ML18227B802
| ML18227B802 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 01/18/1978 |
| From: | Robert E. Uhrig Florida Power & Light Co |
| To: | Stello V Office of Nuclear Reactor Regulation |
| References | |
| L-78-24 | |
| Download: ML18227B802 (6) | |
Text
REGULATORY INFORNATION DISTRIBUTION SYSTEM
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DISTRIBUTION FOR INCOMING MATERIAL 50-250 REC:
STELLO V NRC ORG:
UHRIG R E FL PWR 5 LIGHT DOCDATE:
01/18/78'ATE RCVD: 01/23/78 DOCTYPE:
LETTER NOTARIZED:
NO COPIES RECEIVED
SUBJECT:
LTR 3 ENC1 0
FURNISHING INFO RE STEAN GENERATOR INSPEC RESULTS AND PLAN TO PREVENTIVELY PLUG STEAN GENERATOR TUBES.
PLANT MANE: TURKEY POINT UNIT 3 REVIEWER INITIAL:
XJM DISTRIBUTOR INITIAL'+4+4++++++++++++
DISTRIBUTION OF THIS MATERIAL IS AS FOLLOWS GENERAL DISTRIBUTION FOR AFTER ISSUANCE OF OPERATING LICENSE.
(DISTRIBUTION CODE A001)
FOR ACTION:
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INTERNAL:
EXTERNAL:
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FLORIDAPGWER S( LIGHTCOMPANY 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:
Re:
Turkey Point Unit 3 Docket No. 50-250 Steam Generator Ins ection Results January l8, l978 L-78-24 8jfI,,';,'),=
QA888@78m A
On December 29, 1977, Florida Power S Light Company submitted the results of the recent Steam Generator Inspection of Turkey Point Unit 3, and requested permission to return the unit to power opera-tion in accordance with the unit,'s operating license.
An inspec-tion of the unit's steam generators will be performed during the next refueling, or sooner, if actual operating experience shows that an inspection is warranted.
Florida Power 6 Light Company, in conjunction with its NSSS vendors and other utilities, has been engaged in an extensive program de-signed to enhance our understanding of the denting phenomenon.
As a result of this program, a plan to preventively plug steam genera-tor tubes has been implemented.
The preventive plugging program which has been implemented on Turkey Point Units 3 and 4 has been judged to be overly conserva-tive with respect to justifying a six-month operating interval.
Empirical evidence (i.e., operating history at Turkey Point Unit 4 and inspection results at, Surry) has confirmed that the current plugging pattern is overly conservative and should provide for safe operation beyond the six effective operating months.
Turkey Point Unit 3 has experienced only one tube leak during the past refueling cycle.
This leak did not require an early shutdown for repair.
This leakage frequency certainly shows that steam generator degrada-tion rate is within acceptable bounds.
We have concluded through our denting studies and actual operating experience that the denting phenomenon does not. result in catastrophic tube failures.
Tube failure due to the denting phenomenon is characterized by a slow increase in primary-to-secondary leakage.
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PEOPLE... SERVING PEOPLE
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Director of Nuclear Reactor Regulation Attention:
Nr. Victor Stello, Director Division of Operating Reactors Page Two This leakage is easily detected allowing the unit to be shut down and the leak repaired without exceeding any operating parameters.
Significant degradation of the steam generators would be indicated by an increase in the frequency of tube leaks.
The existing operat-ing limits ensure that leakage rates remain low enough to assure safe and orderly shutdowns, and the required evaluations during shutdowns would provide current assessment of steam generator in-tegrity, should leaks occur.
Florida Power 6 Light Company has determined that a steam generator inspection should be performed during each refueling outage, and that an inspection should be performed sooner only when warranted by actual operating experience.
Xnspecting steam generators prior to the refueling outage would cost consumers an additional l0-l2 milli'on dollars in replacement energy costs.
This inspection would also result in employee exposure of approximately 20-50 man rem.
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Xn addition, the steam generators would be exposed to an oxygenated environment during the inspection, thus accelerating any corrosion processes which may be occurring.
The Turkey Point Plant Nuclear Safety Committee and the Florida Power 6 Light Company Nuclear Review Board have reviewed the steam generator inspection results and the preventive tube plugging program, and have made the following determinations:
l)
A steam generator inspection should be performed at Turkey Point only at each, refueling unless a more frequent inspection is indicated by actual operating experience.
2)
The steam generator operating limitations of the exist-ing operating license are sufficient to ensure that the health and safety of the public are protected.
The review bodies concluded that the return of Unit 3 to operation in accordance with the operating license will not endanger the health and safety of the public, and will not involve an unreviewed safety question.
Very truly yours, Robert E. Uhrig Vice President REU/GDW/RJA:ltm cc:
Robert Lowenstein, Esq.
J.
P. O'Reilly
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