ML12115A109

McGuire Nuclear Station, Units 1 and 2 - Correction Letter for Safety Evaluation for License Amendment Nos. 265 and 245, Regarding Technical Specification Changes to Allow Manual Operation of Containment Spray System

ML12115A109
Person / Time
Site:	Mcguire, McGuire
Issue date:	05/04/2012
From:	Thompson J H Plant Licensing Branch II
To:	Repko R T Duke Energy Carolinas
Thompson J H
References
TAC ME4051, TAC ME4052
Download: ML12115A109 (9)

Text

UNITED NUCLEAR REGULATORY WASHINGTON, D.C. 20555-0001 May 4,2012 Mr. Regis T. Repko Vice President McGuire Nuclear Station Duke Energy Carolinas, LLC 12700 Hagers Ferry Road Huntersville, NC 28078 MCGUIRE NUCLEAR STATION, UNITS 1 AND 2, CORRECTION LETTER FOR SAFETY EVALUATION FOR LICENSE AMENDMENT NOS. 265 AND 245, REGARDING TECHNICAL SPECIFICATION CHANGES TO ALLOW MANUAL OPERATION OF THE CONTAINMENT SPRAY SYSTEM (TAC NOS. ME4051 AND ME4052)

Dear Mr. Repko:

The U.S. Nuclear Regulatory Commission (NRC), by letter dated September 12, 2011 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML11131A133), issued Amendment No. 265 to Renewed Facility Operating License (FOL) NPF-9 and Amendment No. 245 to Renewed FOL NPF-17 for the McGuire Nuclear Station, Units 1 and 2 (McGuire 1 and 2), respectively. The amendments consisted of changes to the TSs in response to your application dated May 28, 2010 (ADAMS Accession No. ML101600256), as supplemented by letters dated November 15,2010 (ADAMS Accession No. ML 103270051), March 23, 2011 (ADAMS Accession No. ML 110840443), and May 2,2011 (ADAMS Accession No. ML 11124A125). The safety evaluation (SE) enclosed with the letter communicating issuance of these amendments contained a number of errors. These errors, and the correct information, are as follows: In the SE, on page 14, in the first paragraph of Section 3.4.1, the second sentence states that "The proposed manual start of the CS is very similar to the original manual start except that the sequence is changed slightly, only one train is started, and the suction will be aligned to the sump .... " Within the CS at McGuire 1 and 2, the CS suction is not aligned to the containment sump. The letter of Duke Energy CarOlinas, LLC (Duke Energy, the licensee) dated May 28,2010, (ADAMS Accession No. ML 101600256), page 48 of Attachment 1, Section 3.3, under the heading "New Sequence," item (b), it states that "Manually align and start containment spray from the containment sump." The text of page 14 of the SE will be changed as follows: In the first paragraph of Section 3.4.1, the second sentence will be revised. The word aligned" will be replaced with the word "aligned. In the SE, on page 28, in the final paragraph of Section 3.5.7, the last sentence states that "Specifically, the total EAB dose increased by 2.77 to 10.92 rem TEDE; the total LPZ dose increased by 0.51 to 2.70 rem TEDE .... " In Duke Energy's letter of May 28,2010, page 40 R. -of Attachment 1, Table 3.2.8-7, shows that the total EAB dose increased by 2.79 rem TEDE to 12.25 rem TEDE. This table also shows that total LPZ dose increased by 0.33 rem to 2.23 rem. The numerical values listed in the current SE on page 28 in the final paragraph of Section 3.5.7, in the last sentence, were included in error by the NRC staff. The text of page 28 of the SE will be changed as follows: In the final paragraph of Section 3.5.7, the last sentence will be replaced by the sentence "Specifically, the total EAB dose increased by 2.79 to 12.25 rem TEDE; the total LPZ dose increased by 0.33 to 2.23 rem TEDE; and ..." In the SE, on page 34, in Table 2, "Time Constants for Containment Spray Removal of Particulate Fission Product (One Train of Spray with Minimum Safeguards Failure)," in the column titled "Time Constant (h(1), Baseline CLB [current licensing basis]," errors have been identified. In Duke Energy's letter of May 28, 2010, page 35 of Attachment 1, Table 3.2.8-4, the particulate spray lambda [or time constant], baseline CLB, value for the time span from 600 seconds to 3,000 seconds is 9.36; and this same quantity for the time span from 3,000 seconds to 3,240 seconds is 7.19;.and this same quantity for the time span from 3,240 seconds to 3,500 seconds is 16.50; and this same quantity for the time span from 7,100 seconds to 8,000 seconds is 1.65. Whereas these values in the NRC staff's SE are 20.00, 9.36, 7.19 and 16.50, respectively. The numerical values listed in the current SE on page 34, Table 2, were included in error by the NRC staff. The text of page 34 of the SE. Table 2. will be changed as follows: In the row starting at 600 seconds and ending at 3,000 seconds, the value for the time constant for the baseline CLB will be changed from "20.00" to "9.36." In the row starting at 3,000 seconds and ending at 3,240 seconds, the value for the time constant for the baseline CLB will be changed from "9.36" to "7.19." In the row starting at 3,240 seconds and ending at 3,500 seconds, the value for the time constant for the baseline CLB will be changed from "7.19" to "16.50." In the row starting at 7,100 seconds and ending at 8,000 seconds, the value for the time constant for the baseline CLB will be changed from "16.50" to "1.65." In the SE, on page 36, in Table 4, "Iodine Partition Fractions for Post-LOCA [Ioss-of-coolant accident] RWST [refueling water storage tank] Release Model for 20 GPM [gallons per minute] ECCS [emergency core cooling system] Backleakage (Proposed Modifications in Place)," in the column titled "Current Licensing Basis, IODEX Release Fraction," an error has been identified in the row for the time-step with a start time of 790 seconds and an end time of 810 seconds. The value of the IODEX Release Fraction for this time-step in Table 4 in the SE is 9.19x1 0-11. In Duke Energy's letter of May 28, 2010, page 32 of Attachment 1, R Repko -Table 3.2.8-2, "RWST Release Model for 20 gpm ECCS Back-Leakage," the value of the IODEX release fraction for the time-step from 790 seconds to 810 seconds is 9.197E-11. The numerical value listed in the current SE on page 36, Table 4, was included in error by the NRC staff. The text of page 36 of the SE, Table 4. will be changed as follows: The IODEX release fraction for the time-step from 790 seconds to 810 seconds will be changed from "9.19x1 O*n" to "9.197x1 O*n." Enclosed are the corrected pages for the NRC staff's SE dated September 12,2011. If you have any questions, please call me at 301-415-1119. Sincerely, Jon Thompson, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-369 and 50-370

Enclosure:

SE correction pages cc w/encl: Distribution via Listserv Corrected pages for Safety associated Amendment 265 Renewed Facility Operating License McGuire Nuclear Station, Unit 1 Amendment 245 Renewed Facility Operating License NPF-17 McGuire Nuclear Station, Unit

-The NRC staff reviewed the licensee's assumptions and analysis with respect to post-accident containment sump pH and concluded that conservative values were used for the key parameters of the calculation. The assumptions are appropriate and consistent with the methods accepted by the NRC staff for the calculation of post-accident containment sump pH. The NRC staff finds the proposed changes acceptable with respect to their impact on LOCA sump pH. 3.4 Human Factors 3.4.1 Description of Operator Action(s) and Assessed Safety Significance The required operator action is to initiate the CS, in lieu of automatic actuation. The proposed manual start of the CS is very similar to the original manual start except that the sequence is changed slightly, only one train is started, and the suction will be aligned to the sump because the RWST will no longer be used as a source for the CS. The cue is the RWST low level alarm that initiates the alignment of RHR and the CS to the sump per procedure steps. This action is considered time-critical by Duke Energy and will be monitored to ensure that time available always exceeds time required. In accordance with the generic risk categories established in Appendix A to NUREG-1764, this task sequence is considered "risk-important" due to the fact that it is required to successfully transition the plant to the sump recirculation phase of a LOCA. Because of its risk importance, the NRC staff performed a "Level One" review, i.e., the most stringent of the graded reviews possible under the guidance of NUREG-1764. 3.4.2 Operating Experience Review The LAR is based on the initiative by the Nuclear Energy Institute and the PWR Owners Group to extend the post-LOCA injection phase and to delay the onset of the containment sump recirculation phase. Duke Energy's participation in that effort brought to bear the operating experience of the nuclear plants involved, including its sister plant, the Catawba Nuclear Station, Units 1 & 2 (Catawba 1 and 2). Industry experience was used to develop operating strategies as well as reasonable frequencies for testing and surveillances of the affected systems. The NRC staff finds Duke Energy's application of operating experience acceptable. 3.4.3 Functional Requirements Analysis and Function Allocation Because this operator action is not a completely new action, a full functional requirements analysis and function allocation was not necessary. Prior experience with manual "restarts" had shown that operators, when allocated this task, had sufficient time and resources available to perform it reliably. If the licensee's engineering analysis had shown that the required tasks could not be done within the time constraints established, the NRC staff would have expected allocation of this function to the operators to be considered infeasible. However, this was not the case and there was no need for either a new functional requirements analysis or further consideration of allocation of function. The NRC staff finds the Duke Energy approach acceptable based on their demonstration of adequate margin to proposed time constraints, their characterization of the action as a time-critical action, and their intent to monitor the feasibility and reliability of the action over plant life.

-system consists of two independent, redundant trains of equipment with each train consisting of a pressurizing filter train fan, filter unit, and associated dampers and duct work. Upon receipt of an ESF signal, both trains are currently credited to start. Consistent with the description in Section 3.1.1.6 of Reference 4, Duke Energy assumed that the CRA VS initiates at the time of the core damage, and begins pressurization and filtration of the control room. Duke Energy also assumes that one train of the CRAVS is immediately secured by the operators; therefore, only one train of CRAVS is credited in the dose analysis. The limiting value for asymmetry in the airflow into the two CRA VS outside air intakes was determined to be 65/35, and the control room atmospheric dispersion factors (X/a) were adjusted to account for the imbalance. Also consistent with the AST analysis approved in Reference 4, the licensee assumed the lower limits for the CRAVS filter train recirculation flow rates. The licensee also calculated doses for both the lower limit and upper limit for the CRA VS intake flow rate. The licensee assumed that the unfiltered inleakage into the control room was 625 cubic feet per minute (cfm) prior to pressurization, and 210 cfm after pressurization for the duration of the event. Other contributors to the post-LOCA control room radiation doses were assessed. In particular, the direct radiation dose to the control room from fission products outside the control room was calculated consistent with the regulatory positions for McGuire 1 and 2's full scope implementation of AST methodology. According to the licensee's analysis, this direct constituent to the radiation dose in the control room was unchanged from McGuire 1 and 2's current AOR and remains 1.26 rem. This value was added to the total effective dose equivalent (TEDE) from post-LOCA transport activity to the CRAVS outside air intakes to yield the total post-LOCA TEDE in the control room. The above noted changes yielded a moderate increase in the post-LOCA TEDE at the exclusion area boundary (EAS). The cumulative impact of these changes on the low population zone (LPZ) dose is small (roughly 0.3 rem TEDE). The baseline dose at the EAS, LPZ and in the control room for the limiting LOCA scenarios are presented in Table 5 of this safety evaluation. Duke Energy then took these baseline values, applied the proposed LAR changes (modeled as the design basis LOCA, with failure of cooling water flow through a heat exchanger of either the RHR system or the CS), and compared the dose results of the proposed LAR changes to that of the baseline analysis. The latter comparison is also presented in the right-hand section of Table 5 of this safety evaluation. Duke Energy's analysis showed that either the RHR system or the CS was verified to be limiting for dose at the offsite locations, and the design basis LOCA, with an initially closed CRA VS outside air intake, was verified to be limiting for the control room dose. Therefore, the NRC staff concludes that for an assumed 2-hour duration, the total dose of the proposed LAR changes increased minimally for the EAS, LPZ, and Control Room. Specifically, the total EAS dose increased by 2.79 to 12.25 rem TEDE; the total LPZ dose increased by 0.33 to 2.23 rem TEDE; and the total Control Room dose increased by 0.61 to 4.86 rem TEDE, all of which are acceptable by NRC staff and remain consistent with the applicable dose acceptance criteria described in RG 1.183. 3.6 Component Analyses Evaluation The NRC staff reviewed Section 3.2.3, "Component Analysis," of the LAR, and requested additional information regarding the summary of results for the CS piping stress analysis, CS piping support re-qualification, and CS modified supports in the reactor building annulus area. Sy letters dated March 23, 2011, and May 2, 2011, the licensee provided the requested summaries, as discussed below, to address the RAI questions.

-Table 2 Time Constants for Containment Spray Removal of Particulate Fission Product (One Train of Spray with Minimum Safeguards Failure) Time Span (sec) Time Constant (hr"') Baseline Proposed Start End CLB Modifications 0 600 0.00 0.00 600 3,000 9.36 0.00 3,000 3,240 7.19 0.00 3,240 3,500 16.50 0.00 3,500 4,000 16.50 0.00 4,000 4,500 16.50 0.00 4,500 4,800 16.50 0.00 4,800 5,000 16.50 9.36 5,000 7,100 16.50 9.36 7,100 8,000 1.65 9.36 8,000 24,600 1.65 0.94 24,600 30,000 1.65 0.94 30,000 40,000 1.65 0.94 40,000 46,000 1.65 0.94 46,000 70,000 1.65 0.94 70,000 80,000 1.65 0.94 80,000 86,400 1.65 0.94 86,400 2,592,000 o(no credit) o(no credit)

-Table 4 Iodine Partition Fractions for Post-LOCA RWST Release Model for 20 GPM ECCS Backleakage (Proposed Modifications in Place) Time-steps Current Licensing Basis Proposed Amendment Start Time (sec) End Time (sec) IODEX Release Fraction Release Rate IODEX Release Rate Release Fraction(cfm) (cfm) 0 790 0.000 0.000 0.000 0.000 790 810 9.197x10*11 2.459x10-1O 0.000 0.000 810 900 2.894x10*09 7.739x1 0.09 0.000 0.000 900 1200 3.443x10*08 9.207x10*08 0.000 0.000 1200 1400 9. 799x1 0.08 2.620x10*07 0.000 0.000 1400 1800 1. 772x1 0.07 4.738x10*07 0.000 0.000 1800 2160 3.486x 10.07 9.321x10*07 0.000 0.000 2160 3600 3.486x10*07 9.321x10*07 1.049x10*06 2.805x10*06 3600 4800 4.228x10*07 1.131x10*06 1.111x10*06 2.970x10*06 4800 6000 4.128x10*07 1.1 04x1 0.06 1.044x10*06 2.791x10*06 6000 7200 3.916x10*07 1.047x10*06 9. 723x1 0.07 2.600x10*06 7200 28,800 3.376x10*07 9.027x10*07 1.099x10*06 2.938x10*06 28,800 36,000 3.284x10*07 8.781 x1 0.07 1.586x10*06 4.240x10*06 36,000 86,400 1.873x10*07 5.008x10*07 1.179x10*06 3.152x10*06 86,400 345,600 3.444x10*07 9 .209x1 0.07 8.273x10*06 2.212x10*05 345,600 2,592,000 6.388x10*06 1. 708x1 0.05 1.230x10*05 3.289x10*05 R. Repko -Table 3.2.8-2, "RWST Release Model for 20 gpm ECCS Back-Leakage," the value of IODEX release fraction for the time-step from 790 seconds to 810 seconds is The numerical value listed in the current SE on page 36, Table 4, was included in error by NRC The text of page 36 of the SE, Table 4, will be changed as follows: The IODEX release fraction for the time-step from 790 seconds to 810 seconds will be changed from "9.19x10-11n to "9. 197x1O-11 ." Enclosed are the corrected pages for the NRC staff's SE dated September 12,2011. If you have any questions, please call me at 301-415-1119. Sincerely, IRA! Jon Thompson, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-369 and SE correction cc w/encl: Distribution via Listserv DISTRIBUTION: PUBLIC LPL2-1 RlF RidsAcrsAcnw_MailCTR Resource RidsNrrDirsltsb Resource RidsNrrDorlLpl2-1 Resource RidsNrrDorlDpr Resource RidsNrrDraAadb Resource RidsOgcRp Resource RfdsNrrLASFigueroa Resource RidsRgn2MailCenter Resource LBenton, NRR RidsNrrPMMcGuire Resource TTate, NRR ADAMS Accession No.Package ML12125A304 Amendment ML11131A133 Correction Letter ML12115A 109 OFFICE NRRlLPL2-1/PM NRRlLPL2-1/LA NRRlMDB/BC NRRlLPL2-1/BC NRRlLPL2-1/PM NAME JThompson SFigueroa TTate (WBlumberg for) NSalgado JThompson DATE 04/25112 04/25/12 05/02/12 05/03/12 05104112 OFFICIAL RECORD COPY