ML20237C790

Informs NRC of Plans to Repower Startup Feedwater Pump at Facility.Commitment Re Startup Feedwater Pump & Associated Valves Will Be Modified Due to Proposed Addl Improvements to DHR Capabilities

ML20237C790
Person / Time
Site:	Davis Besse
Issue date:	12/14/1987
From:	Shelton D TOLEDO EDISON CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
1412, NUDOCS 8712220184
Download: ML20237C790 (5)

Text

l TOLEDO EDISON Docket No. 50-346 DoNALo C. SHELToN va pr.=w-ww f419) P49 2309 License No. NPF-3 Serial No. 1412 December-14, 1987 l

United States Nuclear Regulatory Commission Document Control Desk Washington, D. C.

20555

Subject:

Repowering of Startup Feedwater Pump Gentlemen:

Background:

This is to inform the NRC Staff of Toledo Edison's plan to repower the startup feedwater pump.(SUFP) at the Davis-Besse Nuclear Power Station, Unit No. 1.

Toledo Edison's letter dated November 4,.1985 (Serial No.

1207) stated that the startup feedwater pump would be repowered by the next refueling outage and that control room operation of valves would be provided to address the high energy, moderate energy and seismic pipe concerns.

Since 1979, Toledo Edison has had procedures in effect at the Davis-Besse Nuclear Power Station to provide decay heat removal capability to the reactor core in the event of a sustained loss of all main and auxiliary feedwater. Detailed analyses and testing were used to verify the effectiveness and to improve these procedures. The success of these efforts was documented in NUREG-1177, "The Safety Evaluation Report

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Supporting the Davis-Besse Restart" (Log No. 1997 dated June 10, 1986).

l Additionally, substantial improvements have been made to the plant's

-i steam generator (SG) cooling capability to reduce the likelihood of the completc loss of feedwater event. These improvements included main feed-water and auxiliary feedwater system improvements, the addition of a new electric motor driven feedwater pump (MDFP), and modifications to the steam and feedwater rupture control system (SFRCS). These efforts were also documented in NUREG-1177.

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' Discussion:

The purpose of this letter is to update the NRC Staff regarding Toledo Edison's plans to repower the SUFP.

In addition to enhancements discussed in NUREG-1177, Toledo Edison has proposed further enhancements to the decay beat removal capabilities. These enhancements which are scheduled to be completed during the upcoming fifth refueling outage include:

1)

Replacing the motor operated valves on the discharge of the auxiliary feedwater (AFW) pumps with DC-powered modulating flow control valves.

l These flow control valves will regulate SC level on the same signal which was previously utilized to control AFFT speed following a SFRCS actuation.

2)

Enhancing feed and bleed capability by upgrading the Makeup and i

Purification System to provide redundant flow paths and increased flow capability.

3)

Enhancing reliability of MDFP by replacing the current single motor operated flow control valve which feeds both AFW headers with individual DC-powered flow control valves.

4)

Addition of a flow-limiting cavitating venturf in the auxiliary feedwater flow path to the SG to preclude overfeeding and potential overcooling of the Reactor Coolant System.

5)

Upgrading the MDFP by adding Service Water as an additional source of water for the MDFP. This will provide back up to the condensate storage tanks and the Feedwater system.

Each of the DC-powered modulating control valves discussed in Items 1) and

3) above can be operated either manually or automatically through hand / auto stations located in the control room.

A simplified drawing illustrating the proposed enhancements to the AFW and motor driven feedwater systems is provided in Attachment 1.

Toledo Edison plans to submit a license amendment request relating to the operation of the startup feedwater pump under License Condition 2.C.(3)(t) by January 1988.

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==

Conclusion:==

Based on the proposed additional improvements to the decay heat removal capabilities, Toledo Edison intends to modify its commitment regardfrg the SUFP and associated valves.

The SUFP will be repowered during the fifth refueling outage; however, the associated valves will not be provided with remote (control room) operation capability. Toledo Edison plans to maintain the associated SUFP valves (FW 106, FW 32, FW 91, CW 196 and CW 197) in the norma]Iy closed position. Plant procedures will provide

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1 Docket No. 50-346 License No. NPF-3 l

Serial No. 1412-l Page 3 operator instructions to place the SUFP in service in the unlikely event that the main feedwater pumps (MFPs), the.AFW pumps and the MDFP fail. A I

simplified drawing illustrating the valve configuration is provided in.

Since the plan is not to use the SUFP in Modes 1, 2, or 3, the concerns for high energy, moderate energy and seismic pipe problems will be negated. Toledo Edison intends to use the SUFF only after efforts have failed to start MFPs, AFW pumps and the MDFP. Therefore, repowering the SUFP and utilizing local operation of its associated valves will ensure that the SUFP will be available for use $f required.

Very trul yours, lw Q BJM:bam Attachment cc: DB-1 NRC Resident Inspector A. B. Davis, Regional Administrator (2 copies)

A. W. DeAgazio, NRC/NRR Davic-Besse Project Manager 4

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