B16181, Provides Responses & Commitments to 970117 RAI Re Design of Millstone Unit 3 Station Blackout Sys

Provides Responses & Commitments to 970117 RAI Re Design of Millstone Unit 3 Station Blackout Sys

ML20136A563
Person / Time
Site:	Millstone
Issue date:	02/28/1997
From:	Brothers M NORTHEAST NUCLEAR ENERGY CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
B16181, TAC-M96054, NUDOCS 9703070204
Download: ML20136A563 (10)

Text

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""I* F'"7 "d- ("""'" ' *') **'"'"'d"3*3 Northeast l Nuclear Energy siai<one Noacar Po.e, station

, Northeast Nudear Energy Cornpany P.O. Ikx 128 4

Waterford, CT 06385-0128 (860) 447-1791 Fax (860) 444-4277

'Ihc Northeast Utilities Synicin February 28,1997 Docket No. 50-423 B16181 1

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U.S. Nuclear Regulatory Commission

- Attention: Document Control Desk Washington, DC 20555 Millstone Nuclear Power Station Unit No. 3 Response to Request for Additional Infonnation Related to Alternate AC Power Source Requirements (TAC No. M96054)

The purpose of this letter is to provide Northeast Nuclear Energy Company's (NNECO's) response to the January 17, 1997 NRC Staff request for additional ,

information regarding the design of the Millstone Unit No. 3 Station Blackout (SBO)  !

System. The detailed response is provided in Attachment 1. NNECO's commitments .

associated with this letter are provided in Attachment 2. l I

Should you have any questions regarding this submittal, please contact Mr. James Peschel at (860) 437-5840.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY

/Al0 R M. H. Brottierls' N Vice President - Millstone Unit No. 3 g. -)() f j Attachments I

9703070204 970228 PDR ADOCK 00000423 p PDR ,

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. U.S. Nucl=r Regulatory Commission B16181\Page 2 cc: H. J. Miller, Region I Administrator J. W. ~ Anderson, NRC Project Manager, Millstone Unit No. 3 A. C. Cerne, Senior Resident inspector, Millstone Unit No. 3 W. D. Travers, Dr., Director, Special Projects  !

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Docket No. 50-423 B16181 Attachment 1 Millstone Nuclear Power Station, Unit No. 3 Response to Request for Additional Information Related to Alternate AC Power Source Requirements (TAC No. M96054)

February 1997

l I U.S. Nucl3:r Regulatory Commission B16181\ Attachment 1\Page 2 Millstone Nuclear Power Station, Unit No. 3 Response to Request for Additional Information ,

Related to Alternate AC Power Source Requirements l (TAC No. M96054) l I

Question 1 '

l After a loss of offsite power (LOOP), how soon will the station blackout diesel generator ;

(SBO-DG) auxiliaries be powered from the SBO-DG or another diesel generator? Also, which procedure will cover this requirement?

Response

The SBO-DG auxiliaries will be powered from the emergency diesel generators (EDGs) within the first hour of a postulated 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> LOOP, thereby ensuring availability of the .

SBO-DG at any time during the LOOP. Emergency Operating Procedure (EOP) l 35 ES-0.1, " Reactor Trip Response," will provide the procedural controls to power the l SBO-DG auxiliaries. l Question 2 l l

if the SBO-DG is used to power the auxiliaries:

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a. How long will the SBO-DG be running and at what load?

b. What are the consequences of running the SBO-DG at light load conditions?

c. What is the impact on the SBO-DG fuel supply in view of the fact that the SBO-DG may be running for an additional 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />?

Response

I The SBO-DG will not be used to power the auxiliaries during a LOOP. The SBO-DG is l intended to be used only during an SBO event. Under this condition, the SBO-DG will l power its own auxiliaries in addition to the loads required during the SBO. At times  !

other than during an SBO event, the SBO auxiliaries will be powered from the plant  !

electrical distribution system via normal 4KV buses 34A or 348. Because the SBO-DG will not be run at light load conditions, the consequences of operating the SBO-DG in l such a way are not applicable. In addition, the way in which the SBO-DG is operated will have no impact on the SBO-DG fuel supply. (Please refer to Attachment 3 for a schematic of the SBO-DG interfaces with normal and emergency 4KV buses.)

U.S. Nucl:ar R:gulatory Commission B16181\ Attachment 1\Page 3 Question 3a if another diesel generator is used to power the auxiliaries, provide details of this diesel 4 generator (capacity, connectability, availability, reliability, etc.)

Response

Either of the EDGs will be used to power the SBO-DG auxiliaries.

Capacity - Each EDG has a 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> rating of 5335KW. The sum of the SBO-DG auxiliaries maximum loading of 100.76KW and the LOOP only loading of 4798KW for each EDG is well below the 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> rating of each EDG.

Connectability - The EDGs are available to be connected to 4K ' vgency buses 34C

, and 34D, which in turn supply -1KV normal bu. \ and 34B. Bus 34A or 34B serve as the supply for the SBO auxil .,,cs when the SBO-DG is not operating.

Availability - The EDGs start automatically for a LOOP then accelerate to rated frequency and voltage within eleven seconds.

Reliability - The average EDG reliability for 20, 50, and 100 demands utilized in the SBO safe shutdown scenario document was 1.00,1.00, and 0.985, respectively.

Question 3b Is this a new diesel generator?

Response

The EDGs are part of the original plant design.

Question 3c Provide details on how it will be interfaced with existing switchgear and equipment.

Response

The SBO auxiliaries will be powered by backfeeding through normal bus 34A or 348.

U.S. Nucl:ar Regulatory Commission B16181\ Attachment 1\Page 4 The SBO-DG auxiliaries (including battery chargers) are supplied from normal bus 34A or 34B. Should a LOOP (without an SBO) occur, one or both EDGs will automatically start. The emergency to normal bus tie breaker will automatically open to shed normal buses 34A and 34B from emergency buses 34C and 34D. Existing loads on emergency buses 34C and 34D will be automatically stripped and essential loads will be automatically sequenced back onto bus 340 and/or 34D. (Please refer to Attachment 3 for a schematic of the SBO DG interfaces with normal and emergency 4KV buses.)

Procedure EOP 35 ES-0.1 will bc revised to ensure SBO-DG availability during the postulated eight hour LOOP.

Question 4 Provide details regarding the testing anrf .'perator training requirements resulting from j this modification.

! Response Testing will be conducted to verify that the procedure changes to EOP 35 ES-0.1 will ensure power is provided to the SBO-DG auxiliaries and that the SBO-DG auxiliaries can be powered within one hour of a LOOP.

Classroom, simulator and/or in-plant training, regarding the procedure changes to EOP

35 ES-0.1, will be provided to Licensed and Non-Licensed Operators.

NNECO is continuing to review the licensing and design bases of Millstone Unit Nm 3 4 pursuant to the requirements set forth in the Staffs 50.54(f) letter of April 4,1996. If

any discrepancies are discovered during this review, that affect the conclusions of this

submittal, a supplement will be provided.

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Docket No. 50-423 B16181 Attachment 2 Millstone Nuclear Power Station, Unit No. 3  ;

NNECO's Commitments Associated With Response for Additional Information Related to i Alternate AC Power Source Requirements  ;

(TAC No. M96054)

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l February 1997 l

U.S. Nucl:ar Regulatory Commission B16181\ Attachment 2\Page 2 Enclosure List of Regulatory Commitments The following table identifies those actions committed to by NNECO in this document.  ;

- Any other actions discussed in the submittal represent intended or planned actions by I i NNECO. They are described to the NRC for the NRC's information and are not regulatory commitments. Please notify the Manager - Nuclear Licensing at the Millstone Nuclear Power Station Unit No. 3 of any questions regarding this document or any associated regulatory commitments.

Number Commitment Due B16181-01 Procedure EOP 35 ES-0.1 will be revised Prior to Unit Startup to ensure SBO-DG availability during the postulated eight hour LOOP.

B16181-02 Testing will be conducted to verify that the Prior to Unit Startup procedure changes to EOP 35 ES-0.1 will ensure power is provided to the SBO-DG auxiliaries and that the SBO-DG auxilianes can be powered within one hour of a LOOP.

B16181-03 Classroom, simulator andiv in-plant training, Prior to Unit Startup l regarding the procedure ct.anges to EOP 35  ;

4 ES-0.1, will be provided to Licensed and Non- ,

j Licensed Operators. 1

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I Docket No. 50-423 B16181 t-4 i

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! Attachment 3

! Millstone Nuclear Power Station, Unit No. 3 j Schematic Representing SBO Interfaces with Normal and Emergency 4KV Buses (TAC No, M96054) t l

February 1997 l

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. 4 U.S. Nuclear Regulatory Commission B1,6181%ttachment 3\Page 2 A.

1 Schematic Representing SBO Interfaces with Normal and Emergency 4KV Buses 34C 34A 348 34D EMERGENCY NORMAL NORMAL EMERGENCY I I I I I I I I I L I I I I I I WW mm B

EDG e;. EDG SBO MCC

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