ML060400508

Facsimile Transmission, Draft Request for Additional Information to Be Discussed in an Upcoming Conference Call

ML060400508
Person / Time
Site:	Millstone
Issue date:	03/02/2006
From:	Nerses V Plant Licensing Branch III-2
To:	Darrell Roberts Plant Licensing Branch III-2
Nerses V, NRR//DLPM, 415-1484
References
TAC MC8327
Download: ML060400508 (5)

Text

March 2, 2006 MEMORANDUM TO: Darrell J. Roberts, Chief Plant Licensing Branch I-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation FROM: Victor Nerses, Senior Project Manager (G. Edward Miller for)

Plant Licensing Branch I-2 Division of Operating Reactor Licensing /RA/

Office of Nuclear Reactor Regulation

SUBJECT:

MILLSTONE POWER STATION, UNIT NO. 3 - FACSIMILE TRANSMISSION, DRAFT REQUEST FOR ADDITIONAL INFORMATION TO BE DISCUSSED IN AN UPCOMING CONFERENCE CALL (TAC NO. MC8327)

The attached draft request for additional information (RAI) was transmitted by facsimile on March 1, 2006, to Mr. Paul Willoughby, at Dominion Nuclear Connecticut, Inc. (DNC or the licensee). This draft RAI was transmitted to facilitate the technical review being conducted by the Nuclear Regulatory Commission (NRC) staff, and to support a conference call with DNC in order to clarify certain items in the licensees submittal. The draft RAI is related to DNCs submittal dated September 13, 2005, regarding a Technical Specification change for the recirculation spray system timing for Millstone Power Station, Unit No. 3. Review of the draft RAI would allow DNC to determine and agree upon a schedule to respond to the RAI. This memorandum and the attachment do not convey a formal request for information or represent an NRC staff position.

Docket No. 50-423

Enclosure:

As stated

March 1, 2006 MEMORANDUM TO: Darrell J. Roberts, Chief Plant Licensing Branch I-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation FROM: Victor Nerses, Senior Project Manager (G. Edward Miller for)

Plant Licensing Branch I-2 Division of Operating Reactor Licensing /RA/

Office of Nuclear Reactor Regulation

SUBJECT:

MILLSTONE POWER STATION, UNIT NO. 3 - FACSIMILE TRANSMISSION, DRAFT REQUEST FOR ADDITIONAL INFORMATION TO BE DISCUSSED IN AN UPCOMING CONFERENCE CALL (TAC NO. MC8327)

The attached draft request for additional information (RAI) was transmitted by facsimile on March 1, 2006, to Mr. Paul Willoughby, at Dominion Nuclear Connecticut, Inc. (DNC or the licensee). This draft RAI was transmitted to facilitate the technical review being conducted by the Nuclear Regulatory Commission (NRC) staff, and to support a conference call with DNC in order to clarify certain items in the licensees submittal. The draft RAI is related to DNCs submittal dated September 13, 2005, regarding a Technical Specification change for the recirculation spray system timing for Millstone Power Station, Unit No. 3. Review of the draft RAI would allow DNC to determine and agree upon a schedule to respond to the RAI. This memorandum and the attachment do not convey a formal request for information or represent an NRC staff position.

Docket No. 50-423

Enclosure:

As stated DISTRIBUTION:

Public HWagagel RidsNrrDraAadb LPL1-2 RidsNrrPMVNerses RidsNrrLACRaynor Accession No.: ML060400508 OFFICE LPL1-2/PM LPL1-2/LA EEEB/BC(A) LPL1-2/BC NAME VNerses:em CRaynor MScott DRoberts (GEMiller for)

DATE 3/1/06 2/28/06 2/21/06 3/1/06 OFFICIAL RECORD COPY

REQUEST FOR ADDITIONAL INFORMATION MILLSTONE POWER STATION, UNIT NO. 3 TAC NO. MC8327 By letter dated September 13, 2005, Dominion Nuclear Connecticut, Inc. (DNC) submitted a license amendment request for a change to the recirculation spray system timing in the Millstone Power Station, Unit No. 3, Technical Specifications. The Nuclear Regulatory Commission (NRC) staff requests the following additional information to complete its review.

1. DNCs license amendment request states the following:

Because the four MPS3 [Millstone Power Station Unit No. 3] RSS

[recirculation spray system] pumps are started after a timer delay of approximately 660 seconds following a CDA [containment depressurization actuation signal], there is a limited quantity of water on the containment floor (in the containment sump) for LOCAs [loss of coolant accidents]. As a result there is little margin to suction pipe flashing and for pump NPSH [net positive suction head]. For the limiting case there is approximately 11/2 inches of margin to suction line flashing.

This amount of margin is adequate to support the current licensing basis for operability of the ECCS [emergency core cooling system] for MPS3.

The proposed delay in starting the RSS pump is considered necessary to provide additional water level to the containment floor (and hence suction line flashing and NPSH margin for the RSS pumps prior to their start) to ensure operability of the RSS pumps under the revised licensing basis to be established to resolve GSI-191 [generic safety issue -191].

• Please describe and justify the input and assumptions used to calculate the minimum water level in the sump after implementing the proposed delay in RSS pumps startup, and provide the minimum value of the post-LOCA sump water level.

• Please provide the analyses performed to determine the margin to suction pipe flashing and NPSH margin for the NRC staffs review. Include calculations of post-LOCA containment pressure and sump temperature.

2. DNCs response to Generic Letter 2004-02 regarding GSI-191, dated September 1, 2005, associated with the current license amendment request, states the following:

... the minimum available margin for the ECCS pumps in the recirculation mode at switchover to sump recirculation, not including the clean screen head loss, will be 7.3 feet. The only pumps which take suction from the sump are the RSS pumps. This limiting margin is the margin to suction line flashing for these pumps. The NPSH margin is less limiting. The clean screen head loss has not been determined but will be small

(<0.1 feet based on experience). The actual value for clean screen head loss will be determined in the final design.

• Please identify and quantify the major contributors to the change of margin to suction line flashing from 1 1/2 inches (current licensing basis) to 7.3 feet (after implementing the proposed change).

• Please provide the value of the current NPSH margin and that after implementing the proposed change.

• Please provide the value of clean screen head loss after determining it.