ML20196B394
| ML20196B394 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 11/25/1998 |
| From: | Schwartz G COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20196B400 | List: |
| References | |
| NUDOCS 9812010094 | |
| Download: ML20196B394 (12) | |
Text
, 2..- , Cammonweahh Ediwn Company Braidwood Generating Station l Houte ol, Ikix H1 Bracesille, IL 60107-9619 Tel H1545&2501 j
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1 November 25,1998 i
U. S. Nuclear Regulatory Commission ;
ATTN: Document Control Desk Washington, DC 20555
Subject:
Application for Amendment to Appendix A, Technical Specifications, to Facility Opvating Licenses !
i Braidwood Station, Units 1 and 2 Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457 l
Reference:
Letter from Stewart N. Bailey (U.S. NRC) to Oliver D. Kingsley, President, NGG, Commonwealth Edison " Issuance Of Amendment", dated August 18,1998.
Pursuant to 10 CFR 50.90, Commonwealth Edison (Comed) proposes to amend Appendix A, Technical Specifications, of "2cility Operating Licenses NPF-72 and NPF-77 to facilitate the replacement of the 125VDC AT&T batteries with new 125 VDC C&D Batteries while in MODE 1-4. The above Reference issued Amendment No. 94 to the Braidwood Station Units 1 and 2 Technical Specification for the replacement of the AT&T batteries. Since the battery replacement can not be performed within the 2-hour duration currently allowed by the Technical Specification for a unit on-line, the proposed change will provide one-time allowances for Braidwood Station Unit 2 to permit the on-line installation of the batteries.
This request will add new actions necessary to support on-line battery replacement.
Actions will permit the operation of Braidwood Station Unit 2 for 10 days while in MODES 1-4 while one DC division is connected to the existing safety related battery charger and a temporary safety related battery. This alignment will be used while the \lj l current battery is replaced and tested. An additional action will provide an 8-hour i
Completion Time to allow the DC bus to be crosstied to the opposite Unit during the
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}\ 9l0 PDR ADOCK 05000456i P PDR H A Unicum Company
November 25,1998 U.S. Nuclear Regulator Commission ;
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disconnection of the current battery and the connection of the charger and temporary battery. This Completion Time will also be entered during the reconnection of the new battery once installed. This evolution will be performed for each DC Division on Braidwood Station Unit 2.
During the replacement of the batteries of Unit 2 with the unit at power, Braidwood Station will capitalize on performing the installation. Performance of this activity with the unit at power will afford the station the opportunity to accomplish the activity while maintaining both units in steady state operation. The lessons learned from the Unit 1 battery replacement will also be available for application as well. The on-line replacement offers several scheduler and economic advantages over performing the activity during an ;
outage. Braidwood Station has reviewed the activity and finds no significant safety consequences associated with performing this activity in the manner proposed.
In general, replacement of the batteries on-line will not only reduce outage scope but will result in a safer and better controlled outage. Details of the proposed change are included in Attachment A.
To facilitate your review mark-ups of the ITS pages are being provided.
l This proposed amendment request is subdivided as follows:
l l 1. Attachment A gives a description and safety analysis of the proposed change in this amendment.
- 2. Attachment B includes the marked-up Improved Technical Specifications (ITS).
- 3. Attachment C describes Comed's evaluation performed in accordance with 10 CFR 50.92(c), which confirms that no significant hazard consideration is l involved.
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- 4. Attachment D provides the Environmental Assessment.
This proposed amendment has been reviewed and approved in accordance with the requirements of Comed's Quality Assurance Program.
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November 25,1998 U.S. Nuclear Regulator Commission I Page 3 1
Comed is notifying the State ofIllinois of this application for amendment by transmitting ;
a copy of this letter and its attachments to the designated State Official. )
Please direct any questions you may have concerning this submittal to T. W. Simpkin at f (815) 458-2801 extension 2980 of this office.
1 Respectfully, y i I ,
George . Schwartz Station Manager l Braidwood Nuclear Generating Station Attachments: Affidavit A-Description and Safety Analysis l B-Braidwood Station ITS Marked-up Pages '
C-Significant Hazards Consideration !
D-Environment Assessment cc: Regional Administrator - USNRC, RIII NRC Senior Resident Inspector-Byron Station ,
NRC Senior Resident Inspector-Braidwood Station l nrc/98081 tit. doc 1
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bcc: Byron Project Manager- NRR Braidwood Project Manager-NRR i Office of Nuclear Facility Safety - IDNS Nicholas Reynolds-Winston and Strawn l
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STATE OF ILLINOIS )
1 COUNTY OF WILL )
l IN THE MATTER OF )
COMMONWEALTH EDISON (COMED) COMPANY ) Docket Numbers BRAIDWOOD STATION UNITS 1 & 2 ) STN 50-456 & 50-457
SUBJECT:
Application for Amendment to Appendix A, Technical Specifications, to j Facility Operating License Nos. NPF 72 and NPF-77; On Line i
Replacement Of AT&T Batteries l
l AFFIDAVIT i
I affirm that the content of this information i:; in ue and correct to the best of my knowledge,information and belief.
esd a / w t2
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George K. chwarti i Station nager Braidwo d Nuclear Generating ation Subscribed and sworn to before me, a Notary Public in and for he State of Illinois, this 5 +6 day of Ode N be r ,1998.
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Notary Public II OFFidlAUSE U!
!! MICHELLE A TURNBULL }l
( ll NOTARY PUSUC. STATE oF ILUNOIS j MY COMMfSSION EXPIRES:o5/12/01 <l
(_______.________.____________ t i
l PageIof 1 . Affidavit-
l ATTACHMENT A DESCRIPTION AND SAFETY ANALYSIS OF PROPOSED CHANGES TO APPENDIX A TECHNICAL SPECIFICATIONS OF FACILITY OPERATING LICENSES NPF-72 AND NPF-77 A.
SUMMARY
OF PROPOSED CHANGES Pursuant to 10 CFR 50.90, Commonwealth Edison (Comed) proposes to amend i Appendix A, Technical Specifications, of Facility Operating Licenses NPF-72 and NPF-77. The proposed amendment . requests a one time change to Improved Technical Specification (ITS) 3.8.4, DC Sources-Operating and ITS 3.8.9, Distribution Systems-Operating. This change is required to support the replacement of the Unit 2 125 volt DC ESF batteries and racks. The proposed one time change will replace ITS 3.8.4 Required Action D with Required Actions necessary to support an on-line change out. One of the Required Actions will permit operation for 10 days in MODES 1-4 while one DC division is connected to the existing safety related battery charger and a temporary, previously qualified safety related, but non-seismically mounted battery. This alignment will be used while the current battery is replaced and tested. An additional 8-hour Completion Time is being proposed to allow the bus to be crosstied during the disconnection of the current battery and the re-connection of the charger and temporary battery. This Completion Time will also be
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entered during reconnection of the new battery (once installed) and removal of the temporary battery. The above evolution will be performed for each DC Division on Unit 2. Battery service and performance tests, Surveillance Requirements, SR 3.8.4.7 l and SR 3.8.4.8, for the new batteries will be performed prior to connectin<; to the bus.
These activities will provide confidence that any perturbations or challenges to the electrical distribution system are minimized.
The proposed one time change to ITS 3.8.9 will add Required Action C.2 which allows a Completion Time of 10 days for restoring DC electrical power distribution ,
- subsystem to OPERABLE status, which is also necessary to support the change out of '
batteries.
l i The proposed changes are described in detailin Secti,.a E of this Attachment. The i marked up ITS pages are shown in Attachment B.
B. DESCRIPTION OF THE CURRENT REQUIREMENTS ITS 3.8.4 Required Actions A through D describe the Completion Times applicable to the DC electrical power subsystem of an operating unit. Required Actions A and B apply to the loss of a charger, while Required Action C allows an operating unit to supply power to a shutdown unit. Required Action D requires that with one of the Page 1 of 7 Attachment A-Description and Safety Analysis
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! DC power subsystem inoperable, except for the allowances of Required Actions A, B, or C, the inoperable DC power subsystem bus be restored to OPERABLE status within two hours.
ITS 3.8.9 Required Actions A and C describe the Completion Times applicable to inoperable AC and DC electrical power distribution subsystems while Required Action B describes the Completion time for an inoperable AC instrument bus electrical power distribution subsystem. Required Actions A and C provide Completion Times of 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> respectively AND 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of the failure to meet LCO. Required Action C.1 provides Completion Times of 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> from discovery of the failure to meet LCO. The proposed Required Action C.2 provides a Completion Time of 10 days for restoring the DC electrical power distribution subsystem to OPERABLE status. Proposed Required Action C.2 is only applicable when replacing the Unit 2 AT&T batteries.
C. BASES FOR THE CURRENT REQUIREMENTS The DC electrical power system provides the AC emergency power system with necessary control power. It also provides motive and control power to DC powered safety related equipment and provides AC instrument bus power to the inveners.
During plant operation, the operability of the AC and DC power sources and associated distribution systems ensures sufficient power will be available to supply the safety-related equipment for: (1) the safe shutdown of the facility; and (2) the mitigation and control of accident conditions within the facility. These conditions are consistent with the initial condition assumptions of the safety analyses and are based on maintaining at least one division of AC and DC power sources and associated distribution system operational during accident conditions coincide ~t with an assumed Loss of Offsite Power (LOOP) event and a single failure of the redundant division.
D. NEED FOR REVISION OF THE REQUIREMENTS Performance of this activity with the unit at power gives the station the opportunity to control concurrent work activities and the distractions associated with them. This ability is not available to the degree desired with the unit in an outage due to the ,
scope of work normally accomplished in an outage. l During the replacement of the Unit 2 batteries with the unit at power, Braidwood will capitalize on a larger number of available personnel for performing the installation. The lessons learned from the Unit 1 battery replacement will also be available for application as well. Replacement of the current AT&T round cell batteries will result in a more reliable DC power system due to the inherent limitations of the currently installed batteries.
The on-line replacement offers several scheduler and economic advantages over performing the activity during an outage. Braidwood Station has reviewed the l
Page 2 of 7 Attachment A-Description and Safety Analysis
activity and finds no significant safety consequences associated witi. performing this activity in the manner proposed.
E. DESCRIPTION OF THE PROPOSED CHANGES The proposed one time change will add two Required Actions to ITS 3.8.4 for Unit 2.
During the proposed on-line replacement of the AT&T batteries with C&D batteries, the normal safety related station battery will be out of service for approximately 10 days. Emergency DC backup power will be supplied to the bus 211 (212) using one bank of AT&T batteries which were removed from Unit 1. All station battery surveillances (including a Service Test) will be performed on the AT&T batteries prior to their use, thus this spare battery will meet all Technical Specification requirements. The existing ESF battery charger will remain connected to the bus in ,
parallel with the spare battery and supply the normal load and maintain the spare j battery in a fully charged condition. The temporary battery will be located in the l Turbine Building. The temporary battery and normal bus charger will be connected 1 to the bus through the same breaker as the current safety related batteries. Although '
this temporary battery is qualified for safety related use, it will not be seismically l mounted. Therefore, the battery would not be considered OPERABLE and a 10 day Completion Time will be required to allow continued operation of the unit during required battery replacement and testing activities.
The temporary battery cannot be connected to the DC bus until the current battery is disconnected. The temporary battery will connect through the same breaker as the current safety related battery. The temporary battery cannot be connected to the DC bus until the current battery has been physically disconnected due to physical limitations and available bus attachment locations. In order to prevent the DC bus from being de-energized, the crosstie breakers to Unit I will be closed. The existing crossties between buses are provided with two normally locked open, manually operated circuit breakers. If one battery is inoperable, procedural and administrative controls will be used to limit the connected load to 100 amps based on maintaining the OPERABLE battery capacity. These controls ensure that combinations of maintenance and test operations will not preclude the system capabilities to supply power to the ESF DC loads. The provisions of administratively controlled, manually actuated, interconnections between the non-redundant Class 1E DC buses increases the overall reliability and availability of the DC systems for each unit in that it provides a means for manually providing power to a DC but at a time when it would l otherwise have to be out-of-service. Also, Control Room alarms are provided to alert the operator when the units are crosstied.
Once the temporary battery and existing charger are connected to the bus, the crosstie will be opened. In addition, the existing ESF battery charger will remain connected to the bus in parallel with the spare battery bank and supply the normal load plus maintain the temporary battery bank in a fully charged condition. An 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Completion Time is proposed to provide sufficient time to safely disconnect the existing battery and then connect the temporary battery to the Unit 2 DC bus. The same 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> allowance will be necessary at the end of the 10 day Completion Time Page 3 of 7 Attachment A-Description and Safety Analysis
to disconnect the temporary AT&T battery bank and connect the new C&D
. batteries.
To assure that any postulated accident on Unit 2 during this brief period will not adversely affect Unit 1, a compensatory measure will be in place to manually open the crosstie during adverse conditions. Specifically, an individual will be monitoring the replacement and if the Unit 1 charger does n >t re-energize as expected following a Loss of Offsite Power (LOOP) and subsequent Diesel Generator start, the crosstie will be manually tripped. This measure ensurea that the battery will only supply the j maximum load profile for Unit 1. Also, if the Unit I charger is available and a Unit 1 ,
DC bus voltage less than 110V is measured, the crosstie will be opened. This parameter indicates that a large DC load exists arad the charger has current limited.
These measures ensure the battery can perform its safety function for Unit 1. Unit 2 will have one operable division of DC and Emergency AC power available for i mitigation purposes. l During a LOCA with offsite AC power the load on a Safety Related battery charger {
is approxiinately 120 amperes. This load does not include invener loads since the inverters will be on their AC feeds through the event.
l If the units are crosstied (during the limited temporary battery connection period) l the worst case load for DC bus carrying both units is approximately 170 amperes.
This value includes the 120 amperes of the LOCA load plus the other units approximately 50 ampere normal DC load. j l
With Unit 2 on the temporary battery bank (no crosstie) and postulating the scenario !
where a LOCA occurs and the temporary bank fails, the charger would trip off or go 1 into current limit (440 amperes). Excessive current draw due to a short on the bus could load the bus to the point where the DC division being supplied by the temporary battery could no longer support the bus. The other unaffected division would be required to shutdown the unit.
During a loss of offsite power (LOOP), the load on a Safety Related bus is approximately 500 amperes. If the units are crosstied during the temporary battery connection period the worst case load for DC bus carrying both units is approximately 1000 amperes. This value includes the 500 amperes of the Unit I load 500 amperes of the Unit 2 load. The bus voltage on Unit I will be sufficient to ;
support its loads. The Unit 2 bus voltage (because of an approximately 10V line loss l on the crosstie) will be sufficient to support all Unit 2 loads with the exception of the two inverter loads. This will result in a trip of Unit 2. The diesels supporting the Unit 1 and 2 affected DC buses will (within 1 minute) restore power to the battery chargers thus boosting the bus voltages back to normal levels.
l If Unit 2 is on the temporary battery bank (no crosstie) in a LOOP scenario where the temporary bank is connected to the DC division, the temporary battery will reliably support the bus. The unaffected division would also be available to support safe shutdown of the unit.
Page 4 of 7 Attachment A-Description and Safety Analysis
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l F. SAFETY ANALYSIS OF THE PROPOSED CHANGES The Improved Technical Specifications do not allow the Unit to be operated for more than two hours with an inoperable battery bank on a DC bus. This change will add 10 day Completion Times (ITS 3.8.4 Required Action E.2 and ITS 3.8.9 Required Action C.2) for restoration of the inoperable battery and associated bus. During this time period the temporary battery, along with the current ESF charger, will be used to supply the bus. This temporary battery consists of the same cells and hardware that are qualified and were previously used in Unit 1 and will, therefore, have the same capacity, margin and capability to fulfill the requirements of supplying power to the DC bus as the existing qualified battery. Since a suitable location could not be found that would support the weight of the temporary batteries and cope with a potential cell rupture, the temporary batteries will be located in the Turbine Building.
The only difference between the temporary battery and the existing qualified AT&T battery is that the temporary battery will not be seismically mounted as it will be located in the non-seismic Turbine Building. During this configuration, all other aspects of the DC system will be in accordance with the current design basis. A loss of the DC bus may be postulated during a seismic event. However, the other division is available and sufficient to cope with the event. In addition, there will be no impact on Unit 1 since the crosstie will not be used during this portion of the battery replacement.
The Battery service and performance tests Surveillance Requirements, SR 3.8.4.7 and SR 3.8.4.8, for the new batteries will be performed prior to connecting to the bus which will prevent any perturbations or challenges to the electrical distribution system. Therefore there is no need to restrict performance of these surveillances during MODES 1-4.
While the affected division battery is being disconnected and later reconnected, the DC bus will be supported via a crosstie from Unit 1. Crosstie of the units at power during the proposed 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Completion Time is acceptable for the following reasons:
There will be no impact on Unit 1. The compensatory measures will ensure that the Unit i battery will be isclated from Unit 2 to prevent a loading scenario beyond the current design of the battery. This action will prevent an accident on i Unit 2 from having an adverse effect on Unit 1.
The normal load on each of the DC busses is approximately 50 to 75 Amperes.
The charger ; are capable of supplying 440 Amperes. The Unit 1 charger would be able to supply both units' loads (approximately 100 to 150 Amperes), keeping the Unit 1 battery fully charged throughout the proposed 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Completion l Time.
l l Based on the above, the Unit 1 battery will be able to perform its safety functions l while crosstied. Additionally, the temporary battery uses cells that are identical to i t
the current Unit 2 batteries and are capable to supply rated voltage and current to the Unit 2 DC Bus during a worst case load profile.
The DC electrical power system provides the AC emergency power system with control power. During plant operation, the operability of the AC and DC power Page 5 of 7 Attachment A-Description and Safety Analysis
l sources and associated distribution systems ensures sufficient power will be available to supply the safety-related equipment for: (1) the safe shutdown of the facility; and (2) the mitigation and control of accident conditions within the facility. These conditions are consistent with the initial condition assumptions of the safety analyses and are based on maintaining at least one division of AC and DC power sources and associated distribution system operational during accident conditions coincident with an assumed Loss Of Offsite Power (LOOP) event and a single failure of the redundant division.
The worst case scenario being considered for the crosstied condition is a dual unit LOOP. The dual unit LOOP bounds the worst case conditions because the loads experienced by the crosstied battery will be at its highest. During this event the Unit 2 DC bus will support all DC loads for the Unit 1 and Unit 2 divisions. This load is more limiting than a Single LOOP with a LOCA. l l
ITS 3.8.4 Required Action D.1 requires restoration of an inoperable battery within 2 {
hours. The proposed change will extend that time to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> in the new proposed ITS 3.8.4 Required Action D.1. The current 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> Completion Time for a battery l inoperable for other reasons will be maintained in ITS 3.8.4 Require Action E.1. I Before commencing the battery replacement, the plant will be required to be in a stable condition with no other Required Actions requiring a unit shutdown in effect and no tornado weather expected during the replacement period. A temporary charger will keep the spare battery fully charged before and during the battery replacement. During the 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> periods of temporary battery connection and l disconnection, the crosstie from Unit I will be utilized to supply the normal Unit 1 )
This crosstie will be disconnected during the unlikely event of a design basis accident !
on Unit 1. If the Diesel Generator fails and the crosstie is opened, the Unit 2 bus will i be de-energized and the other Unit 2 division will be utilized to mitigate the accident.
This is also the case for the existing two hour Completion Time ofITS 3.8.4 Required Action D.I. The consequences of any accident on Unit 2 during the proposed 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Completion Time are identical to those postulated for the existing two hour Completion Time. The only difference is the time period during which the DC l division is in this condition. Additionally, this limiting scenario would occur only if the associated Diesel Generator fails.
There is no impact on Unit 1 due to the capacity of the batteries and the compensatory measures that will be in place. This ensures compliance with 10CFR50, Appendix A GDC-5. ITS LCO 3.0.6 and ITS 5.5.15 " Safety Function Determination Program" will ensure, in the event of a subsequent equipment inoperability that results in a loss of function, that continued operation is restricted in accordance with the applicable ACTIONS of the Specification such that the loss of function does not occur.
A sensitivity study using the Braidwood Probabilistic Assessment (PRA) was
- performed for the on-line activities, which demonstrated the resultant risk is within l acceptable limits. As part of this evaluation, several work practice recommendations l
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evolved which would provide additional confidence of continued functionality.
These involve such issues as battery location, prevailing weather predictions, and monitoring and control of activities in the vicinity, etc.
Additionally, the proposed location of the battery and predicted hydrogen generation j have been reviewed and determined to be acceptable.
1 G. IMPACT ON PREVIOUS SUBMITTALS Braidwood is currently pursuing a conversion to the Improved Technical I i
Specifications. Accordingly, this amendment request is being provided with ITS markups i
H. SCHEDULE REQUIREMENTS Commonwealth Edison requests that the review and approval of the proposed amendment be completed by March 15,1999 to support replacement of the Division i 211 and 212 battery prior to the Unit 2 refueling outage scheduled to begin in May of J 1999.
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i Page 7 of 7 Attachment A-Description and Safety Analysis ,
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