ML20085J721

Forwards Response to Generic Ltr 91-06, Resolution of Generic Issue A-30, 'Adequacy of Safety-Related DC Power Supplies.'

ML20085J721
Person / Time
Site:	Three Mile Island
Issue date:	10/22/1991
From:	Broughton T GENERAL PUBLIC UTILITIES CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-GTECI-A-30, REF-GTECI-EL, TASK-A-30, TASK-OR C311-91-2121, GL-91-06, GL-91-6, NUDOCS 9110290319
Download: ML20085J721 (7)

Text

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Post Office Box 480 Route 441 South Middletown, Pennsylvania 17057 o191 717 944 7621 TELEX 84 2386 i Wnter's Direct Dial Number: l (717) 948-8005 1

October 22, 1991

, C311-91-2121 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 Gentlemen:

Subject:

Three Mile Island Nuclear Station, Unit I (TMI-1)

Operating License No. DPR-50 Docket No. 50-289 Response to NRC Generic Letter 91-06 Resolution of Generic Issue A-30, " Adequacy of Safety-Related DC Power Supplies," Pursuant to 10 CFR 50.54(f)

NRC Generic Letter 91-06 required a response to the questions contained in Enclosure 1 to the letter. The attachment contains the Three Mile Island Nuclear Station, Unit I response.

Sincerely, N

T. G. Bro' hton Vice President & Director, TMI-1 TGB/WGH Attachment cc: Administrator, Region :

TMI Senior Resident Inspector

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-110290319 911022 n PDR ADOCK 05000209 l i 4 P PDR I GPU Nuclear Corporation is a subsidwy of Genera! Pubac Utdt#es Corporation

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C311-91-2121 METROPOLITAN EDIS0N COMPANY JERSEY CENTRAL POWER AND LIGHT COMPANY PENNSYLVANIA ELECTRIC COMPANY GENERAL PUBLIC UTILITIES NUCLEAR COPR0 RATION Three Mile Island lluclear Station, Unit 1 (TMI-1)

Operating License No. DPR-50 Docket No. 50-289 Response to the Generic Letter 91-06 Questions Regarding the Adequacy of Safety-Related DC Power Supplies This letter is submitted in response to Generic Letter 91-06,10 CFR 50.54(f)

Request - Generic Issue (GI) A-30 " Adequacy of Safety-Related DC Power-Supplies." All statements contained in this response have been reviewed, and all such statements made and matter set forth therein are true and correct to

the best of my knowledge.

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T. G. Broughtond Vice President and Director, THI-l Signed and sworn before me this 22nd_ day of October , 1991,

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e C311-91-2121 Attachment Page j of 5 10 CFR 50.54(f) REQUEST SAFETY-RELATED - GENERIC DC POWER SUPPLI ISSVE (GI)ES"A-30 " ADEQUACY

. ons and Responses

1. Unit GPUNC TMI-I

2. a. The number of indepeadent redundant divisions of Class 1E or safety-related de power for this plant is TWO (2) 250V/125V DC.

(Include any separate Class IE or safety-related dc, such as cn>

dc dedicated to the diesel generators.)

b. The number of functionai safety-related divisions of de power necessary to attain safe shutdown for this unit is 1 250 VDC BATTERY.

3. Does the control room at this unit have the following separate, independently annunciated alarms and indications for each division of de power?

a. alams

1. Battery disconnect or circuit breaker open? NO. THE SWITCH IS LOCKED CLOSED BY THE CONTROL ROOM. THE MAIN BATTERY DISCONNECTS ARE LOCKED CLOSED AND CANNOT BE UNLOCKED WITH-OUT THE SHIFT SUPERVISOR'S PERMISSION.

2. Battery charger disconnect or circuit breaker open (both input ac and output dc)? NO. THIS FUNCTION IS ALARMED IN THE CONTROL ROOM. THE ALARM FEEDS INTO A ' BATTERY ALARM TROUBLE" WINDOW. THIS 15 IN ACCORDANCE THE PLANT FSAR SECTION 8.2.2.6.

TMI-1 CURRENTLY HAS TWO BATTERY 1R003LE ALARMS. THE INPUTS TO EACH OF THESE ARE; LOW VOLTAGE, HIGH VOLTAGE, HIGH VOLTAGE TRIP, AND POWER FAILURE. THREE OF THESE ARE ALSO INPUT INTO THE PLANT COMPUTER AND DISPLAYED ON THE COMPUTER ALARM DISPLAY.

THE RESPONSE TO ANY OF THESE CONDITIONS IS TO GO TO THE BATTERIES, VERIFY THE ALARM AND TAKE THE APPROPRIATE ACTION.

BECAUSE THREE OF THE FOUR INPUTS ARE ALSO ON THE COMPUTER ALARM DISPLAY, THE SPECIFIC INPUT IS AVAILABLE IN THE CONTROL ROOM.

THE ACTION REQUIRED IN THESE CASES IS THE SAME. THIS IS

, CONSISTENT WITH GPil NUCLEAR'S GUIDELINES AND STANDARDS FOR OVERHEAD ANNUNCIATORS.

3. de system ground? YES

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• i C311-91-ti23 Att'achment Page 2 of 5

4. de bus undervoltage? R. SEE THE RESPONSE TO 2 AB0VE.

5. dc bus overvoltage? N0. SEE THE RESPONSE TO 2 AB0VE.

6. Battery chargt'r failure? NO. THIS FUNCTION IS ALAkMED IN THE CONTROL ROOM HOWEVER. THE ALARM FEEDS INTO A ' BATTERY ALARM TROUBLE" WINDOW. THIS IS IN ACCORDANCE THE PLA'dT FSAR SECTION 8.2.2.6.

7. Battery discharge? YES

b. Indications l

1. Battery float charge current? NO. THE BATTERY FLOAT CHARGE CURRENT IS COMBINED WITH THE TOTAL LGAD CURRENT ON THE BATTERY CHARGERS. SINCE THE BATTERY CHARGERS ARE CHECKED EVERY WEEK, A PROBLEM WITH THE CHARGE CURRENT WOULD BE DETECTED AT THIS TIME.

THIS FUNCTION IS NOT REQUIRED TO BE MONITORED IN ACCORDANCE ,

WITH FSAR SECTION 8.2.2.6.

2. Battery circuit output current? NO. AN ANALOG METER ON EACH BATTERY CHARGER MONITORS THE OUTPUT CURRENT. THIS FUNCTION IS NOT REQUIRED TO BE MONITORFD IN ACCORDANCE WITH FSAR SECTION 8.2.2.64

3. Battery discharge? YES

4. Bus voltage? NO. EACH 125V DC CHANNEL BUS VOLTAGE IS MONITORED WITH AN ANALOR METER ON THE RESPECTIVE BATTERY CHARGER. If THE BUS VOLTAGE EXCEEDS A LEVEL, AN ALARM WILL BE RECEIVED IN THE CONTROL ROOM VIA THE

• BATTERY TROUBLE ALARM" I WINDOW.

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c. Does the unit have written procedures for response to the above alarms and indications? YES

4. De s this unit have indication of bypassed and inoperable status of u rcuit breakers or other devices that can be used to disconnect the battery and battery charger from its de bus and the battery charger l

from its ac power source during maintenance or testing? AC-DC BREAKERS FOR THE BATTERY CHARGERS ONLY. THE DC DISCONNECT TO THE BATTERY IS

.0CKED CLOSED AND IS NOT ALARMED.

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5. If the answer to any part of question 3 or 4 is no, thers provide information justifying the existing design features of the facility's safety-related de systems. *See note below.

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C311-91-212)

Attachment Page 3 of 5

6. (1) Have you conducted a review of maintenance and testing activities to minimize the potential for human error causing more than one de division to be unavailable? YES and (2) do plant procedures prohibit maintenance or testing on redundaat de divisions at the sr.mo time? YES. REFERENCE PLANT PROCEDURES 1303-11.1, 1420-DC-1A, 1420-DC-1B, AND 1107-2.

If the facility Technical Specifications have provisions equivalent to those found in the Westinghouse and Combustion Engineering Standard Technical Specifications for maintenance and surveillance, then question 7 may be skipped and a statement to that effect may be inserted here.

7. Are maintenance, surveillance and test procedures regarding station batteries conducted routinely at this plant? Specifically:

a. At least once per 7 days are the following verified to be within acceptable limits:

1. Pilot cell electrolyte level? YES

2. Specific gravity or charging current? YES

3. Float voltage? YES

4. Total bus voltage on float charge? YES

5. Physical condition of all cells? YES

b. At least once per 92 days, or within 7 days after a battery discharge, overcharge, or if the pilot cell readings are outside the 7-day surveillance requirements are the following verified to be within acceptable limits:

1. Electrolyte level of each cell? YES

2. The average specific gravity of all cells? YES

3. The specific gravity of each cell? YES

4. The average electrolyte temperature of a representative number of cells? YES

5. The float voltage of each cell? YES

6. Visually inspect or measure resistance of terminals <ad connectors (including the connectors at the de bus)? YES

t C311-91-2121

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c. t.t least every 18 months (REFUELING) are the following vertfled: I

1. Low resistance of each connection (by test)? YES

2. Physical condition of the battery? YES t

3. Battery charger capability to deliver rated ampere .

-output to the d bus? YES

4. The capability of the battery to deliver its design duty cycle '

to the de bus? NO. THE BATTERY IS SUBJECTED TO A TWO HOUR CONSTANT CURRENT LOAD TEST EVERY REFUELING OUTAGE. THE LOAD TEST CLOSELY APPROXINATES THE LOAD DUTY CYCLE FOR THE TWO HOUR TEST IN ACCORDANCE WITH THE MANUFACTURER'S PU6LISHED DATA FOR THE LC-21 BATTERY CELL. THE PLANT TECHNICAL SPECIFICATIONS REQUIRE THE STATION DATTERY T0 OPERATE FOR TWO HOURS.

5. Each individual cell voltage is within acceptable limits during the service test? YES *

d. At least every 60 months, is capacity of each battery verified by performance of a discharge test? YES (EVERY REFUELING)

e. At least nnaally, is the battery capacity verified by performance discharge test, if the battery shows signs of degradation or has reached 85% of the expected service life? YES (EVERY REFUELING)

8. Does this plant have operational features such that following loss of one safety-related de power supply or bus:

y a. Capability is maintained for ensuring continued and adequate reactor cooling? YES

b. Reactor coolant system integrity and isolation capability are maintained? YES i

c. Operating procedures, instrumentation (including indicators and annunciators), and control functions are adequate to ir,itiate i

systems as required to maintain adequate core cooling? YES-9 If the answer to any part of question 6, 7 or 8 is no, then provide u your basis for not performing the maintenance, surveillance and test i

procedures described and/or the bases for not including the operational ,

L features cited.- *See note below, l

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. . p C311-91-2121 Attact. ment  ;

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• Note: for questions involving supporting type information (question numbers 5 and 9) instead of developing and supplying the information in response to this letter, you may commit to further evaluate the need for such provisions during the 3erformance of your individual plant examination for severe accident vulnera)ilities (IPE). If you select this option, you '

are required _to:

(1) So stato in response to these questions, and (2) Commit to explicitly address questions 5 and 9 in your JPE submittal per the guidelines outlined in NUREG-1335 (Section 2.1.6 Subitem 7), " Individual Plant Examination: Submittal Guidance." ,

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