSIS OF SAFETY IMPLICATIONS:
Had the leaks occured during plant operation, any potential contamination would have been contained in the Auxiliary Building.
However, assuming similar leaks in both trains, the intended safety function of the Residual Heat Removal System could possibly have been adversely affected.
CORRECTIVE ACTION:
We are developing a test procedure to operate the systems at various flows and valve alignments to identify, ny vibration problems. This potential problem will be evaluated for Catawbe - tr.it #2 and other Duke Power Company Nuclear Units, and any safety significant proble:.:s will be reported. We anticipate completion of this evaluation and forwarding a supplementary report on our findings by August 13, 1984 t
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