ML18227D269
| ML18227D269 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 04/29/1977 |
| From: | Robert E. Uhrig Florida Power & Light Co |
| To: | Stello V Office of Nuclear Reactor Regulation |
| References | |
| Download: ML18227D269 (10) | |
Text
IVRC FORM 195
,(2 74I UeS, NUCLEAR REGUI'ATORV COMMISSION OOCKET NUMBER lV ISTRIDVTION FQR PA 50 DOCKET MATERIAL FILE NUMBER 0- ZSl Mr. Victor Stello, Jr~
F.ROM:
Florida Power IIt Light Company Miami, Florida Robert ED Uhrig PATE OF OOCUMENT 4/29/77 OATE RECEIVEO 5/5/77 25LETTE R 5ORIGINAI Ocopv DESCRIPTION ONOTORIEEO GKJNCLASSIFIEO PROP INPUT FORM ENCLOSURE NUMBER OF COPIES RECEIVED 3 g / t'&gal g ~
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FLORIDAPOWER & LIGHTCOMPANY April 29, 1977 L-77-133 Office of Nuclear Reactor Regulation Attention:
Victor Stello, Jr., Director Division of Operating Reactors U.
S. Nuclear Regulatory Commission Washington, D. C.
20555
Dear Nr. Stello:
A Re:
Turkey Point. Unit 4 Docket No. 50-251 Steam Generator Ins ection Results C
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On April 25, 1977, Turkey Point Unit 4 was shutdown to investi-gate indications of primary to secondary system leakage through 4C steam generator.
Our inspection showed that. the. following tubes had developed leaks:
Row 2
Column 47 Row 2 Column 61 Row 3 Column 62 Elevation of the leaks was determined by lowering the steam generator water level and noting the level at which the leaks stopped.
Eddy current. measurements were taken of the leaking tubes to the extent possible.
An indication of the extent of denting was obtained by using various size. eddy -current probes.
The results from these inspections are presented in Attachment 1.
We have concluded that the leaks in the three tubes were as a
result of defects in the dented regions located in the proximity, of a tube support plate.
Following the inspection of the leaking steam generator
- tubes, the tubes will be plugged and the secondary side of the steam generator will be hydrostatically tested.
In addition to the leaking tubes, several adjacent tubes will be plugged as a
preventative measure.
The results of the steam generator inspections have been reviewed by the Turkey Point Plant Nuclear Safety Committee and the Florida Power 6 Light Company Nuclear Review Board.
These re-views have resulted in the following conclusions:
PEOPLE... SERVING PEOPLE
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Office,of Nuclear Reactor Regulation Page Two April 29, 1977 1)
The mechanism which initiated the leaks is adequately understood and is as explained in the staff's Safety Evaluation Report on Turkey Point No.
4 Steam Generators dated February ll, 1977.
2)
The leaks were located within hard spot regions and could have been predicted based on our understanding of the initiating mechanism.
3)
The indicated size of the dents in the leaking tubes is not unexpected and is consistent with our understanding of the denting mechanism.
4)
The rate of incidence of leaking tubes does not. indicate a substantial increase in the frequency at. which leaking tubes are encountered.
5)
The potential for the incidence of tube leaks during an additional two week period of operation prior to further inspections of steam generators is acceptably small.
A significant number of leaking tubes is not. expected during the two week period.
The preventative plugging will further reduce the likelihood of additional tube leaks.
6)
In the event that leakage does occur, such leakage would be at a rate similar to that exhibited during past leakage events and can be satisfactorily controlled through use of normal plant procedures.
7)
The incidence of these leaks does not alter the appropriateness of the steam generator inspection program which was described in FPL letters L-77-112 and L-77-117 of April ll, 1977 and April 20, 1977 respectively.
Based on our conversation with Mr. Eisenhut we are committing to pull a tube from a steam generator from Unit 4 during the upcoming refueling outage.
This tube will if possible be a leaking dented tube.
If not possible an alternate tube will be
- pulled, and the choice will be discussed with Mr. Eisenhut.,
or his designated alternate.
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Office of Nuclear Reactor Regulation Page Three April 29, 1977 The Nuclear Regulatory Commission Order of February 8, 1977, requires that NRC approval be obtained prior to resuming reactor operation in the event of primary to secondary leakage attributable to two or more tubes within a twenty-day period.
Florida Power Light Company, in accordance with that order, hereby requests NRC approval to return Turkey Point Unit 4 to operation'.
Very truly yours, Robert E. Uhrig Vice President REU/GDW/cpc Attachment cc:
Mr. Norman C. Moseley, Region II Robert Lowenstein, Esquire
ATTACHMENT 1 INSPECTION RESULTS Location Row Tube,,
Column Elevation of Leak
- 2 47
.61 62 5th Tube Support Plate 4th Tube Support, Plate 4th Tube Support Plate Row Column 47 61 Minimum Size Probe Not Passed
.54 at 2nd TSP
.54 at 2nd TSP
.54 at 3rd TSP Edd Current Results No flaws were indicated in the length of each tube traversed.
- Determined by varying steam generator water level.
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