ML18022A881
| ML18022A881 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 10/25/1991 |
| From: | Vaughn G CAROLINA POWER & LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| REF-GTECI-A-30, REF-GTECI-EL, TASK-A-30, TASK-OR GL-91-06, NLS-91-274, NUDOCS 9111010268 | |
| Download: ML18022A881 (12) | |
Text
ACCELERATED DISTRIBUTION DEMONSTRATION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:9111010268 DOC.DATE: 91/10/25 NOTARIZED: YES FACIL:50-400 Shearon Harris Nuclear Power Plant, Unit 1, Carolina AUTH.NAME AUTHOR AFFILIATION VAUGHN,G.E.
Carolina Power
& Light Co.
RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
SUBJECT:
Responds to Generic Ltr 91-06, "Resolution of Generic Issue A-30,
'Adequacy of Safety-Related DC Power Supples,'"
per 10CFR50.54(f).
DISTRIBUTION CODE:
AOOID COPIES RECEIVED:LTR t ENCLj SIZE:
7 TITLE: OR Submittal:
General Distribution DOCKET 05000400 R
D NOTES:Application for permit renewal filed.
05000400 A
RECIPIENT ID CODE/NAME PD2-1 LA MOZAFARI,B.
INTERNAL: ACRS NRR/DET/ESGB NRR/DST 8E2 NRR/DST/SICB8H7 NUDOCS-ABSTRACT OGC/HDS1 RES/DSIR/EIB EXTERNAL: NRC PDR COPIES LTTR ENCL 1
1 2
2 6
6 1
1 1
1 1
1 1
1 1
0 1
1 1
1 RECIPIENT ID CODE/NAME PD2-1 PD NRR/DET/ECMB 7D NRR/DOEA/OTSB11 NRR/DST/SELB 7E NRR/DST/SRXB 8E OC/LFMB NSIC COPIES LTTR ENCL 1
1 1
1 1
1 1
1 1
1 1
0 1
1 1
1 D
D R
D NOTE TO ALL"RIDS" RECIPIENTS:
D D
PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM P 1-37 (EXT. 20079) TO ELIMINATEYOUR NAMEFROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!
TOTAL NUMBER OF COPIES REQUIRED:
LTTR 24 ENCL 22
Carolina Power 8 Light Company P.O. Box 1551 ~ Aateigh, N.C. 27502 G. E. VAUGHN Vice President Nuclear Services Department GtfT 3S j99)
SERIAL'LS-91-274 United States Nuclear Regulatory Commission ATTENTION:
Document Control Desk Washington, DC 20555 SHEARON HARRIS NUCLEAR POWER PLANT DOCKET NOS.
50-400/LICENSE NOS.
RESPONSE
TO GENERIC LETTER 91-06 ADEQUACY OF SAFETY-RELATED DC POWER SUPPLIES Gentlemen:
The purpose of this letter is to submit Carolina Power 6 Light Company's 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 '4(f)"
for the Shearon Harris Nuclear Power Plant (SHNPP).
The Staff requested written responses to questions provided in Enclosure 1 of the Generic Letter within 180 days of the date of the Generic Letter, which was issued on April 29, 1991.
Please refer any questions regarding this submittal to Mr.
ST DE Chaplin at (919) 546-6623'ours very uly GEV/SDC (GL91-06.hnp)
Enclosure G.
E. Vaughn cc:
Mr. S.
D. Ebneter Ms. B. L. Mozafari Mr. J.
E. Tedrow (NRC-SHNPP)
My commission expi e
Px/!7sr'tQ G.
E. Vaughn, having been first duly sworn, did depose and say that the infor-mation contained herein is true and correct to the best of his information, knowledge and belief; and the sources of his information are officers, employees, contractors, and agents of Carolina Power 6 Light Company.
ffffff
'gffffffffff A ~i~
QnA,M C'otary (S a )
~
As+i g
PUBS 9iiipi0288 leap>p~pp 911025 PDR ADOCK 0500 DR
yC h
II
, 4
ENCLOSURE 1 SHEARON HARRIS NUCLEAR POWER PLANT NRC DOCKET NOS.
50-400 OPERATING LICENSE NOS.
RESPONSE
TO GENERIC LETTER 91-06 ADEQUACY OF SAFETY-RELATED DC POWER SUPPLIES Enclosed is Carolina Power
& Light Company's (CP&L) responses to the NRC questions contained in Generic Letter 91-06 for the Shearon Harris Nuclear Power Plant.
The NRC questions have been repeated with the necessary information provided in the blanks left by the NRC Staff.
In addition, CP&L has provided comments and clarifications to the NRC questions, where appropriate.
Unit 1
The number of independent redundant divisions of Class 1E or safety-related dc power for this plant is two (Include any separate Class 1E or safety-related dc, such as any dc dedicated to the diesel generators.)
b.
The number of functional safety-related divisions of dc power necessary to attain safe shutdown for this unit is one CP&L COMMENT AND CLARIFICATION'o additional comments.
Does the control room at this unit have the following separate, independently annunciated alarms and indications for each division of dc power7 alarms 1.
batterdyisconnect or clrcnlt breaker openy ~n a Battery charger disconnect or circuit breaker open (both input ac and output dc)'P Yes 3.
dc system ground?
Yes
4, 6.
7.
dc bus undervoltage?
Yes dc bus overvoltage?
Yes Battery charger failure?
Yes Battery discharge?
No b.
Indications 1.
Battery float charge current?
No 2.
Battery circuit output current?
Yes 3.
Battery discharge?
Yes 4.
Bus voltage?
Yes Does the unit have written procedures for response to the above alarms and indications?
Yes CP&L COMMENTS AND CLARIFICATIONS:
The Shearon Harris Nuclear Power Plant (SHNPP) safety related DC Power System utilizes two chargers for each train (division) of DC power.
One charger in each train remains online and operational while the second remains offline as a backup.
The safety related DC Power System monitoring features include main control board visual indication and annunciation for both safety related DC power systems (1A-SA & 1B-SB).
In addition, safety related DC battery charger trouble lights and visual system indicators are located locally on each battery charger.
The Shearon Harris Nuclear Power Plant uses a single common annunciator for each division of safety related power to indicate emergency DC power trouble in that division (125 VDC emergency bus A & B trouble).
The separate and independent annunciator for each train facilitates quick trouble diagnosis of the DC power system.
The NRC staff has reviewed and audited the safety related DC Power System during the licensing of the Harris Plant as noted in the Safety Evaluation Report.
Audits such as the Electrical and Instrumentation and Control System Branch Audit conducted in January 1986 has ensured that the DC power system exhibits monitoring features which have proven to provide operations the ability to operate and forecast system operability and malfunctions.
This ensures adequate safety related DC power is available for safe shutdown of the plant.
UESTION 3.a.l.
The 125 VDC emergency bus design does not incorporate a circuit opening device or disconnect means between each safety related
P~ K I
battery and its associated DC bus.
Therefore, an alarm for such a
device is unnecessary.
UESTION 3.&.2.
The system design incorporates, for each train, a loss of AC input power to the charger through the phase failure/loss of input alarm relay.
Battery charger DC output breaker position is effectively monitored by the no current alarm relay, which is located after the DC output breaker.
This alarm relay monitors charger current output and provides annunciation when no DC current is being supplied by the DC charger.
The input and output alarm relays activate the common 125 VDC emergency bus trouble alarm.
This annunciator, located on the main control board, notifies operations of DC system trouble.
For these annunciators to be operational, either the AC input
- breaker, the DC output breaker, or both must be closed to place the alarm circuitry in service.
The requirement for at least one breaker to be closed is to prevent annunciation from the back-up battery charger associated with each division of safety related DC power.
The back-up charger is normally out of service, with the input AC circuit breaker and the DC output circuit breaker open.
UESTION 3.a.3.
System design for a DC ground (ground fault) includes an alarm on the main control board.
The annunciator used is the common 125 VDC emergency trouble alarm.
This alarm is separate and independent for each division of safety related DC power.
UESTION 3.a.4.
The system design incorporates an undervoltage alarm which annunciates the common 125 VDC emergency bus trouble alarm to notify operations of an undervoltage condition.
Emergency bus voltage is also indicated on the main control board by a voltmeter.
Both the alarm and voltage indication are separate and independent for each train of DCpower.
UESTION 3.a.5.
Each division of safety related power incorporates an alarm for the DC battery charger (bus) overvoltage via the common 125 VDC emergency bus trouble alarm.
Again, this alarm is separate and independent for each division of safety related DC power.
UESTION 3.a.6.
Each safety related battery charger is equipped with a charger failure relay which annunciates the 125 VDC emergency bus trouble alarm for the respective train.
The relay and alarm are separate for each division of safety related power.
UESTION 3.a.7.
Conditions that may result in a high battery discharge condition can be detected by a bus undervoltage condition which is alarmed in the control room as described in Section 3.a.4.
UESTION 3.b.l.
Since the safety related battery charger supplies the normal DC plant loads as well as provide the charging current to the DC battery bank, battery charger current is indicated locally at the charger.
Each DC battery charger is equipped with a DC ammeter and DC voltmeter.
UESTION 3.b.2.
When the batteries are supplying the plant DC load, battery output current can be monitored from the DC bus ammeter located in the main control room.
UESTION 3.b.3.
When the batteries take over plant DC load requirements, the rate of discharge can be monitored from the control room by means of a DC ammeter and DC voltmeter.
Each division of DC power has a
DC ammeter and DC voltmeter located on the main control board to enable operations the ability to monitor the DC power system.
UESTION 3.b.4.
Each division of DC power is equipped with a DC voltmeter located on the main control board to allow operations the ability to monitor DC bus voltage.
This voltmeter is used to monitor bus voltage when the DC battery chargers are in service as well as when the batteries assume plant DC load requirements.
Does this unit have indication of bypassed and inoperable status of circuit breakers or other devices that can be used to disconnect the battery and battery charger from its dc bus and the battery charger from its ac power source during maintenance or testing2 No CP&L COMMENTS AND CLARIFICATIONS:
As noted in Section 3.a.l, the DC battery cannot be disconnected from its associated DC bus by means of a circuit breaker or other type device during maintenance or testing.
Therefore bypassed or inoperable indication is not necessary.
. ~
1 J
II tc7,.
When maintenance or testing of a battery charger or its associated input and/or output breakers is necessary, that charger is taken offline and the alternate charger is placed in service.
The online charger has all the indication and alarm features described previously.
If the answer to any part of question 3 or 4 is no, then provide information justifying the existing design features of the facility's safety related dc systems.
- See note below.
CP6L COMMENTS AND CLARIFICATIONS:
See justification for each question answered "No" in the Question Comment and Clarification section of this response.
(1) Have you conducted a review of maintenance and testing activities to minimize the potential for human error causing more than one dc division to be unavailablep Yes and (2) do plant procedures prohibit maintenance or testing on redundant dc divisions at the same time?
Yes 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 the effect may be inserted here.
The SHNPP Technical S ecifications were based on and reviewed b the staff a ainst Westin house Standard draft Revision 5.
Are maintenance, surveillance and test procedures regarding. station batteries conducted routinely at this plantV CP&L COMMENTS AND CLARIFICATIONS:
See statement above concerning SHNPP technical Specifications.
El-5
Does this plant have operational features such that following loss of one safety-related dc power supply or bus:
Capability is maintained for ensuring continued and adequate reactor cooling?
Yes b.
Reactor coolant system integrity and isolation capability are maintained't Yes Operating procedures, instrumentation (including indicators and annunciators),
and control functions are adequate to initiate systems required to maintain adequate core coolingf Yes CP&L COMMENTS AND CLARIFXCATIONS:
No additional comments.
If the answer to any part of question 6, 7, or 8 is no, then provide your basis for not performing the maintenance, surveillance and test procedures described and/or the bases for not including the operational features cited.
- See note below.
- 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 performance of your individual plantexamination for severe accident vulnerabilities (IPE). If you select this option, you are required to:
(1)
(2)
So state in response to these questions, and Commit to explicitly address questions 5 and 9 in your IPE submittal per the guidelines outlined in NUREG-1335 (Section 2.1.6, Subitem 7), "Individual Plant Examination:
Submittal Guidance."
CP&L COMMENTS AND CLARIFICATIONS:
Not applicable based on responses to Questions 6,
7 and 8.
El-6
0