05000346/LER-1979-103-03, /03L-0:on 791023,first & Third Seals in Reactor Coolant Pump 1-1-1 Were Not Staging.Caused by Thermal Shocking Which Occurred During Loss of Offsite Power on 791015.Seal Package Refurbished & Reinstalled

/03L-0:on 791023,first & Third Seals in Reactor Coolant Pump 1-1-1 Were Not Staging.Caused by Thermal Shocking Which Occurred During Loss of Offsite Power on 791015.Seal Package Refurbished & Reinstalled

ML19210D671
Person / Time
Site:	Davis Besse
Issue date:	11/20/1979
From:	Hartigan J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19210D666	List: 05000346/LER-1979-103, Forwards LER 79-103/03L-0 05000346/LER-1979-103-03, /03L-0:on 791023,first & Third Seals in Reactor Coolant Pump 1-1-1 Were Not Staging.Caused by Thermal Shocking Which Occurred During Loss of Offsite Power on 791015.Seal Package Refurbished & Reinstalled
References
LER-79-103-03L, LER-79-103-3L, NUDOCS 7911270441
Download: ML19210D671 (2)

LER-1979-103, /03L-0:on 791023,first & Third Seals in Reactor Coolant Pump 1-1-1 Were Not Staging.Caused by Thermal Shocking Which Occurred During Loss of Offsite Power on 791015.Seal Package Refurbished & Reinstalled

Event date:
Report date:
3461979103R03 - NRC Website

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U.S. NUCLEAR REGULATORY C NRC FORM 366

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LICENSEE EVENT REPORT

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CON'T So7R] l L lgl 0 l 5 l 14 75 PEPORT DATE 80

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6d 69 EVENT DATE 60 61 DOCKET NUYdER 7

8 EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES hit was found by observa l o l 2 l l 0n 10/23/79 at 0440 hours0.00509 days <br />0.122 hours <br />7.275132e-4 weeks <br />1.6742e-4 months <br />, The reactorg l the first and third seals in Reactor Coolant Pump 1-1-1 were not staging.

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This placed the unit in the l power was reduced, and the pump removed from service.

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4 A flux-flow trip; l Action Statement of T.S. 3.4.1 which requires the high flux and flux-o s

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- l o is l l setpoints be reduced to $78.3% of rated thermal power.

The other three reactor coolantg l o ) 7 ) l health and safety of the public or station personnel.

the reduced power level.

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'- J i g o l lThe seal failure is attributed to thermal shocking which occurred during the simultaneous loss of compon j 10/15/79 during which there was 1

- 1i li j i site power incident on stage seal f aces were severely damaged,

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_ [TTTl I second stage f aces were cracked, and the third was not damaged.

l the seal package was refurbished and reinstalled.

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-79-120 DATE OF EVENT: October 23, 1979 FACILITY: Davis-Besse Unit 1 J

IDENTIFICATION OF OCCURRENCE: Reactor Coolant Pump 1-1 seal failure Conditions Prior to Occurrence: The unit was in Mode 1, with Power (MRT) = 1925, and Load (Gross MWE) = 645.

Description of Occurrence:

On October 23,1979 at 0100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />, it was found by observing cavity pressure that the first and third shaf t seals in Reactor Coolant Pump (RCP) 1-1-1 were not staging. As a precautionary measure, the reactor power was reduced to 70% and RCP l-1-1 was removed from service. This placed the unit in the Action Statement of Technical Specification 3.4.1 which requires the thermal power be reduced and the high flux and flux- /1 flux. flow trip setpoints be reduced to f!78.3% of rated thermal power. The flux-6 flux-flow trip setpoint was reduced to 77.5% of rated power at 0519 hours0.00601 days <br />0.144 hours <br />8.581349e-4 weeks <br />1.974795e-4 months <br /> on October 23, 1979.

" Designation of Apparent Cause of Occurrence: On disassembly of the seal package, it was noted that the first stage seal faces were severely damaged, the second stage faces were cracked, and the third stage faces were not damaged. The middle pressure breakdown device tubing was found plugged with seal material which explains the observed low third stage cavity pressure.

The failure can be attributed to the simultaneous loss of component cooling water and seal injection during the loss of offsite power incident on October 15,1979 (see Licensea Event Report NP-32-79-11).

There was also some thermal shocking of the seals when the makeup pump section was changed over from the makeup tank to the Borated Water Storage Tank during the same trip.

Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. The other three reactor coolant pumps were in operation providing adequate circulation at the reduced reactor power level.

Corrective Action

On October 26, 1979, the maintenance outage began to permit seal repairs. Under Maintenance Work Order-79-3340, the seal package was refurbished and reinstalled. The seals on the other three pumps were also rebuilt.

Station personnel and Babcock and Wilcox are investigating possible methods to minimize thermal shocking.

This is the fif th time that seals have been replaced in RCP l-1-1.

Failure Data:

LER #79-103 1398 078