IR 05000269/1986015
| ML20198R734 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 05/28/1986 |
| From: | Blake J, Coley J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML20198R678 | List: |
| References | |
| 50-269-86-15, NUDOCS 8606100185 | |
| Download: ML20198R734 (4) | |
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UNITED STATES
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NUCLEAR REGULATORY COMMisslON
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Report No.:
50-269/86-15 Licensee: Duke Power Company 422 South Church Street Charlotte, NC 28242 Docket No.: -50-269 License No.: DPR-38 Facility Name: Oconee 1 Inspection Conducted: April 23-25, 1986 Inspector:
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Q Date Signed Approved by:
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la e'. Section Chief Date Signed Eng ee ng Branch Di si n of Reactor Safety SUMMARY Scope:
Special announced inspection at Babcock-and Wilcox's Mount Vernon, Indiana Plant in the area of ultrasonic examination on a mockup reactor vessel-to-flange weld for correlation of reflectors between the Oconee vessel and the mockup.
Results:
No violations or deviations were identified.
8606100185 860602 PDR ADOCK 05000269 G.
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REPORT DETAILS
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1.
Persons Contacted Licensee Employees
- B. Cheezem, Quality Assurance Engineer, Inservice Inspection (ISI) Division
- T. Hilderbrand, Quality Assurance Specialist, ISI Other Organizations
- D. Van Petten, Product Manager, Babcock and Wilcox
- J. Walden Level II Examiner, Babcock and Wilcox
- Attended exit interview 2.
Exit Interview The inspection scope and findings were summarized on April 25, 1986, with those persons indicated in paragraph 1 above.
No dissenting comments were received from the licensee.
The licensee did not identify as proprietary any of the materials provided to or reviewed by the inspector during this inspection.
3.
Licensee Action on Previous Enforcement Matters This subject was not addressed in the inspection.
4.
Unresolved Items Unresolved Items were not identified during the inspection.
5.
Ultrasonic Examination of Mockup Reactor Vessel Flange Weld - Obseriation of WorkandWorkActivities(73753)
As a result of inservice inspections performed on the Oconee Unit I reactor vessel during the 1986 outage, ultrasonic indications were recorded in the reactor vessel flange weld and the base material within the weld inspection zone (See Region II Inspection Report 50-269/86-11 for details).
On April 21, 1986, representatives from Duke Power Company, the Electric Power Research Institute, and Babcock and Wilcox met at Region II and presented information on tSe fracture analysis of the reporteu indications as requested by the NRC staff during an April 8,1986 meeting.
At this time, Duke Power Company discussed their plans to perform ultrasonic examinations on a mockup reactor vessel flange at the Babcock and Wilcox
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Mount Vernon, Indiana Plant.
The examinations would be performed to determine whether any of the indications recorded on the Oconee Unit I reactor vessel flange could be attributed to the geometry of the forged flange.
The mockup reactor vessel flange also provided a radiation free environment for examination personnel to develop variations in examination technique for the purpose of discriminating between geometric reflectors, mode converted signals and actual defect indications.
On April 23, 1986, the inspector arrived at Babcock and Wilcox's Mount Vernon Plant to observe the licensee perform the ultrasonic examination on the mockup reactor vessel flange weld.
The examination on the mockup was performed using the same inspection procedure (Babcock and Wilcox's Inservice Inspection Procedure:
ISI-120, Revision 21) and ultrasonic examiner that had detected the indications on the Oconee Unit I reactor vessel flange.
The inspector observed the examination and celibration activities to insure the procedure was being
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implemented in the following areas:
a.
Type of apparatus used
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Search units c.
Calibration requirements d.
Distance-amplitude curve e.
Reference level of monitoring discontinuities f.
Extent of coverage of the weldment g.
Method of demonstrating penetration h.
Methods of evaluation of indications 1.
Recording of inspection results Equipment used in the examination consisted of a Krautkramer USIP-11 ultrasonic instrument and a 1-inch x 2.25 MHZ longitudinal wave transducer.
A 1-inch x 1 MHZ longitudinal wave transducer was also utilized during the evaluation process.
The examination was performed from the mating surface of the flange which included both a cladded surface and a machine surface.
The center line of the weld that was being examined was approximately 32 inches from the cladded surface of the flange.
During the examination of the weld, indications observed between the stud holes in the flange were recorded.
The screen depth of these indications were in the following ranges:
Depth Remarks Concerning Refectors 24.5 inch Indications at this depth were observed around flange between each hole - signals dampened on outside taper of flange.
35.5 inch Indications at this depth were observed at each 90 axis - signals could not be dampened at this depth.
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3 27.5 inch Indications at this depth were only occasionally observed - signals dampened at the bottom of the inside taper on the flange.
37.5 inch Indications at this depth were distributed around flange between stud holes - signals dampened at inside and outside tapers on the flange.
I 30, 32.5, 33 inch Fif teen indications at these depths were distributed around the flange between stud holes.
All but six of the signals at these depths could be dampened on the inside taper of the flange and when measured with a steel rule were actually located at 26.5 inches vertically down from the clad mating surface of the flange.
General clad irregularities were observed when signals at these depths dampened (spot type indica-tions).
The licensee will analyze the data obtained from the Mount Vernon mockup and compare this data to indications recorded during the Oconee Unit 1 examinations. The licensee committed to provide Region II a final report of their analyzed data by June 13, 1986.
In addition to observing the examinations described above, the inspector performed beam spread examinations on the Oconee calibration block notches using Region II ultrasonic equipment. The results obtained by the inspector compared favorably with measurements taken previously by the licensee.
Since recorded indications evaluated for Oconee Unit I did not take into account beam spread enhancement, the indication sizes used in the analysis should be considered conservative.
Within the areas examined, no violation or deviation was identified.