IR 05000346/1982014
| ML20053C386 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 05/10/1982 |
| From: | Danielson D, Ward K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20053C384 | List: |
| References | |
| 50-346-82-14, TAC-48349, NUDOCS 8206020039 | |
| Download: ML20053C386 (6) | |
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U.S. NUCLEAR REGULATORY COMMISSION
REGION III
Report No. 50-346/82-14(DETP)
Docket No. 50-346 License No. NPF-3 Licensee: Toledo Edison Company Edison Plaza 300 Madison Avenue Toledo, OH 43652 Facil4+- Name:
Davis-Besse Nuclear Power Station, Unit 1 Inspection At:
Davis-Besse Site, Port Llinton, OH Inspection Conducted: April 19, 20, and 23, 1982
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Inspector:
K. D. Ward hffbmn w
Approved By:
D. H. Danielson, Chief d 'e//h Materials and Processes Section Inspection Summary Inspection on April 19, 20, and 23, 1982 (Report No. 50-346/82-14(DETP))
Areas Inspected: Damage to auxiliary feedwater headers inside "A" and "B" steam generators. This inspection involved a total of 16 inspector-hours by one NRC inspector.
Results: No items of noncompliance or deviations were identified.
9206020039 820519 PDR ADOCK 05000346 G
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DETAILS Persons Contacted The Toledo Edison Company (TECo)
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Daft, QA Director T. Murray, Station Superintendent T. Myers, Nuclear Licensing Manager R. Peters, Operational Licensing Specialist B. Werner, Administrative Coordinator J. Lingenfelter, Technical Engineer Babcock and Wilcox Company (B&W)
C. Thompson, Group Leader, ISI E. Painter, Jr., SG Outage Coordination L. Lowman, SG Performance Unit Engineer The liartford Steam Inspection and Insurance Company T. Sanford, Authorized Nuclear Service Inspector (ANII)
The inspector also contacted and interviewed other licensee and contractor employees.
- Denotes those present at the exit interview.
Functional or Program Areas Inspected 1.
General Ref. a.
NRC Report 50-346/82-11 (Inservice Inspection)
b.
NRC Report 50-346/82-12 (Inservice Inspection)
c.
MRC Report 50-346/82-13 ("A" and "B" SG)
2.
While Unit 1 was shut down for refueling and during routine eddy current examinations (ET) of the periphery tubes in the "A" and "B" SG's, B&W personnel identified indications of tube denting in the vicinity of the auxiliary feedwater ring headers. The following are the results of the eddy current examinations:
"A" Steam Generator "X" Axis Area Row Tube Indication
130 22% thru wall
129 29% thru wall 105 12; medium ding (4-7 mils)
115 114 small ding (less than 4 mils)
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"B" Steam Generater "X" Axis Area Row Tube Indication
123 Medium ding (4-7 mils) and extra large ding (over 12 mils)
124 extra large ding
127 22% thru wall
129 Small ding (less than 4 mils)
(20% of thru wall)
126 45% thru wall
126 Small ding
130 52% thru wall
126 Small and medium dings
129 Small ding
127 Small ding 103 124 Medium ding 104 123 Medium ding No items of noncompliance or deviations were identified.
3.
The following are tubes that had debris signals located between #15 top support plate (TSP) and the upper tube sheet (UTS). The examinations used to locate the debris was with eddy current and profilom ;ry.
"A" Steam Generator Row Tube Row Tube Row Tube Row Tube
54
51
50
1 104
146
146
106 119 105 122 103 124
126
126
126 112 117
130
126
129
129
129
130
127 113 116 115 114 116 113
127
84
45 140
7
2
148
The following are tubes that have debris indications located by profilometry that were not noted with eddy current.
Row Tube Row Tube Row Tube Row Tube 104 123 134
146
105
Debris indications located by eddy current and profilometry:
"B" Steam Generator Row Tube Row Tube Row Tube Row Tube
130
126
129
130
126
129
127
117
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Row Tube Row Tube Row Tube Row Tube
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S4 127
126
124
123
146
146
104 123 103 124
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129
126
123
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l Debris indications located by profilemetry only.
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Row Tube Row Tube Row Tube Row Tube
130
126 103
104 123
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110 117
No items of noncoupliance or deviations were identified.
4.
In SG "A" and "B" there were eight pins and eight brackets in each, but only four in each SG could be viewed because of the clearance. The inspector observed the following by visual examination and fibescope.
"A" Steam Generator a.
The outer vertical member of the auxiliary feedwater (AFW) header box was distorted (concave) over most of the area viewed. The amount of distortion was estimated to be up to 4 1/2".
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b.
The inner side (tube side) of the header appeared to be square based on a very limited inspection.
c.
No cracks were observed in any welds or base material.
d.
The AFW nozzle thermal sleeve appeared to be correctly positioned in the header.
e.
The dowel pins at two of the four locations were missing and none
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were found.
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f.
The dowel pin at one location was not engaged with the outer l
bracket tab.
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g.
Several tabs (inner and outer) were bent away from the shroud, in one case up to approximately 1/2".
h.
Four header bracket locations on "X" axis side of the generator were visually examined. A summary of results is given below:
The dowel pins at each of the four locations were missing.
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Two outer bracket tabs were broken off.
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The bottom hole ligament on one inner and one outer bracket tab is torn out, j
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Several remaining tabs (inner and outer) were bent away from
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the shroud, in one case up to 1 3/4".
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Five loose parts were observed in the bottom of the steam annulus -
near "X" axis (i.e., three pins and two bracket tabs). All parts have been retrieved. A summary of the parts is given below:
Each pin was somewhat bent.
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The plug weld was still evident on one end of the pin.
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There was some evidence of wear on the pin's ends and center.
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There was evidence of " step-like" depressions on the pins.
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The brackets showed evidence of wear. Dowel pin holes were elliptical.
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The bracket appeared to be broken off at a 45 angle at
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the weld.
The inspector observed the following by fibescope only:
"B" Steam Generator
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a.
The outer vertical member of the AFW header box was distorted (concave) over most of the area viewed. The amount of distortion was estimated to be up to 4".
I b.
The inner side (tube side) of the header appeared to be square based on a very limited inspection.
c.
No cracks were observed in any weld or base material.
j d.
The AFW nozzle thermal sleeve is outside the header. The thermal
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sleeve is misaligned with the hole in the heoder by approximately 1".
The thermal sleeve is below the hole in the header.
e.
Four header bracket locations on the
"X" axis side of the generator were visually examined. A summary of results is given below:
The dowel pins at two of the four locations were missing.
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The dowel pin at one location was not engaged with the outer bracket tab.
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Several tabs (inner and outer) were bent away from the shroud, in one case up to approximately 1/2".
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f.
Approximately one third of the area could be viewed.
J No items of noncompliance or deviation were identified.
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l 5.
On April 23, 1982, the inspector attended a meeting in the NRC Head-
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quarters in Bethesda, MD with personnel representing Davis-Besse i
(TECo), Rancho Seco (SMUD), Oconee (Duke Power), and Babcock Wilcox (B&W), to discuss the damage and recommendations.
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Davis-Besse discussed the following:
l a.
Eddy current examination of peripheral tubes.
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b.
The outward wall of the header distorted inward (concave) as much as 4 1/2".
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c.
Certain header support brackets bent, the bottom ligament torn out, or have broken off,
d.
Dowel pins missing at six of eight locations examined.
e.
Evidence of wear on dowel pins and brackets.
J f.
The three dowel pins and two brackets retireved from the steam annulus area in Unit 1, "A" steam generator.
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g.
Thermal sleeve outside the header on Unit 1, "B" steam generator.
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Rancho Seco indicated they had approximately the same problems and did not go into detail.
Oconee shut down April 23, 1982 and hopes to have a report on their I
once through steam generator auxiliary feedwater header assembly by May 1, 1982.
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TECo, SMUD and Dake Power formed a " Task Force" to determine how to examine the entire header, determine what happened and determine how
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B&W is researching the design.
l The NRC was informed that this is the first time for the headers to be i
examined and that there was no problem in the operation of the plants prior to the examination.
The NRC requested to be informed as the results progress.
No items of noncompliance or deviations were identified.
l Exit Interview
i The inspector met with C. Daft at the conclusion of the inspection. The inspector summarized the scope and findings of the inspection noted in this report.
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