ML081060235

Second Request for Additional Information Related to Turbine Condenser Vacuum - Low Scram Setpoint Change

ML081060235
Person / Time
Site:	Dresden, Quad Cities
Issue date:	04/18/2008
From:	Joel Wiebe NRC/NRR/ADRO/DORL/LPLIII-2
To:	Pardee C Exelon Generation Co
Wiebe, Joel NRR/DORL/LPL3-2, 415-6606
References
TAC MD6250, TAC MD6251, TAC MD6252, TAC MD6253
Download: ML081060235 (6)

Text

April 18, 2008 Mr. Charles G. Pardee Chief Nuclear Officer and Senior Vice President Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3, AND QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 - SECOND REQUEST FOR ADDITIONAL INFORMATION RELATED TO TURBINE CONDENSER VACUUM

- LOW SCRAM SETPOINT CHANGE (TAC NOS. MD6250, MD6251, MD6252 AND MD6253)

Dear Mr. Pardee:

By letter to the Nuclear Regulatory Commission (NRC) dated August 1, 2007, Exelon Generation Company, LLC (Exelon) submitted a request to revise the turbine condenser vacuum - low scram instrumentation function, for the Dresden Nuclear Power Station, Units 2 and 3, and Quad Cities Nuclear Power Station, Units 1 and 2. By letter dated January 30, 2008, the NRC requested additional information (RAI) required to complete the review. Exelon responded to the RAI, by letter dated February 26, 2008.

The NRC staff is reviewing your submittal and response to the RAI and has determined that additional clarification of your response is required to complete the review. The specific information requested was provided in preliminary form by email, to John Schrage, on March 17, 2008. During discussions with your staff on March 18, 2008, the NRC staff clarified the requested information. The preliminary requested information and the clarifications are enclosed. During a discussion with your staff on April 9, 2008, it was agreed that you would provide a response by April 23, 2008.

The NRC staff considers that timely responses to requests for additional information help ensure sufficient time is available for staff review and contribute toward the NRCs goal of efficient and effective use of staff resources. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-6606.

Sincerely,

/RA/

Joel S. Wiebe, Senior Project Manager Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-237, 50-249, 50-254, and 50-265 cc: See next page

Mr. Charles G. Pardee April 18, 2008 Chief Nuclear Officer and Senior Vice President Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3, AND QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 - SECOND REQUEST FOR ADDITIONAL INFORMATION RELATED TO TURBINE CONDENSER VACUUM

- LOW SCRAM SETPOINT CHANGE (TAC NOS. MD6250, MD6251, MD6252 AND MD6253)

Dear Mr. Pardee:

By letter to the Nuclear Regulatory Commission (NRC) dated August 1, 2007, Exelon Generation Company, LLC (Exelon) submitted a request to revise the turbine condenser vacuum - low scram instrumentation function, for the Dresden Nuclear Power Station, Units 2 and 3, and Quad Cities Nuclear Power Station, Units 1 and 2. By letter dated January 30, 2008, the NRC requested additional information (RAI) required to complete the review. By letter dated February 26, 2008, Exelon responded to the RAI.

The NRC staff is reviewing your submittal and response to the RAI and has determined that additional clarification of your response is required to complete the review. The specific information requested was provided in preliminary form by email, to John Schrage on March 17, 2008. During discussions with your staff on March 18, 2008, the NRC staff clarified the requested information. The preliminary requested information and the clarifications are enclosed. During a discussion with your staff on April 9, 2008, it was agreed that you would provide a response by April 23, 2008.

The NRC staff considers that timely responses to requests for additional information help ensure sufficient time is available for staff review and contribute toward the NRCs goal of efficient and effective use of staff resources. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-6606.

Sincerely,

/RA/

Joel S. Wiebe, Senior Project Manager Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-237, 50-249, 50-254, and 50-265 cc: See next page DISTRIBUTION:

PUBLIC RidsNrrLAEWhitt RidsNrrDorlDpr LPL3-2 R/F RidsAcrsAcnw&mMailCenter RidsNrrDorlLpl3-2 RidsOgcRp RidsNrrPMJWiebe RidsRgn3MailCenter ADAMS Acession No. ML081060235 OFFICE LPL3-2/PM LPL3-2/LA LPL3-2/BC NAME JWiebe EWhitt RGibbs DATE 4/17/08 4/17/08 4/18/08 OFFICIAL RECORD COPY

Dresden and Quad Cities Nuclear Power Stations cc:

Corporate Distribution Exelon Generation Company, LLC Via e-mail Dresden Distribution Exelon Generation Company, LLC Via e-mail Quad Cities Distribution Exelon Generation Company, LLC Via e-mail Dresden Resident Inspector U.S. Nuclear Regulatory Commission Via e-mail Quad Cities Resident Inspector U.S. Nuclear Regulatory Commission Via e-mail Chairman Grundy County Board Via e-mail Illinois Emergency Management Agency Division of Disaster Assistance & Preparedness Via e-mail David C. Tubbs MidAmerican Energy Company Via e-mail Managing Senior Attorney MidAmerican Energy Company Via e-mail Chairman Rock Island County Board of Supervisors Via e-mail

REQUEST FOR ADDITIONAL INFORMATION DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3, DOCKET NOS, 50-237 AND 50-249 QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 DOCKET NOS. 50-254 AND 50-265 The NRC staff is reviewing your submittal and response to the RAI and has determined that additional clarification of your response is required to complete the review. The specific information requested was provided in preliminary form by email, on March 17, 2008. During discussions with your staff, on March 18, 2008, the NRC staff clarified the requested information. The preliminary requested information and the clarifications are described below.

1. In response to NRC RAI Question 1.d, Exelon responded as follows for the As-Found setpoint:

ER-AA-520 also establishes the required actions when an As-Found instrument setpoint exceeds the AV, as well as when an As-Found setpoint is within the allowable value (AV), but exceeds the Expanded Tolerance (ET):

If an As-Found instrument setpoint exceeds the AV, the instrument technician will enter the condition into the CAP [Corrective Action Program] by initiating a Condition Report (CR), and will notify the operating Shift Manager that the instrument is potentially inoperable. The operating Shift Manager (SM) will utilize LS-AA-120 to initially screen the condition, including the determination of operability. The SM will also initiate a Work Request (WR) to evaluate and repair/replace the instrument, prior to resetting the instrument to within a setting tolerance (ST).

If an As-Found instrument setpoint is within the AV, but exceeds the ET, the instrument technician will reset the instrument to within the ST, and enter the condition into the CAP program by initiating a CR and notifying the operating SM that the instrument is out-of-tolerance (OOT).

If an instrument cannot be reset to within the ST during calibration, then the instrument technician will initiate a CR to document the information and the instrument will be repaired/replaced.

Enclosure

The response is not consistent with the approach presented in Regulatory Issue Summary (RIS) 2006-17. RIS 2006-17 states the following:

If the as-found TSP exceeds the AV in TSs the channel is inoperable and the associated action requirements are followed. If the change in the measured TSP [trip setpoint] exceeds the predefined limits but the measured TSP is conservative with respect to the AV, and the licensee determines during the surveillance that the instrument channel is functioning as expected and can reset the channel to within the setting tolerance (amount by which as-left setting value is permitted to differ from NSP [nominal trip setpoint]) of the NSP, then the licensee may restore the channel to service and the condition is entered into the licensee's corrective action program for further evaluation. However, if during the surveillance the change in the measured TSP exceeds the predefined limits and the licensee cannot determine that the instrument channel is functioning as required, then the instrument is declared inoperable and the associated TS actions are followed. It is NRC staff's position that verifying that the as-found TSP is within the acceptance band limits during test or calibration is part of the determination that an instrument is functioning as required.

Per RIS 2006-17, if the TSP exceeds the AV then the channel is to be declared inoperable and the associated action requirements are to be followed. Exelon calls it potentially inoperable with the SM to screen the condition for inoperability.

Justify this deviation from RIS 2006-17.

Exelon has further stated that If an instrument cannot be reset to within the ST during calibration, then the instrument technician will initiate a CR to document the information and the instrument will be repaired/replaced. Confirm that the instrument is declared inoperable at this stage and corrective action is initiated per the guidance of RIS 2006-17.

CLARIFICATION Describe the Exelon procedural requirements that ensure the licensed Senior Reactor Operator will declare an instrument channel inoperable if the TSP exceeds the AV.

2. Dresden Nuclear Power Station monthly drift data (20 points) has been provided.

Some of the drift data indicates monthly drift of greater then 0.6" Hg. The maximum drift for switch number 3-0503A is 0.95" Hg. The calculation assumes a quarterly drift tolerance of 0.6" Hg.

Provide the methodology by which the monthly drift data is extended is extended to quarterly drift estimate. In addition, the drift extension methodology should include the 25% allowed extension in the calculation.

Exelon document NES-EIC-20.04, Rev. 2, Appendix J to Analysis of Instrument Channel Setpoint Error and Instrument Loop Accuracy, in Section 2.1.2.2. states,

ComEd has specified that the minimum targeted number of valid data points that are required to make a drift study significant shall be 30 data points. If drift data is available for 30 points then it should be used in the quarterly drift data.

CLARIFICATION Describe the methodology for the Exelon analysis that was used to extend the Dresden Nuclear Power Station surveillance test interval (STI) from monthly to quarterly with respect to NES-EIC-20.04, Revision 2, as well as the original licensing topical report.

Provide the basis for concluding that the results of the analysis are reasonable, with adequate margin, given the drift data provided in the February 26, 2008, letter from Exelon to the NRC.

3. No drift data has been provided for QCNPS. Provide the historical or vendor provided drift data to support the drift, as left, and as found tolerance assumptions.

CLARIFICATION EGC did not provide drift data for QCNPS because the requested STI extension is only applicable to the DNPS instrument. Current TS for QCNPS already specify a quarterly STI. Therefore, no additional response is required.