ML20056B350
| ML20056B350 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 08/20/1990 |
| From: | ENTERGY OPERATIONS, INC. |
| To: | |
| Shared Package | |
| ML20056B349 | List: |
| References | |
| NUDOCS 9008280164 | |
| Download: ML20056B350 (7) | |
Text
c
.; to AECM-90/0153 J
- A..
$UBJECT L
1.
NL-90/08 Surveillance Test of Specific Gravity for ESF Batteries -Table 4.8.2.1-1.
2.
Affected Technical Specifications a).
Table 4.8.2.1-1, Battery Surveillance Requirements -Page 3/4 8-13 b)
Bases 3/4.8.1, 3/4.8.2 and 3/4.8.3 - Page B 3/4 8-2 B.
DISCUSSION 1.
GGNS is requesting a clarification to Technical Specification (TS)
Table 4.8.2.1-1 which adds a note to allow the battery charging current to be used in lieu of specific gravity to verify OPERABILITY-of the Engineered Safety Feature (ESF) batteries following the-service and performance discharge-test.
2.
A statement is added to the Bases to TS 3/4.8.2 to clarify that the-battery charging current may be used in lieu of the s)ecific gravity measurement following the service or performance disc 1arge test.
C.
JUSTIFICATION 1.
The ESF batteries are presently subjected to a service discharge test once every 18 months and a performance discharge test once every 60 months to comply with TS Surveillance Requirement (SR) 4.8.2.1.d & e.
SR 4.8.2.1.b specifies that the quarterly test to demonstrate the OPERABILITY of the batteries '. performed within 7 days of completion of the service and performance discharge tests.
This SR requires that parameters in Ta)le 4.8.2.1-1 meet the
' Category B limits. SR 4.8.2.1.a also requires that the Category A limits be verified at least once per 7 days.
2.
Although the batteries are fully recharged after a discharge test and capable of performing the intended function, a rigorous interpretation of the current TS would delay declaring the batteries OPERABLE until the specific gravity limits of Table 4.8.2.1-1 are satisfied.
However, because of specific gravity gradients which are produced during the recharging process, delays of 3 to 7 days may-occur while waiting for the specific gravity to stabilize. The Bases for TS 3.8.2.1 recognizes that a stabilized charger current is an acceptable alternative to specific gravity measurement for determining the state of charge of the designated pilot cell. As a clarification, this allowance is being added as a footnote to TS Table 4.8.2.1-1 to allow the float charge to be used as alternate means of verifying operability following a discharge test. The footnote will be made applicable to the Category A limits and the Category B Allowable Values.
ObOb P
A9008161/SNLICFLR - 7
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o to AECH-90/0153 3.
The specific gravity of the tested battery drops during a discharge to a value approaching 1.00. On the subsequent recharge, it is normal for the measured specific gravity of the cells to lag behind the:true specific gravity. This is caused by the generation of high saecific gravity sulfuric acid by the )lates during the recharge.
T11s acid sinks toward the bottom of tie _ cell resulting in a specific gravity gradient and )roduces an incorrect low reading at
.the top of.the cell.1 The hig1 specific gravity acid gradually diffuses through the solution.
Depending on the depth of discharge and the recharge voltage, diffusion of the acid through out the electrolyte may take several weeks. Due to the time required for the diffusion process,'the specific gravity parameter measurement does not accurately reflect the battery's state of charge after recharging.
Therefore, the specific gravity parameter measurement 7
is not an accurate indication of the state'of charge of the battery during this time.
4.
The battery charging current is a more accurate indicator of the battery's state of charge following a service or performance discharge test. As the cells a)proach full charge, the battery voltage rises to approach the clarger output voltage, and the charging current decreases to a stabilized value. When the charging current has stabilized at the charging voltage, the battery is charged,-even though specific gravities have not stabilized. For the Division I, II, and III batteries, a float current of 2 amps is indicative of full charge. Using the battery charging current indicator resolves the problems associated with delaying battery rciurn-to service after scheduled discharge tests.
This alternate method of verifying OPERABILITY is discussed in the Bases for TS 3.8.2.1 for the Category A Limits.
l 5.
A discussion of this phenomenon can be found in IEEE 450-1980, "IEEE Recommended Practices for Maintenance, Testing, and Replacement of large Lead Storage Batteries for Generating Stations and l-Substations".
IEEE 450-1980, along with Regulatory Guide 1.129, is referenced in the GGNS TS Bases (page B 3/4 8-2) as the basis for t
demonstrating OPERABII.ITY cf the unit batteries. The need to use an L
alternate means of verifying the state of the battery's charge is recognized in the BWR-6 Standard TS and other BWR-6 plant's TS.
D. -
NO SIGNIFICANT HAZARDS CONSIDERATIONS GGNS is pro)osing with this amendment request a revision to TS Table L
4.8.2.1-1 w1ich would allow the battery charger current to be used in L
lieu of the specific gravity of the electrolyte for determining if the L
battery is OPERABLE following the service and performance discharge ~ test.
L L
The Commission has provided standards for determining whether a no l-significant hazards consideration exists as stated in 10CFR50.92(c).
A L
proposed amendment to an operating license involves no significant hazards if operation of the facility in accordance with the )roposed i
l amendment would not: (1) involve a significant increase in tie probability or consequences of an accident previously evaluated; or (2) create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) involve a significant reduction in a margin of safety.
A9008161/SNLICFLR - 8 L
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L to T
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.AECM-90/0153 1
GGNS has evaluate'dithe no'significant hazards considerations-in its e
request for a license amendment.
Inaccordancewith10CFR50.91(a),GGNS
-is providing the. following analysis of the proposed amendment against the 4
-three standards in 10CFR50.92:
1.
No significant increase in the probability or consequences of an accident previously evaluated results from this change.
Thel0.C. power systems provide normal and emergency D.C. power for
- emergency auiliaries and for control and switching during all modes i
of operation. As'such, the unit = batteries provide a support i
function to other systems and components required to shutdown the 1 reactor and maintain it in a safe shutdown condition after an anticipated operational occurrence or a-postulated design basis accident. The proposed change affects only the method of verifying OPERABILITY of the batteries. The batteries will continue to be.
T
'l 0PERABLE and capable of supplying the loads required to mitigate the consequences of any previously evaluated accident.
i Therefore, no significant increase in the probability or consequences of an accident previously evaluated results from this change.
2.
This change would not create the possibility of a new or different kind of accident from any previously analyzed.
i The proposed change to the surveillance requirement employs an effective method of demonstrating battery OPERABILITY following a discharge test. No changes to the betteries, the supported systems i
or components are proposed. The proposed change will not result in j
changes to the way the supported components and systems are operated.
4 Therefore, the possibility of a new or different accident from any previously analyzed is not created.
3.
This change would not invohc a significant reduction in the margin f
i of safety.
The proposed change will allow the ESF batteries to be declared i
OPERABLE following a discharge test as soon as they have been com) lei.ely recharged rather than waiting for the specific gravity to sta)ilize. Taking -specific gravity measurements during this period of time may yield readings which do not accurately relate to the battery state of charge due to gradients within the battery electrolyte. Although the specific gravity method is normally the preferred means of verifying OPERABILITY, the current IEEE standard 4
recognizes the pattern of charging current delivered by a
. conventional voltage-regulated charger after a discharge provides another method for determining the state of charge. A stabilized charging or float current is a more accurate indicator of return to full charge following a discharge than specific gravity readings.
A9008161/SNLICFLR - 9
" to AECM-90/0153-Using the alternate means of verifying OPERABILITY-ma result in a
- slight' reduction in=the margin of safety, However, t e reduction is not considered to be significant because:
a.
.even though the battery's specific gravity has not stabilized,.
the battery is still capable of 3 -
'ying_.the required ~ loads,:
b.
the TS will. require that the sped :.- gravity be measured within 7' days following the discharge test, i
c.
the alternate means of verifying full charge is consistent with industry practice and fully sufficient to demonstrate the.
battery s OPERABILITY, and ;
t d.
the proposed change will allow the battery to be returned to service at_ an earlier time reducing the unavailability of the O.C. power division.
Therefore, the proposed change will not involve a significant y
reduction in the margin of safety.
Based on the above evaluation, GGNS has concluded that operation in accordance with the proposed amendment involves no significant hazards considerations.
j
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k A9008161/SNLICFLR,
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, NL-90[08_
TABLE 4.8.2.1-1 BATTERY SURVEILLANCE REQUIREMENTS CATEGORY Afl)
CATEGORY B(2)
Parameter Limits for each Limits for each A110wable(3) designated pilot connected cell.
value for each cell connected cell i'.!
Electrolyte
> Minimum levei
> Minimum level Above top of Lavel indication mark, indication mark,
- plates, i
and < %" above and < k" above and not maxiEum-level maxiium level overflowing indication mark indication mark i
i l
Float Voltage 1 2.13-volts
> 2.13 volts (b)
> 2,07 volts l
Not more than i
.020 bclow the 1
i average of all
.[
t 1.190 connected cells Specifig 3 1.195 Average of all Average of all Gravity,)
connected cells connecte cells
> 1.200 1 1.19 c (a) Corrected for electrolyte temperature and. level.
'g(1).ForanyCategoryAparameter(s)outsidethelimit(s)shown,thebattery j b) ' May be corrected for average electrolyte temperature, may be. considered OPERABLE provided that within.24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> all the Category B measurements are taken and found to be within their allowable values, and provided all Category A and B parameter (s) are restored to within limits within the next 6 days.
(2) For any Category B parameter (s) outside the limit (s) shown, the battery may be considered 0PERABLE provided that the Category B parameters are within their allowable values and provided the Category B parameter (s) 1.
are restored _to within limits within 7 days.
(3) Any Category B parameter not within its allowable value indicates an inoperable battery.
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8ASES-A.C. SOURCES.'O.C. SOURCES and DNSITE POWER DISTRIBUTION SYSTEMS (Co
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The surveillance requirements for demonstrating the OPERASILITY of the unit batteries are in accordance with the recommendations of Regulatory Guide 1.129 " Maintenance Testing and Replacement of Large Lead Storage Batteries for Nuclear Power Plants," February 1978, and IEEE Std 450-1980, "IEEE Recommended Practice for Maintenance, Testing, and Replacement of Large Lead Storage. Batteries for Generating Stations and Substations.".
Verifying average electrolyte temperature above the minimum for v5fch the battery was sized, ~ total battery terminal voltage onfloat charge, corm:<, tion resistance values and the performance of battery service and discharge tests ensures i.he effectiveness of the charging system, the ability to handle high L
discharge rates and compares the battery capacity at that time with the rated l
capacity.
i Table 4.8.2.1-1 specifies the Nrmal limits for each designated pilot l
cell and each connected cell for ela:trolyte level, float voltage and specific gravity.
The limits for the designated pilot' cells float voltage and specific gravity, greater than 2.13 volts and 0.015 below the manufacturer's full charge specific gravity or a battery charger current that had stabilized at a low value, is characteristic of a charged cell with adequate capacity.
The normal limits for each connected cell for float voltage and specific gravity, greater than
(
'2.13 volts and not-more than 0.0M below the manufacturer's full charge specific--
gravitywithanaveragespecificpravityofalltheconnectedcellsnotmore than 0.010 below the manufacturer s full charge specific ' gravity, ensures the PERABILITY and capability of the battery. 4
)
Operation with a battery cell's parameter outside the normal limit but within the allowable value specified in Table 4.8.2.1-1 is permitted for up to 7 days.
During this 7 day period:
(1) the allowable values for electrolyte level ensures no physical damage to the plates with an adequate electron transfer capability;-(2) the allowable value for the average specific gravity of all the cells, not more than 0.020 below the manufacturer's recommended full charge specific gravity, ensures that the decrease in rating will be less than the
-safety margin provided in sizing; (3) the allowable value for an individual cell's specific gravity ensures that an individual cell's specific gravity will not be more than 0.040 below the manufacturer's full charge specific gravity and that the overall capability of the battery will be maintained within an i
acceptable limit; and (4) the allowable value for an individual cell's float voltage, greater than 2.07 volts, ensures the battery's capability to perform a
its design function.
I i
GRAND GULF-1 B 3/4 8-2 A%dsed Mo,
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+
INSERT TO BASES PAGE B 3/4 8-2 Exceptiens to the. specific gravity requirements are taken to allow for the normal deviations experienced after a battery discharge and subsequent recharre associated with a service or performance discharge test. The.
specifIcgravitydeviationsarerecognizedbyanddiscussedinIEEE 450-1980.
1,k s
A9008161/SNLICFLR - 11
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