NL-10-1623, Emergency Technical Specification Revision Request for TS 3.7.14, Engineered Safety Features (ESF) Room Cooler and Safety-Related Chiller System - Response to Requests for Additional Information
| ML102310142 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 08/18/2010 |
| From: | Marino P Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-10-1623 | |
| Download: ML102310142 (12) | |
Text
Paula M. Marino Southern Nuclear Vice President Operating Company. Inc Engineering 40 Invemess Center Parkway Birmingham, Alabama 35242 Tel 205.992.7707 Fax 205.992.6165 pmmarino@southernco.com SOUIHERN'\
August 18, 2010 COMPANY Docket Nos.: 50-425 NL-10-1623 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Vogtle Electric Generating Plant Unit 2 Emergency Technical Specification Revision Request for TS 3.7.14 Engineered Safety Features (ESF)
Room Cooler and Safety-Related Chiller System Response to Requests for Additional Information Ladies and Gentlemen:
On August 18, 2010, Southern Nuclear Operating Company (SNC) requested an emergency amendment to the Vogtle Electric Generating Plant (VEGP) Unit 2 Technical Specifications (TS). Appendix A to Operating License NPF-81. The proposed change would revise TS 3.7.14, Engineered Safety Features (ESF)
Room Cooler and Safety-Related Chiller System" such that. with one safety related chiller train inoperable. the allowed Completion Time (CT) for Condition A is extended from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 14 days, on a one-time only basis. The 14 day CT will allow time to repair the Unit 2 A-train ESF chiller while maintaining plant operation.
In subsequent discussion of this emergency TS amendment request, the NRC staff identified the need for certain supplemental information to be provided in writing. Enclosures 1 & 2 provide the SNC responses to these requests for additional information.
This letter contains no new NRC commitments. If you have any questions, please contact Ms. Tracy Honeycutt at (205) 992-6896.
Ms. P. M. Marino states she is Vice President - Engineering of Southern Nuclear Operating Company, is authorized to execute this oath on behalf of Southern Nuclear Operating Company and to the best of her knowledge and belief, the facts set forth in this letter are true.
U. S. Nuclear Regulatory Commission NL-10-1623 Page 2 Respectfully submitted, P. M. Marino Vice President - Engineering Swom,to and su~rbed be. fore me this \'~ daYOf~ ,2010.
~WC1l\l~~~
Notary Public My commission expires: !/-O.J.-e:J..D13 PM M/DWDllac
Enclosures:
- 1. Response to Requests for Additional Information
- 2. List of Essential Equipment Served by Train A ECWS cc: Southern Nuclear Operating Company Mr. J. T. Gasser, Executive Vice President Mr. T. E. Tynan, Vice President - VogUe Ms. P. M. Marino, Vice President - Engineering RType: CVC7000 U. S. Nuclear Regulatory Commission Mr. L. A. Reyes, Regional Administrator Mr. R. E. Martin, NRR Project Manager - Vogtle Mr. M. Cain, Senior Resident Inspector - Vogtle Mr. P.G. Boyle, NRR Project Manager State of Georgia Mr. C. Clark, Commissioner - Department of Natural Resources
Vogtle Electric Generating Plant Unit 2 Emergency Technical Specification Revision Request for TS 3.7.14 Engineered Safety Features (ESF)
Room Cooler and Safety-Related Chiller System Enclosure 1 Response to NRC Requests for Additional Information
Vogtle Electric Generating Plant Unit 2 Emergency Technical Specification Revision Request for TS 3.7.14 Engineered Safety Features (ESF)
Room Cooler and Safety-Related Chiller System Enclosure 1 Response to NRC Requests for Additional Information NRC RAI #1:
Please list all essential equipment [1] that receives cooling from the Unit 2 A-train ESF chiller.
[1] For the purposes of this equipment, consider, "essential" to mean that equipment which is relied upon to terminate or mitigate the effects of a design basis transient or accident.
SNC Response:
See Enclosure 2, "List of Essential Equipment Served by Train A ECWS" NRC RAI#2:
For the safety related loads identified above, specify which loads are still OPERABLE, if any. For the INOPERABLE loads, discuss how your compensatory actions help provide some measure of defense in depth for the INOPERABLE loads.
SNC Response:
All of the loads served by the 2A Essential Chilled Water System (ECWS) are considered INOPERABLE as required by LCO 3.0.6. However, the Conditions and Required Actions of the supported systems (Le. loads) are not required to be entered as allowed by LCO 3.0.6. The 2B ECWS is a separate independent train that provides the required cooling to the equivalent loads in train 28. The compensatory measures put in place ensure work on equipment that could potentially have an adverse impact on the normal chilled water system, the 2B ESF chilled water system or that could affect the availability of the offsite power source are screened and limited to only that deemed necessary to ensure regulatory compliance or to support safe continued plant operation. Additionally, opening doors and installing fans in selected rooms mitigates the potential rise in room temperature ensuring the availability of the housed eqUipment in the event all the chilled water systems are lost. This compensatory measure is not credited with maintaining the equipment in the affected room(s) OPERABLE but is deemed to be a prudent action.
NRC RAI #3:
Please evaluate the operability for each system, structure or component (SSC) identified in #1, above, in light of the loss of the ESF chiller. Provide a summary of this evaluation that addresses the ability of each SSC to perform its intended safety function.
Page 1 of 7
Vogtle Electric Generating Plant Unit 2 Emergency Technical Specification Revision Request for TS 3.7.14 Engineered Safety Features (ESF)
Room Cooler and Safety-Related Chiller System Enclosure 1 Response to NRC Requests for Additional Information SNC Response:
The ECWS is comprised of two separate 100% independent trains. As discussed in the response to RAI #2, none of the loads served by the 2A ECWS are considered OPERABLE. However, all of the loads served by the 2B ECWS are OPERABLE and capable of performing their intended function.
NRC RAI #4:
Considering the results of the evaluation performed in response to #3, above, address the ability of Vogtle Unit 2 to respond to the design basis transients (i.e., loss of offsite power) in a manner consistent with the plant safety analysis, and consistent with licensing basis requirements for shut down cooling and residual heat removal.
SNC Response:
The ECWS is comprised of two separate, 100% independent trains. As discussed in the response to RAI #2, none of the loads served by the 2A ECWS are considered OPERABLE. However, all of the loads served by the 2B ECWS are OPERABLE and capable of performing their intended function. Therefore, the response to the design basis transients is unaffected.
NRC RAI #5:
Considering the results of the evaluation performed in response to #3, above, address the ability of Vogtle Unit 2 to respond to the design basis accidents (i.e., small break loss of coolant accident) in a manner consistent with the plant safety analysis. Also, address the continued ability of Vogtle Unit 2 to meet the core coolability and long term cooling criteria established at 10 CFR 50.46(b)(4) and (b)(5).
SNC Response:
The ECWS is comprised of two separate, 100% independent trains. As discussed in the response to RAI #2, none of the loads served by the 2A ECWS are considered OPERABLE. However, all of the loads served by the 2B ECWS are Operable and capable of performing their intended function. Therefore, the response to the design basis accidents is unaffected.
NRC RAI #6:
Discuss whether the affected SSCs are required to provide spent fuel pool COOling under any off-normal conditions, and if so, what alternative means are available to provide adequate spent fuel cooling.
Page 2 of 7
Vogtle Electric Generating Plant Unit 2 Emergency Technical Specification Revision Request for TS 3.7.14 Engineered Safety Features (ESF)
Room Cooler and Safety-Related Chiller System Enclosure 1 Response to NRC Requests for Additional Information SNC Response:
Spent fuel pool heat exchanger rooms are cooled by train oriented room coolers with both NCW and train-oriented ECW cooling coils for each spent fuel pool cooling train. During normal plant operation, the NCW cooling coil in the room coolers provides the necessary cooling function for the spent fuel pool heat exchanger rooms. In the event of loss of the NCW cooling source while the A train is inoperable, the B train ECW coil will provide the necessary cooling function for the B train spent fuel pool heat exchanger room.
NRC RAI #7:
Please provide additional information to describe why there is a need to extend the completion time for TS 3.7.14.
SNC Response:
The request for a 14 day allowable completion time is based on a number of factors. This work involves a complete teardown of a large, complicated, 300 ton chiller. As the machine is reassembled, parts must be perfectly sealed as the system operates under vacuum. It is not uncommon to have leakage requiring rework and even disassembly for re-sealing. In addition, the amount of water which leaked into the refrigerant will likely necessitate protracted purging for moisture removal 'from the refrigerant system. These are variables that make scheduling the work activity challenging with many unknown contingencies. In this case, complete motor replacement is deemed necessary due to moisture entrainment in the windings and this motor work is the principle driver for the time required to return the 2A chiller to service. Additionally, the size of the machine and the size of the room create challenges with constraining some activities to being performed in series. Special lifting and rigging of large components require detailed planning and limit work activities during lifts. A schedule was generated within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of the LCO entry resulting in a 228 hour0.00264 days <br />0.0633 hours <br />3.769841e-4 weeks <br />8.6754e-5 months <br /> duration. Variables associated with potentially finding corrosion or erosion, damaged soft parts, availability of vendors, the need for special welding, and the aforementioned sealing and purging difficulties have resulted in our request for the schedule duration plus contingency time. Work activities like this on the ESF Chillers have exclusively been performed during refueling outages. As such, planning and scheduling for this discovery activity will require re-evaluation and adjustment.
Page 3 of 7
Vogtle Electric Generating Plant Unit 2 Emergency Technical Specification Revision Request for TS 3.7.14 Engineered Safety Features (ESF)
Room Cooler and Safety-Related Chiller System Enclosure 1 Response to NRC Requests for Additional Information NRC RAI #8:
Paragraph 5.0 of the draft submittal states: "Following a SI-inducing IE, both trains of the ECWS are automatically actuated; on loss of offsite power the ECWS is manually actuated."
Have you confirmed that the other chiller train, Unit 2 B-train chiller train, is OPERABLE?
SNC Response:
The Unit 2 Train B chiller has been confirmed OPERABLE. The Unit 2 Train 8 chiller was walked down to check for similar issues to those discovered on 2A.
The 2B chiller evaporator sight glass had refrigerant in it and there were no signs of water or a film of debris as was observed in Train A. Also, the purge system showed 0.0 minutes of pump-out in the last 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and the purge moisture indicator was Green, confirming that no air or water is leaking into the refrigerant system. On 7/20/2010 at 15:13, surveillance 145108-2 was completed, which demonstrated operability of the Control Room Emergency Filtration System. That test included a 10 hour1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> run of the Unit 2 Train 8 chiller.
NRC RAI #9:
Provide a discussion of the historic reliability of the Vogtle Unit 2 B-train ESF chiller. Include in this discussion the maintenance history and recent surveillance results and trending.
SNC Response:
Each of these chillers is run a minimum of 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> per month to support the CREFS operability run. There are quarterly actuation logic tests that start each chiller also. There are PMs performed on controls and breakers for the chillers that are performed at 18 and 54 month frequencies. There are inspections and motor megger testing at a 54 month frequency. Oil sampling is done every 54 months to check for wear metals and oil degradation. There is a 12.5 year regasket PM that includes mechanical inspection of internal components.
Additionally, there are monthly Engineering walk downs for these chillers. All of these chillers are Maintenance Rule a2 status. There have been control system reliability issues with an average of two failures per year for all four machines.
NRC RAI #10:
How long does each room have before compensatory measures would be required? If portable fans are to be used are sufficient numbers/capability staged and are sufficient power outlets available/accessible that are expected to have power available.
Page 4 of 7
Vogtle Electric Generating Plant Unit 2 Emergency Technical Specification Revision Request for TS 3.7.14 Engineered Safety Features (ESF)
Room Cooler and Safety-Related Chiller System Enclosure 1 Response to NRC Requests for Additional Information SNC Response:
In the documentation of the current peer reviewed PRA model, only room R-B18, "480V SWGR 2BB06", located in the Control Building, is assessed to require operator action (Le. to open the door). According to the VEGP room heat up calculations, the available time to implement the compensatory measure of opening the door is 11.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. It is important to note that room R-B 18 is the Unit 2 Train B 480 vac switchgear room, and this room is not affected by the failure of the ECWS Train A. The room heat-up calculations show that in the event of total loss of room cooling, the SSCs located in the equivalent Unit 2 Train A 480 vac switchgear room will not fail to perform their PRA-credited function within the PRA mission time.
Opening additional doors and using portable fans are not required as compensatory measures, but are contingencies for additional defense in depth to add margin.
The doors identified to be propped open are as follows:
Control Bldg Room B04 480 vac A Train Switchgear Room Control Bldg Room B18 480 vac B Train SWitchgear Room Control Bldg Room B26 125 vdc C Train Switchgear Room Control Bldg Room B29 125 vdc A Train Switchgear Room Control Bldg Room B30 125 vdc B Train Corridor Control Bldg Room B31 125 vdc D Train Switchgear Room Control Bldg Room B36 125 vdc B Train Switchgear Room Fans and the required extension cords have been staged in the vicinity of these rooms. In the situation where NCWS and Train B ECWS are lost, the doors to the rooms listed above will be propped open. The fans will be positioned to draw air from the area outside these rooms and discharge into these rooms.
NRC RAJ #11:
How would opening doors and use of portable fans alter the designed air flow patterns? Would potential airborne radioactivity impede necessary operator/personnel actions in other areas/rooms?
SNC Response:
We expect to open doors and install fans, as described above, only in the case of loss of all HVAC (in the Control Building). On loss of the HVAC there would be no design air flow, hence the only air flow patterns (apart from natural convection) would be those established by the portable fans. In addition, there would be no driving force to introduce radioactivity into the control building, hence there would be no impediment to operator actions in the control building due to airborne radioactivity .
Page 5 of 7
Vogtle Electric Generating Plant Unit 2 Emergency Technical Specification Revision Request for TS 3.7.14 Engineered Safety Features (ESF)
Room Cooler and Safety-Related Chiller System Enclosure 1 Response to NRC Requests for Additional Information NRC RAI #12:
Is the normal chiller a potentially effective backup for the 2B ESF chiller, is it expected to be able to handle post accident heat loads and maintain acceptable post accident or shutdown cooling ambient temperatures?
SNC Response:
Neither ECWS nor NCWS are required to support PRA-credited accident mitigating functions. However, NCWS can be used as a backup for ECWS in those locations served by both systems for all events except loss of offsite power.
NCWS capacity is much larger than ECWS capacity. NCWS is operating and ECWS is in standby during normal power operations. If a reactor trip occurs, NCWS continues to operate unless there is a safety injection signal or loss of offsite power. Therefore, during normal operation and after shutdown, NCWS is the primary source of chilled water. In case of a LOCA, the NCWS trips and the ECWS auto starts on a safety injection signal. However, NCWS could be used as a backup if it is manually restarted.
NRC RAI #13:
Provide clarification regarding surveillance testing to be performed on "protected equipment" during the extended Completion Time period.
SNC Response:
The following surveillances on Unit 2 Train B protected equipment will be required to be performed during the LCO extension for 2A ESF Chiller:
14400-202 TRAIN B CONTROL ROOM EMERGENCY FILTRATION ACTUATION LOGIC TEST The purpose of this test is to generate a Control Room Isolation signal and verify the AUTO start of the Unit 2 Train B CREFS and Train B Essential Chiller. This surveillance begins with the Control Room Normal HVAC in service, simulates a high radiation signal to generate a Control Room Isolation signal, and starts the Train B CREFS and Train B Essential Chiller. Upon completion of the testing, the Train B Essential Chiller is placed in the STOP position during restoration and the Chilled Water Pump is allow to run for two minutes as required by the procedure.
During the two minutes the Train B Essential Chiller is in STOP concurrent with the Train A Chiller being INOP, entry into TS 3.0.3 for two INOPERABLE ESF Chillers will be required. This surveillance must be completed satisfactorily by 8 27-2010 at 15:53.
Page 6 of 7
Vogtle Electric Generating Plant Unit 2 Emergency Technical Specification Revision Request for TS 3.7.14 Engineered Safety Features (ESF)
Room Cooler and Safety-Related Chiller System Enclosure 1 Response to NRC Requests for Additional Information 14510-202 TRAIN 8 CONTROL ROOM EMERGENCY FILTRATION SYSTEM OPERA81L1TY TEST The purpose of this surveillance is to demonstrate the operability of the Unit 2 Train 8 Control Room Emergency Filtration System. This surveillance is typically performed by starting the Train 8 CREFS in conjunction with the Train 8 ESF chiller. However, this surveillance only requires that the Train 8 CREFS be in service. The plan will be to also start a Unit 1 CREFS and ESF chiller to provide the cooling for the Control Room and then place the Unit 2 Train 8 CREFS in service for this surveillance. This configuration will prevent placing Unit 2 Train 8 ES chiller in service thereby avoiding the inoperability during the shutdown steps.
This surveillance must be completed satisfactorily by 8-28-2010 at 09:13.
NRC RAI #14:
The guidelines of Regulatory Guide 1.177, "An Approach for Plant-Specific, Risk-Informed Decisionmaking: Technical Specifications" specifies Traditional Engineering Considerations. Among considerations not addressed in the draft submittal are:
Defense against common cause failures: Discuss the cause of the failure of Unit 2 A-train chiller and what precautions have been taken to eliminate this cause of failure for Unit 2 B-train chiller train.
SNC Response:
The cause of the water intrusion into the refrigerant of the 2A ESF chiller has not been determined. We know that water from the ECWS or from the Nuclear Service Cooling Water (NSCW) system leaked through tubes or around tubes in the tubesheet but the mechanism isn't completely understood. The leak testing, pressure testing, and eddy current testing completed or in progress on the 2A chiller will identify the cause and repair will follow. Results from the investigation will be applied to the 28 ESF chiller and the Unit 1 ESF chillers from a broadness perspective. There have been no previous tube leaks on the VEGP ESF chillers, and, based on our recent experience, operator monitoring will identify leakage on other ESF chillers.
Page 7 of 7
Vogtle Electric Generating Plant Unit 2 Emergency Technical Specification Revision Request for TS 3.7.14 Engineered Safety Features (ESF)
Room Cooler and Safety-Related Chiller System Enclosure 2 List of Essential Equipment Served by Train A ECWS
Vogtle Electric Generating Plant Unit 2 Emergency Technical Specification Revision Request for TS 3.7.14 Engineered Safety Features (ESF)
Room Cooler and Safety-Related Chiller System Enclosure 2 List of Essential Equipment Served by Train A ECWS ECW Is Essential General Room I Component Chilled Water, NCW Is ECW U2Room' Dwg.Re' Description Normal Chilled Water Served By SarvedBy Train Remarks R-D104 2X4DB228 A train Swgr & MCC 2-1555-A7-001 NCW ECW A R-C07 2X4DB228 A train Swgr & MCC 2-1555-A7-OO3 NCW ECW A R-149 2X4DB228 A train Swgr & MCC 2-1555-A7-005 NCW ECW A R-D22 2X4DB228 RHRpumpA 2-1555-A7-OO7 NCW ECW A R-D05 2X4DB228 Cont. Spray Tr. A pump 2-1555-A7-OO9 ECW A R-A98 2X4DB228 CCW Tr. A pumps 2-1555-A7-011 ECW A R-C16 2X4DB228 CVCS Charging Pumps A 2-1555-A7-013 NCW ECW A I R-B119 2X4DB228 SIS Pump A 2-1555-A7-015 ECW A R-A91 2X4D8228 SFP Hx and Pump Room A 2-1555-A7-017 NCW ECW A Control Building Various room A train Swgr, ESF Sequencers, MCC A train 2X4DB233 rooms, A train Battery rooms 2-1532-A7-OO1 NCW ECW A A train Swgr & MCC, Cable Various 2X4D8233 Spreading Room 2-1539-A7-005 NCW ECW A Aux Relay Room Train A and Various 2X4D8233 Cable Spreading Room 2-1539-A7-001 ECW A Piping Pen Rm AX4DB231 2~1551-A7-OO1 NCW Piping Penetration Area 2-1551-A7-OO2 NCW 2X4DB233 Train A cooler 2-1561-E7-001 ECW A Also served by NSCW Control Room AX4DB2311 Control Room (Common to 2-1531-N7-001 ECW A Also served by 1*1531*
2X4DB2331 Units 1 &2) A-1531-A7-001 &2 NCW N7*001 (Unit 1 A train) 2X4DB234 Listing of Componentsl Areas cooled by Essential Chilled Water (ECW)
Some Components are supplied by Essential Chilled Water (ECW) and Normal Chilled Water (NCW) via dual coil cooling Units as indicated NSCW is Nuclear Service Cooling Water Page 1 of 1