ML20062C560
| ML20062C560 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 11/01/1978 |
| From: | Colbert W DETROIT EDISON CO. |
| To: | |
| Shared Package | |
| ML20062C559 | List: |
| References | |
| NUDOCS 7811090172 | |
| Download: ML20062C560 (2) | |
Text
STATUS REPORT TORUS SHELL INDICATIONS AT THE RING BEAM ATTACHFENT WELD ENLARGEMENT INTRODUCTION The primary containment for the Enrico Fermi Atomic Power Plant, Unit 2 was designed, erected, leak tested and N-stamped in accordance with the ASME Boiler and Pressure Vessel Code during the early 1970's. Subsequently, new torus hydrodynamic loads were identified. The new loads were related to pool response due to postulated LOCA and pool response due to main steam relief valve operation. Detroit Edison has committed to a torus modification program that would provide design, analysis and implementation of modifications so that the modified torus structure will withstand these new loads and comply with the acceptable design margins. A detailed description of the torus modification program and the required modifications was submitted to NRC via Amendment No. 12 of the FSAR, Section 3.8.2 and Reference 17.
The installation of the designed modifications is being performed by Reactor Control, Inc. As part of the modification program, the existing 5/16" fillet weld between the ring girder at each mitered joint and the suppression chamber shell is being increased to 3/4" fillets as shown in Figure 1.
In the process of inspecting these welds, defects in the torus shell have been determined.
The location of these defects are illustrated in Detail A of Figure 1.
DESCRIPTION OF NON-CONFORMANCE The defects are oriented parallel to the welds in areas shown in Figure 1 and represent a total defect of 2.2% of the ring beam to shell welds that have been completed. The defects were discovered to be relevant indications through magnetic particle examination and liquid penetrant examination. Documenta-tion providing dimensional description and location of the defects will be available at the site for your future inspection.
CORRECTIVE ACTION PLAN The corrective action plan is currently being developed and will be reported as soon as it will be available.
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