ML20138H871

Forwards Responses to Several Open Items & Items for Verification Re Auxiliary Feedwater Sys,Per 850514 Request

ML20138H871
Person / Time
Site:	Maine Yankee
Issue date:	12/12/1985
From:	Whittier G Maine Yankee
To:	Thadani A Office of Nuclear Reactor Regulation
References
6163L-FWS, GDW-85-255, MN-85-174, NUDOCS 8512170357
Download: ML20138H871 (4)

Text

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. s MAME HARHEE 'ATOMIOPOWER00MPARUe avauslllNe%

(![p (207) 623-3521 e December 12, 1985 MN-85-174 GDW-85-255 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, D. C. 20555 Attention: Mr. Ashok Thadani, Director PWR Project Directorate #8 Division of Licensing

References:

(a) License No. [PR-36 (Docket No. 50-309)

(b) USNRC Letter to MYAPCo dated May 14, 1985 - Auxiliary Feedwater System Evaluation (c) MYAPCo Letter to UStEC dated October 3,1985, Proposed Change #120, Supplement 1, (MN-85-172)

Subject:

Auxiliary Feedwater System Evaluation Open Items Gentlemen:

In Reference (b) you requested that Maine Yankee provide responses to several open items and items for verification with regard to the auxiliary feedwater -system at our plant. Attached to this letter is our response to your request for information.

We trust that this is satisfactory, however, if you have additional questions, please feel free to contact us.

Very truly yours, MAItE YANKEE ATOMIC POWER COM'ANY bhN G. D. Whittier, Manager Nuclear Engineering & Licensing GDW/bjp

Enclosure:

(2 Pages)

I cc: Dr. Thomas E. Murley goo Mr. Cornelius F. Holden 4 0D '.

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' .* --* MAINE YANKEE ATOMIC POWER COMPANY ATTACHNENT l OPEN ITEMS AND ITEMS FOR VERIFICATION NRC Open Item #1:

' The Licensee should provide modifications to Ule Technical Specifications to limit the tima that the turbine driven pump can be inoperable - GS-1.

Maine Yankee Response:

Proposed changes to our Technical Specifications have been provided in Reference (c).

NRC Open Item #2:

The Licensee should provide redundant level indications and alarms for the DWST - additional short term recommendation 1.

Maine Yankee Response:

We have carefully considered this recommendation. We have concluded that the existing level indications and alarms are adequate for the reasons set forth below.

The existing plant' design already provides redundant level indications and alarms for the DWST. Two level indicators are provided, one remote at the main control board, and one local at the tank. The remote level indicator and its transmitter are powered from non-vital ac distribution panel, which is in turn fed from either emergency bus through a manual transfer 1

switch. The local level indication consists of a tank mounted pressure-type gauge which is independent of the remote transmitter.

.Two level alarms are provided at the main control board annunciator, one indicating low level, and the other indicating low-low level. The set point for the low level alarm is 100,000 gallons which provides a minimum of six hours of emergency feedwater supply.. The setpoint for the low-low level. alarm is 10,000 gallons. Each alarm is actuated by an individual level switch. - The annunciator ~ itself is powered from a de distribution 3

panel which is fed from an emergency dc battery.

During power operation, the DWST is a stable reserve of emergency feedwater 'which is not used for other operational needs and, therefore, is not subject to frequent or rapid changes in' inventory. A minimum of

-100,000 gallons is maintained in the tank which provides a minimum of six hours of emergency feedwater supply. Normally approximately 120,000 L gallons of water are maintained in the tank.

The multiple instruments and power supplies providing DWST level

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information make the total loss of level Indication highly unlikely~ .

Furthernare, the parameter being monitored has a very slow rate of change.

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• I MAINE YANKEE ATOMIC POWER COMPANY The addition of another' indicator on the main control board is not justified and could have an overall adverse impact on safety in that unnecessary displays on the main control board are contrary to good human factors practices.

In summary, the design of the existing level indicators and alarms is appropriate. Changes to the existing design are not necessary, and could diminish safety.

NRC Open Itera #3:

Safety grade automatic start circuit for motor driven pumps do not have approved Technical Specifications. As stated in the "SER", ICSB is pursuing this matter - GL-1.

Maine Yankee Response:

Maine Yankee has submitted a proposed change to our Technical Specifications covering the emergency feedwater system in a letter dated January 14,1985 (MN-85-10, Proposed Change #110). It is our understanding from informal communications with the Staff that the matter of the auto-initiation logic testing has been resolved.

NRC Item For Verification #1:

Recommendation of GL The Licensee should provide verification that the valve internals had been removed from the valve and the AFW supply line.

Maine Yankee Response:

The internals to the valve in the AFW supply line have been removed. This action was documented by our letter dated June 12,1985 (Annual Report of Facility Changes in Relief and Safety Valve Failures and Challenges, MN-85-116).

NRC Item for Verification #2:

Long Term Recommendation 4 - The Licensee should provide information regarding operator diversion time in the event a break occurs in the AFW header.

Maine Yankee Response:

A simultaneous rupture of a main steam line and the EFW manifold is a non-credible event which goes beyond the design basis of the plant.

Nevertheless, in the highly unlikely event of such a simultaneous rupture, coupled with a complete loss of normal feed capability, we estimate that the operators would have approximately 35 minutes to divert flow from the EFW manifold and through the 1st point heaters to prevent steam generator dry-out. This is sufficient time for the operators to perform the necessary manual actions required to divert EFW flow through the alternate path.

For more credible events the available time would, of course, be much longer than 35 minutes.

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, , , MAINE Y ANKEE ATOMIC POWER COMPANY NRC Item for Verification #3:

Short Term Recommendation 2 - The Licensee should verify that monthly surveillance testing of the AFW system will include staggered testing so that a surveillance error will not effect [ sic] more than one train.

Maine Yankee Response:

The Technical Specification changes requested in Proposed Change #110 do not specify a staggered test interval for the emergency feedwater system.

1. Maine Yankee will implement procedural controls ~ requiring the EFW tests to be conducted on a staggered basis.

NRC Item for Verification #4:

Seismic Qualification, AFW Power Supplies - The Licensee should provide documentation to show that all upgrades to cabinet anchorages have been completed.

Maine Yankee Response:

In our letter of April 29, 1985 (Maine Yankee Seismic Design Review, MN-85-81), Maine Yankee documented that the upgrades to all electrical cabinets anchorages associated with emergency feedwater have been completed.

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