ML17339A291

Forwards Response to NRC 790726 & 0808 Ltrs Re Offsite Power & Onsite Electrical Distribution Sys.Distribution Sys Test Deferred Pending NRC Review of Encl Info

ML17339A291
Person / Time
Site:	Turkey Point
Issue date:	11/09/1979
From:	Robert E. Uhrig FLORIDA POWER & LIGHT CO.
To:	Gammill W Office of Nuclear Reactor Regulation
References
L-79-323, NUDOCS 7911200362
Download: ML17339A291 (10)

Text

REGULATORY INFORT ION OISTRISUTION SYSTEM +OS)

ACCESSION NBR:7911200362 DOC,DATE: 79/ll/09 NOTARIZED'O DOCKET F'AC'IL;50 250 Turkey f'oint Plantr Unit 3r Florida f'ower and Light C 05000250 50-251 Turkey Po'int Plantr Unit 4r F'lorida Power and Light L 05000251 AUTH s NAME AUTHOR AFFILIATION UHAiGr R E

~ ~ F l or) da Pose'r"'8 Light Co, RECIP,NAME RECIPIEAT AFFILIATION GAMMILLEN ~ Assistant Director for Operating Reactor Projects (Pre 791 SUBJECT; Forwards response to NRC 790726 8 0808 ltrs re offsite power 8, onsite electrical distri6ution sys,Distribution sys test defer ed pending NRC review of encl info.

DISTRIBUTION CODE: A015S COPIES RECEIVED:LTR TITLEi Onsite Emergency Power Systems

~ ENCL 9 SIZE ~

NOTES! WWWM~%%M RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL ACTION: 05 BC oAa~z 7' LA i i) r INTERNA .~ BEG 1 02 NRC PDR 1 1 i i 13 I8E 2 2 15 OELD i 1 ib MPA 1 1 17 AUXIL SYS' BR i 18 I8C SYS BR i 20 ENGR BR 1 1 21 REAC SFTY BR 1 1 22 PLANT SYS BR 23 AOV 'REAC BA 1 24 PllR SYS 8R i 25 AAMBACH T i i 26 TONOIr D i 1 27 MCDONALDrD i 29 BH INKMAN 1 1 30 EEB 1 S HANAUKR i 1 EXTERNAL: 03 LPDR 1 1 04 NSIC 31 ACR8 16 lb

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TOTAL NUMBER OF COPIES REQUIRED; LTTR 46 ENCL 45

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/fEwa aA FLORIDA POWER d LIGHT COMPANY November 9, 1979 L-79-323 Office of Nuclear Reactor Regulation Attn: Mr. William Gammill Acting Assistant Director for Operating Reactors Projects Division of Operating Reactors U. S. Nuclear Regulatory Commission Washington, D. C. 20555

Dear Mr. Gammill:

Re: Turkey Point Units 3 and 4 Docket Nos. 50-250 6 50-251 Station Electric Distribution S stems As a result of NRC letters dated July 26 and August 8, 1979, we have performed evaluations (attached) related to offsite power and the onsite distribution system at Turkey Point Units 3 and 4. Our operating department is now reviewing the evaluations to determine the need for additional Technical Specifications. If such Specifications are needed, we will provide a schedule for their submittaZ by December 15, 1979.

Based on the results of the evaluations and proposed plant modifications, we have deferred scheduling a distribution system test pending NRC review of this submittal.

Please call if you have additional questions on this subject.

Very truly yours, obe

~r.~~

t E. Uhrig Vz.ce President Advanced Systems G Technology REU/ld cc: A. Schwencer, Operating Reactors Branch Sl Harold Reis, Esquire VIIX~SOO>~

PEOPLE... SERVING PEOPLE

A In response to NRC letter dated July 26, l979 Re uest for Additional Information Turke Point 3 and 4 The following response addresses the Request for Additional Xnformation, Turkey Point 3 8 4 enclosed in the NRC letter to PPL dated. July 26, 1979.

Clarification is provided. regarding undervoltage protection. Undervo3.tape coincidence logic is also described.

The undervoltage protection for Turkey Point is not presently as'tated in the Request .for Additional Information attached to the letter of July 26, 1979., The undervoltage'relays are General Electric 12HGA11J70 models. These relays respond. at 405-50$ of 4160V and. are used. as loss protection relays. of'oltage The loss-of-voltage relaying for Turkey Point is presently provid'ed via two relay" per 4160 volt 'bus; relay Al and A2 on bus A, relay Bl and B2 on

. bus B. The A diesel starting sequence and. disco..nection of offsite power to bus A is initiated by actuation of relay Al e.d Bl or by actuation of relay Al and initiation of the B diesel starting sequence. Similarly, the B diesel starting sequ'ence and, d.isconnection o offsite power to Bus B is initiated by actuation of relay B2 and, A2 or by actuation of relay B2 and.

initiation of the A diesel starting seouence. Thus, a spurious actuation, of one.undervoltage relay cannot- initiate the spurious trip of the offsite source and. a single failure of one undervoltage relay to actuate 'ower.

will not preven the remaining relays from initiating at least one diesel sequence.

However, as stated in our letter of. July 21, 1977, our operating practices provide reasonable assurance that voltage on the auxiliary power system (via the auxiliary transformer or start-up transformer} is maintained above.

the minimum voltage required for the proper ope=ation of safety and non>>

safety related. equipment.

Xn order to further ensure that sufficient voltage is present for the auxi3.iary 'busses a design modification is in progress to aM, an undervoltage relay protection system to the present loss of voltage protection scheme.

0 L Xn response to HRC letter to FPL d ted Xiugust 8, 3.979 Re: Adetuuac oi'tation Electric Distribution Ssstess Vol'"See

'he following response addresses the DRC concern that tne offsite power system (grid) and on-site electrical distribution system i of sufficient capacity and capability to automatically start and operate all xequired safety loads Specifically, the HBC required confirmation that potcnti"l ovexloading due to transfer of eithex safety or non-safety 3.oads and.

potential. starting transient pxoblems do not result in unaccept b3y degraded. voltage to safety load" or spurious shedding of s fety 3.oads from the offsite electrical grid.

During 1978 and. 3.979, the'steady state voltage expexierccd on the tx-ansmission system at Turkey Point Plant vaxied. between 235kV and 244kY. Tne lowest voltage on xecord. at Turkey Point, 228kY, occurred for pproximate3y 10 minutes prior to collapse of the grid. on Yiay 16> 3.977- From exp x.ience, therefore, voltages less than 235kV at Turkey Point are considered. transient in nature, with recovery or collapse of the system expected to occur i.n a short period of time.

F1orida Power 5 Light has no contingency plans to l.ower transmission vo3.tages to reduce loads. A 'program is in progress to lower distribution voltages for 1oad reduction, 'but this would. have no effect on the switchy;.rd volta.ges at Turkey Point.

Voltage calculations were performed. based. on the Guideline for Voltage Dxop Calculations enclosed in thc letter of August 8, 1979. The analyses were performed, for an accident condition (which present the largest load demand.)

with the unit electrical system connected to the start-up transform x. (upon a safety injection signal, transfer to staxt-up transformer is automatic).

Although Turkey Point is a multi-unit station, off-site power is supplied to each unit eparatcly and independently of the other. All automatic actions wexe assumed to occur as designed and no credit taken for manual load, shedding.

I A number of loading configurations ~:ere analyzed, assuming different combinations of condensate pumps, intake cooling w ter pumps, and co'~ponent coo3.ing water pumps vere running. For all cases, the following assumption were made for the calculations.

1) Running loads prior to safety injection signal are based on measured loads at the plant with both units at, full power. Highest recoxded loads on busses were used in calculations.

2) Tne power factor of running loads was assumed as .85.

3) Powe factor of starting loads assumed to be .20 for 4kY motors, .42 for emergency containment coolers, .35 for emergency containmcnt filters, and

.60 for valve motor operators.

'4) Starting current assumed to be 6 times FLA fox'otors and 2.1 times FLh. for valve motor operators (based on start-up data for Ste Lucie Unit 1).

5) All running loads were assumed as constant KYA

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A minimum voltage was determineQ for each bus based on the worst case starting voltage drop to safety equipment. A calculation was then performeQ for each case to determine the switchyard voltage required to maintain the minimum voltage on all the busses.

On the first round of calculations, several loading in minimum switchyard voltages above the lowest steady state configurations'esulted voltage on record at Turkey Point of 235KV.

Special instructions for operation have been formulateQ to ensure that the Plant is not run in a'y configuration which would produce results with minimum acceptable voltage greater than 235KV. Xn addition, the switchyard voltage 'at Turkey Point is at a seasonal high at. this period.

Xn event of equipment malfunctions requiring operation of the-Plant.

in a configuration other than mentioned above, the. operators are instructed to ensure the switchyard voltage remains greater than the analysis voltage for that operating condition, or immediately reduce the output on the unit to allow reduction of loading on the critical switchgeax. By taking these administrative actions as outlined above, the voltage analyses verify that sufficient switchyard voltage is available under steady state conditions to run all normal loaQs and simultaneously start all safety loads without damage or spurious separation from the grid.

Xn order to further assure that degraded grid voltage woulQ not, prevent safety equipment from starting, a design moQification is in progress to add undervoltage relays to the 4160V busses anQ the 480V loaQ centers. Until such time that modification can be accomplished, the above administrative actions will be instituted.

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