L-2012-039, Response to NRC Reactor Systems Branch Request for Additional Information Regarding Extended Power Uprate License Amendment Request No. 205 and Non-LOCA Analyses

Response to NRC Reactor Systems Branch Request for Additional Information Regarding Extended Power Uprate License Amendment Request No. 205 and Non-LOCA Analyses

ML12025A081
Person / Time
Site:	Turkey Point
Issue date:	01/23/2012
From:	Kiley M Florida Power & Light Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-2012-039, TAC ME4907, TAC ME4908
Download: ML12025A081 (5)

Text

Florida Power & Light, 9760 S.W. 344 St. Homestead, FL 33035 JAN 2 3 2012 L-2012-039 FPL. 10 CFR 50.90 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555-0001 Re: Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 Response to NRC Reactor Systems Branch Request for Additional Information Regarding Extended Power Uprate License Amendment Request No. 205 and Non-LOCA Analyses

Reference:

(1) M. Kiley (FPL) to U.S. Nuclear Regulatory Colmnission (L-2010-113), "License Amendment Request for Extended Power Uprate (LAR 205)," (TAC Nos. ME4907 and ME4908),

Accession No. ML103560169, October 21, 2010.

By letter L-2010-113 dated October 21, 2010 [Reference 1], Florida Power and Light Company (FPL) requested to amend Renewed Facility Operating Licenses DPR-31 and DPR-41 and revise the Turkey Point Units 3 and 4 (PTN) Technical Specifications (TS). The proposed amendment will increase each unit's licensed core power level from 2300 megawatts thermal (MWt) to 2644 MWt and revise the Renewed Facility Operating Licenses and TS to support operation at this increased core thermal power level. This represents an approximate increase of 15% and is therefore considered an extended power uprate (EPU).

During the Advisory Committee on Reactor Safeguards (ACRS) full committee meeting on PTN's EPU application on January 19, 2012 in Rockville, MD, an ACRS member requested an explanation of an initial condition assumption for the limiting loss of load/turbine trip (LOL/TT) analysis regarding the nominal pressurizer pressure assumed at the onset of the event and the application of instrument uncertainty to this parameter. FPL's response to the NRC's request for additional information is provided in Attachment 1 to this letter.

In accordance with 10 CFR 50.91(b)(l), a copy of this letter is being forwarded to the State Designee of Florida.

This submittal does not alter the significant hazards consideration or environmental assessment previously submitted by FPL letter L-2010-113 [Reference 1].

This submittal contains no new commitments and no revisions to existing commitments.

Should you have any questions regarding this submittal, please contact Mr. Robert J. Tomonto, Licensing Manager, at (305) 246-7327.

A-Gd

Turkey Point Units 3 and 4 L-2012-039 Docket Nos. 50-250 and 50-251 Page 2 of 2 I declare under penalty of perjury that the foregoing is true and correct.

Executed on January -& ,2012.

Very truly yours, Michael Kiley Site Vice President Turkey Point Nuclear Plant Attachment cc: USNRC Regional Administrator, Region II USNRC Project Manager, Turkey Point Nuclear Plant USNRC Resident Inspector, Turkey Point Nuclear Plant Mr. W. A. Passetti, Florida Department of Health

Turkey Point Units 3 and 4 L-2012-039 Docket Nos. 50-250 and 50-251 Attachment 1 Page 1 of3 Turkey Point Units 3 and 4 RESPONSE TO NRC REACTOR SYSTEMS BRANCH REQUEST FOR ADDITIONAL INFORMATION REGARDING EXTENDED POWER UPRATE LICENSE AMENDMENT REQUEST NO. 205 AND NON-LOCA ANALYSES ATTACHMENT 1

Turkey Point Units 3 and 4 L-2012-039 Docket Nos. 50-250 and 50-251 Attachment 1 Page 2 of 3 Response to Request for Additional Information The following information is provided by Florida Power and Light Company (FPL) in response to the U. S. Nuclear Regulatory Commission's (NRC) Request for Additional Information (RAI). This information was requested to support License Amendment Request (LAR) 205, Extended Power Uprate (EPU), for Turkey Point Nuclear Plant (PTN) Units 3 and 4 that was submitted to the NRC by FPL via letter (L-2010-113) dated October 21, 2010 [Reference 1].

During the Advisory Committee on Reactor Safeguards (ACRS) full committee meeting on PTN's EPU application on January 19, 2012 in Rockville, MD, an ACRS member requested an explanation of an initial condition assumption for the limiting loss of load/turbine trip (LOL/TT) analysis regarding the nominal pressurizer pressure assumed at the onset of the event and the application of instrument uncertainty to this parameter. The LOL/TT event for EPU is described in Licensing Report (LR) Section 2.8.5.2.1, "Loss of External Load, Turbine Trip, Loss of Condenser Vacuum, and Steam Pressure Regulator Failure," in Attachment 4 of Reference 1.

FPL's response to the ACRS request is provided below.

Response

The LOL/TT event is analyzed to address both departure from nucleate boiling (DNB) concerns as well as overpressurization concerns. The safety analysis methods employed to address each of these concerns differ slightly to ensure that the most conservative results with respect to each of these acceptance criteria are obtained and reported in the plant's Updated Final Safety Analysis Report (UFSAR). In the case of reactor coolant system (RCS) overpressurization, the standard analysis method requires the modeling of an initial pressurizer pressure that explicitly accounts for a negative pressure uncertainty, i.e., the initial pressurizer pressure is to be set at a value below the nominal operating pressure. By modeling a lower initial pressurizer pressure, the timing of reactor trip on high pressurizer pressure is conservatively delayed. With the reactor trip delayed, the primary-to-secondary power mismatch that results from terminating all secondary-side steam relief with the reactor still operating at full-power conditions would last longer. An extended primary-to-secondary power mismatch time period poses a more serious challenge to the installed pressurizer safety valve capacity, which is the only source of primary-side pressure relief assumed in the typical UFSAR analysis. Thus, delaying reactor trip during the LOL/TT event leads to a more limiting peak RCS pressure.

The LOL/TT analysis performed in support of the Turkey Point EPU models an initial pressurizer pressure of 2197 psia, which accounts for a pressure uncertainty of -53 psi. The analysis results, which were reported in Turkey Point EPU LR Section 2.8.5.2.1 in Attachment 4 of Reference 1, show a maximum RCS pressure of 2746.6 psia, compared to the applicable limit of 2748.5 psia.

To quantify the impact of initiating the same transient from a higher initial pressurizer pressure, a plant-specific sensitivity study was performed. This sensitivity modeled an initial pressurizer pressure of 2303 psia (nominal pressure plus the pressure uncertainty of 53 psi). As expected, the results of this sensitivity show that the maximum RCS pressure reached is less than that reported in the Licensing Report. The table below contains a comparison of several key results from the proposed licensing basis case and the high initial pressurizer pressure sensitivity case.

Turkey Point Units 3 and 4 L-2012-039 Docket Nos. 50-250 and 50-251 Attachment 1 Page 3 of 3 Time Sequence of Events - Loss of Load / Turbine Trip Peak RCS Pressure Case High Initial Licensing Report Case Pressurizer Pressure Event Sensitivity Case Time (seconds) Time (seconds)

Loss of Load / Turbine Trip Initiated 0.0 0.0 High Pressurizer Pressure Reactor Trip 6.3 4.9 Setpoint (2455 psia) Reached Rod Motion Begins 8.3 6.9 Peak RCS Pressure Occurs 8.9 7.5 (2746.6 psia) (2713.8 psia)

Reference

1. M. Kiley (FPL) to U.S. Nuclear Regulatory Commission (L-2010-113), "License Amendment Request for Extended Power Uprate (LAR 205)," (TAC Nos. ME4907 and ME4908),

Accession No. ML103560169, October 21, 2010.