ML12166A404

Email, Request for Additional Information, License Amendment Request to Revise Technical Specification 3.8.1, AC Sources - Operating, Surveillance Requirements Related to Diesel Generator Test Loads, Voltage, and Frequency

ML12166A404
Person / Time
Site:	Wolf Creek
Issue date:	06/14/2012
From:	Beltz T Plant Licensing Branch III
To:	Wideman S Wolf Creek
Beltz T
References
TAC ME7674
Download: ML12166A404 (3)

Text

Lent. Susan From: Beltz, Terry Sent: Thursday, June 14, 20121:40 PM To: 'stwidem@WCNOC.com' Cc: 'wimuile@wcnoc.com'; Hall, Randy; Scales, Kerby; Matharu, Gurcharan; Burkhardt, Janet; Lent, Susan

Subject:

Wolf Creek Generating Station - Request for Additional Information re: License Amendment Request to Change EDG Surveillance Requirements (TAC No. ME7674).

Attachments: Request for Additional Information (ME7674).docx June 14, 2012 Mr. Steve G. Wideman Wolf Creek Generating Station Wolf Creek Nuclear Operating Company

Dear Mr. Wideman:

By letter dated November 30, 2011 (Agencywide Documents Access and Management System Accession No. ML11340A033), the Wolf Creek Nuclear Operating Corporation (WCNOC) submitted a License Amendment Request (LAR) to change the Technical Specifications (TS) for the Wolf Creek Generating Station.

Specifically, the changes would modify the TS Surveillance Requirements (SR) by providing surveillance enhancements to improve operation and testing of the Emergency Diesel Generators and provide a more restrictive voltage and frequency band for operation when not connected in parallel with the offsite sources.

The NRC staff has reviewed the information provided by WCNOC in the LAR and determined that additional information is needed to complete its review. The request for additional information (RAI) is provided as an attachment to this e-mail. The staff is requesting a written response to the RAls no later than July 27, 2012.

Please contact either Randy Hall at (301) 415-4032, or me if you have a concern meeting the proposed schedule for responding to this request and/or if WCNOC would like to have a conference call to discuss the RAls.

Sincerely, Terry A. Beltz, Senior Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission (301) 415-3049 Terry. Beltz@nrc.gov 1

REQUEST FOR ADDITIONAL INFORMATION WOLF CREEK NUCLEAR OPERATING CORPORATION WOLF CREEK GENERATING STATION DOCKET NO. 50-482 LICENSE AMENDMENT REQUEST RELATING TO CHANGES TO EMERGENCY DIESEL GENERATOR SURVEILLANCE REQUIREMENTS TAC NO. ME7674 By letter dated November 30, 2011 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML11340A033), Wolf Creek Nuclear Operating Corporation (WCNOC, the licensee) submitted a License Amendment Request (LAR) to change the Technical Specifications (TS) for the Wolf Creek Generating Station (WCGS). Specifically, the changes would modify the TS Surveillance Requirements (SR) by providing surveillance enhancements to improve operation and testing of the Emergency Diesel Generators (EDG) and provide a more restrictive voltage and frequency band for operation when not connected in parallel with the offsite sources.

The NRC staff has reviewed the LAR and developed the following questions regarding the proposed changes to TS 3.8.1, "AC Sources - Operating," SR related to EDG load, voltage, and frequency testing.

1. The LAR proposed to change the minimum voltage or minimum steady state voltage from 2: 3740 V to 2: 3950 V for SR 3.8.1.2, SR 3.8.1.7, SR 3.8.1.11, SR 3.8.1.12, SR 3.8.1.15, SR 3.8.1.19, and SR 3.8.1.20. The LAR states that the historical data from surveillance tests shows that the minimum operating voltage of the EDG was above 4000 V and raising the minimum EDG voltage more accurately reflects actual system voltage conditions, improves equipment operation, and will provide additional system design margin in the EDG transient calculations. Four degraded voltage relays are set to monitor nominal bus voltage level. The degraded voltage relay setpoint is typically based on the minimum voltage required for equipment operability.

a) Provide excerpts from calculation(s) that establish the limiting voltage for equipment operability.

b) What is the minimum starting voltage for large motors and the voltage drop at the remote safety buses associated with starting large motors such as the Essential Service Water System Pumps?

c) Verify that the degraded voltage relay does not h~ve to be reset during a loss off offsite power event when the EDG is required to supply plant loads.

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2. The LAR proposed to change the minimum steady state voltage and frequency components for SR 3.8.1.2, SR 3.8.1.7, SR 3.8.1.11, SR 3.8.1.12, SR 3.8.1.15, SR 3.8.1.19, and SR 3.8.1.20.

a) Verify that motor operated valve performance (in accident analyses) is not adversely impacted at the lower end of the steady state TS allowable frequency coupled with the frequency and voltage variations allowed in RG 1.9 Rev. 3 during load sequencing.

3. The LAR states that WCGS is in compliance with Regulatory Guidance (RG) 1.9, Revision 3. Final Safety Analysis Report (FSAR), Section 8.1.4.3, states the licensee complies with the guidance provided in RG 1.9, Revision 3, Section 1.4. The LAR states the licensee meets the guidance from RG 1.9, Revision 3, under the section Frequency Considerations, that the frequency should be restored to within 2 percent of nominal in less than 60 percent of each load-sequence interval for step load increase. In amendment 101 (ADAMS Accession No. ML022040294), WCGS was approved for some changes in accordance with RG 1.9, Revision 3, but did not include RG 1.9, Revision 3, Section 1.4.

a) Provide details of the license amendment that approved compliance with RG 1.9, Revision 3, Section 1.4.

b) Provide details of all other sections of RG 1.9, Revision 3, not referenced in amendment 101, that WCGS has adopted.

4. SR 3.8.1.14 proposes to change the range of EDG loading for the 2-hour and 22-hour testing period. The LAR states that "The primary method for determining power requirements for the actual DG motor loads is by using brake horsepower from the pump/fan curves. The brake horsepower will, when appropriate, be obtained from the pump curves at design flow conditions, not at run-out flow conditions."

The intent of this SR is to demonstrate the capability of the EDG to supply safe shutdown loads during the initial conditions of a design basis event when the pumps may be operating under run-out conditions and the EDG has to operate in overload range, and during extended steady state conditions for mitigating the consequences of a design basis accident.

a) Verify that the EDG loading profiles considered for the 'short time' and 'medium time' calculations considered primary and secondary plant system pump operations with varying system pressures due to valve operations, line breaks or temperaturellevel changes. Provide a summary of the calculated loading profile expected during the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of the worst case design basis accident.

b) Verify that the proposed testing associated with the SRs identified in the LAR will envelope the postulated accident profile.

c) The LAR indicates the EDG loading (worst case) was evaluated at the upper end of allowable frequency range. Verify that the lower end of the proposed frequency range does not adversely impact EDG loading due to changes in the pump/motor operating points.

d) Verify that the impact of the proposed change in EDG loading profile has been considered in EDG fuel oil requirements.