ML20129D938
| ML20129D938 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 10/22/1996 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20129D934 | List: |
| References | |
| NUDOCS 9610250206 | |
| Download: ML20129D938 (6) | |
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UNITED STATES p
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NUCLEAR REGULATORY COMMISSION
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WASHINGTON, D.C. 20seH001
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f SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION l
RELATED TO AMENDMENT NOS. 53 AND39 TO FACILITY OPERATING LICENSE NOS. NPF-87 AND NPF-89 1
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TEXAS UTILITIES ELECTRIC COMPANY I
COMANCHE PEAK STEAM ELECTRIC STATION. UNITS 1 AND 2 DOCKET NOS. 50-445 AND 50-446
1.0 INTRODUCTION
By application dated July 31, 1996 (TXX-96432), as supplemented by letters dated August 23 and 27 (TXX-96447 and TXX-96451), and September 19, 1996 (TXX-96469), Texas Utilities Electric Company (TU Electric /the licensee) requested changes to the Technical Specifications (TSs) (Appendix A to
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Facility Operating License Nos. NPF-87 and NPF-89) for the Comanche Peak Steam Electric Station (CPSES), Units 1 and 2.
The proposed changes are associated with plant modifications in which the inverters and battery chargers are being replaced and a spare inverter is being installed for each safety train. The following TS changes are proposed:
(1) change the acceptance values for amperes and voltage for the 18-month surveillance test of the battery chargers; (2) clarify the meaning of the term " associated inverter" used in the context of energizing 118-V ac instrument buses during Modes 1 through 6; and (3) delete the protection channel and the vital bus ratings for the ll8-V ac instrument buses identified for Modes I through 4.
In response to a request for additional information during subsequent telephone conversations, 1U Electric submitted sketches and statements in the supplemental letters of August 23 and 27, and September 19, 1996, and in a meeting with the staff on October 2, 1996, confirming that the existing batteries have adequate capacity to supply updated inverters and meet the criteria described in the CPSES Final Safety Analysis Report (FSAR), and the battery charger rating increase from 225 amps to 300 amps will not impact Emergency Diesel Generator (EDG) loading and the interfacing cable will not be replaced since the cable is rated greater than 300 amps.
The supplemental information provided in letters dated August 23 and 27, and September 19, 1996, and the information provided at October 2, 1996, meeting documented in a meeting summary dated October 16, 1996, was clarifying in nature and did not change the initial no significant hazards consideration determination.
2.0 BACKGROLWD TU Electric is modifying plant equipment in CPSES, Units 1 and 2.
As a part of this modification, the associated inverters and battery chargers will be replaced and a spare inverter will be added to each train during the next refueling outage of each Unit.
For standardization, all the new replacement 9610250206 961022 PDR ADOCK 05000445 PDR
. inverters, including the installed spare, will be rated 10 kVA. The larger battery charger capacity will also be needed to account for the increased load that is drawn by the replacement inverters. The battery chargers and the associated inverters are part of the ll8-V ac single-phase 60-Hz uninterruptible power supply (UPS) to critical instrumentation and control circuits.
For each unit, there are four Class IE UPSs for balance-of-plant (BOP) instrumentation and four Class IE UPSs for the reactor protection system.
The proposed TS changes reflect modification of the equipment related to UPS.
3.0 EVALUATION 3.1.
Chanae Proposed for Surveillance Reauirement 4.8.2.lc.4)
The existing TS surveillance requirement (SR) 4.8.2.1.c.4), requires that at least once per 18 months the battery charger shall be demonstrated operable by verifying "the battery charger will supply at least 225 amperes at 130 volts for at least 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />."
TU Electric proposes to change "at least 225 amperes at 130 volts" to "at least 300* amperes at greater than or equal to 130 volts," and to add the following footnote:
"* 225 amperes for Unit 2 until replacement of the battery charger during the third refueling outage for Unit 2."
The presently installed battery chargers are being replaced with new battery chargers to increase the design capacity from 225 to 300 amperes. The larger capacity is needed to handle the increased load for the replacement inverters which are being installed by the same plant modification.
In response to the staff's question during a phone call about the existing battery capacity (batteries will not be replaced) to supply increased loads that will result from upgrading of the inverters, the following additional information was submitted in the letters of August 23 and 27, 1996:
The associated calculation considered the inverter upgrade (including an increase in rating from 7.5 kVA to 10 kVA) and determined that the capacity of the associated batteries is adequate to meet the 4-hour coping duration with the battery charger inoperable in the event of a station blackout.
TU Electric confirmed that CPSES Class IE 125-V de system continues to satisfy the following FSAR criteria:
FSAR Section 8.3.2.1, which states, in part:
"The Class IE 125-V battery systems supply power to Class lE loads without interruption during normal operations or DBA [ design-basis accident] conditions."
FSAR Section 8.3.2.1.2, which states, in part:
"Each Class IE 125-V de system has the capacity to continuously supply all connected normal running load while maintaining its respective battery in a fully charged condition.
Each battery is capable of carrying the
. essential load continuously for a period of four hours in the event of total loss of onsite and offsite ac power."
Footnote to FSAR Tables 8.3-4 and 8.3-48, which states:
"The battery loads are bounded by maximum battery sizing loads which include 15% design margin."
The de system capacity described above is verified in Calculation EE(B)-053 Revision 5, CCN No. 8.
TU Electric submitted the following information in a letter dated September 19, 1996:
TU Electric has considered the impact of the new battery chargers on the Emergency Diesel Generator (EDG) capacity and determined that the EDG loading is acceptable. The loading impact is addressed in calculation EE-CA-0007-3377 Revision 1, CCN #3, " Unit 1 Diesel Generator Database Report."
The cables interfacing with the battery chargers will not be replaced. The cables were originally designed for 300 amps battery chargers and therefore suitable for the new battery chargers.
CPSES Class 1E battery sizing calculations do not differentiate between design basis accident (DBA) and station blackout (SBO) loads. The calculations assure that batteries are adequately sized to feed all de loads (inclusive of all DBA, SBO, and other loads connected to the battery) for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> in case of loss of ac power, with the margin of 15% after considering aging factor of 1.25 and taking into account the temperature correction factor for the minimum electrolyte temperature of 67'F.
The calculations also assure that the battery end of the duty cycle voltage is equal to or greater than 105 volts.
Battery duty cycle of 4-hours meets the CPSES SB0 coping requirements.
CPSES Class 1E battery sizing continues to meet these requirements after inverter / battery charger modification. These evaluations for battery capacity and voltage profile are documented in calculations 16345-EE(B)-053 Revision 5, CCN #8, " Sizing Verification-Class 1E Batteries and Battery Chargers" and EE-CA-0009-3025 Revision 0, CCN #1, " Station Blackout-Class 1E Battery Capacity." The adequacy of available voltage at the equipment terminal has been established, in various calculations, based on battery output voltage of 105 volts. The adequacy of the de input terminal voltage at the UPS inverters has been verified in the calculation 16345-EE(B)-011 Revision 8, CCN #3,
" Validation of Cable Sizing Calculation - DC System for Class 1E Cables Based on Voltage Drop and Ampacities."
The results of the above calculations were submitted by TV Electric. These calculations are for Unit 1 only. The NRC staff finds that the batteries have
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a margin greater than 15%, considering aging and temperature correction 1
factors. Also, batteries are sized for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> duty cycle for any mode of operation (SB0 or DBA). At the end of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> battery terminal voltage will be maintained above 105 volts. All of the voltage drop calculations for de loads were performed with the worst case battery terminal voltage of 105 volts. The worst case voltage at the inverter input terminal is 103.18 volts de, which is above the minimum required inverter voltage of 100 volts. The charging current for the battery charger is increased to 269.64 amps based on
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recharging the completely discharged battery within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> while simultaneously carrying continuous de load.
l The worst case continuous loading on the EDG based on the battery i
charger / inverter upgrading is calculated at 5780.3 kW.
The EDG continuous rating is 7000 kW.
The EDG loading will be limited to 6300 kW due to I
surveillance test requirement. The EDG loading after upgrading will be below l
6300 KW.
The cable size from battery charger to de distribution board is 2-1/C #750 MCM. The calculated worst case ampacity for that cable is 608 amps which is l
well above the battery charger output current of 375 amps (current limit).
The ac input cables of the battery charger are 2/0 Triplex. The worst case 1
ampacity for that cable is 106 amps, which is above charger input current of j
99 amps (current limit).
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Upon review of CPSES FSAR, NRC staff finds that Unit 2 EDG loading are below i
6300 kW. The inverter / charger modification reduced the EDG loading for Unit 1.
The similar modification for Unit 2 will reduce the Unit 2 EDG j
loading and will be below 6300 kW.
The Unit 2 battery load profiles are lower than that of Unit I and hence Unit 2 batteries will have a greater than 15% margin after aging factor (25%)
and temperature correction (for the minimum electrolyte temperature of 67'F) factor are accounted for in assessing the battery capacity. The charging current for Unit 2 will be reduced.
Hence charging current of 300 amps as determined for Unit I will be conservative for Unit 2.
I The input and output cables sizes for Unit 2 battery chargers are same as that l
of Unit 1.
Based on the above, the change of battery charger rating from 225 amps to 300 amps is acceptable for Unit I and Unit 2.
1 The addition of " greater than or equal to 130 volts" is consistent with NUREG-1431, " Standard Technical Specification for Westinghouse Plants.
Therefore, this change is acceptable.
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i The TS change will be imple;4nted on Unit 1 immediately (in the upcoming 4
refueling cycle); but this change will not be effective on Unit 2 until j.
battery chargers are replaced in the third refueling outage. The addition of the footnote is acceptable.
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3.2.
Channes Pronosed for TS 3/4.8.3. Onsite Power Distribution j
TS 3.8.3.lc, Id, le, and If (and its associated note) and TS 3.8.3.2b and 2c, pertaining to the ll8-V ac instrument bus, refer to being energized from the
" associated inverter." The proposed change clarifies " associated inverter" by adding the following footnote:
" Associated inverter is the dedicated inverter or installed spare inverter." The bases for TS 3/4.8.3 are also revised to reflect this change, and to note the basis for the proposed change.
l CPSES, Units I and 2, each have two protection channels and two vital bus l
inverters for the instrument buses for each safety train. The design modification will install a spare 10-kVA inverter for each safety train. The t
l proposed design modification allows each spare inverter to be aligned manually to substitute for any of the other four inverters in that train. Manual l
interloc!:r and procedural controls ensure that a spare invtrter feeds the loads of orly one inverter at a time and that the power source for the spare i
i inverter is the same as for the inverter whose loads are being fed by the spare inverter. The spare now replaces the dedicated inverter as the l
associated inverter for that bus.
i The proposed change to the TC is to add a footnote defining the term
" associated inverter" as follows:
" Associated inverter is the dedicated 2
inverter or the installed spare invarter." The Bases section of the TS 3/.8.3 i
also reflects thi> change sad notes the underlying basis. The proposed change is acceptable.
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3.3.
Chanae Proposed for TS 3.8.3.1. Onsite Power Distribution - Operatina 1
l Action statements 3.8.3.lb and c show the protection channel and vital bus rating respectively as "7.5 kVA" and "10 kVA." The proposed change deletes i
the rating description. The proposed change, also, clarifies " associated inverter" by adding the following footnote:
" Associated inverter is the j
dedicated inverter or installed spare inverter."
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' of design modification, the associated inverters and battery charp rs l
wili ce replaced. All new replacement inverters, including the installed 4
spare, will be rated 10 kVA.
In the existing design, the inverters for the i
UPS bus related to the reactor protection system are rated at 7.5 kVA. Since all of the inverters are of the same rating, there is no need to identify the bus by hVA rating. By this change, the applicability or the original intent of the action statements are not altered.
The proposed change is acceptable.
o B.
4.0 STATE CONSULTATION
4 In accordance with the Commission's regulations, the Texas State official was notified of the proposed issuance of the amendments. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
l The amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, i
of any effluents that may be released offsite, and that there is no l
s 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 (61 FR 44363). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR l
51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
6.0 (PNCLUSION 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) 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 recurity or to the health and safety of the public.
Principal Contributor:
S. K. Mitra Date: October 22, 1996