ML20023D629
| ML20023D629 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 06/14/1982 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Reed C COMMONWEALTH EDISON CO. |
| Shared Package | |
| ML20023D584 | List: |
| References | |
| FOIA-83-89 NUDOCS 8305250144 | |
| Download: ML20023D629 (7) | |
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uallTE3 STATES NUCLEAR REGULATORY COMM15SION i
I RE01081 Ill 799 ROOSEVELT ROAD
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oLEN ELLYN, ILLINolt 40137 i
t June 14, 1982 d
Docket No. 50-373 Docket No. 50-374 Commonwealth Edison Company ATTN Mr. Cordell Reed Vice President Post Office Box 767 Chicago, IL 60690 Gentlemen:
In reference to our letter of December 2, 1981, concerning admittance of U.S. Nuclear Regulatory Commission personnel to your facility, we request that you add the following names to Enclosure 2 to provide for mescorted access to protected areas within the LaSalle facility.
This certifies that the individuals listed below are employees or contractors of the U.S. Nuclear Regulatory Conunission. To our knowledge, they do not possess adverse character traits or indications of aberrant behavior. They have been screened to the national level (includi.ng a criminal records check);
no disqualifying offenses were noted. Trustworthiness has been determined by a review of their employment records. Based on the above, I recommend that these employees be granted unescorted access to protected areas of your facility.
Name
'USNRC' Organization Badge ~No.
Clearance Romuald Lipinski Headquarters B0428 L
Sai Chan Headquarters B0112 L
A "Q" access authorization is based on a satisfactory full-field investigation conducted by the Office of Personnel Management (OPM), the Federal Bureau of Investigation (FBI), or another U.S. Government agency which conducts personnel security investigations. An "L" access authorization is based on a satisfactory National Agency Check (NAC) conducted by the Office of Personnel Management.
Sincerely,
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smes G. Kepp Yr
[RegionalAdministrator cc: Mr. R. H. Holyoak, Station Superintendent Resident Inspector, RIII
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EVA1.UAT10ii 0F TECHNICAL REPOR
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Assessment of the Effects of Nicked Reinforcing Steet Report
Title:
Report No.:
H. Singh Sargent & Lundy Engineers Chicago, Illinois Date of Report:
November 1981
References:
1.
"Probabilistic Analysis on nicking on Rebars at Clinton Power Station" by M. Amin and T. Y. Su, Sargent and Lundy Engineers, SAD-395, April 1982 2.
" Influence on Nicking on Rebar Ductility at Byron and Braidwood Stations" by M. Amin and T. Y. Su, Sargent and Lundy Engineers, SAD-398, March 1982 Reviewer:
S. P. Chan, NRC/SEB Date of Review:
June 15,1982 9
SUTY1ARY_
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,7 in the cour se of study to assess the effect of nicked reinforcing steel i
with the tungsten carbide drill bit during the installation of concrete expansion anchors, two major concerns were addressed on the effect of I
nicked steel bars; reduction in bar ductility and reduction in bar strength. This report emphasizes both concerns.
Tests at the Illinois Institute of Technology in 1978 demonstrcted a ductility reduction to 2.2% in nicked bars with report mit'l ductility of 9.4%.
Ever since it has been assumed that the bar ductility after nicking would be approximately 2%. Additional information on probabilistic analysis is contained in References 1 and 2 which indicated that more than 94% of aLL nicked bars at Byron and Clinton plants wiLL have ductilities greater than 5.5%
This report presents the analytical approach for assessing the required bar ductility in both flexural members and shear walls at ultimate load.
The analytical approach demonstrates that the minimum required bar N
ductility for flexeral members designed to: ultimate loads in accordance.
with ACI 318 is 4.5% and (b) for impact loads is 5.5%.
Appendix A to the report provides supporting calculations for these results. Design.
charts for flexural members and shear walls have been developed to assess the capacity of nicked reinforcing steel, showing no-nick zones of the concerned structure and the additional reinforcements required.
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v Appendix 8 to the report provides information of additional tests on the i
effects of nicked reinforcing steel and excerpts of a paper entitledj
" Experience with Concrete Anchors on Northeast Utilities Construction Projects" presented at ASCE Specialty Conference on Construction Practices at Penn State University, September 16-18, 1981. The paper concludes that nicked reinforcing steel does not effect the ultimate i
strength of the bar.
DISCUSSION The S&L report deals with the analytical approach used in calculating the required ductility in flexural elements at ultimate Loads considering moment redistribution and other requirements of ACI 318. The ductility or ultimate strain is calculated from the moment / curvature relationshi'p established by the proposed method of analysis and basic assumptions.
The effect of strain hardening of steel reinforcement is formed and not for strength calculation. We feel that this analytical approach is reasonable and acceptable.
In case that the reduced ductility of a nicked bar is thought to be less than the calculated required ductility, the strength of the area should be re-analyzed by incapa'citating the suspicious bar.
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f The report addresses, in Appendix B, the test results of rebars dritted with i
i carbide bits.
Four dritt bit sizes (3/8",1/2", 3/4", and 1") and five bar sizes (Nos. 5, 8,11,14, and 18) were used in the test program.
i Three specimens for each combination pair provided a total of 60 tests.
4 A control specimen of each bar size was taken from the same bar as the other speciment. The control bars were not dritted but tensite tested for.
comparison purpose ar.d baseline data. OriLLing was done in a downward, j
vertical position with continuous pressure for not less than 15 seconds.
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The following observations had been made:
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Reduction in ultimate strength due to dritting ranged from 0% to 2% for att bars except that of N5 rebars from 3% to 6%.
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ALL bars broke above the specified yeild and ultimate strengths. The control bar had an ultimate strength 25% greater than was required.
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The deepest penetration into the body of the bar was I
approximately 1/8" while the defect diameters ranged from l;
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7/16" to 9/16".
The test results reported in Appendix 8 have identified the largest nick which can be inflicted on reinforcing steel by a tungsten carbide drill-bit. The utility. recommendation, of 4/29, that 1/2" dia'. x 1/8" deep i
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defects should be acceptable.
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hl These tests and observations, reported in Appendix B, were performed for-Millstone III Project and were Jimilar to those at 'the Clinton and Briadwood sites. Justification has been establish'ed that the test results are applicable to LaSalle.
CONCLUSION The analytical modet and assumptions used in this report for the assessment nf bar ductility are reasonable and Logical. The proposed method of analysis is consistent with the requirement of ACI Code 318 and is acceptable. The minimum required bar ductility for flexural members as calculated by this analytical approach vir.j.5% for ultimate non-impact 4
t toads and 5.5% for impact LoadeL oro.otoo easeptable and may be used o
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gu,idelines for estimating ductility requirements in case of moment redistribution.
We believe that the effects of nicked reinforcing steel by the tungsten carbide drill bit are negligibly smaLL and wiLL not have any significant ht$
effect on the structure integrity of reinforced concrete h wa $
nd and shear wall elements.
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