ML17219A298

Forwards Confirmatory Analyses Required Per Amend 16 to License NPF-16 Re Low Temp Overpressure Protection

ML17219A298
Person / Time
Site:	Saint Lucie
Issue date:	01/09/1987
From:	Woody C FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF ADMINISTRATION (ADM)
References
L-87-4, NUDOCS 8701130163
Download: ML17219A298 (16)

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• CCESSIQN NBR:

FAC IL:50-389

• UTH. NANE WOODY'. O.

REC IP. NAI'1E REQU1 ORY INFORNATION DISTRIBUT 9 SYBTEN (RIDS) 8701130163 DOC. DATE: 87/Oi/OV NOTARIZED:

NO St.

Lucie Planti Unit 2i Flol ida Power 5 Light Co.

AUTHOR AFFILI*TIQN Flol ida Potoer Zc Light Co.

RECIPIENT AFFILIATION Record Sel vices Branch (Document Conti ol Desk )

DOCKET ¹ 05000389

SUBJECT:

Forwards confirmatory analysis per 861016 Amend 16 to License NPF-16 l e low temp overpressul'e protection.

Confirmatory analgsisi "Possible Low Temp Overpl essul'e Pl otection SMs *lignments...

included in 861016 ltr.

DISTRIBUTION CODE:

A001D COPIES RECEIVED: LTR ENCL SIZE:

TITLE:

QR Submittal:

General Distribution NOTES:

RECIPIENT ID CODE/NANE PWR-8 EB pWR-8 FQB pWR-8 PDS PD 01 pWR-8 PEICBB INTERNAL: ADN/LFt'tB NRR/DHFT/TSCB 04 COP IEB LTTR ENCL 1

1 5

5 1

1 0

1 1

RECIPIENT ID CODE/NAi'iE PWR-8 PEICBB PWR-8 PDS LA TOURIQNYi E PWR-8 RBB ELD/HDS2 NRR/ORAB COP IEB LTTR ENCL 2

1 0

1 1

1 0

0 EXTERNAL: ECM BRUBKEo S NRC PDR 02 1

1 1

1 LPDR NSIC 03 05 TOTAL NUNBER OF COPIES REQUIRED:

LTTR 22 ENCL 18

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III

P. O. BOX 14000, JUNO BE'ACH, FL 33408.0420 gyAllg~g r

JANuAnY 09 1987 L-87-4 U. S. Nuclear Regulatory Commission Document Control Desk Washington, D. C. 20555 Gentlemen:

Re:

St. Lucie Unit 2 Docket No. 50-389 Confirmatory Analyses for Low Tem erature Over ressure Protection By letter dated October l6, l986 (E. G. Tourigny to C. O. Woody) the NRC issued Amendment No. I6 to Facility Operating License No. NPF-l6 for St. Lucie Unit 2.

This amendment consisted of changes requested by Florida Power & Light Company (FPL) to the reactor coolant system pressure/temperature limit figures.

The amendment also added the shutdown cooling system (SDCS) relief valves as Low Temperature Overpressure Protection (LTOP) devices.

In the Safety Evaluation issued with Amendment No. I6, the staff required FPL to submit confirmatory analyses by January l5, l987.

The confirmatory analyses, entitled "Possible LTOP System Alignments and the Required Supporting Analyses" were included as an attachment to the staff's October l6, l986 letter.

Attached to this letter are the above required confirmatory analyses.

Please contact us if you have any question about these analyses.

Very truly yours, C.. Woo Group V President Nucle nergy COW/EJ W/gp Attachment cc:

Dr. J. Nelson Grace, Region II, USNRC Mr. Alan Schubert, Florida Dept. of Health and Rehabilitative Services Harold F. Reis, Esquire i

8701130163 870109 PDR ADOCK 05000389 I

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ATTACHMENT CONFIRMATORY ANALYSES REQUIRED PER ST. LUCIE UNIT 2 AMENDMENT No. I6 TO FACILITY OPERATING LICENSE NPF-l6 Res onse to I.a.

A mass addition transient due to simultaneous operation of two High Pressure Safety Injection (HPSI) and three charging pumps was considered as one of the two most limiting pressure transients which provided a basis for the original St. Lucie Unit 2 Low Temperature Overpressure Protection (LTOP) system.

(See Reference (I), Subsection 5.2.6.2.I).

The original LTOP system was also based on the Pressure/

Temperature (P/T) limits for 0 to 2 years and included two Power Operated Relief Valves (PORVs) with the LTOP setp'oints of 460 psia and 490 psia which were designated for transient mitigation over the entire LTOP temperature range.

To preclude violation of the P/T limits for 5 Effective Full Power Years (EFPY),

IO EFPY, etc., in the case of a pressure transient at the lower Reactor Coolant System (RCS) temperatures, a lower relief valve setpoint was required.

It was determined that reducing the setpoint would not, by itself, preclude violation of new P/T limits if the limiting pressure transients previously assumed were also used as a basis for a new LTOP analysis.

As a result, less severe overpressurization events were assumed for the new St.

Lucie Unit 2 LTOP system.

(See Reference (2), Response to Question I). These assumptions, although less conservative than those used previously, meet the requirements for LTOP systems, specified in Reference (3), and the Limiting Conditions for Operation (LCOs) of Reference (4), paragraphs 3.I.2.3, 3.I.2.4, 3.5.2, and 3.5.3.

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In the most recent LTOP evaluation, no HPSI pumps were assumed to be operable at Tc 200oF.

However, a mass addition transient due to simultaneous operation of one HPSI and three charging pumps at these temperatures was analyzed.

The peak RCS pressure in this transient, if mitigated by one Shutdown Cooling System (SDCS) relief valve, was calculated to be 345 psia.

An analysis was performed to determine if one HPSI pump can be operable to Tc l85 F if the RCS is depressurized with a vent of greater than or equal to 3.58 square inches.

The analysis confirmed that one HPSI pump can be operable under the above conditions.

As a result Technical Specifications 3.I.2.I and 3.I.2.3 requiring HPSI pump operation were satisfied.

An additional evaluation revealed a

marginal difference between the peak pressure of 345 psia discussed above and the controlling pressure of 343 psia which was used to identify heatup and cooldown rates.

(This controlling pressure was assumed to equal the rounded off peak pressure in the Reactor Coolant Pump (RCP) start transient with one SDCS relief valve.)

Using Pcont = 345 psia instead of Pcont 343 psia does not significantly change the identified heatup and cooldown rates.

Consequently, it was concluded that, based on LTOP considerations, one HPSI, pump can be aligned to the RCS during the entire LTOP mode including the RCS temperatures below I85 F.

Res onse to I.c.

Following are the sequences of events during the most limiting pressure transients which were used as a basis for the St. Lucie Unit 2 LTOP analysis.

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I. RCP Start in Water-Solid RCS With Secondar

-to-Primar T = 40 F Time (sec)

IA. With a PORV Event Analysis Setpoint

~VI 0.0 Operator starts a RCP.

RCS pressure begins to rise from the initial value 300 6.4 6.5 PORV opens at the specified setpoint RCS pressure reaches a peak (at the PORV inlet) and starts decreasing 470 473.3 7.l PORV closes at the reseat pressure and RCS pressure begins to rise 462 6.4 - 600 PORV cycles open and closed.

Peak pressures at the PORV inlet IB. With a SDCS Relief Valve (SDCSRV) 47 I.O to 474.5 Time (sec)

Event Analysis Setpoint

~Vl 0.0 Operator starts a RCP.

RCS pressure begins to rise from the initial value 300 3.0

3. I 3.7 SDCSRV starts opening at 3% accumulation RCS pressure reaches a peak (at the SDCSRV inlet) and starts decreasing RCS pressure reaches a minimum, and starts increasing 360 362. I 359.8 9.0 RCS pressure reaches a maximum (at the SDCSRV inlet) and starts decreasing slowly 9.0-600 RCS pressure continues to decrease with the SDCSRV partially open, or until the valve closes at I 0% blowdown 362. I 3 I 6.5 The transient was not analyzed up to t = 600 sec.

However, in either case, the peak pressure of 362.I psia will not be exceeded, because the intensity of the transient diminishes with time.

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11. Mass Addition Due to One HPSI and Three Char in Pum 0 eration in Water-Solid RCS with a PORV Time (sec)

Event Analysis Setpoint

~VI 0.0 Inadvertent safety injection actuation.

RCS pressure begins to rise from the initial value 300 3 3%

PORV opens at the specified setpoint and RCS pressure starts decreasing 470 4.0" PORV closes at the reseat pressure and RCS pressure begins to rise 462 3.3 600 PORV cycles open and closed.

Peak pressures at the PORV inlet 470++

Estimated

++ Based on comparison between the setpoint and the equilibrium pressure of 375 psia which was calculated for this transient.

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Res onse to I.d Three overpressurization events were chosen and

analyzed, as indicated in Reference (2), Response I. These are:

- RCP Start

- Two charging pump operation

- Inadvertent actuation of a HPSI pump, with simultaneous operation of three charging pumps.

These events were assumed to be mitigated by either one PORV, with a setpoint of 470 psia, or one SDCS relief valve, with a setpoint of 350 psia.

The pressure transient analyses result in the peak (maximum) RCS pressures in each transient.

These pressures are provided below:

w/PORV w/SDCS Relief

~VI (I)

RCP Start (2)

Two Charging Pumps (3)

I HPSls and 3 Charging Pumps 535 473 492 342.7 34 I.O 345.0 The identified controlling pressures (i.e. the most limiting pressures) were as follows:

Pcont 535 psia, when LTOP is provided by the PORVs.

Pcont 343 psia, when LTOP is provided by the SDCS relief valves.

It should be noted that a controlling pressure generally identifies an RCS pressure limit which will not be exceeded during any overpressurization event that could occur in the corresponding temperature region while being mitigated by an applicable relief valve.

When applied to IO CFR 50 Appendix G P/T limit curves, a controlling pressure also provides a

lower bound pressure limit for these curves.

In other words, a controlling pressure is generally more limiting than the P/T limits above it. Therefore, no P/T limits above the controlling pressure will be exceeded during normal operation or an overpressurization event.

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P/T limits below the controlling pressure are considered theoretical since restrictions on heatup and cooldown rates (which are a

part of LTOP requirements) prevent operation based on these limits.

REFERENCES I) St. Lucie Unit 2 Final Safety Analysis Report

2) FPL Letter L-86-353 dated September 4,

l 986

3) NRC Branch Technical Position RSB 5-2, Overpressurization Protection of Pressurized Water Reactors While Operating at Low Temperatures

4) St. Lucie Unit 2 Technical Specifications EJ W3/004/7

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