Text

Issuance of Amendment Request to Revise Technical Specification for Residual Heat Removal System Air Handler Unit 1
	ML16004A352
Person / Time
Site:	McGuire
Issue date:	02/03/2016
From:	Geoffrey Miller; Plant Licensing Branch II
To:	Capps S; Duke Energy Carolinas
	Miller G
References
	CAC MF6666
	Download: ML16004A352 (22)
	v • d • e

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Mr. Steven D. Capps Vice President McGuire Nuclear Station Duke Energy Carolinas, LLC 12700 Hagers Ferry Road Huntersville, NC 28078-8985 February 3, 2016

SUBJECT:

MCGUIRE NUCLEAR STATION, UNIT 1: l_SSUANCE OF AMENDMENT RE:

REQUEST TO REVISE TECHNICAL SPECIFICATIONS FOR RESIDUAL HEAT REMOVAL SYSTEM AIR HANDLER UNIT 1 (CAC NO. MF6666)

Dear Mr. Capps:

The U.S. Nuclear Regulatory Commission has issued the enclosed Amendment No 281 to Renewed Facility Operating License NPF-9 for the McGuire Nuclear Station, Unit 1. The amendment consist of changes to the Technical Specifications (TSs) in response to your application dated August 28, 2015*(Agencywide Documents Access and Management System (ADAMS) Accession No. ML152448179), as supplemented by letter dated November 13, 2015 *

(ADAMS Accession No. ML15331A039).

The amendment modifies the TS Completion Time for TS 3.5.2, "ECCS [Emergency Core Cooling System] - Operating," Condition A. Specifically, the amendment allows a one-time extension of the Completion Time to support maintenance on residual heat removal air handler unit 1A.

A copy of the related Safety Evaluation is also enclosed. A Notice of Issuance will be included in the Commission's biweekly Federal Register notice.

S..

If you have any questions, please call me at 301-415-2481.

Docket No. 50-369

Enclosures:

1. Amendment No. 281 to N PF-9

2. Safety Evaluation cc w/encls: Distribution via Listserv Sin;t (3~.)

G. Edward Miller, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 DUKE ENERGY CAROLINAS, LLC DOCKET NO. 50-369 MCGUIRE NUCLEAR STATION, UNIT 1 AMENDMENT TO RENEWED FACILITY OPERATING LICENSE Amendment No. 281 Renewed License No. NPF-9

1.

The Nuclear Regulatory Commission (the Commission) has found that:

A.

The application for amendment to the McGuire Nuclear Station, Unit 1 (the facility), Renewed Facility Operating License No. NPF-9, filed by the Duke Energy Carolinas, LLC (licensee), dated August 28, 2015, as supplemented by letter dated November 13, 2015, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commission's rules and regulations as set forth in 10 CFR Chapter I; B.

The facility will operate in conformity with the application, the provisions of the Act, and the rules and regulations of the Commission; C.

There is reasonable assurance (i) that the activities authorized by this amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commission's regulations set forth in 1 O CFR Chapter I; D.

The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E.

The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commission's regulations and all applicable requirements have been satisfied.

2.

Accordingly, the license is hereby amended by page changes to the Technical Specifications as indicated in the attachment to this license amendment, and Paragraph 2.C.(2) of Renewed Facility Operating License No. NPF-9 is hereby amended to read as follows:

(2)

Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 281, are hereby incorporated into this renewed operating license. The licensee shall operate the facility in accordance with the Technical Specifications.

3.

This license amendment is effective as of its date of issuance and shall be implemented within 30 days of issuance.

Attachment:

Changes to License No. NPF-9 and the Technical Specifications FOR THE NUCLEAR REGULATORY COMMISSION Michael T. Markley, Chief Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulatior:i Date of Issuance:.february 3, 2O1 6

ATTACHMENT TO LICENSE AMENDMENT NO. 281 RENEWED FACILITY OPERATING LICENSE NO. NPF-9 DOCKET NO. 50-369 Replace the following pages of the Renewed Facility Operating Licenses and the Appendix A Technical Specifications (TSs) with the attached revised pages. The revised pages are identified by amendment number and contain marginal lines indicating the areas of change*.

Remove License Page NPF-9, page 3 TS Page 3.5.2-1 License Page NPF-9, page 3 TS Page 3.5.2-1

4)

Pursuant to the Act and 1 O CFR Parts 30, 40 and 70, to receive, possess and use in amounts as required any byproduct, source or special nuclear material without restriction to chemical or physical form, for sample analysis or instrument calibration or associated with radioactive apparatus or components; (5)

Pursuant to the Act and 10 CFR Parts 30, 40 and 70, to possess, but not separate, such byproducts and special nuclear materials as may be produced by the operation of McGuire Nuclear Station, Units 1 and 2, and; (6)

Pursuant to the Act and 10 CFR Parts 30 and 40, to receive, possess and process for release or transfer such byproduct material as may be produced by the Duke Training and Technology Center.

C.

This renewed operating license shall be deemed to contain and is subject to the conditions specified in the Commission's regulations set forth iri 10 CFR Chapter I and is subject to all applicable provisions of the Act and to the rules, regulations, and orders of the Commission now or hereafter in effect; and is subject to the additional conditions specified or incorporated below:

(1)

Maximum Power Level The licensee is authorized to operate the facility at a reactor core full steady state power level of 3469 megawatts thermal (100%).

(2)

Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment No. 281, are hereby incorporated into this renewed operating license. The licensee shall operate the facility in accordance with the Technical Specifications.

(3)

Updated Final Safety Analysis Report The Updated Final Safety Analysis Report supplement submitted pursuant to 10 CFR 54.21(d), as revised on December 16, 2002, describes certain future activities to be completed before the period of extended operation.

Duke shall complete these activities no later than June 12, 2021, and shall notify the NRC in writing when implementation of these activities is complete and can be verified by NRC inspection.

The Updated Final Safety Analysis Report supplement as revised on December 16, 2002, described above, shall be included in the next scheduled update to the Updated Final Safety Analysis Report required by 10 CFR 50.71 (e)(4), following issuance of this renewed operating license.

1 Until that update is complete, Duke may make changes to the programs described in such supplement without prior Commission approval, provided that Duke evaluates each such change pursuant to the criteria set forth in 1 O CFR 50.59 and otherwise complies with the requirements in that section.

Renewed License No. NPF-9 Amendment No. 281

3.5 EMERGENCY CORE COOLING SYSTEMS (ECCS) 3.5.2 ECCS-Operating LCO 3.5.2 Two ECCS trains shall be OPERABLE.

APPLICABILITY:

MODES 1, 2, and 3.

ECCS -Operating 3.5.2

NOTE------------------------------------------------

1 n MODE 3, both safety injection (SI) pump or RHR pump flow paths may be isolated by closing the isolation valves for up to 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months to perform pressure isolation valve testing per SR 3.4.14.1.

ACTIONS CONDITION REQUIRED ACTION COMPLETION TiME A.

One or more trains A.1 Restore train(s) to 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s*

inoperable.

OPERABLE status.

AND At least 100% of the ECCS flow equivalent to a single OPERABLE ECCS train available.

B.

Required Action and B.1 Be in MODE 3.

6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months associated Completion Time not met.

AND B.2 Be in MODE 4.

12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months

For Unit 1 only, the Completion Time for Required Action A.1 may be extended one-time to 10 days during the 1A RHR AHU repair evolution and is contingent on meeting the compensatory measures described in MNS correspondence letter MNS-15-093. Upon completion of the repair evolution, this footnote is no longer applicable and will expire on March 31, 2016.

McGuire Units 1 and 2 3.5.2-1 Amendment Nos. 281/166

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 281 TO RENEWED FACILITY OPERATING LICENSE NPF-9

1.0 INTRODUCTION

DUKE ENERGY CAROLINAS, LLC MCGUIRE NUCLEAR STATION, UNIT 1 DOCKET NO. 50-369 By letter dated August 28, 2015, Duke Energy Carolinas, LLC (Duke Energy), the licensee, in the Agencywide Documents Access and Management System (ADAMS) (Accession No. ML15244B179), and supplemented on November 13, 2015 (Accession No. ML15331A039) requested a change to the Technical Specifications (TS) to McGuire Nuclear Station, Unit 1 (collectively, the license amendment request (LAR)). The amendment proposes to change the system restoration Completion Time (CT) in TS 3.5.2, "ECCS [Emergency Core Cooling Systems] - Operating," to allow for repairs to the Unit 1 Residual Heat Removal (RHR) air handling unit (AHU). *The supplemental letter dated November 13, 2015, provided additional information that clarified the application, did not expand the scope of the application as originally noticed, and did not change the NRC staff's original proposed no significant hazards consideration determination as published in the Federal Register.

The proposed revision is a one-time change to TS 3.5.2, Condition A, to facilitate repairs to the Unit 1, 1 A RHR pump motor AHU. TS 3.5.2, Required Action A.1 applies to one inoperable ECCS train. The licensee has stated that an adverse trend in AHU performance indicates the need for repairs that cannot be completed within the 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months CT.

The LAR is being submitted to request a one-time CT for Required Action A.1 for 1 O days. This would be an extension of the CT by 168 hours0.00194 days 0.0467 hours 2.777778e-4 weeks 6.3924e-5 months for a total of 240 hours0.00278 days 0.0667 hours 3.968254e-4 weeks 9.132e-5 months . Upon completion of the repair the proposed footnote would no longer be applicable and would expire on March 31, 2016. The request is deterministic and involves the use of an alternate source of forced cooling to the 1 A RHR pump room. This alternate source of cooling will ensure, that the 1A RHR system remains available throughout the maintenance evolution.

2.0 REGULATORY EVALUATION

Appendix A to Title 1 O of the Code of Federal Regulations (1 o CFR) Part 50 provides General Design Criteria (GDC) that must be considered when developing principal design criteria for a water-cooled nuclear power plant. Section 3.1 of the McGuire Updated Final Safety Analysis Report (UFSAR) discusses conformance with the GDC. The proposed amendment was evaluated against the following GDC, as incorporated into the McGuire licensing basis through the UFSAR:

GDC 2 - Design Bases for Protection Against Natural Phenomena Structures, systems, and components (SSCs) important to safety shall be designed to withstand' the effects of natural phenomena such as earthquakes, tornadoes, hurricanes, floods, tsunamis, and seiches without loss of capability to perform their safety functions. The design bases for these SSCs shall reflect: (1) appropriate consideration of the most severe of the natural phenomena that have been historically reported for the site and surrounding area, with sufficient margin for the limited accuracy, quality, and period of time in which the historical data have been accumulated, (2) appropriate combination of the effects of normal and accident conditions with.the effects of the natural phenomena and (3) the importance of the safety functions to be performed.

GDC 3 - Fire Protection SSCs important to safety shall be designed and located to minimize, consistent with other safety requirements, the probability and effect of fires and explosions. Noncombustible and heat resistant materials shall be used wherever practical throughout the unit, particularly in locations such as the Containment and Control Room. Fire detection and fighting systems of appropriate capacity and capability shall be provided and designed to minimize the adverse effects of fires on SSCs important to safety. Firefighting systems shall be designed to assure that their rupture or inadvertent operation does not significantly impair the safety capability of these SSCs.

GDC 4-Environmental and Missile Design Bases SSCs important to safety shall be designed to accommodate the effects of and to be compatible with the environmental conditions associated with normal operation, maintenance, testing, and postulated accidents, including loss-of-coolant accidents. These SSCs shall be appropriately protected against dynamic effects, including the effects of missiles, pipe whipping, and discharging fluids, that may result from equipmentfailures.and from events and conditions outside the nuclear power unit.

GDC 34 - Residual Heat Removal A system to remove residual heat shall be provided. The system safety function shall be to transfer fission product decay heat and other residual heat from the reactor core at a rate such that specified acceptable fuel design lim.its and the design conditions of the reactor coolant pressure boundary are not exceeded.

Suitable redundancy in components and features, and suitable interconnections, leak detection, and isolation capabilities are provided to assure that for onsite electric power system operation (assuming offsite power is not available) and for offsite electric power system operation (assuming onsite power is not available) the system safety function can be accomplished, assuming a single failure.

GDC 35 Emergency Core Cooling A system to provide abundant emergency core cooling shall be provided. The system safety function shall be to transfer heat from the reactor core following any loss of reactor coolant at a rate such that (1) fuel and clad damage that could interfere with continued effective core cooling is prevented and (2) clad metal-water reaction is limited to negligible amounts.

Suitable redundancy in components and features, and suitable interconnections, leak detection, isolation, and containment capabilities shall be provided to assure that for onsite electric power system operation (assuming offsite power is not available) and for offsite electric power system operation (assuming onsite power is not available) the system safety function can be accomplished, assuming a single failure.

3.0 TECHNICAL EVALUATION

3.1 Background

In its letter dated August 28, 2015, the licensee stated that 1A RHR pump motor AHU vibration testing has shown higher than normal vibration for the AHU. As noted during testing, vibration is higher when the AHU starts and then settles out c;\\S the fan continues to run. Analysis of the vibration data indicates potential looseness in the rotating equipment bearing housing or between the bearings and the fan shaft. Internal inspections of the AHU (while running and while idle) were perforr;ned in May 2015, and no indications of structural looseness were observed. Because of the results of the internal inspection, it is currently believed that looseness associated with the bearing is causing the elevated vibration readings.

Should the vibration reach unacceptable levels, it will be necessary to remove the AHU from service to effect repairs and ensure that its function is maintained. Due to the configuration of the AHU and the confined working conditions, the necessary repair work is expected to exceed the current TS 3.5.2 - 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months CT.

3.2

System Description

In its letter dated August 28, 2015, the licensee stated in the LAR that although the RHR system is used to remove heat from the Reactor Coolant System (RCS) during unit cooldown, that function is not used during periods of power operation. However, the system also serves as part of the ECCS, and this function is affected by the proposed change.

The function of the RHR system as part of the ECCS is to provide core cooling and negative reactivity to ensure that the reactor core is protected after a large break loss-of-coolant acCident (LOCA) that results in the RCS pressure being below the RH R pump shutoff head The RHR portion of the ECCS consists of two redundant, 100%' capacity trains. The system is designed to perform its safety function assuming a single failure of safety-related equipment.

An AHU is interlocked with each RHR pump and will automatically start with the pump. Each

AHU is located in the room with its respective RHR pump and is equipped with a service water cooling coil and a belt-driven centrifugal fan. The AHU is designed to maintain the RHR pump room at a maximum temperature of 145 °F. Without sufficient cooling, as provided by the AHU, the associated RHR pump would not be assured of meeting its mission time during accident conditions.

Additional information on the RHR system is found in the McGuire Nuclear Stations Updated Final Safety*Analysis Report (UFSAR), Section 6.3, "Emergency Core Cooling System".

3.3 Proposed changes The proposed LAR would revise the CT for Required Action A.1 of TS 3.5.2 from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to 240 hours0.00278 days 0.0667 hours 3.968254e-4 weeks 9.132e-5 months (10 days) on a one-time basis. In its original LAR dated August 28, 2015, the licensee proposed a footnote to be added to the TS page stating

For Unit 1 only, the Completion Time that one train of ECCS can be inoperable as specified by Required Action A.1 may be extended beyond the "72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months " for up to 10 days during the 1A RHR AHU repair evolution. This allowance may be used one-time for the 1 A RHR AHU repair and is contingent on meeting the compensatory measures and commitments described in MNS LAR submittal correspondence letter MNS-15-069. Upon completion of the repair and restoration, this footnote is no longer applicable and will expire on March 31, 2016.

During the NRC staff's review of the LAR, the licensee subsequently revised the proposed TS footnote (see Section 3.4.6 of this Safety Evaluation).

As stated above, there are proposed compensatory measures associated with this LAR. The seven proposed compensatory measures are:

1. The alternate forced cooling equipment (chiller and AHU) will be installed and tested in accordance with the engineering change (EC) process prior to exceeding th~ normal 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months allowed outage time {AOT)1 associated with TS 3.5.2, Required Action A.1.

2. At least one ground water drainage system (WZ) 'C' sump pump will be available prior to exceeding the normal 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months AOT associated with TS 3.5.2, Required Action A.1.

3. The following SSCs will be protected prior to exceeding the normal 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months AOT associated with TS 3.5.2, Required Action A.1, and elective maintenance to them will be deferred during the repairs to the IA RHR pump motor AHU:

o 1 B RHR train o

1 B Nuclear Service Water System (NSWS) train o

1 B Component Cooling Water System (CCWS) train o

1 B Emergency Diesel Generator (EOG) o Power supply to the alternate cooling equipment o

One WZ C sump pump 1 As used in the licensee's submittal, AOT and CT are synonymous.

4. Prior to exceeding the normal 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months AOT associated with TS 3.5.2, Required Action A.1, McGuire will monitor the National Weather Service for potential severe weather conditions. To the extent practical, severe weather conditions will be avoided.

5. Prior to exceeding the normal 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months AOT associated with TS 3.5.2, Required Action A.1, and daily thereafter, McGuire will contact the Transmission Control Center (TCC)

regarding system grid stability. To the extent practical, system grid instability will be avoided.

6. Prior to exceeding the normal 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months AOT associated with TS 3.5.2, Required Action A.1, roving fire watches will be established in the following areas to minimize the chance of fire-induced LOCAs:

a. Unit 1 4.16kV Switchgear Rooms

b. Unit 1 Auxiliary Feedwater Pump Room

c. 1 B Diesel Generator Room

d. Fire Area 14 - vicinity of 1/2EMXB1

e. Fire Area 19 - vicinity of 1/2EMXG

f.

Fire Area 25 - vicinity of 1 IC02

7. Prior to exceeding the normal 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months AOT associated with TS 3.5.2, Required Action A.1, procedures will have been developed to start the alternate cooling when required,

. and personnel will be designated to ensure that the equipment is started before room temperatures exceed the limits.

During the NRC staff's review of the LAR, the licensee subsequently revised the compensatory actions such that they would be implemented prior to the beginning of the maintenance evolution (see Section 3.4.3 of this Safety Evaluation).

3.4

NRC Staff Evaluation

The licensee has proposed a Unit 1 LAR that would revise the CT for Required Action A.1 of TS 3.5.2 from 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months to 240 hours0.00278 days 0.0667 hours 3.968254e-4 weeks 9.132e-5 months (10 days) on a one-time basis. A footnote would be added to TS 3.5.2 that would allow one train of ECCS to be inoperable for up to 10 days during the Unit 1

, 1 A RHR AHU repair evolution.

The focus of this evaluation is based on several key issues which include:

1. Unit 1 - 1A RHR AHU repair

2. Defense-in-depth concept for Unit 1 - 1 A RHR functionality

3. Compensatory measures

4. RHR operations in Modes 4 and 5

5. Evaluation of Safety Margin

6. Technical Specifications Requirements 3.4.1 Unit 1 - 1 A RHR AHU repair In the LAR, the licensee stated that the 1 A RHR AHU will have to be completely disassembled in order to make the required repairs. Given the location of this AHU, access to the enclosure internals is limited. Removing the cooling coils is required to best facilitate this access. Once the cooling coils are removed, maintenance will validate that no structural looseness exists, and both fan bearings will be replaced. Again, due to space requirements, replacement of the bearings will be done sequentially because there is insufficient room to do both replacements at one time.

The licensee indicated that replacement parts necessary for any anticipated contingency repairs are available on site, and continuous coverage will be present until the work is complete.

Based on the NRC staff's review, the 240-hours of planned AHU maintenance and repairs has 65 hours7.523148e-4 days 0.0181 hours 1.074735e-4 weeks 2.47325e-5 months for unanticipated repairs which includes fan wheel crack and significant shaft damage.

The NRC staff requested the licensee clarify the availability of all spare parts and required testing under the proposed repair time line of 240 hours0.00278 days 0.0667 hours 3.968254e-4 weeks 9.132e-5 months (Request for Additional Information (RAI) #2).

In response to RAI #2 the licensee stated that beyond the bearings whose replacements are already in the scope of work, a fan shaft, a fan wheel, and a fan belt are also in stock and on-site. There are no spare cooling coils on site; however, although it is possible for them to be damaged during removal or reinstallation, any damage could likely be weld-repaired. The licensee indicated that such repairs, if necessary, were factored into the 65-hours for unanticipated work. Any testing associated with potential repairs to the cooling coils would fall

. into the normal post-maintenance testing on the AHU that will be performed after the already planned repairs.

Based on the above, the NRC staff concludes that the licensee has the necessary spare parts on site for the 65-hours of contingency plans to allow adequate time for unexpected repairs and for return to service of the 1A RHR AHU. Since no spare parts are available for the cooling coils, weld repair may be necessary, however, the licensee has indicated that they are prepared and equipped to do the repairs and the NRC staff is confident that any required weld repairs could be completed within the 65 hour7.523148e-4 days 0.0181 hours 1.074735e-4 weeks 2.47325e-5 months contingency window. However, if weld repairs are extensive or complex and exceed the contingency duration, a unit shutdown will be required.

Therefore, the NRC staff finds that the licensee has adequately addressed the scope of the 1A AHR AHU repairs, associated time line, and has addressed contingencies for return to service within 240 hours0.00278 days 0.0667 hours 3.968254e-4 weeks 9.132e-5 months . Therefore, the NRC staff concludes that the amount of additional time requested is appropriate for the scope of the repair.

3.4.2 Defense-in-depth for Unit 1 - 1A RHR Functionality In the LAR, the licensee stated that, for the duration of the repairs to the 1A RHR AHU, alternate forced cooling equipment will be installed. The alternate forced cooling will consist of a temporary chiller, a temporary air handling unit, hoses, and electrical hookup.

This alternate cooling will be manually started if the 1 A AHR train is required. The licensee performed an analysis and determined that the 1 A AHR pump may be operated for up to an hour without the room temperatures becoming excessive. Additionally, the licensee stated that procedures have been developed to start the alternate cooling, when required, and personnel will be designated to ensure that the equipment is started before room temperatures exceed the limits. Although the AHR would be able to perform its design functions with this equipment installed, because the alternate cooling is non-safety, the Unit 1 1A AHR train would not be considered operable.

The licensee stated that the temporary chiller and temporary AHU are commercial-grade components that are built to industry standards. The alternate AHU will be installed in the 1 A AHR pump room and will be located above the floor using seismically qualified mounting.

The temporary AHU fan will be powered from an electrical panelboard in its vicinity. The temporary chiller will be powered from a welding receptacle in its vicinity. The power for both the chiller and the AHU is not safety-related, but is drawn from a permanent station power source, SMXA, which can be fed from either Unit 1 or Unit 2.

The temporary chiller will use the Fire Protection (RF) system as the cooling water supply.

Although the RF pumps are not supplied with safety-related power, they are supplied from diverse power sources; two of the motor-driven fire pumps are connected to the McGuire switchgear, and the third has a separate electrical supply line.

The NRC staff reviewed the licensee's Engineering Change (EC) process with respect to continued functionality of the 1 A RHR system train ECCS function and to ensure that the measure would not adversely impact the safety function of other SSCs that are not part of th~

1 A AHR train system train. In its RAI, the NRC staff requested the licensee to clarify details of the engineering change to support this determination. Specifically, the NRC staff requested information related to 1A AHR room heat' load calculations, available heat removal capacity with the temporary chiller, fire protection flow rate and water temperature requirements to support the heat removal capacity, internal missile analysis for this temporary equipment, loss of refrigeration evaluation for this temporary chiller/AHU, failure modes and affect analysis of this temporary chiller/AHU related to safety-related equipment in the area and available clearance between the temporary chiller/ AHU and the maintenance work that will be performed on the AHR 1A fan (RAI #1).

In it'.s response to RAI #1, the licensee stated that Site System Engineering provided an evaluation to document that, should the 1 A AHR pump start while repairs to the associated AHU are ongoing, manually starting the temporary cooling equipment within one hour would not cause the room temperature limit of 145 °F to be exceeded. This was based on a conservative assumption that the room temperature would rise 15-20 °F/hr when the pump is running without forced cooling and that the initial room temperature is 90 °F. This analysis was based on station operating experience when one of McGuire's containment spray pumps (similarly-sized pump in a similarly-sized room) was previously run without its AHU in service.

The one-hour allowance is for starting the temporary chiller and AHU. Forced cooling would be provided within one hour, so the engineering evaluation did not assess the impact on room temperature beyond that period. The total sensible heat load for the 1 A AHR pump room is 96,815 BTU/hr. The temporary chiller is rated at 144,000 BTU/hr, and the temporary AHU is r

rated at 107, 170 BTU/hr; therefore, the temporary equipment is sized to provide sufficient cooling for the room.

The chiller ratings are based on a cooling water flow rate of 36 gpm at 85 °F. The 2 inch fire protection (RF) system drain line being used to supply cooling water to the chiller is capable of providing at least 36 gpm to the chiller, and the impact of this flow diversion on the RF system has been considered. The oversized chiller ratings allow for additional margin should the RF water temperature rise above 85 °F. Based on the above, the NRG staff cononcludes that the licensee has properly evaluated the impact of the load on the fire system and there is additional margin, should the RF water temperature rise above 85 °F.

The temporary chiller is installed in a hallway on the level above the 1 A AHR pump room and is not in the vicinity of any other equipment. The design of the chiller is such that missiles would not be generated during a catastrophic equipment failure: Installation testing of the temporary chiller prior to the 1A AHR AHU maintenance work would provide assurance that all connections are tight and that refrigerant levels are correct, which minimizes the potential for a loss of refrigerant. However, if a loss of refrigerant did occur, it would not have an impact on the operability of any permanent plant equipment (near the chiller), including the Unit 1 1 B AHR pump train.

The potential for the temporary AHU, which is installed inside the 1 A AHR pump room, to fail catastrophically has also been evaluated. Based on the design (squirrel-cage fan with multiple attachment points), there is a low chance of fan blades energetically exiting the device.

Although postulated missile damage to the 1 A AHR pump would not be expected, it should be noted that the temporary AHU would only be in operation following an automatic AHR pump start. Therefore, the likelihood of missile damage is even more remote. Given this consideration the NRG staff considers that there is a very low chance of missile damage from the temporary equipment if operating. Further, the equipment would only be operated if AHR was in service,.making the likelihood of missile damage even more remote.

The temporary AHU is installed in the 1 A AHR pump room and is locatetJ approximately 15 feet away from the permanent AHU. The distances and orientations are such that the planned work on the permanent fan would not damage the temporary AHU.

Based on the above, the NRG staff has determined that the temporary equipment (AHU with chiller and fire water cooling) are designed* adequately with an 11 % margin to maintain the Unit 1 1A AHR pump available during repairs to the Unit 1 1A AHR AHU. Room heatup of the Unit 1 1 A AHR is controlled with operator actions to take place within one hour to start-the temporary AHU and chiller if the 1 A AHR pump is started. In addition, the licensee has adequately addressed the potential of missiles from the temporary equipment, and stated that given a missile event there would not be a loss of Unit 1 AHR function. Also, the licensee has adequately addressed the potential of refrigerant leaks and stated that given a loss of refrigerant event there would not be a loss of Unit 1 AHR function.

The licensee stated in the amendment request that a potential break in the 2 inch cooling water supply hose could cause fire protection (RF) to introduce water to elevations 716' or 695' of the Auxiliary Building. The existing flooding analysis calculations have already reviewed the impact of a failure of six inch and eight inch RF piping, as such failure of a two inch hose is bounded.

Due to the low volume in the closed loop, a break in the 1.5 inch insulated chilled water loop is not a flooding concern.

The NRG staff requested.the licensee to clarify the potential-effects of a rupture of the cooling water supply hose from RF (RAI #4). In response, the licensee stated that the 2 inch rubber hosing used to supply RF water to the temporary chiller is rated for 200 psi. The RF supply pressure is 1!3SS than 150 psi, so the system pressure is within the design limits of the hose.

When connected to the chiller, the hose is not routed near any equipment that would be harmed by water spray in the event that the hose does break. The 1.5 inch hose used to connect the chiller to the AHU inside the 1 A AHR pump room is rated for 250 psi, which bounds the 45 psi pressure that would be seen in this closed loop. In the event of hose failure, water could spray into the pump room until the limited volume of water in the loop (approximately 60 gallons) fully drained. However, due to the fully-enclosed nature of the 1 A AHR pump motor, this brief period of spray would not adversely affect the equipment. Furthermore, floor drains inside the pump room would ensure that excessive volumes of water do not remain on the floor.

The NRG staff considers that the 2-inch rubber hose (rated at 200 psi) is adequate for the RF pressure (150 psi) to support the temporary chiller operations. In addition, the NRG staff considers that the 1 Y2 inch insulated hose (rated at 250 psi) is adequate for the qhilled water pressure (45 psi). Also water spray, in the event of either hose breakage, does not negatively affect Unit 1 AHR operations.

In conclusion, the NRG staff concludes that the temporary equipment that will be in place to maintain functionality of the Unit 11A AHR pump during repairs to the Unit 1 1A AHR AHU is of sufficient design, capacity, and reliability to support the AHR operation, if needed. Additionally, there is sufficient justification that operations of the temporary equipment which includes a chiller, AHU, and various hoses would not negatively affect the Unit 1 AHR B train in the event of any failures.

3.4.3 Compensatory Measures In the LAA, Duke Energy provided seven proposed compensatory measures to be implemented during the repair of the AHR AHU. The licensee's original LAA indicated that the compensatory actions would performed prior to exceeding the 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months AOT.

The NRG staff requested an explanation of the logic to have the compensatory actions performed before exceeding the normal 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months AOT versus having them performed prior to rendering the AHR system inoperable. Specifically, the NRG staff requested a justification for why performing these 7 compensatory actions at this point of the work has a benefit for defense-in-depth function and a justification for why training is not a part of these commitments as it relates to procedures for operating the temporary AHU equipment (RAI #3).

In response, the licensee stated that all compensatory measures that were proposed previously to be performed prior.to exceeding the normal 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months AOT have been conservatively reworded to ensure that they are performed prior to entering the repair evolution for the AHU. The licensee indicated that no training is warranted for the procedure used to start the1 temporary cooling equipment because the steps are simple and straightforward and because normal maintenance practices include pre-job briefings, which drive review of procedure steps prior to work evolutions.

(

Per the licensee's November 13, 2015, supplement, the revised compensatory actions are as follows:

1. The alternate forced cooling equipment (chiller and AHU) will be installed and tested in accordance with the engineering change (EC) process prior to the 1 A THT AHU repair evolution.

2. At least one ground water drainage system (WZ) 'C' sump pump will be available prior to the 1 A AHR AHU repair evolution.

3. The following SSCs will be protected prior to the 1 A AHR AHU repair evolution, and elective maintenance to them will be deferred during the repairs to the IA AHR pump motor AHU:

o 1 B AHR train o

1 B Nuclear Service Water System (NSWS) train o

1 B Component Cooling Water System (CCWS) train o

1 B Emergency Diesel Generator (EOG) o Power supply to the alternate cooling equipment o

One WZ C sump pump

4. Prior to the 1A AHR AHU repair evolution, McGuire will monitor the National Weather Service for potential severe weather conditions. To the extent practical, severe weather conditions will be avoided.

5. Prior to the 1 A AHR AHU repair evolution, and daily thereafter, McGuire will contact the Transmission Control Center {TCC) regarding system grid stability. To the extent.

practical, system grid instability will be avoided.

6. Prior to the 1 A AHR AHU repair evolution, roving fire watches will be established in the following areas to minimize the chance of fire-induced LOCAs:

o Unit 1 4.16kV Switchgear Rooms o

Unit 1 Auxiliary Feedwater Pump Room o

1 B Diesel Generator Room o

Fire Area 14 - vicinity of 1/2EMXB1 o

Fire Area 19 - vicinity of 1/2EMXG o

Fire Area 25 - vicinity of 1 IC02

7. Prior to the 1 A AHR AHU repair evolution, procedures will have been developed to start the alternate cooling when required, and personnel will be designated to ensure that the equipment is started before room temperatures exceed the limits.

The NRC staff considers the seven compensatory actions, which includes testing, sump pump availability, protected equipment, monitoring of weather service, contacting the transmission control center, fire watches, and procedures adequately described and address compensatory actions during the repairs for Unit 1 1A AHR AHU AOT for the proposed240 hours of repair.

Further, the NRC staff considers the implementation of the compensatory actions prior to inoperability of the RHR system to be appropriate. Based on the above, the NRC staff finds the compensatory actions to be of an appropriate scope and that they will be implemented in a timely fashion to minimize the likelihood of needing RHR and maximize the likelihood of the RHR function being available, if needed.

3.4.4 RHR Operations in Modes 4 and 5 The licensee stated that the proposed LAR involves a one-time extension to TS 3.5.2 to.

facilitate repairs to the 1A RHR AHU. During the AHU repair evolution, important equipment (i.e., the opposite train) will be protected and compensatory measures will be in place. These activities are controlled by the licensee's normal risk management program. TS 3.5.2 Mode of applicability is Modes 1, 2, or 3. Based on the NRC staff's review, the repair work is assumed to have started with Unit 1 in Modes 1, 2 and 3. The original LAR did not discuss the course of action during a Unit 1 reactor trip or other requirement to transition to a lower mode with the 1 A RHR AHU ongoing maintenance. This is of interest because, unlike the other ECCS systems, the RHR system is typically in service and used for decay heat removal when in Modes 4 or below.

The NRC staff requested the licensee to address the potential for the TSs to require a transition to Mode 4 or Mode 5 with only one RHR pump Operable. Specifically, the licensee was requested to address Unit 1 Technical Specification Required Actions that direct transition to Mode 4 and Mode 5 with only one Operable RHR train (since the Unit 1 1A RHR AHU is being repaired). Additionally, the licensee was asked to describe any necessary steps and additional compensatory measures that have not been previously addressed with respect to Mode 1, 2 or 3 (RAI #5).

In response, the licensee stated that if McGuire Unit 1 fails to meet TS 3.5.2, it must be in Mode 4 within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months . This situation could occur if the 1A RHR AHU repair work takes longer than anticipated such that the proposed AOT extension ruris out. In such a scenario, operators would take action to bring the unit into the required mode per TS 3.5.2.

Once in Mode 4, TS 3.5.3, "ECCS - Shutdown," only requires one RHR pump to be operable.

As long as the unit remains in Mode 4 (or in Mode 5 with the RCS loops filled), a single operable RHR pump is sufficient to meet the requirements of TS 3.5.3, TS 3.4.6, "RCS Loops Mode 4,"

and TS 3.4.7,. "RCS Loops - Mode 5, Loops Filled." TS 3.4.8, "RCS Loops Mode 5, Loops Not Filled,. does require two operable RHR trains, but since one train can fulfill the function, the second train is required only for redundancy. Under normal circumstances, the decision to enter reduced inventory operations is under operator control, but a LOCA could result in the loops not being filled. Further, the licensee indicated that, if this occurred while maintenance on the 1A RHR AHU was underway, the temporary cooling equipment would allow the 1A RHR train to remain available. The 1 B RHR pump would be unaffected and would remain operable.

Completion of repair work to the 1A RHR AHU to restore train operability would occur as allowed by plant conditions. With only one operable RHR train, McGuire Unit 1 can be brought down to Mode 5 and still meet its TS requirements as long as the RCS loops remain filled, so no additional compensatory measures or commitments are necessary. Previously existing plant procedures are sufficient to ensure the safety of the public.

Based on the above, the NRC staff concludes that the licensee has appropriately evaluated what actions would be necessary if the plant were required to transition to a lower mode of operation while exercising the extended Completion Time.

3.4.5 Evaluation of Safety Margin

In the LAR the licensee stated that, with respect to safety margin, two key points were evaluated;

1)

Codes and Standards or alternatives approved for use by the NRC are met.

The design and operation of the 1 A RHR system train is not altered by the proposed TS Completion Time extension. The 1 A RHR train is periodically removed from service for maintenance and testing.

2)

Safety analysis acceptance criteria in the plant licensing basis are met or proposed revisions provide sufficient margin to account for analysis and data uncertainties.

The safety analysis acceptance criteria stated in the UFSAR are not impacted by this change. The proposed change will not allow plant operation in a configuration-outside the design basis. The requirements regarding the ECCS functions credited in the accident analysis will remain the same. As also discussed in this LAR, a defense-in-depth measure will assure the 1A RHR pump remains available to perform its ECCS function even while the 1A AHR AHU is out of service. As such,' it can be concluded that safety margins are not impacted by the proposed change.

Based on the above, the NRC staff concludes that the Unit 1 1A RHR AHU is not being physically altered or modified and 'Like tor like' parts will be utilii;ed in the rework of the 1A RHR AHU. Additionally, the proposed action completion time does not result in an unreasonable decrease in the availability of a redundant train of RHR (3 days verses 1 O days): Therefore, an adequate margin of safety will be maintained for the extended completion time.

Thus, the NRC staff determines that the extended allowed completion time is not in conflict with Codes and Standards approved for use by the NRC relevant to the Unit 1 RHR system. Safety analysis acceptance criteria as specified in the UFSAR, particularly for the ECCS function postulating a large break LOCA, are met during the extended allowed completion time, assuming no additional failures.

3.4.6 Technical Specifications Requirements In the LAR, the licensee requested to add a note to TS 3.5.2 to support the repairs for 1 A AHR AHU. The note states:

For Unit 1 only, the Completion Time that one train of ECCS can be inoperable as specified by Required Action A. 1 may be e~tended beyond the "72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months " for up to 1 O days during the 1 A RHR AHU repair evolution. This allowance may be used one-time for the 1 A AHR AHU repair and is contingent on meeting the compensatory

~

measures and commitments described in MNS LAA submittal correspondence letter

MNS-15-0 69. Upon completion of the repair and restoration, this footnote is no longer applicable and will expire on March 31, 2016.

As indicated in its RAI, the NRG staff identified the language in the note was not consistent with the recommended style of Standard Technical Specifications, Westinghouse Plants, Revision 4.0, NUREG - 1431. Specifically, the NRG staff noted that the original footnote is not succinct and has potential for misinterpretation. Also, when a compensatory *measure is a condition of a Technical Specification, it should not be referred to as a comr:nitment in the TS wording.

In response, the licensee provided a revised footnote. This footnote is more succinct and no longer refers to the compensatory measures as "commitments." Specifically, the revised footnote states:

For Unit 1 only, the Completion Time for Required Action A.1 may be extended one-time to 1 O days during the 1 A AHR AHU repair evolution and is contingent on meeting the compensatory measures described in MNS correspondence letter MNS-15-093. Upon completion of the repair evolution, this footnote is no longer applicable and will expire on March 31, 2016.

The NRG staff considers the revised footnote to be appropriately succinct, have a low chance for misinterpretation, and appropriately characterizes the compensatory actions. Thus, the NRG staff finds the revised footnote acceptable. Inclusion of these actions in the TS footnote establishes the compensatory actions as a licensing obligation rather than a commitment.

4.0 STATE CONSULTATION

In accordance with the Commission's regulations, the North Carolina State official was notified of the proposed issuance of the amendments. The State official had no comments.

5.0 ENVIRONMENTAL CONSIDERATION

The amendments change a requirement with respect to the installation or use of facility components located within the restricted area as defined in 1 O CFR Part 20. The NRG staff has determined that the amendments involve no significant increase in the amounts and no significant change in the types of any effluents that may be released offsite and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (80 FR 65810). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 1 O CFR 51.22(c)(9). Pursuant to 1 O CFR 51.22(b ), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.

6.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, that: ( 1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) there is reasonable assurance that such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributor(s):

Date: February 3, 2016 L. Wheeler K. West S.Sun D. Frumkin E. Miller

ML16004A352 OFFICE NRR/LPL2-1/PM NRR/LPL2-1/LA NAME GEMiller SFigueroa DATE 02/02/16 01/7/16 OFFICE DSS/STSB/BC OGC NAME RElliott*

SFowler (NLO)

DATE 01/21/16 01/22/16 DSS/SRXB/BC EOesterle*

01/13/16 DORL/LPL2-1/BC MMarkley 02/03/16

v t e Letter Sequence Approval
CAC:MF6666, AOT Extension to 7 Days for LPI and Containment Spray - BAW-2295-A, Rev. 1 (Approved, Closed)
Initiation Request Acceptance... Administration Questions 26 October 2015 Answers 13 November 2015 Results Approval Other:
MONTHYEAR2015-11-13 [Table View]

ML16004A352