ML20029B432

Application for Amend to License NPF-3,revising Tech Spec 3/4.8.2.3 Re Electrical Power Sys

ML20029B432
Person / Time
Site:	Davis Besse
Issue date:	03/01/1991
From:	Shelton D CENTERIOR ENERGY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20029B433	List: ML20029B432 ML20029B434
References
1898, TAC-M79672, NUDOCS 9103070288
Download: ML20029B432 (8)

Text

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Devs teses (419)2 4 2300 Docket Number 50-346 License Number NPF-3 Serial Number 1898 March 1, 1991 l

United States Nuclear Regulatory Commission Document control Desk Vashington, D. C. -20555 Subj ec t : License Amendment Request to Revise Technical Specification 3/4.8.2.3, E)cetrical'Pover Systems,'D.C. Distribution -

Operating (TAC No. H79672) k Centlement, i Enclosed is an application for an amendment to the Davis-Besse Nuclear Power Station (DBNPS), Unit Number 1, Operating License NPF-3, Appendix A -

Technical Specifications-(TS). This application requests a revision to TS 3.8.2.3 and its associated Bases based on the model TS's recommended by the Nuclear Regulatory Commission (NRC) to Toledo Edison in an NRC letter dated July 16, 1981 (Toledo Edison letter Log Number 756). Specifically, this vill allow Toledo Edison to utilire an alternate method of determining battery operability following service or performance discharge surveillance testing.

Use of this alternate method of determining battery operability vill allow for a potential reduction of six to eight days in critical path duration during a refueling outage. Accordingly Toledo Edison requests that the NRC approve this amendment.by September 1, 1991, for use during the seventh  ;

reiueling outage. -

If you have any questions, please contact Mr. R. V. Schrauder, Manager -

Nuclear Licensing,-at (419) 249-2366.

Very y yours, KBR/mmb m_Q ces. p. M. Byron,-DB-1 NRC Senior Resident Inspector A. B.: Davis, Regional Administrator, NRC Region III D. C. Di:Ianni, DB-1 NRC Senior Project Manager General J. Villiams, Chief of Staff, Ohio Adjutant General's Office i State of Ohio

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. Dockst Nu2bar 50-346 Liccnse Nu:bar NPT-3 Serial Number 1898

. Enclosure Page 1 Application for Amendment to facility Operating License Number NPF-3 Davis-Besse Nuclear Power Station Unit Number 1 Attached are requested changes to the Davis-Besse Nuclear Power Station, Unit Number 1 Facility Operating License Number NPF-3. Also included is the Safety Assessaent and Significant flazards Consideration.

The proposed changes submitted under cover letter Serial Number 1898 r concerni Appendix A. Technical Specification 3/4.8.2.3, " Electrical Pover Systems, D.C. Distribution - Operating".

Appendix A, Technical Specification 3/4.8.2.4, " Electrical Power Systems, D.C. Distribution - Shutdown".

Technical Specification Bases 3/4.0, " Electrical Pover". *

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Bya flR f'^'* %==~

D. C. Shelton, Vice President, Nuclear - Davis-Besse Svorn and Subscribed before me this 1st day of March. 1991.

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. Docket Numb 2r 50-346 Licensa Numb 3r NPF-3 Serial. Number 1898 Enclosure Page 2 The following information is provided to support issuance of the requested changes to the Davis-Besse Nuclear Power Station, Unit 1, Operating License Number NPF-3, Appendix A, Technical Specifications 3/4.8.2.3, " Electrical Power Systems, D.C. Distribution - Operating" Technien1 Specification 3/4.8.2.4, " Electrical Power Systems, D.C. Distribution - Shutdown":

Technical Specification Bases, 3/4.8, " Electrical Power Systems".

A. Time Required to Implement: This change is to be implemented within 45 days after the NRC issuance of the License Amendment.

B. Reason for change (License Amendment Request 90-0050):

This License Amendment Request (LA3) proposes revision of Davis-Besse Nuclear Pover Station (DBNPS) Operating License TS 3/4.8.2.3, TS Table 4.8-1, Battery Surveillance Requirements, to allov incorporation of the Nuclear Regulatory Commission (NRC) recomtnendations made in a letter to Toledo Edison dated July 16, 1981 (Toledo Edison letter Log Number 756).

Specifically, by adding a footnote to Table 4.8-1 this LAR vill allow the use of a battery charging current of less than 2 amps when on a float charge in lieu of specific gravities to as a means of determining battery operability following battery service or performance discharge surveillance testing. TS 3/4.8.2.4 is also affected by this proposed revision as Surveillance Requirement 4.8.2.4.2 refers back to Table 4.8-1.

Safety Assessment and Significant Hazards Consideration: See C.

attachment.

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. Dockot husber 50-346 Licenso Nu:bar NPF-3

> Serial. Number 1898 Attachment Safety Assessment and Significant Hazards Consideration for License Amendment Request 90-0050 J

T T,1f t Revision of Technical Specification (TS) 3/4.8.2.3, " Electrical Pover l Systems, D.C. Distribution - Operating" and TS 3/4.8.2.4, " Electrical Power Systems, D.C. Distribution - Shutdovn" DESCRIPTION:

This License Amendment Request (LAR) proposes revision of Davis-Besse Nuclear Power Station (DBNPS) Operating License TS 3/4.8.2.3, TS Table 4.8-2, Battery Surveillance Requirements, to allow incorporation of the Nuclear Regulatory Commission (NRC) recommendations made in a letter to Toledo Edison (TE) dated July 16, 1981 (TE letter Log Number 756).

Specifically, by adding a footnote to TS Table 4.8-1 this LAR vill allow the use of a battery chargir g current of less than 2 amps when on a float charge in lieu of specific gravities as a means of determining station battery operability following battery service or performance discharge surveillance testing. TS 3/4.8.2.4 is also affected by this proposed revision as Surveillance Requirement (SR) 4.8.2.4.2 refers back to TS Table 4.8-1.

Presently, after charging the station battery following a battery service or performance discharge surveillance test, a several day delay is required while avalting specific gravity equelization. IEEE Standard 450-1980, "IEEE Recommended Practice for Haintenance, Testing, and Replacement of Large 1,ead Storage Batteries for Generating Stations and Substations", allovs for the use of a stabilized battery charging current as indication that a battery is charged in lieu of specific gravities. This provision vould allov a potential reduction of six to eight days critical path duration during the seventh refueling outage.

TE requested information from the station battery manufacturer on the validity of using less than two amps battery charging current as indication of sufficient charge on the station battery as discussed in the IEEE Standard. In February 1991, the manufacturer conducted testing to determine the state of charge on a battery if, following a battery service or performance discharge test, a battery is recharged until a battery charging current of less than two amps is reached. The manufacturer stated that at this point, a battery, such as the station battery, vould be approximately 95 percent fully charged.

The current station battery has a 20-year design life and is certified by the manufacturer for a nuclear service life of 16 years. The station battery was sized to include a 25 percent margin to account for aging. TE has reviewed the station battery loading calculations and has determined that even including the 95 percent factor discussed above, the station battery vill still be able to satisfy its design load requirements at the

Docket Number 50-346 License Number NPF-3 Serial Number 1898

Attachment Page 2 end of service life. Thus, for the purpose of determining station battery operability following a battery service or performance discharge test, the utilization of a battery charging current of less than two amps when on a float charge is an acccotable alternative to the use of specific gravities.

A revision is proposed for the associated TS Bases 3/4.0, " Electrical Power Systems", to state, consistent with the proposed TS Table 4.8-1 changes, that a stabilized battery charging current may be used in lieu of specific gravities after battery service or performance discharge tests.

This LAR is similar to a revised TS approved by the NRC for the Grand Gulf Nuclear Power Station, Unit 1, Facility Operating License No. NPW29, as Amendment 29, dated October 9, 1990 (TAC No. 77294). It is also similar to the guidance provided by the NRC to Toledo Edison in their July 16, 1981 letter (TE letter Log Number 756).

SYSTEMS, COMPONENTS, AND ACTIVITIES AFFECTED:

This LAR affects the battery service and performance discharge surveillance testing for the station battery.

SAFETY FUNCTIONS OF THE AFFECTED SYSTEMS, COHp0NENTS AND ACTIVITIES:

Davis-Besse has four 125 VDC 1500 ampere-hour (based on an eight hour discharge) lead-acid batteries arranged to form two independent 250/125 VDC systems. Each battery is normally maintained in a fully charged condition and is normally float charged at approximately 132 volts from its associated battery charger. Battery discharge vill occur either when the DC requituments temporarily exceed the charger capacity or during a loss of a battery charger supply. The battery with the largest load vas used in sizing the capacity and ampere rating of all four batteries. The batteries are sized to supply the anticipated DC and instrument AC supply for a period of one hour after the loss of the battery charger supply. The one-minute rating of the batteries includes starting current requirements of the DC motors, diesel generator flashing, and current requirements for operation of the 13.8ky, 4.16ky, and 400v breakers and all continuous loads. A twenty-five percent over-capacity was designed into the sizing to account for the loss of battery capability over the 20-year design life due to battery aging.

The safety function of the battery service and performance discharge surveillance testing is to ensure that the station battery has sufficient capacity to supply the intended loads and to determine degradation when compared to the rated capacity and previous test data. The quantotiv surveillance testing is used to measure specifie parameters to enrute the station battery is fully charged following the battery service and performance discharge tests.

EFFECTS ON SAFETY:

The station battery is presently subjected to a battery service test once every 18 months and a performance discharge test once every 60 months per SR 4.8.2.3.2.d and e, respectively. Although the station battery may be

Docket Hunber 50-346

, License Number NPF-3 Seria) Number 1898 Attachment Page 3 fully charged following a battery service or performance discharge test, the present vording of Table 4.8 1 requirements for specific gravity measurements vould require several days delay vhile avatting specific gravity stabilization. The use of charging current as an indientor of the battery's state of charge is discussed in Appendix B to IEEE Standard 450-1980. TS Bases 3/4.8, " Electrical power Systems", references this IEEE Standard as providing the basis for the surveillance requirements for TS 4.8.2.3 and TS 4.8.2.4 The IEEE Standard indicates that an acceptable equivalent method for ensuring sufficient charge following a discharge test is the use of a stabilized battery charging current at float voltage.

The specific gravity of the battery drops during a discharge test, and on ,

the subsequent recharge, it is typical for the measured specific gravity to '

lag behind true specific gravity. This is caused by the generation of high specific gravity sulfuric acid during the recharging process that sinks to the bottom of the cell. This stratification phenomenon vill cause incorrect measured specific gravity readings. Several days are required for diffusion to equalize the specific gravity throughout the battery cells.

The battery charging current is a more accurate indicator of the battery's state of charge following n discharge tert. Battery charging current at the beginnisig of a recharge is typically several hundred amps. As the hattety approaches full charge, the battery voltage rises to the chcrger output voltage ar.d the charging current decreases to a stabilized value. Vhen the charger current has stabilized, the battery is charged, even though specific gravity readings vill not confirm the true state of the battery for several days. Both the Grand Gulf amendment and the July 16, 1981 NRC guidance utilize a battery charging current of less than 2 amps as indication of a stabilized battery charging current. Allowing the use of the battery l cnarging current as un indicator of the state of the battery charge vould resolve the delays in returning the battery to an operable status associated with vaiting for specific gravities to stabilize following battery service or performance discharge testing. Since the use of battery charcing current in lieu of specific gravities under these conditions is an equivalent, alternate method, margins of safety are not affected.

Accordingly, the proposed revision to Table 4.0-1 to allov the use of a stable battery charging current of less than 2 amps when on a float charge in lieu of specific gravities for determining station battery operability following a battery service or performance discharge test has no effect on safety.

SIGNIFICANT HAZARDS CONSIDERATION:

The NRC has provided standards in 10 JFR 50.92(c) for determining whethei a significant hazard exists due to a proposed amendment to an opera'ing l C

License for a facility. A proposed amendment involves no significant l hazards consideration if operation of the facility in accordance with the l proposed shenges vouldi (1) Not involve a significant increase in the  ;

l

l

< Docket Number 50 346 l

License Number NpF-3 a

Serial Number 1898 i Attachment Page 4 probability or consequences of an accident previously evaluatedt (2) Not create the possibility of a nov or different kind of accident from any previously evaluated or (3) Not involve a significant reduction in a margin of safety. Toledo Edison has reviewed the proposed changes and determined that a significant hazards consideration does not exist because operation of the DBNpS in accordance with these changes vouldt i la. Not involve a significant increase in the probability of an

accident previously evaluated because the use of a stable battery charging current of less than two amps when on a float charge is an acceptable, equivalent method of determining station battery operability following a battery service or performance discharge test. Batteries determined operable are capable of petforming their intended function and there is no associated nignificant increase in the probability of an accident.

Ib. Not involve a significant increase in the consequences of an i

accident previously evaluated because the use of a stable battery charging current of less than tvo amps when on a float charge is an acceptable, equivalent method of determining station battery operability following a battery service or performance discharge test. Batteries determined operable are capable of performlag their intended function and there is no associated significant increase in the consequences of an accident.

2a. Not create the possibility of a new kind of accident from any accident previously evaluated because this change proposes an alternate, equivalent method of determining station battery operability following a battery service or performance discharge test. No modifleations are being made to the butteries, the charging equipment, or the distribution system.

2b. Not create the possibility of a different kind of accident from any accident previously evaluated because this change proposes an alternate, equivalent method of determining station battery operability following a battery service or performance discharge

test. No modifications are being made to the batteries, the charging equipment, or the distribution system.

3. Not involve a significant reduction in a margin of safety because the use of the station battery charging current as an indicator of the state of the battery charge following battery service or i performance discharge testing is alloved by 1EEE 450-1980 which is referenced in the TS Bases Section as the basis for the battoiv surveillance requirements. As verified by the battery manufacturer, a battery chatging current of less than two ampo indicates the battery is approximately 95 percent fully changed.

This value, when taken into consideration with the design matgins and the loading calculations for station battery capacity anfi servhc life, ensure that the station bat tery vill be capable of meetins its design load requirements throughout its servlee life.

l Therefare, t.e margin of safety is not significantly reduced.

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Docket Nu:bar 50-346

, Lietns Numb 3r NPF-3 Setial Number 1998

- Attachment Page 5

, CONCLUSION:

On the basis of the above, Toledo Edison has determined that the License Amendment Request does not involve a significant hazards consideration. As this License Amendment Request concerns 1roposed changes to the Technical Specifications that must be reviewed by the Nuclear Regulatory Commission, this License Amendment Request does not coa 9titute an unrevieved safety question.

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ATTACHHL3:

Attached are the proposed marked-up changes to the operating License.

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