ML19340E206

Re-evaluation of Safety-Related Concrete Masonry Walls.

ML19340E206
Person / Time
Site:	Three Mile Island
Issue date:	11/17/1980
From:	GENERAL PUBLIC UTILITIES CORP.
To:
Shared Package
ML19340E202	List: ML19340E201 ML19340E206 ML19340E209 ML19340E212 ML19340E213
References
IEB-80-11, NUDOCS 8101060637
Download: ML19340E206 (5)

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Three Mile Island Unit 1 Reevaluation of Safety-Related Concrete Masonry Walls NRC IE Bulletin 80-11 GPU Nuclear Corporation 100 Interpace - Parkway t

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TABLE OF CONTENTS Enclosure 1 - Summa ry 2 - Criteria for the reevaluation of concrete masonry walls 3 - Justification for the criteria for the reevaluation of concrete masonry' walls 4 - General arrangement of the block walls 5 - Configuration of the block walls 6 - Floor response spectra 7 - Results of the wall reanalysis 8 - Construction practices (masonry wall specification) 9 - Schedule

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ENCLOSURE 1 o

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SUMMARY

1. Reevaluation Criteria In enclosure 2 a reevaluation criteria document is provided to establish the design requirements and the analytical technics for structural reanalysis of the concrete block walls.

2. Justification for the Criteria A detailed justification document for the above reevaluation criteria is provided in enclosure 3.

3. General Arrangement The general arrangement of the block walls including the wall identification number, floor elevation and the plant structures are shown in enclosure 4.

4. Configuration of Block Walls For block wall configuration, specific location, type of material and function, see enclosure 5.

5. Flcor Response Spectra The floor response Spectra curves used for the reanalysis of the block walls are shown in enclosure 6.

6. Results of the Block Wall Reanalysis a) Reanalysis Status In the sixty day response we had identified eighteen safety related walls that required reanalysis. To date, six walls have been completely reanalyzed. The prelim-inary reanalysis of the remaining 12 walls is scheduled to be completed by mid December. For complete reevalua-tion schedule, see enclosure 9.

In the course of the plant survey, it was determined that the bottom elevation of the lowest cable tray is at least a foot above the top elevation of the block walls. Therefore, it was concluded that the failure of the block wall Nos. FHB-1 and FHB-2 cannot possibly jeopardize the integrity of the trays. Thus, these walls were precluded from further reanalysis.

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2 b) Ecuipment Loads The effects of the equipment support loads were included in the final reanalysis of the block walls.

The equipment support system generally consists of steel brackets and/or unistrut, with special fittings, anchored to the wall.

c) Final Reanalysis The results of the final reanalysis for wall Nos.

AB- 5, AB- 6, AB- 8, AB-9, AB-10 and AB-13 show the cal-culated stresses to be well below the allowables, see enclosure 7.

7. Construction Practices Enclosure 8 is the original plant design masonry specifica-tion that outlines the requirements for the material, codes and standards, testing and installation for the concrete masonry walls.

8. Schedule Enclosure 9 shows the schedule for complete reevaluation of the remaining walls. This schedule is based on the exper-ience to date, performing the reanalysis of the concrete block walls.

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ENCLOSURE 2 ,

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