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% .....m v -i [ f I:.M 4L M MEMORAt;C' J M Fuk: J. Tapia, RIV n, wong, IE FROM: G. Arndt Mechanical / Structural Engineering Branch Civision of Engineering Tec.tnology, RES S'J3 JECT: R.G. 1.10, REY. 1, DATED 1/2/ n '
, Our conference call on March. 9,1984, coverec the history of R.G.1.10, in particular past and current interpretations of paragraphs 4 (Tensile Test Frequency) and 5 (Procedure for Substandard Tensile Test Results).
A May 13, 1973 memo to attendees sumarized a meeting held with Erico Products Inc. to discuss interpretations of the then relatively r.ew R.G. 1.10. The practical implementations of the reg guide criteria were discussed, with results as recorded in that r.emo.
A. Sampling Frequency
- 1. R.G.1.10, paragraph 4, clearly noted that the frequency for the taking of samples for testing would be on an "each splicing crew" basis.
- 2. Later, when ASME Section III, Division 2, replaced R.G. 1.10, item 1, was not explicitly stated.
- 3. In 1980-81, an attempt was made within the ASMt III-2 Co mittee to clarity this point, but did not pass.
- 4. Subsequently, correspondence by tne NRC kept consistently reiterating the original RG 1.10 "per crew" basis for the takino of test samples.
B. Evaluation Lriteria
- 1. Erico also requested in their April 25, 1973 letter clarification of on which basis to apply the evaluation and acceptance group of "each 15 consecutive test samples" (noted in Paragraph 5 of R.G.1.10).
- 2. The May 13, 1973 nemo noted that't'his basis is the total output _
of all splicers, not "per crew," and applied to tne subsequent taking of accitional investigative samples, or the calculation of the running average tensile strength of "the 15 consecutive samples."
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- 3. This claritication, althougn pernaps relatively less conservative than if done on a "per crew" basis, accepted wna-were perceived as the- realities of (a) considerable bookkeeping to keep samples tested sequentially by crews, and (b) a crew's grcup of finished splices represented by the tested sa.tples could extend well back into completed concrete work - too late to effectively control the process without risking difficult and costly removal of emt,edded splices.
- 4. This clarification, althougn relatively less conservative tnan the "per crew" basis, was nevertneless considered sufficiently conservative.
First, the entire effort to quantify an acceptable recar splice test program was the result of each applicant for a license proposing a different rebar splice cuality control program. A stancard, acceptable Oc program for rebar splices was needed to save time in license reviews. Other reasonable alternatives were not precluded, and no attempt was made to cover all details of an acceptable QC program in RG l.10. It was considered reasonable to allow some latitude for the exercise of com.on sense in the field until proven otnerwise.
Second, considerable test data had been, and was being, taken on these rebar splices. As a result, a reasonable level of confidence existed in the reliability of achieving the specified product. This has since been reinforced by an enormous data base that has validated the original premise. In fact, based on the mass of good data availh the AS"E 111-2 code halved the_samolino frecuency_fremgo,lifor,tArebar.
splices using sleeves witn terrous fD ter ...e. NKU staff serving as memoers on tne com Wmee supported the change.
Even tnough occasional interpretive disagreements nave occurred, and will Itkely continue to crop up, the end result of the program has been a genera t ty high confidence level that the specif f e:: proper-fes have been ,
met in place in tne structures. In fact, the subject of rebar splice quality control has been such a tempting statistical top 1c, that in retrospect, it has pernaps been burdened with some measure of over-regulation, ratner than under-regulation.
W .h E. Gunser Arndt '
f Meenarfcal/ Structural tngineering Branch Division of tngir(eering Technology, RES FREEDOM OF INFORMATION ACf REQUEST 9t- ycr c/%7
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un 211984 j MEMORANDUM T0: Dennis Cru hff' eld,,Special Waterford Team Leader FROM: L. C. Shao, Deputy Director, DET/RES
SUBJECT:
CONSULTANT'S EVALUATION OF CONSTRUCTION ADE0UACY OF WATERFORD BASEMAT During the initial concrete pouring of the Waterford Basemat (especially Blocks 6,1 and 2), there were violations of specification requirements.
As a part of the assignments under the Special Waterford Civil / Structure
- and Piping / Mechanical team, I asked Robert E. Philleo, to be our consultant to independently review how these concrete construction violations will affect the structural integrity and safety of the mat. Mr. Philleo has outstanding credentials and has about 40 years of experience in concrete construction, research and design. He is Past President of the Anerican Concrete Institute and was Chief of the Structures Branch, Directorate of Civil Works. Office of Chief of Engineers, U. S. Army Corps of Engineers, supervising structural design and concrete technology for the World's largest engineering organization. Enclosed is a copy of his evaluation (Enclosure 1) based on his observation of the records and physical inspection of the concrete mat itself. It is Mr. Philleo's opinion that in spite of the violations, the construction was adequate to ensure the safety of the structures. Detailed justifications were given to support his conclusion. The conclusion of his evaluation is extracted from the main report as follows
"The construction of the basemat was adequate to insure the safety of the structure. While there were several violations of specification requirements or missing records, none were of a nature which would impair structural integrity. Most of the violations or omissions pertained to provisions intended to preserve the workability of the concrete such as air content, slump, temperature, age of concrete at time of discharge,
, and number of revolutions of the mixer drum. Because the mat was placed l
during the winter and early spring when workability problems are not i
critical and because a large part of the concrete was passed through I pumps, which constitute a good inspection tool for assessing workability, the lack of documentation of some of the backup workability data is
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relatively unimportant. For the same reason the concrete was easy to
( consolidate, and departure from ideal placing procedures should not prove significant. Failure to document moist curing is not significant I because of the massiveness of the structure; and the occasional failure l
to maintain the required curing tennperature was probably an advantage in removing heat from the structure. Irregularities in Cadweld inspection were administrative rather than technical, and errors in handling reinforcing steel were inconsequential. Waterstop problems apparently were adequately dealt with; but in any event they do not affect safety. FREtuv,.i vi %na,._,nw ACT REQUEST
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2 Strength of the concrete is well documented. It exceeds the design strength by a' larger margin than reqairef by American Concrete Institute standards. This fact and the fact that concrete was placed under favorable physical conditions and in favorable weather, neither of which were conducive to the development of cold , joints or internal voids, testify to the safety cf the structure insofar as'it is affected by the construction process. Adequacy of design was not addressed in this investigation."
Also enclosed witithe enclosure are copies of his resumes in the brief and extended versions. (Enclosures 2 and 3).
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L. C. Shao, Deputy Director Division of Engineering Technology Office of Nuclear Regulatory Research
Enclosures:
- 1. Evaluation of Concrete Construction Adaquacy, in The Basemat Waterford Unit No.i 3
- 2. Brief Resume
- 3. Extended Resume cc: H. Denton .
R. Minogue 3
'/ t V. Stello t "Cn W D. Ross D. Eisenhut 4 J. Collins :
J. Gagliardo )
J. Scinto / l S. Turk G. Arlotto ,
R. Vollmer '
- J. Knight t G. Lear R. Shewnaker ,',
D. Jeng ,
J. Ma C. Siess, ACRS J. Tapia, Region IV -
I FREEDOM OF INFORMATION ACf R_Q A 5!
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