ML20010E228
| ML20010E228 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Byron, Braidwood, Quad Cities, Zion, LaSalle  |
| Issue date: | 08/26/1981 |
| From: | Swartz E COMMONWEALTH EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| Shared Package | |
| ML20010E229 | List: |
| References | |
| IEB-79-02, IEB-79-2, NUDOCS 8109030223 | |
| Download: ML20010E228 (3) | |
Text
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C:mm:;nwnith Edi=n one f ast N e onM PT1 Chtca p rhno:s Address Reply to Post Off'ce Box 767 N
Chicago. I:hnois 60690 August 26, 1981,f pam, ir k,7 { PE f t '50 Mr. James G.
Keppler, Director Directorate of Inopection and g.
e L T' 0 2193 } n. 21 Enforcement - Region III M u.smxw,%,
U.S.
Nuclear Regulatory Commission A
n** m ng 799 Roosevelt Roao 9.^
Glen Ellyn, IL 6U137
/
7
_ f Suoject:
Dresden Station Units 1, 2 and 3 Quac Cities Station Units 1 and 2 Zion Station Un1*
1 and 2 LaSalle County Station Units 1 and 2 Byron Station Units 1 and 2 Braidwood Station Units 1 and 2 Supplemental Response to I.E.
Bulletin 79-02 NRC Docket Nos, 50-10/237/249, 50-254/265, 50-295/304, 50-373/374, 50-454/455, and 50-456/457 Reference (a):
Cordell Reed letter to J.
G.
Keppler dated July 5,
1979.
Dear Mr. Keppler:
Tne Commonwealth Edison Company committed, in Reference (a), to perform static, dynamic and relaxation testing of expansion anchors to verify that the static and dynamic characteristics and capacities of the concrete expansion anchors used in our Nuclear Stations conform to the requirements of I.E.
l Enclosed for your use are three (3) copies of our Summary Report entitled " Static, Dynamic and Relaxation Testing of Expansion Anchors in Response to NRC I.E.
Bulletin 79-02" dated July 20, 1981.
However, the actual raw cata is not enclosed.
Due to its voluminous nature, the data is being kept in our files and will be made available for your review, if reouested.
The purpose of the test pragram was to supplement che previous responses wnich had referred to these tests.
The specific items addressed by these tests are ultimate static capacities of various types of expansion ancnors, 1 cad-displacement relationships f !!
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J.
G.
Keppler August 26, 1981 for these anchors, behavior of expansion anchors subjected to simulated seismic events and other cyclic loads, base plate flexibility ana its ef fect on anchor loads, and the phenomenon of l
relaxation (loss of anchor preload) witn time.
2 These tests which were divided into 4 phases (A thru D),
have provided a clear understanding of anchor behavior under a wide range of static and dynamic loadings and the effect of various parameters on that behavior.
l Phase A which involved static tension tests of single anchors ptcvided an understanding of individual anchor behavior.
It was noted during this series of tests that the level of preloading of the anchor at the time of testing does not af fect the ultimate capacity of the anchor.
l In Phase B type tests, wedge, sleeve, and shell type anchored plate assemblies were cyclically loaded to simulate seismic or pipe transient type loadings.
These tests were oerformed in reinforced concrete and concrete block walls.
These tests showed I
that ancho's embedded in concrete block and mortar can withstand cyclic load levels of at least 25% of the anchor ultimate static capacity.
Tests in reinforced concrete showed that anchors could witnstand cyclic loads up to 50% of the anchor ultimate static capacity.
Once again, it was determined that preload was not a determining factor as far as capacity of the anchor was concerned.
Phase C tests were static tests on anchored base plate assemblies for purposes of determining the ef fects of prying action on flexible plates.
The results of these tests show that prying action is in the order of 15-20% of the applied load.
This increase is lower than originally anticipated due to the lower stiffness j
modulus of expansion anchors installed in concrete.
Phase D tests were run to determine the amount of j
relaxation of load that occurs in an anchor after it has been preloaded.
After the cyclic tests were completed, which showed that preload is not required to withstand cyclic loading, it was subsequently determined the relaxation phenomenon is not of great concern.
A major finding as a result of these tests is that loss of preloading in an anchor does not affect the static ultimate load capacity of the anchor, nor is preload required in an anchor to withstand cyclic loadings.
In our judgement this finding should eliminate the need for any pretension surveillance requirements.
l
J.
G.
Keppler August 26, 1981 We believe that this submittal completes our commitments made in the Reference (a) letter.
Should you have any further questions regaroing this matter, please contact this office.
Very truly yours,
[-
E.
Douglas Swartz Nuclear Licensing Administrator Enclosure EDS/1m cc:
Director, Office of Inspection and Enforcement Region III Inspector - All Stations 2456N l
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