ML18227D409
| ML18227D409 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 03/21/1978 |
| From: | Robert E. Uhrig Florida Power & Light Co |
| To: | Stello V Office of Nuclear Reactor Regulation |
| References | |
| L-78-98 | |
| Download: ML18227D409 (7) | |
Text
REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS>
DISTRIBUTION FOR INCOMING MATERIAL 50-251 DOCDATE: 03/21/78 DATE RCVD: 03/27/78 ORG:
UHRIG R E
FL PWR
- 8. LIGHT REC:
STELLO V NRC DOCTYPE:
LETTER NOTARIZED; NO COPIES RECEIVED
SUBJECT:
LTR 3'NCL 0 FURNISHING
SUMMARY
RE SEQUENCE OF EVENTS ASSOCIATED WITH DISCOVERY OF SUBJECT FACILITY"S LOOSE TUBE PLUG, FOUND ON 03/10/78, ALONG WITH APPLICANT"S REVIEW OF THIS MATTERS AND ACTIONS INTENTED TO BE TAKEN.
PLANT NAME:TURKEY PT 83 REVIEl JER INITIAL:
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DISTRIBUTION:
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780860018 THE END
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<yA>"lips FLORIDA POWER 8( LIGHTCOMPANY March 21, 1978
,L-78-98 Director of Nuclear Reactor Regulation Attention:
Mr. Victor Stello, Director Division of Operating Reactors U.
S. Nuclear Regulatory Commission Washington, D. C.
20555
Dear Mr. Stello:
8 cP EzElyeu ~
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Re:
Turkey Point Unit 4
Docket Number 50-251 Steam Generator Ins ection On March 1, 1978 (L-78-82) Florida Power 6 Light Company submitted the results of the recent steam generator inspection performed for Turkey Point Unit 4.
On March 10, 1978 we reported that subsequent to the submittal of that report we found a loose plug, in the channel head of the 4A steam generator.
On March 14, 1978 we met with you and members of your staff to discuss this event.
After this meeting, we gave members of your staff copies of the tube-sheet.
photographs discussed below.
This letter summarizes the sequence of events associated with our discovery of the loose tube plug, along with our review of the matter, and actions that we intend to take.
A description of the events associated with our finding the plug follows:
On February 14, 1978, Unit 4 was shut down to repair a tube leak and to conduct a steam generator inspec-tion.
The "as-found" tube sheet photographs were taken in steam generator 4A on February 19, 1978.
We completed plugging 167 tubes (334 plugs) in steam generator 4A on March 3, and took the first set of 's-left" photographs We found,.three tube ends which had not been plugged in steam generator 4A as required by our plugging program.
Two were on the hot leg side and one was on the cold leg side.
780860018 9/
PEOPLE... SERVING PEOPLE
4
-.. Mr. Victor Stello L-78-98 March 21.,
1978 On March 4th we plugged the two tube ends in the hot leg which had not been plugged.
Upon entry into the cold leg side we found a tube plug in the bottom of the channel head.
We removed the loose plug, plugged the third tube end, and took a second set of "as-left" photographs.
On March 5, we determined from analysis of the as-left photographs that the tube plug which we found in the 4A steam generator channel head had come from the tube with coordinates Row 1 Column 50.
This tube was originally plugged in November 1976.
The as-found photographs taken on February 19, 1978 showed a plug installed in the subject tube.
On March 5, 1978 the tube (RlC50) was replugged.
A sampling of 32 plugs in the general vicinity of R1C50 were checked to ensure they were not loose.
This was approximately 10%
of the installed tube plugs in that channel head.
None of the plugs checked were loose.
It should also be noted that tube Row 1 Column 50 was not leaking at the time it was plugged in November 1976, nor was it leaking at this time.
The plug which dropped out was examined and found to have never been exploded.
The events described above were reviewed and evaluated.
We concluded that the plug which dropped out did not represent a general condition of the steam generator.
This conclusion was based on our operating experience to date with plugged steam generator
- tubes, as well as the operating experience of other utilities.
The sample of tube plugs checked for tightness provided further assurance that the dropped plug did 'not represent a general condition within the steam generator but was rather a
singular occurrence.
We further concluded that the dropped plug did not constitute a threat to the health and safety of the public and did not involve an unreviewed safety question.
This determination was based on our ability to detect and analyze foreign objects in the reactor vessel, limitations on primary to secondary leakage through steam generator tubes and the loose plug being evaluated to be a singular occurrence.
,On March 9 and 10, 1978 while reviewing the tapes recorded by the metal impact monitoring system (MIMS) of the startup of Unit 4, we determined that a metallic object had moved about in the reactor coolant system for about one minute.'oyer, a four
I it
Mr. Victor Stello L-78-98 Page Three minute interval on March 7, and for about twelve seconds on March 8.
The object apparently had about the same mass as the object heard previously and reported in our letters of July 27 and July 29, 1977.
The object has been dormant since the March 8 movement.
Measurements made of the core barrel movement have shown 'that the core barrel motion is unchanged since the last measurement, indicating that the presence of any objects in the vessel is not restricting the motion of the core barrel.
Our preliminary analysis of the tapes indicates that the object(s) do not, pose a safety hazard.
A report descxibing this event in more detail and the results of our analyses will be for-warded to you by March 23, 1978.
The Plant Nuclear Safety Committee and the Company Nuclear Review Board have reviewed the finding of the loose plug in Steam Generator A, the metallic object in the reactor vessel, and the resultant actions taken.
They agreed that these incidents did not constitute a threat to the health and safety of the public and did not involve an unreviewed safety question.
They also concluded, however, that a thorough review of steam generator tube plugging operations is warranted.
This review will consist of an evaluation of the adequacy of Westinghouse and Florida Power and Light Company procedures and practices associated with steam generator tube plugging.
A report of the conclusions of this evaluation and a summary of any resultant changes which we intend to make will be forwarded to you by May 1S, 1978.
If you should'have
'any questions concerning this matter, please feel free to contact me.
Very t
- yours, ob rt E. Uhrig Vice President.
REU:GDW:sl cc:
James P. O'Reilly, Region II Robert Lowenstein, Esquire