ML18228A434
| ML18228A434 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 05/08/1978 |
| From: | Robert E. Uhrig Florida Power & Light Co |
| To: | Stello V Office of Nuclear Reactor Regulation |
| References | |
| Download: ML18228A434 (10) | |
Text
s//> 78 REGULATORY INFORNATION DISTRIBUTION SYSTEN (RIDS)
DISTRIBUTION FOR INCOI"lING MATERIAL 50-250 REC:
STELLO V NRC ORG:
UHRIG R E FL PWR 8c LIGHT DOCDATE: 05/08/78 DATE RCVD: 05/i6/78 DOCTYPE:
LETTER NOTARIZED:
NO COPIES RECEIVED
SUBJECT:
LTR 3 ENCL 3 FORWARDING "TURKEY POINT UNIT 3 EXTENSION OF AUTHORIZED OPERATlNG INTERVAL" JUSTIFIYING CONTINUED OPERATION OF UNIT 3 FOR AN ADDL TWO EQUIVALENT OPERATING NONTHS BEYOND THE CURRENTLY AUTHORIZED SIX EQUIVALENT OPERATING NONTHS.
PLANT NANE: TURKEY PT 03 REVIEWER INITIAL:
XJN DISTRIBUTOR INITIAL:~
DISTRIBUTION OF THIS MATERIAL IS AS FOLLOWS 4444%<<<+++4++4+<+
GENERAL DISTRIBUTION FOR AFTER ISSUANCE OF OPERATING LICENSE.
(DISTRIBUTION CODE AOOi>
FOR ACTION:
INTERNAL:
EXTERNAL:
BR CHIEF CER4+W/7 ENCL REG FILE++W/
ENCL HANAUER4+W/ENCL EISENHUT44 W/ENCL BAER++W/ENCL EEB~~M/ENCL J.
NCGOUGH++W/ENCL LPDRiS NlANI FL+4 W/ENCL TIC~~W/ENCL NSIC4 <W/ENCL ACRS CAT B>4W/i6 ENCL NRC PDR+>W/ENCL OELD44LTR ONLY CHECK+%M/ENCL SHAO4+W/ENCL BUTLER++W/ENCL J COLLINS+4W/ENCL DISTRIBUTION:
LTR 40 ENCL 39 SIZE:
2P+3P THE END CONTRO HR:
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FLORIDA POWER 5 LIGHT COMPANY May 8, 1978 L-78-168 Office of Nuclear Reactor Regulation Attention:
Mr. Victor Stello, Jr., Director Division of Operating Reactors U. S. Nuclear Regulatory Commission Washington, D. C.
20555
Dear Mr. Stello:
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~C EDX Re: Turkey Point Unit No.
3 Docket No. 50-250 Facilit 0 eratin License No.
DPR-31 In accordance with Facility Operating License No.
DPR-31 Subsection 3.E.5, Florida Power s Light, Company (FPL) is required to place Turkey Point Unit No.
3 'n a cold shutdown condition within six (6) equivalent full power-months of operation from February 1,
1978, to perform an inspection of steam generators.
- However, FPL may be exempted from this requirement if (1) an inspection of the steam generators is within this six (6) month period as a result of the requirements of Subsections 3.E.2, 3,
or 4 of the license, or (2) if an acceptable analysis justifies continued operation.
The attachment to this letter, "Turkey Point Unit 3 Extension of Authorized Operating Interval," contains an analysis developed by FPL and its NSSS vendor.
FPL has concluded that the results of the analysis show that the susceptibility for stress corrosion cracking of steam generator tubing is acceptably low, and thus, explicitly justifies continued operation of Turkey Point Unit No.
3 for an additional two (2) equivalent operating months beyond the currently authorized six (6) equivalent operating months.
This analysis is being submitted prior to the forty-five (45) days before the end of the operating interval.
However, if at all possible, we would appreciate a tentative
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Mr. Victor Stel Jr., Director
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U.
S. Nuclear Regulatory Commission Pa e
Two response by June 1, 1978, which will allow us to adjust our outage schedule for our power plants for the remainder of the year.
Very truly yours,.
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Vice President REU:WAK:dt Attachment cc:
Mr. J.
P. O'Reilly, Region XX Robert Lowenstein, Esquire
TURKEY POINT UNIT 3 EXTENSION OF AUTHORIZED OPERATING INTERYAL At the end of the current NRC authorized operating period, Turkey Point Unit 3 will be approximately 6
EFPH beyond closure.
This will be approxima,tely the same situation that Turkey Point Unit 4 was in at the last steam generator inspection when comparing these two units on the basis of the most progressed flow slot closure.
A review of the results for the most affected steam generator (Steam Generator
- 8) for Turkey Point Unit 4 obtained during the last outage indicates that four tubes in the tubelane region restricted a 0.540 inch probe.
This compares quite favorably with the number of 0.540 inch restricted tubes, i.e.
five, predicted in the previous request for an extension of operating time for Turkey Point Unit 4.
A review of the location of these four restr icted tubes with respect to the predicted strain contours at 5
EFPM beyond closure, indicates that the 17.5A tube hoop strain contour more appropriately indicates the extent of progression of 0.540 inch restricted tubes away from the flow slot area.
This has'lso recently been utilized for the Surry units.
Considering the 17.54 tube hoop strain contour for Steam Generator B
of Turkey Point Unit 4 during the previous inspection and prior to preventive plugging during this outage, there were less than 100 unplugged tubes within this contour.
For a similar condition of Turkey Point Unit 3 and considering the current level of plugging in the most affected steam generator (Steam Generator B) for this unit, it is estimated that there will be less than 144 unplugged tubes wi thin the 17.5/ tube hoop strain contour.
Therefore, at the end of 6 EFPM beyond closure for Turkey Point Unit 3, it can be predicted by the ratios below that:
0.540 inch restricted tubes in tubelane TP 4 at 5
EFPH beyond closure Unplugged tubes TP 3 within x
17.5/ strain contour at 5
EFPH x 6 mos.
Unplugged tu es TP 4 wsthln 5 mos.
17.5/ strain contour at 5
EFPM 4
x x =
7 tubes 144 6
100 5
which will restrict a 0.540 inch probe in the tubelane region of Steam Generator B.
In order to determine the tubes within the 17.5% tube hoop strain contour at 6
EFPM beyond closure, the number of tubes within this contour at 12 EFPM beyond closure was estimated.
At 12 EFPM beyond closure, less than 258 unplugged tubes will be contained within this contour.
This estimate again is based on the current plugging level of Steam Generator B.
- Thus,
l HA fl
at 6
EFPM beyond closure,,it is estimated that less than 17 additional tubes would be within this contour, i.e.,
Unplugged tubes in TP 3
Increase in tubes within 17.54 within the 17.55 strain
+
strain contour from 5 EFPN contour at 5
EFPM to 12 EFPN x
1 mo.
7 mos
~
144 + (258-144.)xl/7
= 161 unplugged tubes would be within this contour.
An extension of the current operating period to 8 months would produce the following:
4 x
~~0 x
8/5
=
9 tubes 144 restricted to the 0.540 inch probe and less than 144
+
(258-144) 3/7
=
193 unplugged tubes jn the 17.5% tube hoop strain contour.
Although i;t would not be expected that all nine of the 0.540 inch restricted tubes would develop through wall cracks during a postulated main steam line break (NSLB) accident, those tubes are assumed to leak at a rate associated with a 0.3 inch crack at the NSLB differential pressure.
The use of a conservative crack aspect ratio of 6 for Turkey Point Unit 3 would yield a tight crack of length 0.3 inches when it became through wall.
Tests results indicate that such a crack would not burst below 5000 psid (well above differential pressure occurring during NSLB) and for differential pressures experienced during NSLB would yeild a leakage of less than 0.05 GPH.
Considering the 9 tubes above, it is estimated that this would result in a total increase in leakage of:
9 x
0.05 GPM/leak
=
0.45 GPN
- This, added to the.3 GPN leakage assumed to be present at the start of HSLB (which would increase to 0.7 GPH due to NSLB hp), yields a
total leakage of 1.2 GPH for the best estimate of leakage (at 8 EFPM during a postulated HSLB}.
This leakage rate is very conservatively bounded by the previously submitted NSLB accident analysis.
The extremely conservative margin contained within this analysis is demonstrated by the followi.ng:
Assuming that all 193 unplugged tubes bounded by the 17.5Ã tube hoop strain contour (at 8 EFPH) could develop through wall cracks during a postulated NSLB accident, the maximum leakage resulting from these tubes would be less than 10 GPH.
An analysis was previously submi'tted analyzing primary to secondary leakage during a postulated HSLB for Turkey Point Unit 4 assuming a
leak rate of 10 GPN concurrent with NSLB.
This analysis applies to Turkey Point Unit 3 and bounds both the best
'stimate leakage of 1.2 GPN and the very conservative upper bound leakage.
Thus, the conclusions, previously drawn with regard to the HSLB accident remain valid.
Also, such low leakage rates during NSLB would have a negligible effect on the DNBR transient, on the percent of coolant volume lost by either contraction or leakage, and on the time to terminate the core transient.
LOCA effects previously analyzed still apply since these effects are only dependent on the size and number of through wall cracks existi ng at the time of the accident.
The size and number of cracks are maintained within safe values by the.3 GPH per steam generator operating limit already imposed.
The effect of secondary to primary leakage duri ng LOCA would be negligible relative to primary system thermal hydraulic parameters when compared to the effects of the LOCA on these parameters.
Based upon the results of this analysis, Florida Power 8 Light Company has concluded that Turkey Point Unit 3 can be safety operated an additional two (2) equivalent operating months beyond the currently authorized six (6) equivalent operating months.
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