NL-12-0819, Response to Request for Additional Information Regarding License Amendment Request for Technical Specification Table 3.3.1-1

Response to Request for Additional Information Regarding License Amendment Request for Technical Specification Table 3.3.1-1

ML12125A026
Person / Time
Site:	Farley
Issue date:	05/03/2012
From:	Ajluni M Southern Co, Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-12-0819
Download: ML12125A026 (6)

Text

Mark J. Ailuni. P.E. Southern Nuclear Nuclear Licensing Director Operating Company. Inc.

40 Inverness Center Parkway Post Office Box 1295 Birmingham. Alabama 35201 Tel 205.992.7673 Fax 205.992.7885 May 3,2012 SOUTHERN'\'

COMPANY Docket Nos.: 50-348 NL-12-0819 50-364 U. S. Nuclear Regulatory Commission ATTI\I : Document Control Desk Washington, D. C. 20555-0001 Joseph M. Farley Nuclear Plant - Units 1 and 2 Response to Request for Additional Information Regarding License Amendment Request for Technical Specification Table 3.3.1-1 Ladies and Gentlemen:

By letter to the U. S. Nuclear Regulatory Commission (NRC) dated September 9, 2011 (Agency Documents Access and Management System (ADAMS) Accession No. ML112521438), Southern Nuclear Operating Company (SNC) submitted a license amendment request (LAR) regarding Joseph M. Farley Nuclear Plant, Units 1 and 2 to add Surveillance Requirement 3.3.1 .14 to Technical Specification Table 3.3.1-1, "Reactor Trip System Instrumentation," Function 3, "Power Range Neutron Flux High Positive Rate." By letter dated April 4,2012 (ADAMS Accession No. ML12088A207), the NRC provided SNC with a Request for Additional Information letter containing three questions regarding the nuclear performance and codes review aspects of the LAR.

The Enclosure to this letter contains SNC's response to these requests .

This letter contains no NRC commitments. If you have any questions, please contact Jack Stringfellow at (205) 992-7037.

U.S. Nuclear Regulatory Commission NL-12-0819 Page 2 Mr. M. J. Ajluni states he is Nuclear Licensing Director of Southern Nuclear Operating Company, is authorized to execute this oath on behalf of Southern Nuclear Operating Company and, to the best of his knowledge and belief, the facts set forth in this letter are true.

before me this .3~J <C~"'-': :. . :. .,.;F-day of-'rv'-'--'l..... _ _, 2012.

.~ - - 0 My commission expires: / /- 2 -( :)

Respectfully submitted, M. J. Ajluni Nuclear Licensing Director MJAlRMJI

Enclosure:

Response to Request for Additional Information cc: Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bost, Executive Vice President & Chief Nuclear Officer Mr. T. A. Lynch, Vice President - Farley Mr. B. L. Ivey, Vice President - Regulatory Affairs Mr. B. J. Adams, Vice President - Fleet Operations RTYPE: CFA04.054 U S. Nuclear Regulatory Commission Mr. V. M. McCree, Regional Administrator Mr. R. E. Martin, NRR Project Manager - Farley Mr. E. L. Crowe, Senior Resident Inspector - Farley Alabama Department of Public Health Dr. D. E. Williamson, State Health Officer

Joseph M. Farley Nuclear Plant - Units 1 and 2 Response to Request for Additional Information Regarding License Amendment Request for Technical Specification Table 3.3.1-1 Enclosure Response to Request for Additional Information

Enclosure to NL-12-0819 Response to Request for Additional Information

RAI-01

The control rod withdrawal at power (RWAP) safety analysis presented in Chapter 15 of the Updated Final Safety Analysis Report (UFSAR) was intended to demonstrate that core protection reactor trips prevent exceeding specified acceptable fuel design limits (SAFDLs). As such, the analytical methods used in the RWAP safety analysis use large conservatisms relative to fuel design limits. One reason for the focus on meeting SAFDLs with the RWAP safety analysis is the RWAP event has traditionally been considered to be non-limiting with respect to reactor coolant system (RCS) pressure limits. Please elaborate on the reasons for the change in the analytical approach of the RWAP safety analysis to now consider RCS overpressure conditions as opposed to the traditional focus on SAFDLs and supply technical justification in support of it.

SNC Response to RAI-01 As discussed in the last paragraph on page E1-2 and in the first paragraph on page E1-3 of the license amendment request (LAR), Westinghouse Nuclear Safety Advisory Letter 09-1 discussed the potential for reactor coolant system (RCS) overpressurization due to a control rod withdrawal during power operation (RWAP). The RWAP is a Condition II event which has always been examined with respect to RCS overpressurization by Westinghouse. Previously, the RCS pressure limits were generically shown to be met. However, this conclusion was based on the assumption that a low initial power level was always conservative for RCS pressure for this event. In late 2008, it was determined that higher initial power levels could potentially yield more limiting results for RCS pressure. Based on this information, an investigation was undertaken, and the RWAP analyses, for all plants for which Westinghouse is responsible, were revised to consider higher initial power levels and the impact on RCS pressure. Credit was taken in the Joseph M. Farley Nuclear Plant (FNP) Units 1 and 2 analyses for the positive flux rate reactor trip function.

RAI-02

On page E1-4 of the LAR the worst case analyzed for the affect of RWAP on the RCS is presented. This case indicates that the rod cluster control assemblies (RCCAs) were released via the high pressurizer pressure signal, but indicates the positive flux rate trip (PFRT) was responsible in other cases. Please provide the initial conditions and time sequence of events for the worst case analyzed (peak RCS pressure) RWAP RCS overpressure analysis in which the PFRT signal was responsible for releasing RCCAs. Please provide this information in a tabular form similar to that of the case presented on page E 1-4 of the LAR and indicate the maximum RCS pressure reached with and without the PFRT credit.

SNC Response to RAI-02 A total of 640 cases were analyzed with power levels ranging from 8% power to 102% power and reactivity insertion rates ranging from 15 pcm/sec to 90 pcm/sec. Of those 640 cases, the limiting case, with respect to the peak RCS pressure, is the case presented on page E1 - 4 of the LAR. Specifically, the initial power level is 75% power, initial ReS pressure is 2200 psia, initial vessel average temperature is 575.65°F, the initial pressurizer water volume is 740.15 fe and the reactivity insertion rate is 27 pcm/sec. This case tripped on the high pressurizer E-1

Enclosure to NL-12-0819 Response to Request for Additional Information pressure reactor trip function, with a safety analysis setpoint of 2440 pSia. The peak RCS pressure reached is 2715.5 psia, which is well below the limit of 2748.5 psia. Each of the other 639 cases had a peak RCS pressure of less than 2715.5 pSia.

In this particular worst case (peak RCS pressure), the PFRT signal was not the initiating trip signal for the RCCAs. However, the high positive flux rate signal was the initiating trip signal in numerous other cases that were run. Had the high positive flux rate reactor trip function not been credited in other cases, the current limiting case (with the high pressuruizer pressure signal trip) would no longer be the limiting case, and the RCS pressure limit would have been exceeded. A combination of the high pressurizer pressure reactor trip function, the high neutron flux reactor trip function and the positive flux rate trip reactor trip function provide overpressurization protection over the range of power levels analyzed.

RAI-03

The RWAP overpressure reanalysis results are presented in the LAR as a justification for crediting the PFRT, which is not currently done, and to ensure the associated response time for the PFRT, currently listed as "N/A" in the FNP UFSAR, is verified on a routine basis through the inclusion of SR [Surveillance Requirement] 3.3.1.14 in TS Table 3.3.1-1. Please provide clarification on the plans of Southern Nuclear Operating Company, Inc. to reflect the change in associated response time for PFRT and the RWAP overpressure reanalysis results in an update of the UFSAR, pursuant to the requirements of Title 10 of the Code of Federal Regulations (10 CFR), Part 50, Section 50.71, "Maintenance of records, making of reports."

SNC Response to RAI-03 The list below details the changes to the FNP FSAR pending approval of the subject LAR:

• The trip correlation in Table 7.2.4 for the reactor trip "Positive neutron flux rate" for Accident 15.2.2 will be designated "P," since it is explicitly credited in the analysis.

• Table 7.2-5, Functional Unit 3: The UNA" will be replaced with U::5 0.65 (a)". (Section 7.2.3.1 defines entries in this table as "The response time limits assumed in the safety analyses ... ")

• Table 15.1-3. Add a new entry as follows:

Trip Function Limiting Trip Point Assumed in Time Delay (s):

Analyses Power range high positive 9% of RTP 0.65 neutron flux rate 2 seconds lag time constant Delete the note at the end of the table which, states, "The positive flux rate trip is not explicitly modeled in the non-LOCA transient analyses."

• In Section 15.2.2.1, add the following to the list of automatic features of the reactor protection system:

"F. Power range neutron flux instrumentation actuates a reactor trip if two of four E-2

Enclosure to NL-12-0819 Response to Request for Additional Information channels exceed a specified positive flux rate. (This trip is credited for the RCS overpressure limit. It is not credited in the reactor core protection analyses.)"

• Add the following paragraph to the end of Section 15.2.2.1:

"Reference 15 documents that a conservative analysis has been performed, assuming the reactor trip points listed in Table 15.1-3 that ensures that the RCS overpressure limit will not be exceeded for an uncontrolled rod withdrawal during power operation."

• Add the Westinghouse Project letter (ALA-09-121, Dated 11/10/2009) as Reference 15 to the Section 15.2 References.

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