ML13190A016

Oconee, Units 1, 2, and 3, Licensing Basis for the Protected Service Water System - Responses to Request for Additional Information - Supplement 5

ML13190A016
Person / Time
Site:	Oconee
Issue date:	06/28/2013
From:	Batson S L Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML13190A016 (7)

Text

DUKE SCOTT L. BATSONVice President 4nENERGY.

Ocone Nuclear StationDuke EnergyONOI VP / 7800 Rochester HwySeneca, SC 29672864-873-3274 864-873-4208 fax10 CFR 50.90 Scott.Betson@duke-energy.com June 28, 2013Document Control DeskU.S. Nuclear Regulatory Commission Washington, DC 20555-0001

Subject:

Duke Energy Carolinas, LLCOconee Nuclear Station, Units 1, 2, and 3Docket Numbers 50-269, 50-270, and 50-287,Renewed Operating Licenses DPR-38, DPR-47, and DPR-55Licensing Basis for the Protected Service Water System -Responses toRequest for Additional Information

-Supplement 5

References:

1. Letter from T. Preston Gillespie, Jr., Vice President, Oconee Nuclear Station,Duke Energy Carolinas, LLC, to the U. S. Nuclear Regulatory Commission, "Tornado and High Energy Line Break (HELB) Mitigation License Amendment Requests (LARs) -Responses to Request for Additional Information,"

datedDecember 16, 2011.2. November 16, 2012, E-mail from John Boska, U.S. NRC, to Timothy D. Brown,Duke Energy Carolinas, LLC.By letter dated December 16, 2011, Duke Energy Carolinas, LLC (Duke Energy),submitted License Amendment Requests (LARs) for the Oconee Nuclear Station (ONS)proposing revisions to the High Energy Line Break (HELB) licensing bases (Ref. 1). Thissubmittal included proposed Protected Service Water (PSW) Technical Specifications andsystem descriptions.

On November 16, 2012, Duke Energy received RAI 170 concerning heat load changesin certain areas of the station associated with the operation of the PSW system (Ref. 2).This submittal contains Duke Energy's response to RAI 170.If you have any questions in regard to this letter, please contact Stephen C. Newman,Regulatory Affairs Senior Engineer, Oconee Nuclear Station, at (864) 873-4388.

Aool U. S. Nuclear Regulatory Commission June 28, 2013Page 2I declare under penalty of perjury that the foregoing is true and correct.

Executed onJune 28, 2013.Sincerely, Scott L. BatsonVice President Oconee Nuclear StationEnclosure U. S. Nuclear Regulatory Commission June 28, 2013Page 3cc: (w/enclosure)

Mr. John P. Boska, Senior Project Manager(by electronic mail only)U. S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation 11555 Rockville PikeRockville, MD 20852Mr. Victor M. McCree, Administrator, Region IIU.S. Nuclear Regulatory Commission Marquis One Tower245 Peachtree Center Ave., NE, Suite 1200Atlanta, GA 30303-1257 Mr. Eddy L. CroweNRC Senior Resident Inspector Oconee Nuclear StationMs. Susan E. Jenkins, ManagerRadioactive

& Infectious Waste Management SC Dept. of Health and Environmental Control2600 Bull St.Columbia, SC 29201 Enclosure Responses to Request for Additional Information Supplement 5

EInclosure

-Responses to Request for Additional Information

-Supplement 5June 28, 2013 Page 2RAI #170:"The NRC staff is aware that the addition of the PSW booster pump and main PSW pump to theauxiliary building will increase the heat load there when they are in use. Please describe theeffects of the heat load during an event when the PSW system could be used, such as a majorfire in the turbine building which renders inoperable all electrical buses and equipment located inthe turbine building.

Discuss if any equipment located in the auxiliary building or the reactorbuilding which is qualified under 10 CFR 50.49 and is needed to respond to the event willexceed its qualified environmental conditions, and what steps are being taken to address thisconcern."

Duke Energy ResponseIntroduction Cooling to the Auxiliary Building (AB) relies upon operation of the Low Pressure Service Water(LPSW) system, the AB Chilled Water Systems and switchgear located in the Turbine Building(TB). Normal and emergency cooling to the Reactor Building (RB) relies upon operation of theLPSW system and switchgear located in the TB. During Protected Service Water (PSW)scenarios that affect equipment located in the TB requiring use of the PSW/High PressureInjection (HPI) System, the potential exists for a loss of power and cooling water to the ABand/or RB ventilation systems.

With an extended loss of environmental cooling in these areasand assuming limiting design conditions, the heat load from operation of the PSW/HPI Systemcould lead to temperature increases in the AB and RB. Analyses are being performed detailing the bounding PSW/HPI equipment temperature limits as well as the predicted RB and ABtemperature increases.

The bounding predicted temperature increases in the AB and RB havebeen projected to eventually reach the documented temperature design limits of certainPSW/HPI mitigating components over an extended period of operation.

In order to address this concern and ensure PSW/HPI mitigating component design temperature limits will not be exceeded during PSW/HPI System operation, alternate cooling water andpower to the existing ventilation systems will be provided to recover from the loss of ventilation to the AB and RB.The new systems will be installed in two phases. For Phase 1, the ventilation components willsupport operation of the PSW system for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to accommodate establishment of a hotshutdown safe and stable condition.

Phase 2 will provide for extended PSW/HPI Systemoperation to meet NFPA 805 requirements.

The need to place the AB and RB ventilation systems in service is not projected to beimmediate following a PSW scenario and varies based on the plant location and coolingcapacity selected.

The actions to place the alternate system in service are to be assured bymeans of staffing, procedures, training and qualifications.

Auxiliary BuildingThe normal source of power and/or cooling water to the existing plant AB ventilation systemsmay be impacted by the PSW scenario.

As part of the AB alternate ventilation modifications, numerous Air Handling Units (AHUs) and exhaust fans will receive alternate power and/orcooling water. It is unlikely that the full complement of AHUs and exhaust fans will be Enclosure

-Responses to Request for Additional Information

-Supplement 5June 28, 2013 Page 3necessary to support the operation of the PSW system in the AB. As the AB is a single buildingwith numerous interconnections throughout the various elevations, there is overlap in theoperation of the AHUs and exhaust fans. These interconnections can be further enhanced bythe opening of doorways.

The final selection of needed AHUs and exhaust fans may varybased on the cooling capacity provided to the existing components.

Additionally, certain areaswithin the AB have been identified with very few PSW/HPI components that have limiting designtemperatures.

For the AB, a new chilled water system will be installed using portable chillers and permanently installed piping to selected AHUs. The new cooling system will be named the Alternate ChilledWater (AWC) system. The modification to be installed will consist of chillers and necessary piping, valves, etc. to supply chilled water to selected AHUs that supply air to the ControlComplex (Control Room, Cable Room and Equipment Room), the Penetration Rooms, andportions of the AB. There will be two main headers -one which generally feeds AHUs normallysupplied by the AB Chilled Water Systems (WC or CW) and one which generally feeds AHUsnormally supplied by LPSW.The chillers, AHUs and exhaust fans will be capable of being powered from a new electrical distribution system fed from the PSW switchgear with the appropriate distribution

centers, motorcontrol centers and transformers.

Reactor BuildingThe normal cooling water (LPSW) to the RB ventilation systems may be impacted by the PSWscenario.

RB alternate cooling will be provided by means of lake water to one RB Cooling Unit(RBCU). A diesel driven pump will take suction from Lake Keowee and feed lake water througha connection to the LPSW supply lines to one RBCU on each unit. The RBCU fan will also beprovided with an alternative power source from the PSW electrical system. If the normal powersource was degraded or lost, power transfer equipment would be utilized to transfer thealternate power source to the RBCU.Design BasesThe new alternate cooling equipment will meet the following design criteria:

-Inclusion in the QA-5 program in accordance with Duke Specification OSS-0254.00 4022, the Duke Quality Assurance Topical Report and as discussed in UFSAR Chapter 17.-Provide for a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> mission time (Phase 1).-Provide for extended PSW/HPI System operation to meet NFPA 805 requirements (Phase2).-Not have seismic operational requirements other than not being permitted to interact withother seismically-protected SSCs during a seismic event.-Not be protected from a tornado or from an external flood.-No assumed single failure since the Standby Shutdown Facility provides a diverse safeshutdown system to the PSW/HPI System.-Lake Keowee is available.

Enclosure

-Responses to Request for Additional Information

-Supplement 5June 28, 2013 Page 4Existing repowered equipment will retain their current quality classification.

Environmental Qualification PSW is not required to meet the single failure criteria because it provides added "defense-in-depth" protection by serving as a backup to existing safety systems.

AB or RB Ventilation is notrequired during the initial mitigation of an NFPA 805 fire in the TB that disables the 4160 Vessential electric power distribution system. However, ventilation is required for long-term recovery and plant cool down. Fires are not design basis events to be considered forenvironmental qualification per the Oconee Nuclear Station Environmental Qualification CriteriaManual. Therefore, PSW equipment is not within the scope of IOCFR50.49 except for PSWequipment that interfaces with safety-related components that are presently qualified under1OCFR50.49.

For examples, reference the Duke Energy response to RAI 165 (letter datedNovember 2, 2012). Safety-related components that interface with PSW equipment that arepresently qualified under 1 OCFR50.49 will not exceed their existing environmental qualification.

PSW components are designed to perform their functions in the environment they are expectedto operate.