ML19317F535

Ro:On 770930,defect Discovered in Governor on Auxiliary Feed Pumps Installed at Facility.Potential Created for Failure of Both Auxiliary Feed Pumps to Come Up to Design Speed Upon Startup.Superceded Util 771005 Ltr

ML19317F535
Person / Time
Site:	Davis Besse
Issue date:	10/11/1977
From:	Roe L TOLEDO EDISON CO.
To:
References
391, NUDOCS 8001150849
Download: ML19317F535 (3)

Text

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NRCVISTRIBUTION FoR PART 50 DOCKET MATLilAL 7hCN" EPORT FROM: cATE oF DOCUMENT TO: " .

Toledo Edison Company 10/11/77 Mr. James G. Keppler Toledo, Ohio cATE RECEIVED Lowell E. Roe 11/4/77 PRCP (NPuT PoRM NUMBER oP CCPf ES RECEIV E D

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Consists of a report of a defect in a component installed in the Davis-Besse Unit No. 1 (governor on the auxiliary feed pumps).....

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+ nM cDO EDISON October 11, 1977 LOWELL E. ROE v4. e,.e.m

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Serial No. 391 f 4191 259-5242 Docket No. 50-346

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A.9 [s$., 4CE;'.]'^ .N $M Mr. James G. Keppler ,. : / NOy

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799 Roosevelt Road 'l. 527' Glen Ellyn, Illinois 60137

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Dear Mr. Keppler:

This letter supersedes my letter to you on this subject dated October 5, 1977.

In accordance with 10 CFR Part 21.21(b), this is a report of a defect in a component installed in the Davis-Besse Nuclear Power Station Unit No. 1.

The component involved is the governor on the auxiliary feed pumps.

The auxiliary feed pumps were supplied by Byron Jackson Pump Division.

The steam driven pump turbine was supplied by Terry Corporation to Byron Jackson. In turn, the turbine governor was supplied to Terry Corporation by Woodward Governor Company. The turbine governor is identified as a type PG-PL, which has a servomotor control employing a Bodine Electric Company motor.

The defect involves a potential for the governor to bind under certain conditions and preventing the turbine from coming up to design speed.

The operating procedures for this equipment called for the governor to be placed in the high speed stop position prior to shutting down the turbine. Investigation has shown that with the Bodine servomotor driving against the high speed stop, a misalignment force is applied to the T-bar of the governor linkage. This misalignment force creates a potential for the governor to bind at a speed position less than design speed upon a turbine startup. This misalignment force does not always cause the governor to bind and this misalignment force can be removed by driving the Bodine servomotor away from the high speed stop.

The sefety hazard which could be created is the potential for both auxil-iary feed pumps to fail to come up to design speed upon startup. This could result in a substantial loss of auxiliary feedwater flow to the steam generators when such flow was required. This in turn could cause I significant reactor coolant system pressure / temperature transients, and j significant boiling in the reactor coolant system if substantial decay '

heat were present in the reactor core. 7,_,, .

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TheavIluationandidentificationofthisdefectwasprovidedtomeon September 30, 1977, and was discussed with Mr. T. Harpster of your office on September 30, 1977.

There are two identical auxiliary feed pumps with the turbine governors, described above, installed in the Davis-Basee Nuclear Power Station Unit No. 1.

The corrective action taken was to modify the governor including the removal of portions of the pneumatic speed-setting mechanism to assure that the governor will properly respond to speed demand signals. The pneumatic speed-setting mechanism was never an integral part of the functioning of the governor, because the governor employed servomotor control. This modification was accomplished at the Woodward Governor Company facilities. Subsequent testing at these facilities has proved the proper functioning of the gover'.or. The modifications were completed prior to the current unit startup. The governors have been tested for proper functioning on auxiliary steam, and the surveillance test will be completed during Mode 3 of the current startup.

Yours very truly, Q / ! /

Lowell E. Roe Vice President Facilities Development db b/9-10 L - - - . .

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