05000346/LER-1982-019, Forwards LER 82-019/01X-1

Forwards LER 82-019/01X-1

ML20053E039
Person / Time
Site:	Davis Besse
Issue date:	05/28/1982
From:	Murray T TOLEDO EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
K82-836, TAC-48349, NUDOCS 8206070551
Download: ML20053E039 (1)

LER-2082-019, Forwards LER 82-019/01X-1

Event date:
Report date:
3462082019R00 - NRC Website

text

_

C TOLEDO

%s EDISON May 28, 1982 Log No. K82-836 FILE: RR 2 (NP-32-82-03)

Docket No. 50-346 License No. NPF-3 Mr. James G. Keppler Regional Administrator, Region Ill Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn. Illinois 60137

Dear Mr. Keppler:

Enclosed are three copies of Revision 1 to Licensee Event Report 82-019 includ-ing the respective supplemental information sheets. The revision to the report is indicated by a "1" in the left margin of each page.

This reissue of Revision 1 is due to a typographical error on the cover letter (Log No. K82-806) issued May 24, 1982. This error listed the Licensee Event Report as82-016 instead of 82-019. Please replace your previous copies of this report with the attached revision.

Yours truly, Tc~, D Wic Terry D. Murray Station Superintendent Davis-Besse Nuclear Power Staticn TDM/lmr Enclosure CC: Mr. Richard DeYoung, Director Office of Inspection and Enforcement Enc 1: 30 copies Mr. Norman Haller, Director Office of Management and Program Analysis Encl: 3 copies Mr. Luis Reyes Resident Inspector Encl: 1 copy THE TOLEDO EDtSON COMPANY EDISON PLAZA 300 MADISON AVENUE s e <<

TOLEDO. OHIO 43652 #'"

8206070551 820528 PDR ADOCK 05000346 S PDR gt{ 'b g

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LICENSEE EVENT REPORT lh

, , COMTROL BLOCCt: l l l l l l (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) 6 f f I l l8 o3 I n L6CENSEE 7

l D l aCODE l s I 1 l@l010 l- l010 14 15 l01010 l- 1010 l@l LICENSE NUMSER 25 4l 11 26 11 11 Il@l$7 CAT Sdl@

LICENSE TYPE JO l l COYT 10111 Za"c' 60l L l@l 015101010131416 @l0 l411 19 l812 l@l01512141812 8 61 68 69 EVENT DATE 74 75 REPORT DATE 80l@

I DOCKET NUMBER EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h Io12l l(NP-32-82-03) During the steam generator eddy current inspection, it was discovered l IOI3I Ithat some of the steam generator tubes located adjacent to the auxiliary feedwater l 10141 l header showed potential interaction with the header support system. Secondary side l

[TITl lmanways from Steam Generators 1-1 and 1-2 were removed, and it was discovered by di- l l 0 s Irect visual observation and fiberoptic inspection that the auxiliary feedwater headers l ,

1Ol7I lwere not securely fastened and had experienced damage. Further inspections since the l 1OI8IIinitial submittal are detailed as of May 17, 1982 on the attached Supplemental Infor- l oh C0oE SuBCOoE COMPONENT CODE SU8C D'E S E lO19l l cl nl@ LnJ@ l a l@ Ix lx I x1 xi xl xl@ Lx_J@ Laj @ 19 20 7 8 9 to 11 12 13 18

_ SEQUENTIAL OCCURRENCE REPORT REVISION LER RO EVENT YEAR R EPORT NO. CODE TYPE NO.

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,, 21 22 23 24 26 27 28 29 30 31 TAK N ACT ON ON PL NT MET HOUN SB IT FOR B. SUPPL 1 MANUFACTURER I33r l@Lx_J@ lal@ La_J@ l 210 i010 i Lvj@

41 iv i@ l NI@ la 10 11 15 l @ 47 34 3b J6 37 40 42 43 44 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS i,go,lThe damage appears to have been caused by the localized collapse of the steam bubble l

[ilil lwithin the hesder during injection of cold auxiliary feedwater, resulting in large l

} ,,,,,l differential pressures across the walls of the headers. Proposed corrective actions  ;

g,,3yj include a change to external auxiliary feedwater headers. This report will be revised;

,,,,i; as further information becomes available.  ;

80 7 8 9 SA S  % POWER OTHER STATUS OISCO RY DISCOVERY DESCRIPTION l l Cl@l TUBE INSPECTION I li_[5] l nl @ l0 l0 10 l @ l MODE 6 ACTIVITY CO TENT RELE ASED OF ret.E ASE AVOUNT OF ACTIVITY LOCATION OF RELEASE l1l6ll Zl @ lZ_j @l NA 44 l l 45 NA l 80 7 8 9 10 It PERSONNEL E XPOSURES NUM8ER TYPE DESCR'PTION NA l f'iTT110101 O l@La_J@l PERSONNE L INJU IES NUMBER DESCRIPTION l

[ I"Il 8! 901 Ol Ol @ l12NA 7 11 80 LOSS OF OR DAMAGE To FACILITY TYPE DESCRIPTION l

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@l 10 NA 80 l2lOl ISSUEl Northwestern 8 9

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7 10 {} 97 r DVR #82-048 NAME OF PREPARER ad PHONE:

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 Description of Occurrence: During the steam generator eddy current inspection, it was discovered that some of the steam generator tubes located adjacent to the aux-iliary 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 auxiliary feedwater header was not securely fastened to the upper shroud and had experienced 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 potential contact between the tubes and header assem-bly, three tubes contain pluggable indications.

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

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

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

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

Further inspections have been performed since the initial submittal, and the follow-ing information provides the status of those inspections as of May 17, 1982.

A detailed video inspection supplemented by selective ultrasonic (UT) and dye pene-trant (PT) testing is underway. Video inspections have been performed on both steam 1

generators. To date, the areas inspected include all eight dowel pin / bracket loca-tions (external brackets only) on each header, the head'r e to shroud interface and the bottom, top, and outboard side of each header for its extire circumference.

LER #82-019

4 .

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-32-82-03 Page 2 Ultrasonic and dye penetra- testing was performed on the portion of the header accessible in the manway o. steam generator 1-2; a portion of the bottom and out-board plates and the connecting weld was examined. This area was choosen for test-ing because of its accessibility and because the deformation of the. header in this area was more severe than in any other location. The existing auxiliary feedwater piping has been disconnected from the steam generators to allow removal of the aux-iliary feedwater thermal sleeves and to provide an additional inspection port. Dye penetrant testing of the inner wall of the auxiliary feedwater header has been con-ducted through the resulting hole and UT and PT examinations of the auxiliary feed-water nozzle area are being conducted.

The results of the video inspections indicate conditions similar to those previously reported. Six of the eight dowel pins in steam generator 1-2 and two in generator 1-1 are no longer in place. No broken brackets other than the two previously re-ported on generator 1-2 have been identified. The deformation of the header is not symmetrical; in some locations the outboard wall is indented (concave) as much as 4h" while in other areas little or no damage is noted. This non-uniform deforma-tion has led to gaps between the header and shroud of as much as half an inch on generator 1-2 with less noticeable gaps in generator 1-1. In steam generator 1-2 the entire header has been rotated approximately 1/2 inch with respect to its ver-tical axis through the center of the steam generator and has shifted approximately 1/2" away from the manway. No corresponding rotation was noted in steam generator 1-1, although a small off-axis shift has occurred.

The entire header is structurally sound. Other than the deformations previously 1 noted, no indications of weld or material cracking have been found. The UT and PT examinations on the header at the manway of steam generator 1-2, and the PT exam-inations of the inner wall of the header, accessible through the auxiliary feed-water nozzle, support this finding. Preliminary results of the UT and PT examina-tions of the auxiliary feedwater nozzle area of the shell indicate that no damage occurred as a result of auxiliary feedwater splashing back on the nozzle from the misalignment between the header and the thermal sleeve on steam generator 1-1.

Additional inspections are underway and will be detailed in a future revision to this report.

Designation of Apparent Cause of Occurrence: Although the possible failure mech-anisms are still being evaluated the damage appears to have been caused by the localized collapse of the steam bubble within the header during injection of cold auxiliary feedwater, resulting in large differential pressures across the walls of the header. This problem may have been complicated by the large thermal grad-ients which develop across the walls of the header material during an injection.

The new external ring header design will not be subjected to similar failure mech-anisms.

Analysis of Occurrrence: There is no danager to the health and safety of the pub-lic 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.

LER #82-019

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-32-82-03 Page 3 Corrective Action: Two major objectives must be satisfied by the corrective actions taken for this problem. The existing internal auxiliary feedwater header must be restrained to preclude further damage to the steam generator tubes, and a means to inject auxiliary feedwater to the steam generatore must be provided. To satisfy these objectives the internal auxiliary feedwater header will be attached to the shroud on which it currently rests, and an external auxiliary feedwater ring will be installed with eight injection nozzles to provide auxiliary feedwater flow. The existing auxiliary feedwater nozzle will be blank flanged and the internal header will not be used for flow distribution.

To stabilize the internal header, eight holes will be drilled through the steam generator shell and shroud near each dowl pin and bracket location. Those dowel pins and brackets which are not or cannot be securely fastened to the header or the shroud will be removed. If any additional dowel pins or internal brackets are found to be missing they will be located and retrieved. The header will then be centered on the shroud and the assembly will be securely fastened to the shroud.

Although the exact method by which the header will be attached to the shroud has not yet been identified, several methods are being considered. The concept of header stabilization is still under review. The seismic and accident loads to 1 which the header may be subjected are currently being evaluated to ensure that the header will remain in place.

The eight holes drilled in the steam generator shell and shroud for header stab-ilization work will also be used as points of injection for an external feedwater ring header. The design of the external header system is similar to the design on earlier B & W units. The design includes an external, split ring header, with eight, fifty inch long J-pipe risers feeding into the steam generator through thermal sleeves, directively into the tube bundle. Auxiliary feedwater will be injected into the steam generator tube bundle approximately three inches higher than in the earlier header design. Since injection at this higher elevation results in an increased susceptibility of the steam generator tubes to flow induced vibra-tions, compensating measures to reduce the flow volocity into the tube bundle have been taken. Eight injection nozzles will be used at Davis-Besse as opposed to ,

the six in the earlier external header design and the throat diameter on the ther-mal sleeve will be increased from 2 inches to 2 inches. This report will be updated as further information becomes available.

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

LER #82-019 i

IQLEDO EDISON COMPANY --

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