ML20248H184
| ML20248H184 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 09/29/1989 |
| From: | Fay C WISCONSIN ELECTRIC POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| CON-NRC-89-117 VPNPD-89-517, NUDOCS 8910110205 | |
| Download: ML20248H184 (4) | |
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. POWER COMPANY.
234 W McNgan.PO Box 2046.Mdwoukee,W 53201
'(414) 221-2345 VPNPD-8 9-517 NRC-8 9-117 '
September 29,.1989
'U.S.
NUCLEAR REGULATORY COMMISSION Document Control DeskE Mail Station P1-137 i
Washington, D.C.
20555 Gentlemen:
DOCKET NOS. 50-266-AND 50-301 DESCRIPTION OF REVISED BATTERY TESTING PROGRAM POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 Your_ letter dated' July 21, 1989, which forwarded the results of-the Enforcement Conference conducted on June 2, 1989 reported-as Inspection Reports Nos. 50-266/89021 (DPR) and 50-301/89020 (DPR),.requestod a description of what Wisconsin Electric now
.believesito be'a-satisfactory battery testing program'and the 3 justification:for those positions.
Attachment I contains this description and the' associated justification.
Upon your review and general concurrence with our proposed program, we will submit a license amendment change application to incorporate f
this program into the Point Beach Technical Specifications.
If you~have any questions regarding our proposed battery testing program, please contact us.
-Very truly yours,
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'C. W. Fay Vice President Nuclear Power Department
. Attachment cc:
NRC Regional Administrator, Region III NRC Resident Inspector l
8910110205 690929
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t ATTACRMENT 1 DESCRIPTION AND JUSTIFICATION OF REVISED BATTERY TESTING PROGRAM POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 DOCKETS 50-266 AND 50-301 DESCRIPTION OF REVISED TESTING PROGRAM 1
Before placing a newly installed safety related station battery into service, the battery shall be subjected to a Service Test as described in IEEE Std. 450-1987, IEEE Recommended Practice for Maintenance, Testing, and Replacement of Large Lead Storage Batteries for Generating Stations and Substations.
The discharge rates shall envelop the calculated battery duty cycle that would be seen following a plant trip and loss of all A.C. power.
Battery discharge time shall be no less than one hour.
This requirement shall apply to all safety related station batteries installed after January 1, 1989 including the new DOS and D06 replacement batteries.
Each safety related station battery shall be subjected to a Performance Test, as described in Section 6 of IEEE Std. 450-1987, at five year intervals.
In addition, each safety related station battery shall be subjected to annual Performance Tests when a) the battery has reached 85% of its rated service life, b) the battery capacity drops more than 10% of rated capacity from its capacity determined from the previous test, or c) the battery capacity drops below 90% of the manufacturer's rating.
Battery capacity shall be determined using the method described in Section 6.5 of IEEE Std. 450-1987.
The battery replacement criteria described in Section 7 of IEEE Std. 450-1987 shall be followed for all safety related station batteries installed after January 1, 1980 Also, each safety related station battery shall be subjected to a Service Test as described above when the calculated duty cycle substantially changes.
A substantial change shall be when any portion of the calculated duty cycle that exceeds the Performance Test discharge rate is increased by more than 10%, or, when any portion of the calculated duty cycle that does not exceed the Performance Test discharge rate increases such that it does exceed the Performance Test discharge rate.
Such a Service Test shall satisfy the requirements for a Performance Test.
JUSTIFICATION OF REVISED TESTING PROGRAM Particular items of concern to assure a safety related station battery will be able to perform its safety function are: 1) the battery system has a sufficient amount of usable stored energy,
- 2) the integrity of the battery system components are adequate to convert the chemical energy and deliver the electrical energy, and, 3) the battery systems electrical connections are adequate to allow delivery of the stored energy to the distribution
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I system.
The amount of usable stored energy (capacity) is determined in several ways.
On a short term basis, cell voltages and electrolyte specific gravities are monitored to determine the state of charge.
This monitoring is presently (and will continue to be) performed monthly on the Point Beach Nuclear Plant safety i
related station batteries.
On a long term basis, state of charge is not, by itself, the best indicator of battery capacity due to aging effects.
Aging effects can be detected through periodic j
l performance discharge testing which is a direct measure of the i
battery capacity.
Discharge testing on a short term basis is not recommended due to the limited number of discharges batteries are designed for.
Typical battery capacity vs. time curves are essentially linear up to and beyond 85% of the rated life with capacity decreasing very slowJy.
Near the end of rated life, however, capacity decreases more rapidly.
As a result of this characteristic, capacity testing during the first 85% of battery life is only required infrequently and a periodicity of once every five years is acceptable.
Near the end of life, more frequent capacity testing is prudent to detect the transition from slow capacity decrease to fast capacity decrease.
Annual testing is then appropriate since detection of this transition point (or ' knee')
within the year still leaves ample time for battery replacement planning and execution.
Exposing batteries to elevated temperatures will accelerate aging.
In extreme cases, elevated temperature exposure could cause the ' knee' of a battery capacity vs. time curve to appear earlier than 85% of life.
The temperature control units for the safety related station batteries at Point Beach are designed to keep the batteries from experiencing.any extreme temperatures.
In addition, the room and electrolyte temperatures are monitored for each safety related station battery to assure adverse accelerated aging is not experienced.
The adequacy of the battery system electrical connections and the integrity of the system components are also determined in several ways.
On a short term basis, the electrical connections and system components are visually inspected for signs of deterioration, degradation, corrosion, contamination, or other anomalies.
Also, as stated above, cell voltages and specific gravities are trended which can also show signs of system degradation.
On a longer term basis, adequate electrical connections are verified by measuring their resistance.
These inspections are performed annually at Point Beach and will continue to be performed.
To provide additional verification of station battery operability, the battery can be discharge tested to the most demanding duty cycle.
The most demanding duty cycle for station batteries D105 and D106, the load seen following a plant trip and
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loss of all A.C. power, is enveloped by the Performance Test duty cycle.
Therefore, only the Performance Test is required.
Station battery D05's worst. case duty cycle is seen upon a Unit 1 trip coincident with a loss of all A.C. power.
This exceeds the Performance Test duty cycle by 76 amps for the first minute and is enveloped by the Performance Test for the remaining 59 minutes.
The worst case duty cycle for D06 is seen upon a Unit 2 trip coincident with a loss of all A.C. power.
This duty cycle I
exceeds that of the Performance Test by 152 amps for the first
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minute and is enveloped for the remaining 59 minutes.
These first~ minute loads represent 8% and 16% more current than the Performance Test discharge currents for only 1/60th of the j
discharge period.
Since the variations in the two different types of duty cycles are small in magnitude and duration, only the Performance Test is required.
Based on modifications presently being considered, station battery DOS and D06 loading may be reduced before additional Performance Testing is required.
Thus, their worst case duty cycles would be fully enveloped by their Performance Test duty cycle if these modifications are installed.
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