ML17219A702
| ML17219A702 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 07/17/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17219A701 | List: |
| References | |
| NUDOCS 8707240099 | |
| Download: ML17219A702 (6) | |
Text
p,S Cy IIh0 Rangy P0 C0O Cy
- ~4 O ~
0 ~
ENCLOSURE UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATING TO CONFIRMATORY ANALYSIS REGARDING TECHNICAL SPECIFICATIONS FOR LOW TEMPERATURE OVERPRESSURE PROTECTION SYSTEM FLORIDA POWER AND LIGHT COMPANY ST.
LUCIE UNIT NO.
2 DOCKET NO. 50-389
1.0 INTRODUCTION
The original design basis for St. Lucie, Unit 2 uses power operated relief valves (PORVs) for overpressure protection during low temperature operating conditions.
The licensee's analyses in the FSAR assume an inadvertent actuatior of a safety injection signal which results in the startup of one high pressure safety injection (HPSI) pump and three charging pumps for a postulated mass addition transient.
The results of the analyses support plant operation in the temperature range within which the low temperature overpressure protection (LTOP) system is required.
In letters dated July 15, September 4, and October.10, 1986, the licensee proposed changes to the pressure and temperature limits (Figures 3.4-2 and 3.4-3) of the technical specification (TS).
The licensee also proposed to modify the LTOP system to use the shutdown cooling system (SDCS) relief valves for LTOP during heatup and cooldown when any RCS cold-leg temperature is less than 142 F and 161', respectively.
The PORVs are used for LTOP during heatup and cooldown when any RCS cold-leg temperature is above 142' and 161',
respectively.
To support the new P/T limits, the new LTOP system and their setpoints, the licensee provided the results of analyses in the above stated submittals.
In these
- analyses, the licensee assumed only two out of three charging pumps added water to the RCS for a postulated mass addition event when the RCS cold-leg temperatures are less than 200'.
This assumption is 8707200099 870717 PDR ADDC>C 0500OSS9 It P
pDR
1 t.
nonconservative and deviates from the original licensing basis documented in FSAR.
In the staff safety evaluation issued with Amendment No.
16 the Facility Operating License No.
NPF-16 for St. Lucie Unit 2, the staff required FPL to submit confirmatory analyses supporting all possible LTOP system alignments.
These confirmatory analyses should use assumptions consistent with the plant original design bases of record, i.e., to assume the startup of one high pressure safety injection (HPSI) pump and three charging pumps for a postulated mass addition transient.
In a letter dated January 9, 1987, the licensee submitted its required confirmatory analyses for the staff review.
- 2. 0 EVALUATION The licensee stated in its submittal dated January 9, 1987, a mass addition transient due to simultaneous operation of one HPSI and three charging pumps at the RCS cold-leg temperature of less than 200' was analyzed.
The peak RCS pressure in this transient, if mitigated by one SDCS relief valve, was calculated to be 345 psia.
There is a marginal difference between'he peak pressure of 345 psia discussed above and the controlling pressure of 343 psia which was used to specify heatup and cooldown rates in accord with the pressure/temperature limits during low temperature operating conditions.
Using a control pressure of 345 psia instead of 343 psia does not significantly change the specified heatup and cooldown rates.
The staff has evaluated the pressure/temperature limits specified in the Figures 3.4-2 and 3.4-3 of the TS and agreed with the licensee's assessment that the slightly higher peak pressure in the RCS would not significantly affect the safety function of the LTOP system.
Section 3.4. 1.4. 1 of the TS requires SDCS in operation when the RCS cold-leg temperatures are less than 200'.
Therefore, the RCS peak pressure could be limited by one of the SDCS relief valves during a postulated mass addition transient.
~
~
4
3.0 CONCLUSION
Based on the above evaluation, the staff concludes that the results of the licensee's confirmatory analysis have resolved the staff's concern identified in Amendment No.
16 to Facility Operating License No. NPF-16'for't.
Lucie Unit 2.
Therefore, the staff finds that the changes made for LTOP system and TS of St. Lucie Unit 2 meet the applicable regulatory guidance and requirements and are acceptable.
Dated: July 17, 1987
~ ~
c
~l
'V i
1"