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UNITED STATES 4,
NUCLEAR REGULATORY COMMISSION j
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WASHINGTON, D. C. 20555
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gyG j 71988 Docket Nos.:
50-317/318 MEMORANDUM FOR:
R. Capra, Project Director Project Directorate I-1 Division of Reactor Projects I/II i
FROM:
Faust Rosa, Chief Electrical Systems Branch Division of Engineering & Systems Technology
SUBJECT:
STATION BATTERY TECHNICAL SPECIFICATION AMENDMENT REQUEST Dlant Name:
Calvert Cliffs 1 and 2 Docket Nos.:
50-317/318 TAC Nos.:
61710/61711 Resp. Directorate: PD I-1/DRP Project Manager:
S. A. McNeill Review Branch:
SELB/ DEST Review Status:
Complete INTRODUCTION Baltimore Gas and Electric, on April 14, 1986, requested, among other things, changes to pages 3/4 8-8, 8-9, and 8-10 of the Calvert Cliffs nuclear units 1 and 2 technical specifications, and addition of page 3/4 8-10a. The proposed changes are quoted below.
In a memorandum to S. McNeill, PM, dated August 29, 1986, D. Crutchfield, AD/PWR-B stated that the staff had found change proposals numbered 1 through 6, inclusive, and change proposal number 12, acceptable. (The changes proposed will be listed, below, using the same numbers). The NRC requested additional information on proposed changes numbered 7 to 11, inclusive. The licensee responded by letter, on April 28, 1987. The succeeding memorandum treats items 7 to 11 for which licensee supplied additional information.
The staff, now, reconrnends accepting, in addition to the proposed changes previously recommended for acceptance, items 7 and 11. Technical specification change proposals 8, 9, and 10 are not acceptable to the staff because the licensee has not provided sufficient assurance to the NRC that station control battery per-formance will not be adversely affected.
In addition, because there seems to be little, if any, operational advantage to the licensee, the staff will not examine
Contact:
C. Morris, SELB/ DEST X23284 QW N KA I
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R. Capra items 8, 9, and 10, further without a convincing demonstration that battery per-formance can be enhanced, or at least not degraded by adopting any one or all of these three changes to the Calvert Cliffs technical specifications.
- Further, staff, by this memorandum, rescinds the staff's previous acceptance of proposed change 12 for reasons adduced below.
DISCUSSION The licensee's proposed technical specification changes, using the same numbering as D. Crutchfield's memorandum of August 29, 1986, are:
1.
The minimum long term cell voltage is to be changed from 2.10 to 2.13 volts.
2.
A specification is added in which the average electrolyte tempera-ture of a representative number of cells is to be above 60 F.
3.
The minimum long term average over all cells, of the specific gravity of the electrolyte is changed from 1.200 to 1.205.
4.
A specification that requires resistance measurements between cells is added.
5.
A specification that requires an annual performance discharge test for any battery which shows degradation or that has reached 85% of its service life is added.
6.
The option to perform the battery service test using actual emergency loads is deleted.
7.
The electrolyte level specification is changed to: Less than 1/4 inch above the high level mark and higher than the low level mark.
The basis for the difference between item 7, here, and item 7 as proposed by Baltimore Gas and Electric, and described by D. Crutchfield in his memorandum, is explained below.
8.
The short term minimum cell vcitage is changed from 2.10 to 2.07 volts.
9.
The specifications which limit individual cell voltage and specific gravity decreases between performance discharge tests are deleted.
- 10. The long term minimum specific gravity for each cell is changed from 1.200 to 1.195. The short term minimum specific gravity, averaged over all cells, is changed to 1.195.
The short term minimum specific gravity for each cell is changed to 1.175.
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- 11. The dummy load profile used to_ simulate the design duty cycle during battery service tests is deleted from the technical specification (and i
is transferred to the Updated Final Safety Analysis Report.) The part of 11. in parentheses is added by this memorandum.
- 12. The requirement to do a battery service test and a performance discharge test every 60 months is cha,79ed; a performance discharge test. only, is required to be performed evnry 60 months.
i EVALUATION OF PROPOSED CHANGES l
The following evaluation of the proposed technical specification changes is con-fined to items 7 to 11 which were not previously accepted by the staff.
Item 7.
The proposed minimum level of, "Above top of plates..." for short term is-unacceptable because the bottom of the so called " Standard Prevent (Funnel and Fire Arrester)" would be uegovered if the battery electrolyte level were less than one inch above the tops of the battery plates. The' licensee, in Attachment 1 to Baltimore Gas and Electric response of April 28, 1987 to the NRC RAI of October 3, 1986, states, on page 1:
" Additionally the bottom of the stem on the Prevent Assembly should be covered in order to ensure hydrogen exits the cell through...the Prevent Assembly." This is also the position stated in IEEE Std. 450-1980 Appendix D Section D1. Adding i
Water. "However, for safety, if flame arresting vents are provided, water should be added before the electrolyte level reaches the bottom of the funnel stem."
Since the licensee's submittal indicates that charge swell is less than 3/4 inch, it would be imprudent to allow electrolyte levels to go outside the range proposed in this memorandum. The purpose of pro-
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posed change, number 7, appears to be to lessen the frequency of battery maintenance; but the Calvert Cliffs battery construction does not allow electrolyte levels outside those described above.
Item 8.
Licensee's response to this item does not provide a basis for lowering cell minimum from 2.10 to 2.07 volts. Nor does the response describe a significant advantage to doing so. Accordingly the proposed change is denied.
l Item 9.
Licensee's response to NRC RAI of October 3, 1986 given as Attachment 1 item 3, is not sufficiently responsive; licensee states, ".. we believe i
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j R. Capra i that by measuring and comparing individual cell. deviations for specific-gravity from the average of all connected cells we can more accurately measure battery capacity." Nothing in the technical specification, or elsewhere, prevents the licensee from calculating averages as well, but belief in a preferred procedure, or a conviction regarding the motives of the author's of IEEE Std 450-1980, also cited by licensee, are not convincing arguments. Accordingly, the proposed technical specifica-tion change is denied.
Further, there does not seem to be present sufficient advantage to the licensee to justify further review of this iter.
Item 10. Baltimore Gas and Electric states that under conditions given in their Response to. Item 4, pg. 4, Attachment 1 to Baltimore Gas and Electric response of April 28, 1987 to NRC Request For Additional Infomation Batteries 11,~ 21 and Reserve will have capacities of 100.8%, a drop of about 10% from the batteries capacity at an electrolyte specific gravity of 1.205.
Accordingly, licensee may increase the long tem average specific gravity from 1.200 to 1.205, but may not reduce the limit on cell average specific gravity from 1.200 to 1.195.
Item 12.
In their April 14, 1986 Request for Amendment, Baltimore Gas and Electric stated, in connection with proposed technical specification change 12 (NRC numbering):
" Currently the Technical Specifications require a perfomance discharge test to be done subsequent to the battery service test every 60 months. The perfomance discharge test is a more stringent test and is sufficient, by itself, to demon-strate that the battery meets design requirements. Elimina-tion of the battery service test, when the perfomance discharge test is perfomed, reduces unnecessary testing and would contribute to battery life expectancy."
In response to this proposed change the NRC staff memorandum of October 3, 1986 to S. McNeil, PM for Calvert Cliffs, stated;
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" Item 12 requests that battery service test would not be ac-complished following the perfomance discharge test. We con-cur with the licensee that the perfomance discharge test is a more stringent test and is sufficient by itself, to demon-strate that the. battery capacity has not been degraded below an acceptable level. We found the proposed change acceptable."
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i R. Capra !
The SELB staff cannot find acceptable the proposal to delete the battery i
. service test requirement because: Regulatory Guide 1.129 states in Section C.1, "The battery service test... should be perfomed in i
j addition to the battery perfomance discharge test. The battery ser-vice test should be perfomed... with intervals between the tests not to exceed 18 months." R.G.1.129 also states in Section C, "Confomance with the requirements and recommendations for the... testing... of i
lead storage batteries for nuclear power plants that are specified by l
IEEE Std. 450-1975... provides an adequate basis for complying with the L
requirements of the Commission's regulations with respect to the...
testing.. [of] lead storage batteries... except in those cases 'in which the... licensee proposes an acceptable alternative..."
The staff, then, can accept a proposal to delete an operating require-4 ment imposed by a Regulatory Guide, if a licensee proposes an accept-i able alternative.
In this instance, the licensee's proposed change, item 12 is not considered an acceptable alternative by the staff be-1[
cause, while it is true that a lead calcium storage battery has a limited number of discharge cycles built into it, a number dependent on the amount and rate of discharge, among other factors, and it is desirable to reduce unnecessary testing, the problem is to determine whether or not a given test, in this case the battery service test, I
is unnecessary when a performance discharge test has just been i
performed, i
The 18 month interval minimum between service tests is an ad hoc, con-l sensual limit. Deviations of a few months from it are not known to result in significant degradations in a battery's capability with re-spect to its duty cycle; although the importance to battery capability 1
of the test interval must increase with battery age. What is proposed i
by the licensee is that the battery service test interval be doubled whenever a perfomance test is made and a battery service test is not.
The basis offered for doing only the perfomance discharge test is that the performance test is more severe and, therefore, tests every-thing that the following battery service test will. But, this is not l'
so; by definition, a battery service test is a constant current test designed to demonstrate that a battery can discharge at a specified current for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> or until an individual cell voltage - in the case of batteries 11, 12, 21, 22, and Reserve, it is 1500 ampere-hours /.
8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> = 188 amperes - drops to 1.75 volts when, if all cells. follow the same voltage time curve, the battery voltage will fall to some voltage greater than 105 volts. Such a test is severe in that some 4
cells in the series can go below 1.75 v, a limit described by lead acid. battery manufacturers as the damage level. But, the battery i
~ duty cycle calls for currents in excess of 188 amperes throughout
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the 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> duration, following a trip and a blackout, and signifi.
cantly in excess of the 188 ampere level; see FSAR, Table 8-10, and Technical Specification Section 4.8.2.3.2.d.2.
It is not necessarily true that a battery that can deliver 188 amps for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> can also deliver 850 amperes for 1 minute at a battery voltage greater than 105 v.
Thus, the reason Regulatory Guide 1.129 requires the battery l
service test, in addition to the performance test, is that the fonner tests the battery discharge rate and the latter tests the battery ampere hour capability. Neither' rating necessarily entaih the other.
The problem here is that no argument, either from theory or from opera-ting experience, has been adduced by the licensee'to show that there exists sufficient correlation between the two tests that missing one battery service test, when a performance test has demonstrated battery ampere hour capacity, will not result in an unacceptable increase in the unavailability of a plant battery in respect to its discharge rate ceiling.
The staff considers that an acceptable alternative to doing both tests every 60 months would be to combine the perfonnance discharge and battery service tests by following the battery service test current time curve for the first two hours and, subsequently, the performance discharge test, curve suitably modified, by reducing test duration for the remaining rated ampere hours at 188 amperes.
CONCLUSION
.The preceding safety evaluation concludes the review of the lice : ee's proposed technical specification changes relating to station control battu les. Although the staff has rejected proposed technical specification changes 8.
), 10 and 12, the licensee should make the remaining proposed changes, namely: i: ems 1 through 7, inclusive, and item 11.
. original 51En86 BTI ya.zt W Faust Rosa, Chief Electrical Systems Branch Division of Engineering & Systems Technology cc:
S. A. McNeill Distribution:
Docket File Nos. 50-317/318 SELB Rdg.
J C. Morris (PF)(2)
D. Tondi j
F. Rosa i
Calvert Cliffs S/F C :SELB/ DEST.
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