ML20052E623

LER 82-019/01T-0:on 820426,some Steam Generator Tubes Adjacent to Auxiliary Feedwater Header Showed Potential Interaction W/Header Support Sys.Header Found Insecurely Fastened & Damaged.Cause & Corrections Being Investigated

ML20052E623
Person / Time
Site:	Davis Besse
Issue date:	04/30/1982
From:	Batch S TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20052E620	List: ML20052E619 ML20052E623
References
LER-82-019-01T, LER-82-19-1T, TAC-48349, NUDOCS 8205110292
Download: ML20052E623 (6)

Text

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EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h l o 121 l (NP-32-82-03) DurinJ the steam generator eddy current inspection, it was discovered l l o l 3 I l that some of the steam generator tubes located adjacent to the auxiliary feedwater l Io I4 l l header showed potential interaction with the header support system. A secondary side l IOIsl I manway from Steam Generator 1-1 was removed, and it was determined by direct visual l l o le i I observation and fiberoptic inspection that the auxiliary feedwater header was not l l 0 l 7 l l securely f astened and had experienced damage. Inspection of the other steam genera- l loisl l tor yielded similar results. l 80 7 8 9 SYSTEV CAUSE CAUSE COVP. VALVE CODE CODE SU8 CODE COYPONENT CODE SUSCODE SUBCODE lol91 7 8 9 l C l H l h W h l

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-32-82-03 DATE OF EVENT: April 19, 1982 FACILITY: Davis-Besse Unit 1 Conditions Prior to Occurrence: The unit was in Mode 6, with Power (MWT) = 0 and Load (Gross MWE) = 0.

Description of Occurrence: During the steam generator eddy current inspection, it was discovered that some of the steam generator tubes located adjacent to the auxiliary feedwater header showed potential interaction with the header support system. A secondary side manway from Steam Generator 1-1 was removed, and it was determined by direct visual observation and fiberoptic inspection that the auxili-ary feedwater header was not securely fastened to the upper shroud and had experi-enced damage. Inspection of the other steam generator yielded similar results.

These inspections have identified:

(1) Ten peripheral tubes in the 1-2 SG and fourteen peripheral tubes.in the 1-1 SG based on eddy current examinations may have been in contact with the AFW header assembly.

(2) As a result of this potenial contact between the tubes and header assembly, -

three tubes contain pluggable indications.

(3) The amount of tube ID reduction on the damaged tubes is less than 20 mils.

(4) The outward wall of the header is distorted inward (concave) as much as 4 ".

(5) Certain header support brackets are bent, and on some the bottom ligaments are torn out or have broken off.

l (6) Dowel pins are missing at six of eight locations inspected. Three dowel pins and two brackets have been retrieved from the steam annulus area in 1-2 SG.

(7) There is evidence of wear on dowel pins and brackets.

(8) The auxiliary feedwater nozzle thermal sleeve was not in alignment with the header on Unit #1 (1-1 SG).

See drawings on pages 3 through 5.

This incident is being reported in accordance with Technical Specification 6.9.1.8.

Designation of Apparent Cause of Occurrence: The root cause of this event has not yet been determined. The investigation is still continuing, no conclusions have yet been drawn. This will be updcted as information becomes available.

LER # 82-019

i i' TOLEDO EDISON COMPMiY DAVIS-BESSE NUCLEAR ~ POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-32-82-03 Page 2 4

, Analysis of Occurrence: There is no danger to the health and safety of the public or to station personnel. The steam generators are not in use at this time since the unit is shutdown for the refueling outage. There have been no actuations of the auxiliary feedwater system where the header was unable to deliver adequate flow.

Corrective Action: Toledo Edison is working is connection with contractors and other owners to evaluate possible corrective actions. This report will be updated as information becomes available.

Failitre Data: There have been no previously reported incidents of auxiliary feed-water header damage.

LER #82-019 i

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