ML18057A752
| ML18057A752 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 02/12/1991 |
| From: | Slade G CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9102250249 | |
| Download: ML18057A752 (2) | |
Text
.. *,
GB Slade General Manager POWE RI Nii NllCHlliAN'S PRDliRESS Palisades Nuclear Plant: 27780 Blue Star Memorial Highway, Coven, Ml 49043 FEB 121991 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT -
FOLLOWUP TO INSPECTION REPORT 90017 Replacement of the steam generators at Paltsades is nearing com~letion. This project required a temporary opening into the side of the post-tensioned
~ontainment structure. During the course of the NRC review of the project, a question was raised regarding possible adjustment of the periodic tendon surveillance program which might result from containment opening work.
With tendon replacement work now completed, the containment structure has been restored to its original design.
Replacement of both concrete and tendons proceeded as planned and without specific difficulties. Discussion of the containment opening work and our conclusion regarding future tendon surveillarice is provided below.
A total of 130 tendons (70 vertical and 60 hoop) were affected during the project. Fifty-one tendons located at the opening were removed; the remaining were only detensioned.
One tendon was damaged while creating the opening and was replaced with a new, identical cable.
Visual inspection was performed on all removed tendons. Surface rust was observed on several wires of two tendons. These wires were wiped clean.
Three other tendons had wires with minor pitting. Metallurgical exam concluded that the pitting had existed_since original construction. Tensile testing was performed to verify acceptable strength for reuse of these tendons.
The results were satisfactory.
Twelve lift-off measurements were made during detensioning to assess pre-job conditions. These measurements provided additional data to the containment prestressing system surveillance program required by Technical Specification 4.5.4.
One tendon with slightly low lift-off readings will be retested in our 1992 surveillance
- The concrete used for the restoration of the containment opening has demonstrated close similarity in structural characteristics to those of the
- .-.4.:1 910212 9102250~~~ 05000255 PDR ADUU=,
F'DR A CMS' ENERGY COMPANY Q
1~.
existing concrete, such as strength, creep and shrinkage. These structural characteristics support the assumptions used in the tendon force calculation.
Therefore, the reliability of tendon performance is not expected to deviate from those tendons which were not affected by the steam generator replacement activities.*
Our conclusion is that the SGRP affected tendons will behave in a manner similar to remaining unaffected tendoni, and, therefore, we plan no substantial changes to the ongoing surveillance program.
The next tendon surveillance testing is scheduled during the 1992 refueling outage.
One vertical and two hoop tendons from the SGRP opening area will be included in the representative test sample.
Selection from this area will be consistent with the intent of random sampling requirements of the.technical specifications. Barring_ any abnormal test results at that time, no further special testing would be performed in the future.
~Ll~--
Gerald B Slade General Manager
.CC Administrator, Region III, USNRC NRC Resident Inspector - Palisades