ML111780675
| ML111780675 | |
| Person / Time | |
|---|---|
| Site: | Kewaunee  |
| Issue date: | 06/27/2011 |
| From: | Price J Dominion Energy Kewaunee |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 10-063C, TAC ME4011 | |
| Download: ML111780675 (9) | |
Text
Dominion Energy Kewaunee, Inc.
5000 Dominion Boulevard, Glen Allen, VA 23060 June 27, 2011 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Dominion Serial No. 10-063C L1C/JG/RO Docket No. 50-305 License No. DPR-43 DOMINION ENERGY KEWAUNEE, INC.
KEWAUNEE POWER STATION RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION:
LICENSE AMENDMENT REQUEST 236, AUTOMATIC OPERATION OF TRANSFORMER LOAD TAP CHANGERS (TAC NO. ME4011)
By application dated June 1, 2010 (reference 1), and as supplemented by letter dated January 18, 2011 (reference 2), Dominion Energy Kewaunee, Inc. (DEK), requested an amendment to Facility Operating License Number DPR-43 for Kewaunee Power Station (KPS).
A clarifying letter was also submitted on March 14, 2011 (reference 3).
The proposed amendment would revise the KPS current licensing basis (CLB) to allow the use of new automatic load tap changers (LTCs) in both manual and automatic mode on new transformers that provide offsite power to KPS.
Subsequently, the Nuclear Regulatory Commission (NRC) staff transmitted a request for additional information (RAI) regarding the proposed amendment (reference 4). The RAI questions and associated DEK responses are provided in Attachment 1 to this letter.
This response has no impact on any other aspect of License Amendment Request 236.
If you have any questions or require additional information, please contact Mr. Jack Gadzala at 920-388-8604.
Sincerely, J.
la rice Vi e P esident - Nuclear Engineering
Serial No. 10-063C LAR 236 RAI Responses Page 2 of 3 COMMONWEALTH OF VIRGINIA
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COUNTY OF HENRICO
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The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by J. Alan Price, who is Vice President - Nuclear Engineering of Dominion Energy Kewaunee, Inc.
He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that Company, and that the statements in the document are true to the best of his knowledge and belief.
Acknowledged before me this Ginger LyRA Rutherford NOTARY PUBLIC Commonwealth of Virginia Reg. # 310847 My Commission Expires 4/30/2015
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Attachment:
- 1. NRC Request for Additional Information Questions and DEK Responses One new commitment is made in this letter (summary follows):
DEK commits to implementing procedural controls to prohibit LTC operation in the automatic mode when the Delta-V monitoring capability is not fully functional unless an acceptable alternative modeling capability is available.
These procedural controls will be in place prior to operating the LTC in automatic mode.
References:
- 1. Letter from L.
N. Hartz (DEK) to Document Control Desk (NRC), "License Amendment Request 236, Automatic Operation of Transformer Load Tap Changers," dated June 1, 2010.
2.
Letter from L. N. Hartz (DEK) to Document Control Desk (NRC), "Supplement and Response to Request for Additional Information:
License Amendment Request 236, Automatic Operation of Transformer Load Tap Changers (TAC NO.
ME4011," dated January 18,2010.
3.
Letter from J. Alan Price (DEK) to Document Control Desk (NRC), "Clarifying Response to Request for Additional Information:
License Amendment Request
- 236, Automatic Operation of Transformer Load Tap Changers (TAC NO.
ME4011," dated March 14, 2011.
4.
E-mail from Karl D. Feintuch (NRC) to Jack Gadzala (DEK), Thomas Breene (DEK), Gurcharan Matharu (NRC), and Roy Matthew (NRC), "ME4011 RAI for KPS License Amendment Request Re:
automatic operation of Load Tap Changers," dated May 23,2011.
cc:
Regional Administrator, Region III U. S. Nuclear Regulatory Commission 2443 Warrenville Road Suite 210 Lisle, IL 60532-4352 Mr. K. D. Feintuch Project Manager U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 08-H4A 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector Kewaunee Power Station Public Service Commission of Wisconsin Electric Division P.O. Box 7854 Madison, WI 53707 Serial NO.1 0-063C LAR 236 RAI Responses Page 3 of 3
Serial No.1 0-063C ATTACHMENT 1 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION:
LICENSE AMENDMENT REQUEST 236 AUTOMATIC OPERATION OF TRANSFORMER LOAD TAP CHANGERS NRC REQUEST FOR ADDITIONAL INFORMATION QUESTIONS AND DEK RESPONSES KEWAUNEE POWER STATION DOMINION ENERGY KEWAUNEE, INC.
Serial NO.1 0-063C Page 1 of 5 NRC REQUEST FOR ADDITIONAL INFORMATION QUESTIONS AND DEK RESPONSES By application dated June 1, 2010 (reference 1), and as supplemented by letter dated January 18, 2011 (reference 2), Dominion Energy Kewaunee, Inc. (DEK), requested an amendment to Facility Operating License Number DPR-43 for Kewaunee Power Station (KPS).
A clarifying letter was also submitted on March 14, 2011 (reference 3).
The proposed amendment would revise the KPS current licensing basis (CLB) to allow the use of new automatic load tap changers (LTCs) in both manual and automatic mode on transformers that provide offsite power to KPS.
Subsequently, the Nuclear Regulatory Commission (NRC) transmitted a request for additional information (RAI) regarding the proposed amendment (reference 4). The RAI questions and associated DEK responses are provided below.
NRC Question 1 Provide an overview of the existing procedures used for communicating postulated grid voltage required for plant shutdown.
Response
The interface coordination agreement between DEK and the grid operator, American Transmission Company (ATC), currently specifies that ATC will notify DEK when certain grid conditions exist.
One of these conditions is low calculated post-trip voltage. ATC obtains data on the loads (MW and MVAR) being carried by the reserve auxiliary transformer (RAT) and the tertiary auxiliary transformer (TAT) at KPS. This data is an input for ATC computer modeling to determine post-trip voltage.
Currently, ATC is required to inform KPS of calculated post-trip voltage on request; or, immediately if the predicted post-trip grid voltage drops below 140 kV and cannot be mitigated within 15 minutes.
If notified by ATC that calculated post-trip voltage is below the minimum acceptable value, DEK would evaluate the offsite power supply circuits for operability.
Procedure OP-KW-NOP-SUB-003, "RST and TST Load Tap Changer Operation,"
provides direction for operating the LTCs, including direction for communicating grid voltage information.
DEK notifies ATC when load tap changers will be operated manually and obtains calculated post-trip voltage from ATC.
The calculated post-trip voltage value is used to determine if offsite power will be operable at the various tap positions on the LTC.
This procedure also directs that operators inform ATC of the requirement to notify DEK if the calculated post-trip voltage is below the minimum acceptable value.
Serial NO.1 0-063C Page 2 of 5 Additionally, a current standing order to KPS operators provides minimum LTC tap settings for each offsite power supply circuit's LTC in order for the circuit to be operable within the voltage band required to be maintained by ATC.
NRC Question 2 Provide an overview of the proposed changes in the Delta-V monitoring function that will be required to allow operation of the LTCs in automatic mode.
Response
The Delta-V monitoring function provides a programmed load/voltage forecast warning indication to aid in assuring offsite power supply operability.
Processes are being developed to ensure ATC provides DEK with this information.
The Delta-V monitoring function (programmed load/voltage forecast warning indication) is required to be functional to support automatic operation of the LTCs. Since the Delta-V monitoring* function is a support function for LTC operation in the automatic mode, procedural controls are required to specify LTC operation in the manual mode in the event of its failure (unless an acceptable alternative modeling capability is available). In addition, if the Delta-V monitoring function is unavailable, procedural controls are required to prohibit placing the LTCs in the automatic mode (unless an acceptable alternative modeling capability is available).
Presently, the ability to transfer the LTCs into automatic mode is physically disabled pending both NRC approval of the amendment request and ATC's implementation of the Delta-V monitoring function.
The Delta-V monitoring function differs from the current calculated post-trip voltage methodology. The calculated post-trip voltage methodology calculates a post-trip grid voltage, while the Delta-V monitoring function will provide a percentage change value for voltage on each offsite circuit (following a plant trip) based on its associated transformer's loading.
Based on preliminary analyses, the maximum permissible predicted voltage change for offsite circuit operability is expected to be no greater than 1.46%.
As currently envisioned, ATC would monitor this function and receive an alarm if the predicted voltage change exceeds the allowed value.
ATC would initiate actions to restore grid conditions so that the predicted voltage change is returned to an acceptable value. ATC would notify DEK if the predicted voltage change cannot be restored to an acceptable value within 30 minutes.
DEK will develop response procedures that will direct management of transformer loading among the three principle onsite transformers (RAT, Main Auxiliary Transformer (MAT), and TAT) to restore the predicted voltage
Serial NO.1 0-063C Page 3 of 5 change to an acceptable value and thereby return the affected offsite power circuit to operable status.
NRC Question 3 Provide a summary of procedural guidance that will prohibit automatic LTC operation without the Delta-V monitoring function.
Response
Since the Delta-V monitoring function is a required support function for operation of the LTCs in automatic mode, procedural controls will require operation of the LTCs in the manual mode when the Delta-V monitoring function is unavailable (unless an acceptable alternative modeling capability is available).
In addition, if the Delta-V monitoring function is unavailable, the procedural controls will prohibit placing the LTCs in automatic mode (unless an acceptable alternative modeling capability is available).
Presently, the ability to transfer the LTCs into automatic mode is physically disabled pending both NRC approval of the amendment request and ATC's implementation of the Delta-V monitoring function.
Procedural guidance will be developed and implemented prior to operation of the LTC's in the automatic mode and implementation will follow approval of this amendment request.
Current plans call for this procedural guidance to direct that operators verify the Delta-V monitoring function is available prior to placing an LTC in automatic mode.
In the event that the Delta-V monitoring function is or becomes unavailable, response procedures are planned which will direct that operators either operate the LTCs in manual mode or ensure an acceptable alternative modeling capability is available for continued LTC operation in automatic mode.
NRC Question 4 Provide a summary of procedural guidance that will be used when the LTCs are operational in automatic mode, and the ATC monitoring function is unavailable. Include details on guidance available to ATC personnel required to inform KPS when the monitoring capability is not available.
Response
ATC is in the process of implementing the Delta-V monitoring function, which will then enable DEK to take advantage of operating the LTCs in the automatic mode (after NRC approval of the amendment request).
Following implementation of the amendment,
. plant procedures will control LTC operation in the automatic mode based on the
Serial No. 10-063C Page 4 of 5 availability of the Delta-V monitoring function (or an acceptable alternative modeling capability).
Should a loss of the Delta-V monitoring function occur, such that real time prediction is unavailable, DEK plans to rely on an alternative grid evaluation to assure offsite power supply operability with the LTCs in automatic mode. Alternative grid evaluations, which are developed in advance, determine worst case Delta-V for given sets of pre-existing contingencies.
Operators would distribute loads between the MAT and the RAT as necessary to establish conditions such that the evaluated Delta-V would be within acceptable values for ensuring that required safety functions are supported by the associated offsite power source. The resulting bus alignment would provide assurance of offsite power operability while the monitoring function was being restored.
Planned changes to the interface coordination agreement between DEK and ATC would require ATC to notify DEK in a timely manner (within 30 minutes) regarding loss of monitoring capability.
NRC Question 5 Provide a regulatory commitment to prohibit the automatic LTC transformer operation without the Delta-V monitoring capability being fully functional.
Response
Presently, the ability to transfer the LTCs into automatic mode is currently disabled, pending both NRC approval of the amendment request and ATC's implementation of the Delta-V function. Administrative controls are also in place which prohibit enabling of the automatic LTC feature. These administrative controls will remain in place until both of the activities below are complete. The license amendment implementation process will ensure that required prerequisites are in place prior to operation of the LTCs in the automatic mode.
DEK commits to implementing procedural controls following approval of the amendment request to prohibit LTC operation in the automatic mode when the Delta-V monitoring capability is not fully functional unless an acceptable alternative modeling capability is available.
Specifically, this commitment includes the following:
DEK will develop and implement response procedures that direct management of transformer loading among the three principle onsite transformers (RAT, MAT, and TAT) so as to maintain the predicted Delta-V voltage at an acceptable value; and to restore it as necessary to return the affected offsite power circuit to operable status.
Serial NO.1 0-063C Page 5 of 5 DEK will develop and implement procedural guidance prior to operation of the LTCs in the automatic mode. Current plans call for this new guidance to direct that operators verify the Delta-V monitoring function is available prior to placing an LTC in automatic mode.
In the event that the Delta-V monitoring function is unavailable, response procedures are planned to direct that operators either operate the LTCs in manual mode or ensure an acceptable alternative modeling capability is available for continued LTC operation in automatic mode.
DEK will develop and implement
- changes, via the interface coordination agreement between DEK and ATC, which will require ATC to notify DEK in a timely manner (within 30 minutes) regarding loss of monitoring capability.
The above discussed procedural controls will be incorporated into Procedure OP-KW-AOP-EG-001, "Abnormal Grid Conditions," and Procedure OP-KW-NOP-SUB-003, "RST and TST Load Tap Changer Operation."
References
- 1. Letter from L. N. Hartz (DEK) to Document Control Desk (NRC), "License Amendment Request 236, Automatic Operation of Transformer Load Tap Changers," dated June 1, 2010.
2.
Letter from L. N. Hartz (DEK) to Document Control Desk (NRC), "Supplement and Response to Request for Additional Information:
License Amendment Request 236, Automatic Operation of Transformer Load Tap Changers (TAC NO.
ME4011," dated January 18,2010.
3.
Letter from J. Alan Price (DEK) to Document Control Desk (NRC), "Clarifying Response to Request for Additional Information:
License Amendment Request
- 236, Automatic Operation of Transformer Load Tap Changers (TAC NO.
ME4011," dated March 14,2011.
4.
Email from Karl D. Feintuch (NRC) to Jack Gadzala (DEK), Thomas Breene (DEK), Gurcharan Matharu (NRC), and Roy Matthew (NRC), "ME4011 RAI for KPS License Amendment Request Re:
automatic operation of Load Tap Changers," dated May 23,2011.