ML17216A500
| ML17216A500 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 04/17/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17216A499 | List: |
| References | |
| NUDOCS 8604230449 | |
| Download: ML17216A500 (2) | |
Text
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO LARGE BREAK LOCA ECCS ANALYSIS FLORIDA POWER 5 LIGHT COMPANY, ET AL.
ST.
LUCIE PLANT, UNIT NO.
2 DOCKET NO. 50-389 INTRODUCTION Florida Power and Light Company (FP8L) letter L-86-37 from C. 0.
Woody (FP8L) to Frank J. Miraglia (NRC), dated January 31, 1986, provided the results of the St. Lucie Plant, Unit No.
2 large break loss of coolant accident (LOCA) reanalysis.
This reanalysis was performed by Combustion Engineering (CE) in order to correct a potential non-conservatism in the treatment of axial power distribution and peaking factor in the CE large break LOCA evaluation model.
Additional information of a confirmatory nature was obtained in letter L-86-158 dated April 10, 1986.
The reanalysis also accounted for additional steam generator tube plugging of up to 1250 average length tubes per steam generator.
This represents a total tube plugging of approximately 155 compared to about 4% (300 tubes plugged per steam generator) in the previous analysis.
EVALUATION All of the LOCA ECCS performance analyses were made using the NRC approved CE large break LOCA ECCS evaluation model.
Slowdown, refill/reflood hydraulics, and hot rod temperature calculations were performed assuming fuel parameters that bound the current fuel cycle and expected conditions for future cycles of St. Lucie 2.
In response to NRC concerns relating to the selection of-the power distribution used in the analysis, CE performed a sensitivity study that showed that a 1.55 power peak located at an elevation of 65% of the active core height was the most adverse axial shape.
This was, therefore, the limiting axial power shape used to reanalyze the large break LOCA.
The double-ended guillotine break at pump discharge with a discharge coefficient of 1.0
( 1.0 DEG/PD) produced the highest peak clad temperature of 2106'F, a peak local oxidation of 16.125, and the highest core wide oxidation of less than 0.70%, thereby meeting the 10 CFR 50.46 acceptance criteria limits of 2200'F, 175 and lX, respectively.
8604230449 860417 PDR ADOCK 05000389 PDR The analysis accounts for steam generator U-tube plugging of 1250 average length tubes per steam generator.
As of April 1986, 178 tubes have been plugged in the "A" generator and 133 tubes have been plugged in the "B" generator of St. Lucie 2.
In a telephone conversation, the licensee stated that asymmetric steam generator plugging was considered and it was concluded that symmetric tube plugging analysis implicitly covers unequal plugging between generators provided no more than 1250 tubes are plugged in either steam generator.
This information was confirmed in letter L-86-158 dated April 10, 1986.
The analysis also assumed a lower augmentation factor that resulted in reduced heat transfer from the hot rod to its surrounding rods.
The results of the new analysis done in conformance with 10 CFR 50.46 show that St. Lucie 2 may be operated at a core power level of 2700 MWt and a peak linear heat generation rate (PLHGR) of 13.0 kw/ft.
These are equal to the existing limits for St. Lucie 2.
CONCLUSION The large break LOCA ECCS reanalysis presented for St. Lucie 2 supports operation at a core power level of 2700 MWt and a
PLHGR of 13.0 kw/ft.
The analysis assumed steam generator tube plugging of up to 1250 average length tubes per steam generator.
The analysis also properly accounted for a previously indicated potential non-conservatism in the treatment of axial power distribution and power peaking factor.
Based on the above, the staff concludes that the reanalysis demonstrates'hat St. Lucie 2 is in compliance with the criteria contained in 10 CFR 50.46.
Principal Contributors:
L. Kopp D. Sells Date:
April 17, 1986