RBG-47062, Unit 1, Response to Request for Additional Information on License Amendment Request 2009-05, 24-Month Fuel Cycles

Unit 1, Response to Request for Additional Information on License Amendment Request 2009-05, 24-Month Fuel Cycles

ML102360140
Person / Time
Site:	River Bend
Issue date:	08/17/2010
From:	Roberts J Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RBF1-10-0131, RBG-47062
Download: ML102360140 (13)

Text

Entergy Operations, Inc.

River Bend Station 5485 U. S. Highway 61N St. Francisville, LA 70775 Entergy Tel 225 381 4149 Fax 225 635 5068 jrober3@entergy.com Jerry C. Roberts Director, Nuclear Safety Assurance RBG-47062 August 17, 2010 U. S. Nuclear Regulatory Commission Attn.: Document Control Desk Washington, DC 20555-0001

SUBJECT:

Response to Request for Additional Information on License Amendment Request 2009-05, 24-month Fuel Cycles River Bend Station - Unit 1 Docket No. 50-458 License No. NPF-47

REFERENCES:

1. Entergy letter to NRC, dated August 10, 2009, License Amendment Request 2009-05, 24-month Fuel Cycles (Letter No.

RBG-46932)

2. Entergy letter to NRC, dated June 16, 2010, Modification of License Amendment Request 2009-05 (Letter No. RBG-47043)

2. NRC letter to Entergy (via email), dated August 6, 2010, Request for Additional Information (RAI)

RBF1-10-0131 File Code No.: G9.5

Dear Sir or Madam:

On August 10, 2009, Entergy submitted a request to amend the station's operating license to allow implementation of 24-month fuel cycles (Reference 1). During their review, the NRC staff determined that additional information is needed to complete the processing and approval of Entergy's request. The request for that information was transmitted to Entergy per Reference 3.

Attachments 1 and 2 to this letter contain the requested information. Attachment 3 contains the marked up page from River Bend Station Technical Specifications that supports the response to question no. 2 on the RAI. Note that the response in Attachment 2 partially supersedes the information contained in Reference 2, in that Entergy is proposing to extend Surveillance Requirement 3.3.8.1.4, Logic System Functional Test, from 18 to 24 months, as originally requested in Reference 1.

-Acic)(

,11UL

RBG-47062 August 17, 2010 Page 2 of 2 This letter contains no commitments. If you have any questions on this matter, please contact David Lorfing, Manager- Licensing, at 225-381-4157.

I declare under penalty of perjury that the foregoing is true and correct. Executed on August 17, 2010.

Sincerely, Director - Nuclear Safety Assurance : Response to RAI Question No. 1 : Response to RAI Question No. 2 : Mark up of proposed change to Technical Specification page 3.3-73 cc: Regional Administrator U. S. Nuclear Regulatory Commission Region IV 612 E. Lamar Blvd., Suite 400 Arlington, TX 76011-4125 NRC Senior Resident Inspector P. 0. Box 1050 St. Francisville, LA 70775 U. S. Nuclear Regulatory Commission Attn.: Mr. Alan B. Wang One White Flint MS 0-8 B1 11555 Rockville Pike Rockville, MD 20852-2738 Mr. Jeffrey P. Myers Louisiana Department of Environmental Quality Office of Environmental Compliance Attn.: OEC-ERSD P. O. Box 4312 Baton Rouge, LA 70821-4312

Attachment 1 RBG-47062 Response to Question No. 1

Request for Additional Information:

(1) With respect to Setpoint calculations, the licensee stated in pagel9 to Attachment 1 of the LAR dated August 10, 2009, "As necessary, RBS setpoint calculations, and affected calibration and functional test procedures, have been revised, or will be revised prior to implementation, to reflect the new 30-month drift values." To ensure compliance with TSTF-493, Revision 4, or RIS 2006-17, provide the necessary calculations and affected calibration and functional test procedures for all instrumentations where the projected drift values are outside the existing design allowances.

Response

The evaluations associated with the River Bend Station License Amendment Request 2009-005, 24-month Fuel Cycles, determined that there were no required changes to any Technical Specification Allowable Value or Technical Requirements Manual Nominal Trip Setpoint. The only required change to the Technical Specifications or Technical Requirements Manual is the calibration frequency, from eighteen months to twenty-four months. There were no projected drift values that were determined to be Outside the existing design allowances.

The original Nominal Trip Setpoint, Allowable Value and Analytical Limit design bases were established from the supplier design requirements. JCalculations were developed approximately 10 to 15 years ago to confirm that the plant conditions (measurement and test equipment, device accuracies, drift, etc,) were conservative relative to the assumptions in the design basis. These original calculations, subsequent revisions (including those made in support of a 24 month fuel cycle), and the methods of calibration continue to confirm that the existing Technical Specification Allowable Values and Technical Requirement Manual Nominal Trip Setpoints are conservative with respect to the original design basis. None of the drift values calculated in support of the 24 month fuel cycle are outside the existing design allowances as established by the safety system supplier.

The tables and charts on the following three pages summarize important values created by or relative to the listed setpoint calculations. These are a-sample of the setpoint calculations evaluated in support of the proposed change to a 24 month fuel cycle at River Bend Station. The other setpoint calculations reviewed and revised, as necessary, for this project were evaluated using the same methodology as those summarized in this document. Table 1 provides values relative to two calculations that required revision as a result of the development of site specific drift values based on surveillance histories.

Table 2 provides values relative to two calculations where the instrument drift allowance in the existing, currently issued, setpoint-calculations bound the drift values calculated based on surveillance histories.

Table 2 provides a comparison of the drift values found in the existing listed calculations with those calculated based on surveillance histories. Note that the existing allowance for drift is larger than the value determined by analysis, demonstrating the reason these calculations do not need to be revised.

Table 1 shows that the setting tolerance band of the calibration procedure for the instrument loops analyzed by the revised calculations is less than the square root of the sum of the squares of loop reference accuracy and measurement and test equipment accuracy. Additionally, as a minimum, the setting tolerance is included in the total loop uncertainty of all the River Bend setpoint calculations reviewed for this project.

Furthermore, the River Bend surveillance procedure as-found limits include the setting tolerance, but not any other allowances for uncertainty. Setting tolerances are normally based on instrument reference accuracies, but are sometimes based on limitations in supplier design documents if they are more restrictive. If a surveillance finds an instrument loop calibration outside the as-found tolerance a condition report is written.

The charts included on the following pages as Figures 1 and 2 provide a graphic representation of how the calculated NTSP2 changed as a result of the incorporation of the surveillance history based drift values in the calculations listed in Table 1. These charts illustrate how the calculated NTSP2 changed, but that it was not necessary to change the NTSP in the Technical Requirements Manual (TRM) or the Allowable Value (AV) in the Technical Specifications. Note that the Technical Specification Allowable Values and TRM Nominal Trip Setpoints were established prior to the creation of these calculations. The calculations were created as part of a margin verification effort to prove that the Technical Specification Allowable Values and TRM Nominal Trip Setpoints are conservative based on NRC accepted setpoint methodology.

The above discussion and the following tables and charts demonstrate that the setpoint calculations and associated surveillance procedures affected by the change to a 24 month fuel cycle at River Bend Station meet the intent of NRC Regulatory Issue Summary 2006-17.

Table I ChannA TR___ .... pM__ a Sam.....Set...-...

..... ....-........... Mn

.......... F' Calculation Tech Spec TRM Current Revision of Calculation Revision of Calculation for 24 Month Fuel Cycle Surveillance SRSS of Number & Allowable Trip Procedure RAL &

Title Value Setpoint Calc. Calc. Loop Drift Margin, Calculated Calc. AV Calc. Loop Drift Margin, Calculated Maximum M&TE (Abbrev.) (AV) (NTSP) AV NTSP2 Allowance TRM Probability NTSP2 Allowance TRM Probability Acceptable (DJ) NTSP to of LER (DJ) NTSP of LER As-Found &

NTSP2 Avoidancet to Avoidancet As-Left NTSP2 & NTSP2 NTSP2 & Loop NTSP NTSP Tolerance B21*008 < 1.88 1.68 _<1.92 1.84 + 0.020 0.16 psi 96.25% & < 1.92 1.83 + 0.029 0.15 psi 97.19% & +/-0.0188 psi +/-0.024 ADS psig psig psig psig psi > 99.90% psig psig psi > 99.90% As-Found psi Drywell +/-0.0180 psi Press High As-Left E51*011 - < 20 psig 10 psig < 24.42 19.32 +/- 0.54 psi 9.32 psi > 99.90% & 5 24.42 19.25 + 0.67 psi 9.25 psi > 99.90% & +/-0.113 psi +/-0.143 RCIC psig psig > 99.90% psig psig > 99.90% As-Found psi Turbine +/-0.110 psi Exhaust As-Left Diaphragm Press High Isolation t These probabilities were obtained from a standard normal distribution table with the values for the standardized normal random variable Z determined in the setpoint calculation or, in the case of the TRM Trip Setpoint (NTSP) and Tech Spec Allowable Value, using uncertainty values determined in the setpoint calculation.

Table 2 Sample of Set Point Calculations where Drift Allowances in Currently Existing Calc Bound Calculated Drift Values Calculation Number & Title (Abbreviated) Loop Drift used in Existing Calculation Loop Drift Calculated for 24 Month Fuel Cycle B21 *002 ATWS Recirc. Pump Trip - Reactor Press.

High

+/- 9.654 psig + 7.869 psig C71*003 Turbine Control Valve Fast Closure RPS +61.6, -72.9 psig Trip

+/- 100.00 psig

AL < 2.00 psig No Change Current Calc A V < 1.92 psig 1.92 psig 24MFC Calc AV TS AVM 1.88 psig No Change Current Calc NTSP - 1.84 psig - < 1.83 psig 24MFC Calc NTSP As Found (+0.0188)

As Left (+ 0.0180)

TRM NTSP 1.68 psig No Change (Current Plant Setpoint) As Left (- 0.0180)J As Found (-0.0188)

Current Revision B21*008 24MFC Revision B21*008 3URE I

AL < 25.00 psig - No Change CurrentCalc AVV- 24.42 psig -5 24.42 psig 24MFC Calc AV TS AV"<20 psig No Change CurrentCalc NTSP _ 19.32 psi -_. 1,9.25 psig 24MFC Calc NTSP As Found (+0.113)

As Left (+0.110)

TRM NTSP 10.00 psig (Current Plant Setpoint) } No Change As Left (-0.110)

As Found (-0.113)

Current Revision E51*011 24MFC Revision E51*011 FIGURE 2

Attachment 2 RBG-47062 Response to Question No. 2

Request for Additional Information:

With respect ot SR 3.3.8.1.3 and SR 3.3.8.1.4, the licensee is proposing to perform SR 3.3.8.1.3, Channel Calibration, at 18 months frequency and SR 3.3.8.1.4, Logic System Functional Test, at 24 month frequency. Provide justification for how and why the SR 3.3.8.1.3 can be performed at 18 months frequency and the SR 3.3.8.1.4 at 24 months frequency.

Response

SR 3.3.8.1.4 encompasses the requirement to perform an LSFT every 18, months for the loss of voltage and degraded voltage instrumentation on the 4.16kV emergency -

switchgear. That test is generally performed at the same time as the instrument calibrations specified by SR 3.3.8.1.3 as a matter of convenience in scheduling and logistics. By Reference 2, those two SRs were removed from the scope of the original amendment request. It is now proposed that the frequency of SR 3.3.8.1.4 be changed from 18 to 24 months. RBS has evaluated the feasibility of separating the performance of calibration from the LSFT as detailed below.

As defined in RBS Technical Specifications, an LSFT shall be a test of all required logic components (i.e., all required relays and contacts, trip units, solid state logic elements, etc.) of a logic circuit, from as close to the sensor as practicable up to, but not including, the actuated device, to verify operability. The LOGIC SYSTEM FUNCTIONAL TEST may be performed by means of any series of sequential, overlapping, or total system steps so that the entire logic system is tested.

A channel calibration shall be the adjustment, as necessary, of the channel output such that it responds within the necessary range and accuracy to known values of the parameter that the channel monitors.

,In the case of RBS degraded voltage relays, channel calibration verifies the relays susceptible to equipment drift are reset within their required band. The LSFT ensures that the logic circuit, which includes all wiring, breakers and auxiliaries, is performing as designed and that the function of the logic circuit is being satisfied. The LSFT does not perform any calibration of equipment that is necessary to eliminate equipment drift.

Because the LSFT only performs a logic functional check, and does not test whether equipment drift is within allowable limits, and because the history of the affected LSFTs demonstrate a reasonable level of reliability (see Attachment 5 of LAR 2009-05), it is allowable to extend the frequency of the associated surveillances.

Performance of the calibration involves installation of jumpers and lifting of electrical leads. Restoration of those devices to their proper configuration is assured by procedural controls, in that concurrent verification of the restoration by a second qualified technician is documented in the procedure.. These controls are adequate to assure that the operability of the affected circuits is restored at the completion of the test.

The LSFT does not verify the restoration of a channel to service at the completion of the

Channel Calibration or Channel Functional Test, since these tests may be performed as an integrated part of the LSFT.

As explained previously, the channel calibration verifies that the degraded voltage relays susceptible to setpoint drift are reset within their required band. The degraded voltage channel calibration can be performed with the plant in operation at the 18-month Frequency. to this letter contains the marked up page TS 3.3-73 indicating the proposed change for the Frequency of SR 3.3.8.1.4 from 18 months to 24 months.

Attachment 3 RBG-47062 Mark up of Technical Specification page TS 3.3-73

LOP Instrumentation 3.3.8.1 SURVEILLANCE REQUIREMENTS KIC~T

1. Refer to Table 3.3.8.1-1 to determine which SRs apply for each LOP Function.

2. When a channel is placed in an inoperable status solely for performance of required Surveillances, entry into associated Conditions and Required Actions may be delayed for up-to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> provided the associated Function maintains DG initiation capability.

SURVEILLANCE FREQUENCY SR 3.3.8.1.1. Perform CHANNEL CHECK. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> SR 3.3.8.1.2 Perform CHANNEL FUNCTIONAL TEST. 31 days SR 3.3.8.1.3 Perform CHANNEL CALIBRATION. 18 months SR 3.3.8.1.4 Perform LOGIC SYSTEM FUNCTIONAL TEST. )*months RIVER BEND 3.3-73 Amendment No.81