ML20084L812
| ML20084L812 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 09/09/1968 |
| From: | Pailleo R ARMY, DEPT. OF, CORPS OF ENGINEERS |
| To: | US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML17198A202 | List: |
| References | |
| NUDOCS 8305230738 | |
| Download: ML20084L812 (3) | |
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Comments on
" Report on Honeycombing, Turkey Point Unit 3 Containment P.at"
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The report prepared by Bechtel Associates for the Florida Power and Light Company is quite cornplete, particularly in the inve s t iga t ive phase, and generally satisfactory. However, the following ec:mnents ara in order:
Investigation.
The investigation by coring, chipping, end soniscope was adequate for dealing with the indicated problem. The soniscope survey in particular was thorou;;h and helpful in assessing the conditien of the There is, however, one discrepancy in the interpretation of the mat.
data which tends to weaken the conclusions.
In most of the cases in which a readable signal was not received, it has been demonstrated that obstructions other than accidental voids were present.
Hence, the absence of a strong signal did not necessarily indicate the presence of voids.
At elevation 3.0 it was concluded that many received signals were weak because, as a result of a surveying error, the signal paths passec through tendon trumpets. Those which were not through trumpets generally produced good results. However, in one sector of the ma t these conclusions are in disagreement with the path locations shown in Appendix E (Drawing No. 5610 C-148).
According to Figure 12 of the Whitchurst report high horizontal velocities were obtained at the 3.0 f t level in test positions 19 through 28 and position 30 in Section 4-S; and according to Figure 13 high velocities were obtained in test positions 1 through 3.
Appendix E shews that all these paths pass through trumpets. Either the plotted hhCK05000250 738 700209 D
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locations are in error or the conclusion that trumpets interrupt signala is invalid. A personal conta et by telephone with Professor Whitchurst did not succeed in resolving this matter.
It would be well if it c ou ld
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be cleared up.
O therwise, the conclusiom of the Whitchurst report are consistent with Appendix E.
Although details of the s tructural design are not available, I
the mat appears to be sufficiently intact to carry the wall loads provided i
the concrete adjecent to the tendons has the quality and continuity assumed in design.
Proposed Remedial Measures. The grouting procedure outlined in the report should prove adequate. During the execution of the work frequent samples should be taken to check expansion of the grout since it is sensitive to field conditions.
y The report is not clear as to how much of the repair will be by grouting and how much by shotcrete. Shotcrete should be applicable to a i
significant portion of the work.
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5 Preventive Measures.
In paragraph V-2.0 it is stated that a low j
-slump was required to minimize shrinkage and creep effects.
- Actually, very little shrinkage can occur in so large a mass; and any sort of crack-ing resulting from volume change is unlikely with the large amount of s teel which is incorporated.
In most mass concrete structures emphasis is placed on the lowest possible water and cement contents for the pur-pose of minimizing temperature rise and the subsequent thermal stresses which accompany cooling. Such structures are normally unreinforced, an 1 4
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these measures are taken to prevent cracking. None of theac control measures appear important in those heavily reinforced mats.
Em;)ha s is should be placed primarily on strength and workability.
If an extra i
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inch of slump is needed for proper placement, there is no reason why 1
it should not be used. There is also no need for two types of concrete.
i Apparently, some difficulty could have beca prevented on Unit 3 if it had
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been possible to divert some of the concrete fecm the inside to the cut-side. Honeycomb should be prevented by:
N Considering placing problems when settin5; steel, a.
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Providing an adequato number of tremics to restrict the "A
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M Using a very workabic concrete with a slump higher than j
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3 inches if necessary.
a Summarv.
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A very good inves tigation was carried out which, except for one inconsistent group of conclusions, adequately detailed the extent of d
the problem.
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The grouting repair procedure, which was developed in the runufac turer's shop is adequa te.
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In future work more emphasis should be placed on concrete N
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workability.
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ROBERT E. PHILLEO
--E 9 Septer3er 19o8 4
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