ML20084L206

Forwards Comments Re Rept on Honeycombing - Turkey Point Unit 3 Containment Mat. Mat Sufficiently Intact to Carry Wall Loads Provided Concrete Adjacent to Tendons Has Quality & Continuity Assumed in Design

ML20084L206
Person / Time
Site:	Turkey Point
Issue date:	09/06/1968
From:	Philleo R ARMY, DEPT. OF, CORPS OF ENGINEERS
To:	Reinmuth G US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML17198A202	List: ML20084L029 ML20084L032 ML20084L206 ML20084L209 ML20084L812
References
NUDOCS 8305200347
Download: ML20084L206 (6)

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ENCCW-EC 9 Septc:6cr 1968 i

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Mr. G. W. Reinmuth i 1

Reactor Inspector Division of Compliance  :

1 U. 3.' Atemic Energy Cocaicsion Washington, D. C. 20545

Dear Mr. Reinmuth:

Inclosed is a ccpy cf ry rc"itw of the "Rcpert on I!oneyec Oing 1 Turkey Point Unit 3 Centsirsent P.at." Plcnc let na knau if I can bo of further help. .

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> My copy of the report is returned hercuith.

• 3 Sincorcly yours, ,

i l 2Inb1 nonrar :. PHILLEO, Chief  !

an' l'ccearch and Development

! and 5 tcadards Sectica Concretc Ercnch, Za;inecrin3 Div l Civil Wrh3 l cci .r. Frank Iona  !

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8305200347 700209  ;

PDR ADOCK 05000250  :

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j. Cor.cnts on l

" Report on Honeycombing, Turkey Point Unit 3 Containment Mat"

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The . report prepared by Lechtel Associates for the Florida Power a'nd Light Company is quito complete, particularly in the inves tiga tive phase, and generally satisfactory. However, the following ec=.ents are I in~ order:

i Investication. The investigation by coring, chipping, and scniscope i

l 9 was adequate for dealing with the indicated problem. The soniscope survey II l

i in particula'r was thorough and helpful in assessing the condition of the '

'[ mat.

There is, however, one discrepancy in the interpretation of the .

3 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 accidcatal voids were present. Hence, the absence of a strong signal did not necessarily indicate the presence of voids. '

.i At el vation 3.0 it was concluded that many received signals were weak becauke, as a result of a surveying error, the signal paths passed I

I through tendon trumpets. Those which were not through trumpets generally produced good results. HowcVer, in one sector cf the mat these conclu:.icn; I

arc in disagreement with the path locations shown in Appendix E (Drawin;; i

• No. 5610 C-148). According to Figure 12 of the Whitchurst reporg high horizontal velocities were obtained at the 3.0 ft level in test positions 1 19 througn 28' and position 30 in Section 4-5; and according to Figure 13 high velocities were obtained in test positions 1 through 3. Appendix C

, i, shows i that all those pa ths pass through trumpets. Either the plotted 1

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locations ar'c in error or the conclusion that trumpets interrupt signal-is invalid. A personal conta = by telcphone with Professor Wnitcherut j did not succeed in resolving this matter. It would be well if it cou t,:

{ be cleared up. Otherwis e , the cenclusicrs of the Whitehurst report are I

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consistent with Appendix E.

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j Although details of the structural design are not available, the \

i mat appears to be sufficiently intact to carry the wall loads provided 1

l the concrete adjacent to the tendons has the quality and continuity l assumed in design.

1 i Proposed Remedial Measure s. The grcuting procedure outlined in the

' report should prove adequate. During the execution of the work frequent

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' samples should be taken to check expansion of the grout since it is

• sensitive to field conditions. '

I l The report is not clear as to how much of the repair will be by f

grouting and how much by shoterete. Shotcrete should be applicabic to .i

, significant portion of the werk.

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jPreventive Measures. In paragraph V-2.0 it is stated that a low

,; slump; was required to minimize shrinkage and creep effects. Actually, very little shrinkage can occur in so lar2e a mass; and any sort of cra d-ing resulting' from volume change is unlikely with the large amount of

, steel which is incorporated. In = cst mass concrete structures emphasis is placed on 'he t icwest possible water and cement contents for the pur-pose of minimizing temperature rise and the subsequent thermal stresses I which accompany cooling. Such structures are normally unreinforced, ,,m:

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I these measures are taken to prevent cracking. None of these control measures appear important in thaso heavily reinforced mats. Emphasis i

should be placed primarily on strength and workability. If an extra

' inch of slump is needed for proper placement, there is no reason why it should not be used. There is also no need for two types of concrete. )

Apparently, some difficulty could have been prevented on Unit 3 if it had -

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i been possible to divert some of the concrete frcm the inside to the out-I side. Honeycomb should be prevented by:

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! a. Considering placing problems when setting s tacl, k

.;- bf Providing an adequate nurler of trcaics to restrict the t

horizontal flow of concrete, and

p. c. Using a very workable concretc with a slump higher than .

,  ! 3 inches if necessary. ,

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1. A very good investigation was carried out which, except for one inconsistent group of conclusions, adequately detailed the extcut of i

the problem.

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The grouting repair precedure, which was developed in tha ,

t f manufacturer's shop is adequate. *

3. In future work more c:nphasis should be placed on concrete j workability.l i

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j ROBE 2T E. PHILLEO 9 Septe:rber 1968 l

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