ML20245D468

Submits Final Response to NRC Bulletin 88-004, Potential Safety-Related Pump Loss. Configuration & Capacities of Min Flow Lines for Seven safety-related Sys Evaluated Adequate to Preclude pump-to-pump Interaction & Damaging Vibration

ML20245D468
Person / Time
Site:	Davis Besse
Issue date:	04/14/1989
From:	Shelton D TOLEDO EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
1-871, IEB-88-004, IEB-88-4, TAC-69906, NUDOCS 8905010004
Download: ML20245D468 (3)

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.J TOLEDO

%ma EDISON A Centerar Energy Company Docket Number 50-346 DONALD C. SHELTON License Number-NPF-3 weuwe (419]249 2300 Serial Number 1-871 April 14, 1989 United States Nuclear Regulatory Commission Document Control Desk Washington, D. O. 20555

Subject:

Final Response to Nuclear Regulatory Commission (NRC) Bulletin Number 88-04: Potential Safety Related Pump Loss (TAC 69906)

Gentlemen:

Toledo Edison (TE) previously responded to NRC Bulletin Number 88-04 in letters dated September 8, 1988 and December 16, 1988 (Serial Numbers 1-823 and 1-849). In the first of these responses, TE provided information concerning the tests, calculations, and reviews conducted on pumps in the seven safety related systems at Davis-Besse that were determined to be susceptible to the concerns of the subject bulletin. The conclusions of the first response vere that pump-to-pump interactions are not a concern and that the current minimum recirculation line capabilities are adequate for all but  ;

possibly the pumps used.in the Decay Heat / Low Pressure Injection (DH/LPI) and

-High Pressure Injection (HPI) Systems. The new vendor for these pumps (i.e.,

Ha'/vard Tyler) would not confirm the adequacy of the minimum flow capacities recommended by the original vendor and sugpsled that these pumps be tested at minimum flow conditions.

1 The second response addressed the results after testing the DH/LPI and HPI pumps at minimum flow conditions. Vibration measurements, obtained during the minimum flovrate testing of these pumps, confirmed the adequacy of the minimum recirculation line for the HPI pumps; however, the DH/LPI pumps demonstrated an unexpected increase in vibration at four times running speed during minimum flow conditions, with DH/LPI Pump Number 1 having a noticeably higher vibration than Pump Number 2. Toledo Edison promptly evaluated this finding and concluded that the DH/LPI pumps vould not fail due to the identified l g" o' , vibration prior to performing their design function (i.e., the pump? vould l

, p.

operate at least 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> at minimum flow). In order to more accurately y a. ' quantify the length of time that the DH/LPI pumps can be operated at the g minimum flow condition without operability concerns, additional analyses were ha undertaken. This letter presents the results of these analyses.

• The results of these analyses were originally scheduled to be submitted in March; however, delays in completing the analyses necessitated requesting an N . extension until April 14, 1989. This request was granted by Mr. T. V.

• O Vambach, the NRC/NRR Davis-Besse Senior Project Manager, on March 30, 1989.

I Sk Il wa.o TOLEDO, OHIO 43652 THE TOLEDO EDISON COMPANY EDISON PLAZA 300 MADISON AVENUE

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6 Docket Number 50-346

. Licence Number NPF-3 Serial Number 1-871 Page 2 The analyses performed on the Davis-Besse DH/LPI pumps included static calculations of the steady radial load on the impeller, the shaft fatigue strength, and the rated bearing life. Additionally, a dynamic model of the pump and shaft was developed to evaluate the vibration characteristics of the pump at a frequency of four times running speed.

The results of these analyses indicate that vibrations of less than 1.0 in/see at a frequency of four times running speed are acceptable for the minimum flow condition. (Note: The maximum vibration level measured for the Davis-Besse DH/LPI pumps was 0.68 in/sec at this condition.) The dynamic bearing load analysis indicates that bearing failure should not occur prior to 16,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> of operation at minimum flow. (Note: The DH/LPI pumps are not expected to have to operate for over 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> at minimum flow.) These findings demonstrate the acceptability of Davis-Besse's DH/LPI pumps at their current vibration levels.

In TE's December 16, 1988 response (Serial 1-849), it was also stated that the results of vibration tests on Component Cooling Vater (CCV) Pump Number 1-1 and 1-2 would be provided in the final report. However, re-evaluation of the vibration test data for CCV Pump Number 1-3 led to a change in position on the necessity to perform a vibration test on CCV Pump Numbers 1-1 and 1-2. The highest amplitude of vibration for CCV Pump Number 1-3, which was previously tested for the purposes of the subject Bulletin at minimum flow, was well below the Action Level of TE's Vibration Monitoring and Analysis Program (VMAP). Additionally, the vibration data for all three CCV pumps does not indicate a resonance at the running speed of the pumps, (or any multiple of it) such as was evident in the DH/LPI pumps. Since CCW Pump Numbers 1-1 and 1-2 are the same model as Pump Number 1-3 and the piping for all three is geometrically similar, TE has concluded that the vibration characteristics of CCV Pump Numbers 1-1 and 1-2 vould not be significantly different than that for Number 1-3 at minimum flow.

The analyses performed for the DH/LPI pumps and the re-evaluation of the CCV Pump Number 1-3 data completes those efforts deemed necearcry to ratisfy the concerns of NRC Bulletin Number 88-04. Toledo Edison has concluded that the configuration and capacities of the minimum flov lines for the seven safety-related systems evaluated are adequate to preclude pump-to-pump interaction and damaging vibration resulting from hydraulic instability or impeller recirculation.

Should you have any questions, please contact Mr. R. V. Schrauder, Nuclear Licensing Manager, at (419) 249-2366.

Very truly ours,

( ,

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CFM/dlm cc: P. M. Byron, DB-1 NRC Resident Inspector A. B. Davis, Regional Administrator, NRC Region III T. V. Vambach, DB-1 NRC Senior Project Manager

} ...'Dockat'Numbar 50-346

.-' V Licensa Nunbar NPF-3 Serial Number 1-871 Enclosure-

,Page_ 1 FINAL RESPONSE TO NRC BULLETIN 88-04 .,

FOR, DAVIS-BESSE NUCLEAR POVER STATION

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UNIT NO. 1 This letter is submitted in conformance~vith Atomic Energy Act of 1954 Section 182a, in response to NRC Bulletin 88-04: " Potential Safety-Related Pump

' Loss."'

li D. C. Shelton, Vice President, Nuclear Sworn and subscribed before me this 14th day of April, 1989.

LA.L A4L Notarf.Public, State of Ohio LAURIE A. !!!NKLE Notary Pubh. Stata of Ohio My Commission Expires May 15.1991

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