ML19291B677
| ML19291B677 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 10/01/1973 |
| From: | Maccary R US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Deyoung R US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 7911110122 | |
| Download: ML19291B677 (3) | |
Text
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E Distribution:
OCT 011973 Docket File 50-289 " -
L:TR SEB RF Dockat No. 50-289 gam g o g 9-Richard C. DeYoung. Assistant Director j o a M a M J
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o for Pressurized Water Reactors Directorate of Licensing METROPOLITAN EDISON COMPANY. THREE MILE ISLAND NUCLEAR STATION. UNIT NO.1. TENDON ANCHORAGE ZDSES Plant Name: Three Mile Island. Unit il Licensing Stage: Post-OL ACRS Meeting Docket Number: 50-289 Responsible Branch and Project Manager: PWR-4 R. M. Bernero Applicant's Response Date Necessary for Coupletion of Next Action Planned on Project: None Required Description of Response: Evaluation Review Status: Complete As a result of a field investigation and a report submitted by the applicant the structurel Engineering Branch has concluded that there be additional intervals of tendon anchorage zone visual surveillance imposed. The details of the evaluation and recommendations are con-tained in the enclosure.
R. R. Maccary. Assistant Director for Engineering Directorate of Licensing
Enclosure:
Structural Evaluation of the Anchorage Zones of Vertical
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Prestressing Tendons
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METROPOLITAN EDISON COMPANY THREE MILE ISLAND NUCLEAR STATION UNIT #1 DOCKET NO. 50-289 STRUCTURAL EVALUATION OF THE ANCHORAGE ZONES OF VERTICAL PRESTRESSING TENDONS The report entitled, " Report on Containment Building Vertical Tendon Upper Bearing Plates", has been reviewed and evaluated by the Struc-tural Engineering Branch.
In addition, a field trip was made to the site to examine the condition of the vertical tendons' anchorage zone on the top surface of the ring girder. As a result of this information the following evaluation statement it provided.
The intent of the Ames dial gauges as instrumentation was to:
- 1) measure the differential movement between the concrete and the steel bearing plates and to (2) give warning in order to protect the safety of the ten-don jacking crews. The arrangement for the instrumentation is judged to have been unsatisfactory as indicated in the applicant's report.
In addition, no provisions were made for a " smooth" contact surface at the elevation of the concrete so that dial location movements could not record concrete surface irregularities as though they were actually differential displacements between the concrete and the steel bearing plate.
It is to be noted that the data indicated that in one case under a load of 1700 kips there was an upward movement of 0.18 inches which indicates a totally unreal response to load.
Consequently it is the Staff's opinion that the data gathered and reported for the differential movements is unreliable.
Field examination of the anchor zones of those tendons in question and others not in question exhibited no evidence at this time to indicate that detrimental voids exist under the bearing plates. Therefore, the staff feels that based on the above facts there is no need to initiate destructive test methods to gain further information at this time. The ls1/ M2
. staff recommendation is that visual surveillance be imposed by incor-poration into the technical specifications for the facility as a part of the prestressing tendon surveillance program. The staff will require tendons V26, V31 and V70 to be among the nine (9) vertical tendons to be included as part of the tendon surveil. lance program outline on page 4-35 of Section 15 of the FSAR.
In addition it will be required that the anchorage zone of the nine (9) vertical tendons designated for surveillance be visually examined just prior to the structural accept-ance test for the' containment, at the peak test load, after the test and then at six (6) month intervals for the two (2) years following the test. The visual examination is to consist of a mapping of any cracking observable under a 5-power eye piece with the extent of crack-ing being pennanently noted on the structure and the estimated width of crack determined by an optical comparison gauge.
Other evidence of changes in the area around the anchorage zone such as spalling, cracks through painted surfaces, etc. should be noted. Reporting of each surveillance period will be as prescribed in the Technical Specifications.
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