ML17199T464
| ML17199T464 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities, 05000000 |
| Issue date: | 12/10/1987 |
| From: | Johnson I COMMONWEALTH EDISON CO. |
| To: | Murley T Office of Nuclear Reactor Regulation |
| References | |
| 3955K, NUDOCS 8712150011 | |
| Download: ML17199T464 (6) | |
Text
- '
CommonAlth Edison One First Na.I Plaza, Chicago, Illinois Address Reply to: Post Office Box 767 Chicago, Illinois 60690 - 0767 December 10, 1987 Mr. Thomas E. Murley, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555 subject:
Dresden Station Units 2 and 3 Quad Cities Station Units 1 and 2 "Supplemental Information Pertaining Ongoing Embedment Plate Assessment Program" NRC Docket Nos. 50-237/249 and 50-~~~/265
Reference:
Letter from I.M. Johnson to A.B. Davis dated Oct9ber 19, 1987
Dear Mr. Murley:
Upon completion of the Embedment Plate Assessment Program, Commonwealth Edison provided an Executive summary Report for the above referenced letter. During the review of this document, additional questions were raised by members of your staff.
In response to our November 23, 1987 conference call with members of yo*ur staff as well as NRC Region III personnel (attendance list attached),
Commonwealth Edison is providing additional supplemental information regarding the Embedment Plate Assessment Program..
we are providing th~ fqi~pwing to you:
- 1)
Allowable load summary for the exterior region of embedment plat~s with 24 inch strap anchor spacing; and 2.) - supplemental information regarding the disposition of embedment plates with 24 inch strap anchor spacing; and
T. December 10, 1987
- 3)
Supplemental information regarding the embedment plate displacement criteria.
Please direct any questions regarding this matter to this office
- r. M. Joli n
Nuclear Licensing Administrator lm Attachment cc:
T. Ross - NRR M. Grotenhuis - NRR A. B. Davis - RIII 3955K Dresden Resident Inspector Quad Cities Resident Inspector
CONFERBNCB CALL w/NRC Re:
EMBEDMENT PLATE PROGRAM November 23, 1987 9:00 a.m. CST
,1*
I. M. Johnson CECo/Nucle.ar Licensing B. Javidan
~
~
CECo/BWR EI)gineering
- ~--
P. Bhatt Sargent & Lundy R. Knoebal Sargent & Lundy P. Gazda Sargent & Lundy T. Ross NRR R. Lapinski NRR D. Danielson NRR Region III
- s. Gavula NRR Region III 3955K
Allowable Load Summary For The Exterior Region Of Embedment Plates With 24 Inch Strap Anchor Spacing The following table summarizes the allowable loads for strip embedment plates with 24" spacing for attachments located in the exterior region of plates.
These allowable loads have been developed using the same methodology and acceptance criteria as for the 18" spacing allowables.
ALLOWABLE LOAD
SUMMARY
EXTERIOR REGION OF PLATE -
24" STRAP ANCHOR SPACING ALLOWABLE LOADS UN-ITS KIPS & INCHES PHASE NO.
DESCRIPTION Pre walkdown 1
Generic allowable loads for 2~"x2~" attachment located close to plate edge.
Pre walkdown 2
Generic allowable loads for 4"x4" attachment located close to the edge of plate.
Post walkdown, pre U.T.
3 Generic allowable loads for 4"x4" attachment located within l" of ceri.ter line of plate.
OBE Operating Basis Earthquake SSE Safe Shutdown Earthquake LOADING T
- 16. 8' GUL 3.7
GUQ HUL UL Upper Limit allowable loads utilized as an interim criteria during the assessment program only as a measure of operability.
MT -
_._..,. **.. *. '*..'"..,,..,. *~*
\\
~
LONGITUDINAL AXIS '
.*.., -; * *.*., OF EMBEDMENT. *PLATE*
ML 18.l 22.0 25.5 17.1 20.8 24.1 17.l 20.8 24.1
Supplemental Information Regarding the Disposition of Embedment Plates with 24" Strap Anchor Spacing As described in Appendix 'C' of the "Sumroary Report on Assessment of Embedment Plates", there are 83 mark "A" plates at Elevation 517'~6" slab in the Dresden Unit 2 Reactor Building.
Of these 83 plates, 23 were ultrasonically tested and 12 were found to have 24" strap anchor spacing and 11 were found to have 18" spacing.
These 23 plates were assessed using appropriate allowable loads and determined to be adequate.
The remaining 60 mark ~A" plates were not subject to ultrasonic testing since they were found to satisfy FSAR allowable loads assuming both 18" and 24" spacing.
At the completion of the assessment program, no other plates at Dresden and no plates at Quad Cities were found to have 24" spacing.
This finding confirms the assumptions which were discussed in Appendix C of the summary report for this program.
~* *'... :*.* -
Supplemental Information Regarding The Embedment Plate Displacement Criteria As described in Appendix 'A' of the "Summary Report on Assessment of Embedment Plates", a plate displacement limit at the attach-ment point of 0.25" has been imposed for SSE loading.
This limiting deflection is for the embedment plate only and was instituted in accordance with good engineering practice to control the de-formation of the ewbedment plate itself.
This plate displacement limit is more restrictive than the FSAR and the AISC specification since no explicit deflection limits have been specified in these documents.
The actual plate displacements noted during the embedment plate assessment program for the typical actual SSE loads are consider-ably smaller than the imposed limit.
In addition, it should be noted that the 0.25" plate displacement limit does not govern any of the generic SSE allowable loads for all of the plates with 18" strap anchor spacing.