ONS-2017-069, (ONS) - Additional Information Regarding License Amendment Request for Temporary Completion Time for One Keowee Hydro Unit Inoperable for Generator Stator Replacement

(ONS) - Additional Information Regarding License Amendment Request for Temporary Completion Time for One Keowee Hydro Unit Inoperable for Generator Stator Replacement

ML17292A050
Person / Time
Site:	Oconee
Issue date:	10/13/2017
From:	Teresa Ray Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LAR 2015-08. Supp 3, ONS-2017-069
Download: ML17292A050 (6)

Text

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~,ENERGY Thomas D. Ray Vice President Oconee Nuclear Station Duke Energy ON01VP J 7800 Rochester Hwy Seneca, SC 29672 o: 864.873.5016 ONS-2017-069 10 CFR 50.90 f 864.873.5791 Tom.Ray@duke-energy.com October 13, 2017 ATTN: Document Control Desk U. S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville, Maryland 20852

Subject:

Duke Energy Carolinas, LLC Oconee Nuclear Station (ONS)

Docket Numbers 50-269, 50-270, and 50-287 Renewed Facility Operating License Nos. DPR-38, DPR-47, and DPR-55 Additional Information Regarding License Amendment Request for Temporary Completion Time for One Keowee Hydro Unit Inoperable for Generator Stator Replace.ment License Amendment Request No. 2015-08, Supplement 3 On February 26, 2016, Duke Energy Carolinas, LLC (Duke Energy) submitted a License Amendment Request (LAR) requesting the Nuclear Regulatory Commission (NRC) approve a Technical Specification {TS) change that adds a temporary Completion Time to TS 3.8.1 Required Action C.2.2.5 to allow time to perform major maintenance on each Keowee Hydroelectric Unit (KHU). By email dated September 13, 2017, the NRC requested Duke Energy submit additional information associated with the LAR. Enclosure 1 provides the requested information. Enclosure 2 provides the regulatory commitments made in this submittal.

Inquiries on this response to request for additional information should be directed to Boyd Shingleton, ONS Regulatory Affairs Group, at (864) 873-4716.

I declare under penalty of perjury that the foregoing is true and correct. Executed on October 13, 2017.

Sincerely,

!!::: l),~

Vice President Oconee Nuclear Station

Enclosures:

1) Duke Energy Response to NRC Request for Additional Information

2) Regulatory Commitments

U. S. Nuclear Regulatory Commission

• October 13, 2017 Page 2 cc w/enclosures:

Ms. Catherine Haney, Administrator, Region II U.S. Nuclear Regulatory Commission Marquis One Tower .

245 Peachtree Center Ave., NE, Suite 1200 Atlanta, GA 30303-1257 Ms. Audrey Klett, Project Manager (by electronic mail only)

Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 0-8G9A

• 11555 Rockville Pike Rockville, Maryland 20852 Mr. Eddy Crowe NRC Senior Resident Inspector Oconee Nuclear Station Ms. Susan E. Jenkins, Manager, (by electronic mail only: jenkinse@dhec.sc.gov)

Infectious and Radioactive Waste Management, Bureau of Land and Waste Management Department of Health & Environmental Control 2600 Bull Street Columbia, SC 29201

ENCLOSURE 1 Duke Energy Response to NRC Request for Additional Information (RAI)

Enclosure 1 - Duke Energy Response to NRC RAI Page 1

• , License Amendment Request No. 2015-08, Supplement 3 October 13, 2017 RAl4 In its letter dated January 30, 2017 (ADAMS Accession No. ML17032A347), the licensee responded to RAI 2 and indicated that plant modifications would be in place by the end of 2018.

During routine discussions with the NRC licensing project manager throughout August 2017, Duke Energy has indicated that the plant modifications described in the licensee's response to RAI 2 might not be completed before the first scheduled stator replacement. In its letter dated February 3, 2014 (ADAMS Accession No. ML14035A453), the licensee indicated that it monitors its off-site power sources at a frequency of once every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Therefore, the staff requests the licensee to provide the following:

1) a description of (a) the most recent power cable inspections and replacements in the switchyard including the results of the power cable inspections and replacements

2) a description of what additional compensatory measures, controls, or actions (e.g.,

increased frequency of roving watches, administrative controls, work restrictions and durations, etc.) would be performed to explicitly monitor off-site power sources, minimize impacts to off-site power sources, and protect plant equipment essential for safe shutdown during the period for when the stator replacement and associated maintenance is being performed.

Response to RAI 4

1) Detailed inspections of power cable connections in the transformer yard and other potential problem areas were performed as a result of the open phase condition identified on the Unit 3 startup transformer (CT-3) on December 7, 2015. The broken Y-phase conductor on CT-3 was repaired and the conductors to the other two phases were trimmed. Conductors on the Unit 1 startup transformer (CT-1) were found degraded and repaired. No other undesired conditions were found.

A monthly inspection of the startup transformers is conducted and includes a check for degraded or damaged cables or connectors. A visual inspection of the drop line (the line connecting the overhead conductor to the transformer) connections to each startup transformer is performed daily during operator rounds. This is the same inspection that identified the open phase condition on the Unit 3 startup transformer (CT-3) on December 7, 2015. Since then, no additional issues have been identified while performing this inspection. Offsite power is provided to each Oconee Nuclear Station (ONS) unit through the unit startup transformers.

The drop lines to CT-1 were replaced in March of 2016. At that time, a detailed inspection was performed on all drop line components. No iss_ues were identified.

The drop lines to CT-2 will be replaced in the upcoming Unit 2 Fall 2017 outage. A detailed visual inspection on all drop line components was performed in December of 2015. No issues were identified.

The drop lines to CT-3 were replaced in April of 2016. At that time, a detailed inspection was performed on all drop line components. No issues were identified.

- Duke Energy Response to NRC RAI Page 2 License**Amendment Request No. 2015-08, Supplement 3 October 13, 2017

2) The operator rounds inspection will be performed on the drop lines for startup transformers without an Open Phase Protection (OPP) system just prior to entering dual Keowee Hydro Unit (KHU) outages associated with each stator replacement. This visual inspection will be performed on each shift (day and night) for the duration of the dual KHU outages. The frequency of inspections will be increased to twice per shift should severe weather occur during the dual KHU outage. Duke Energy has previously committed to not start a dual KHU outage if severe weather conditions are forecasted to occur within the next 2 days.

Daily inspection will resume during the extended single KHU outage.

No discretionary maintenance or testing will be allowed on the Standby Shutdown Facility (SSF), Protected Service Water (PSW), Emergency Feedwater (EFW) and essential AC Power Systems, and the offsite power system (230 kV Switchyard) during the KHU generator stator replacement outages. Also, the steam-drive emergency feedwater pump on each ONS unit and the Lee Combustion Turbines (LCTs) and Central Switchyard will be protected during the stator outages. These and other risk reduction measures were committed to in the LAR for the Keowee stator replacement dated February 26, 2016 (ML16064A020).

- Duke Energy Response to NRC RAI Page 1 License Amendment Request No. 2015-08, Supplement 3 October 13, 2017 REGULATORY COMMITMENTS The following commitment table identifies those actions committed to by Duke Energy Carolinas, LLC (Duke Energy) in this submittal. Other actions discussed in the submittal represent intended or planned actions by Duke Energy. They are described to the Nuclear Regulatory Commission (NRC) for the NRC's information and are not regulatory commitments.

1 The drop lines to CT2 will be replaced in the upcoming Unit 2 Fall 2017 outage Fall 2017 outage.

2 The operator rounds inspection will be performed on the drop lines for startup transformers without an Open Phase Protection (OPP) system just prior to entering dual Keowee Hydro Unit Prior to and during (KHU) outages associated with each stator replacement. This dual KHU stator visual inspection will be performed on each shift (day and night) outage work for the duration of the dual KHU outages. The frequency of inspections will be increased to twice per shift should severe Weather occur during the dual KHU outage.