ML20005B390
| ML20005B390 | |
| Person / Time | |
|---|---|
| Site: | Marble Hill |
| Issue date: | 06/25/1981 |
| From: | Hamm R, Parme A AFFILIATION NOT ASSIGNED, HAMM ENGINEERS, INC., PARAMETER, INC. |
| To: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| Shared Package | |
| ML20005B389 | List: |
| References | |
| CON-NRC-05-80-251, CON-NRC-5-80-251 NUDOCS 8107080165 | |
| Download: ML20005B390 (25) | |
Text
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-. r REV11N OI? Till EVAL.UATI ON Ol' CONCRI'.TE 3
AT MARRI.E HII.L NUCLEAR GENERATION STATION UNITS 1 AND 2 REPORT NO. IE-124
. June 25, 1981 Prepared for:
linit ed Stat es ';uel ea r Regulat ory Commiss ton i
j of f ice i.f Inspectton and I:nforcement 1
NRC Cont ract 05-R O-2 's 1 PAR: NRC-1E-80/81, Task 02 f
by:
,_,,l'a rme',
AlIr I..
Consul t ing I:ngineer l.a.lolla, Ca111 orn la f \\;.M:aDg4' ;' '<i:s'kJ1 'M 0. N '~ PE.
-S f3 7;gD c, 4
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.y Iv Rolland C. Hamm, P.E.
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Ilanm Engineers, Ins.
i O NO. C 237;; [-
San Diego, Californih' E *..
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civil Thru:. PARAMETER, INr.
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Consul t.ing Eng ineers
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~8107080165 810701 PDR ADOCK 05000
o NOTI CI'.
l This report was prepared as an account of l
work sponsored by an agency of the United i
States Government. RNeither the United States Government nor any agency thereof, or any of j
their employees, makes any warranty, expressed l
or implied, or assumes any legal liability or l
responsibility for any third party's use, or the results of such use, of any informat ion,
apparatus, product or process disclosed in this report, or ' represents t hat its use by such third part y woolet not in f r iner pr ivat el v owned rights.
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SUMMARY
STATEMENT Based on the investigation made, the concrete structures ct Marble Hill Nuclear Generating Station, Units 1 and 2, were found to have been constructed of very good quality concrete material (of higher strength than required or specified), but with concrete placement which f ailed to meet requirements.
This necessitated repairs to bring the af f ected structures into compliance for acceptance without qual if ica t ion.
The task began with.a review of the original Sargent 6 1. undy Report, SL-3753, Evaluation of In-Place Concrete at Marble Hill Nuclear Generating Station, Units 1 and 2, dated November 20, 1979. Discussions with the licensee, Sargent & Lundy Engineers and NRC resulted in preparation of report er ata, withdrawal I errata, and then issuance of a revised report.
Revision 1 was issued on November 21, 1980.
The Revision 1 Raport was a well prepared document containing reliable information.
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}
Based on the numerous investigations made and a comprehensive review I
of the SL-3753 Report, Revision 1, along with the inspection of surfaces and the findings from the line drilling and/or coring of SL-3753 test areas, we are able to verify that internal concrete in the saf ety-related Category I structures of the Marble 11111 Nuclear Plant consist s of homogen-eous concrete with a 95% reliability and 95% confidence Icvel.
This, com-bined with the localized critical st ructural st rengt h demands, y iel d s a confidence and reliability level above 95% for structural adequacy.
Tim s,
the quality of the internal concrete in the structures is acceptable.
1
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lj Tha cuspincien of censtructicn dictated by NRC on August 15, 1979, was prompted by the observation of numerous surface defects and inadequate patching.
The number of visibic surface defects greatly exceeded that which would have been obtained by good practice.
The contrast between the good quality of the interior concrete and the concrete near the sur-face and at construction joints is due primarily to the dif ficulty of pro-perly vibrating the concrete between the layer of reinforcement and the forms and not properly preparing construction joints.
The open space between the reinforcement and the forms is considerably less than that prevailing in the interior.
Therefore, consolidation of the concrete near the surface was more dif ficult than in the interior.
The dif ference in the quality of concrete between the interior and the surface concrete and construction joints was confirmed in a number of cases where nondes-tructive testing was made adjacent to surface def ec ts.
In spite of the apparently inferior concrete at the surface and at construction joints the interior concrete testing revealed solid concrete.
Eased on our investigation of a selected number of visible surface 3
defects, identified by the licensee in the Construction Verification Pro-gram No. SPP-5, we are able to verify that the surfacc preparations made and repair of the concrete patch and repair areas observed were cor.sistent with good construction practice.
i Based on the review of information furnished relating to the exam-ination of concrete surfaces under the Construction Verification Program t
No. SPP-5, we conclude that the program is very extensive and thorough and should identify all concrete patches and repair areas. Based on review of procedures for repair and evaluat ion of conc ret e pat che.s and repair areas, we are able to verify that they are consistent with good construct ion practice.
Fu r t he r, if the, procedures are followed and high 2
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standards of workmanship are maintained, the structural integrity and bio-logical shielding requirements of the concrete structures should he met.
It is recommended that repairs made of those concrete patches and repair areas, evaluated as structural defects, be inspected and evaluated six months af ter their completion. This should determine if the integrity of the repair patching has been adversely af fected by either shrinkage of repair material or dif ferential volume change of the new and old concrete.
It is also recommended that the grout used in repairs of concrete patches and repair areas have concrete strergths as close as possible to the orig-inally placed concrete in order that new and old concrete involved in the repair have closer moduli of elasticities. This is particularly recommended for areas where strain compatibility is desired because of adverse ef fects from dif ferent strains.
Visible inspection of concrete rurfaces of inaccessible areas iden-tified in the SPP-5 Program, which have not had forms removed and are there-fore inaccessible, was not made and is not addressed in this report.
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Scep7 of Invnntigatinn The following is the Scope of Work of the investigation as indicated in NRC Contract 05-8 0-251 PAR:NRC-IE-80181, Task 52.
Provide NRC-IE assistance as a technical consultant in the review of:
(1) Concrete deficiencies, known as "honeycombing," found at Marble Hill facility through visual observation; (2)
The program to determine if internal voids exist; (3)
The repair procedures; (4)
The complete repairs; and (5)
The evaluation of the af fected structures to determine whether they meet the original design intent.
The effort involved review of the techniques used to locate voids, discontinuities, etc., to determine if all significant deficiencies had in all probability been detected. These techniques included coring, pulse echo, and through transmission.
The repair procedures and repairs, made as a result of the findings of the investigations, were also to be reviewed for adequacy.
The main basis of our review ef fort was the report submitted by the licensee a.nd its references as prepared by Sargent & Lundy, Report SL-3753, Evaluation of In-Place Concrete, Marble Hill Generating Station, Units 1 and 2, dated November 20, 1979.
The objectives of the investigation were as follows :
(1)
To provide an independent assessment of the type and extent of deficiencies in concrete const ruction, defined as honeycombing, and/or voids that could have safety significance; (2)
To provide an independent assessment of any needed repairs or remedial actions; and (3)
To provide independent conclusions regarding the capability of the affected structures to perfor,m the intended design functions.
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/SY
Ba ckground The safety-related concrete work at Marble 11111 Nuclear Cencrat ing Station, Units 1 and 2, was halted under NRC's Order Confirming Suspension of Construction, dated August 15, 1979. This order was issued as a result of quality control and construction management inade qua cies. Some surface def ects in the concrete were found by the NRC to have been improperly patched. Additional problems with concrete placement and quality control procedures were also identified during NRC inspections.
On July 17, 1980, NRC retained, through Parameter, Inc., Alf red L.
Parme and Rolland C. Hamm as independent consultant s.
The initial effort of the task was slowed by the need for comprehensive review and study and the receipt of related information. The investigation of internal concrete continued through March,1981. At that time, the independent con su l t ant s requested line drilling and/or coring of designated SL-3753 test areas.
From March,1981, to June,1981, the investigation continued and was related to surface defects which were identified under Construction Verification Program No. SPP-5.
Based on an NRC determination that the scope of our task order had essentially been met, a final report with appropriate qualifications of our conclusions was requested on June 15, 1981, by NRC Region III to be prepared as soon as possible.
5
Ev71uetiin of Structurni Adaqutcy A.
Concrete Strength Information furnished by the contractor identified the amount of concrete placed in the Category I safety-related structures at the Marble Hill Facility as approximately 92,000 cubic yards.
Information furnished by Sargent & Lundy identified four (4) concrete mix designs as being used at Marble Hill. The mix designs had 3500 psi or 5500 psi specified design strengths. A summary of the 91-day compression strength test results, made during placement of concrete, along with pertinent concrete quality control information is shown in Table 1.
With respect to 3500 psi concrete (Concrete Mix No. 01) review of the strength test data revealed that all of the individual cylinder tests (average of two cylinders made f rom a sample) and all of the averages of three consecutive cylinder test values exceeded the 3500 psi specified design strength.
Table 1 shows a standard deviation of 606 psi, a coef ficient of variation of 10.8% and a within test variation of 2.9%.
These values indi-cate good to excellent standard of concrete control (i.e., materials, concrete manufacture, and testing) when compared with concrete industry standards which are identified in ACI 214-77 shown in Table 3.
The 5023 psi allowable design strength shown in Table 1 is mentioned in the SL-3753 Report, Revision 1.
Review of cylinder strength test data in Table 1 indicates a lower value than 5023, but still somewhat in excess i
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of the specified design strength of 3500 psi.
Strength values of the lowest 25 test values of the 689 reported values f or the 3500 psi concrete are shown in Table 2.
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With rasp;ct to 5500 poi concrete (Concrete Mix Nos. 26, 27 and 28),
review of strength test data revealed that all of,the averages of three consecutive cylinder tests exceeded the 5500 psi specified design strength.
All of the individual cylinder test values except one, for Concrete Mix Nos. 26, 27, and 28, were not less than 500 psi below the 5500 psi value.
Table 1 shows standard deviation values between 530 psi and 590 psi, coef ficients of variation between 7.6 and 8.8%, and within - test coeffi-cients of variation (i.e., spread of test results) from 2.9 to 3.7%.
These values indicate good to very good standard of concrete control according to the concrete indurtry standards of control which are shown in Table 3.
The SL-3753 Report, Rr. vision 1, identifies an allowable design strength of 6126 psi for the 5500 psi concrete. Table 1 identifies three design strengths (6144, 5810 ar.d 6244 psi) for the three 5500 psi concrete mixes.
Individual test values more than 500 psi below the 6126 psi value and the average of three consecutive cylinder test values which were less than the 6126 psi value are shown in Table 4.
Strength values of the lowest 9 of 547 reported test. values for 5500 psi concrete are shown in Table 4.
Review of cylinder test data in Table 3 identifies an allowable design strength value in excess of the specified or required 5500 psi strength, but slightly less than the 6126 psi value noted above.
It should be noted that the strength of concrete for Mix Nos. 01, 26, 27 and 28 exceeds the specified design strength.
Should it be desir-able to utilize higher strength in future work, it is recommended that the strength level which is to be used should be determined on the basis of Chapter 4.7(a) and (b) and 4.8.2.3 of ACI 318-77 Building Code.
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1 Based en th2 chova strength and quality control information, we are able to conclude.that all the concrete placed in Category I safety-related structures at the Marble Hill Nuclear Plant is of good to excellent quality and has strengths higher than required for both the 3500 psi and 5500 psi concretes.
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B.
St ruc t u rni Con sid era t ion s The homogeneity of the concrete as ascertained by the nondest ruc tive testing, combined with tne results of the 91-day cylinder tests and unit weights obtained, give assurance that the quality of concrete provides ad equate structural strength and biological shielding.
Besides this, t'nere are other pertinent factors which contribute to further assurance of the structural adequacy.
First, in all beams and structural slabs, the percentage of rein-forcement used is so low, t ha t the capacity of the critical sections are controlled by the strength of the steel.
Based on struc tu ral information furnished by S&L and perusal of engineering drawings for the maximum per-centage of reinforcement employed, a reduction of 30% in concrete strength would decrease the bending capacity by only 5%.
Thus, the presence of small voids in the compressive region of the beams and structural slabs would have an insignificant ef fect on beam ficxural resistance.
In columns, reduction in concrete strength has a direct relationship with structural capacity when the capacity is related primarily to the magnitude of axial load imposed.
However, the colu ans designed in confor-mance to prevailing practice based on the ACI code have about 30% greater margin of safety than beams due to the smaller $ factor employed for columns.
Thus, the structural strength of a framing system with columns and beans stressed to "the same percentage of design strength is dictated by the capa-city of the beam.
9, 8%
The preceding deals essentially with the resistance to bending and axial load. However, the structural capacity is also related to shear capacity of the concrete.
For the Marble Hill plant, the shear stresses induced are in general well below the allowable values.
This is primarily due to the low height to length ratios of tha walls and long spans of the beams involved.
The wave reflection observed in the nondestructive testing in some cases were interpreted as indicating a localized lack of bond.
On questioning and evaluation of this salient factor, this interpretation l
was qualified to mean a lack of adhesion between the concrete and rein-forc ement.
This phenomenon of imperfect adhesion between concrete and reinforcement prevails in most concrete construction and is inherently taken into account in allowable bond values.
In assessing the signifi-cance of lack of adhesion, it must be recognized that adhesion plays a minor role in supplying bond resistance.
Most of the bond resistance is provided by the bearing of the concrete on the deformations of the steel reinforcement.
The size of separation reported to be between the concrete and reinf orcement, termed lack of adhesion, has minor ef fect on this latter interaction.
Thus, there is no significant decrease in bond strength.
Furthermore, the allowable bond values used do not take into account the increase in bond resistance due to the presence of closely spaced stirrups which exist at critical shear sections.
Stirrups, by increasing the splitting strength of the concrete, increases bond resistance.
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C.
Intsrnni Cencrste The investigation of internal concrete at Marble Hill involved the in-place Category I and II concrete. The NRC required examination of existing concrete by randomly selecting and testing a statistical sample representative of both congested and uncongested volumes.
The Sargent and Lundy selection of 60 test areas met the NRC criteria.
The calculated number of test areas (with zero defects or no unacceptable discontinuitics),
needed by standard and well accepted statistical methods to meet the 957; reliability level with 95% confidence, is 58.4.
Testing of more areas yielding zero defects, therefore, results in a reliability level higher than 95% with 95% confidence.
The information contained in the original SL-3753 Report was in part inaccurate, unclear and insufficiently comprehensive.
These conditions did not permit independent veriff. cation of the S&L conclusion that the in-place concrete at Martie Hill met structural integrity and biological shielding requirements with 95% reliability and a 95% confidence level.
Subsequent review of errata sheets to the original SL-3753 Report did not resolve all of the identified concerns.
Our investigation identified two test areas in which grout was apparently placed in lieu of concrete.
The nondestructive testing in these areas did not reveal the presence of any discontinuity.
If the two areas were not included in determining a confidence level (i.e.,
using 58 test areas), the confidence level obtained (with zero def ects found) would be 94.9% with a 95% reliability.
Therefore, accepting 94.9%
as a 95% value, the omission of these two test areas would still result 11
in a confidenco level of 95%.
In our judgment, this confidence Icvel is increased by the fact that the fif ty-eight test areas involved over 1400 independent nondestructive tests.
The magnitude of the increase is dif ficult to judge.
The designation of test areas as congested or uncongested was re-viewed. An independent classification of the areas selected by Sargent
& Lundy resulted in dif ferent classifications. However, it is felt t ha t such determinations are somewhat arbitrary and no particular standard has been established.
It was concluded that the Sargent & Lundy designations of areas as congested or uncongested were reasonable.
4 The nondestructive testing performed was microseismic test eng (Pulse Echo and Through Transmission). The through transmission method was utilized on three columns and the pulse echo method on the remaining test area s.
One of the three column areas was also tested at a nearby location using the pulse echo method.
The through transmission method is designated by ASTM Standard C597-71, Standard Method of Test for Pulse Velocity Through Concrete.
The pulse. echo method is not designated by an industry standard.
However, it as an acceptable method that is capable of identifying the presence of non-interconnecting air voids in the con-crete as small as 1/8" to 1/2" diameter.
The review and related discussions concerning SL-3753 Report, Revision 1, included comparison of the data analysis information with the field test records and meeting notes.
This review revealed discrepancies as to designations assigned by R. Muenow. Specifically, designation of discontinuities as honeycomb, cracks and major separations which were
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rcpstted in th2 ficld recordo end me2 ting notes contrasted with the discus-sions and conclusions documented on data analysis, sheets found in the SL-3753 Report, Revision 1.
The key critical aspect of the nondestructive microseismic testing (Pulse Echo) is the validity of interpretation made *uy R. Muenow and other participants regarding the extent and siza of discontinuities identified during the nondestructive testing performed. As a result of discussions with R. Muenow and others who are reputable, experienced, and presently involved in the field of microseismic testing, we have concluded that the method of nondestructive testing performed at Marble Hill is acceptabic.
The interpretations made and equipment used by R. Muenow are at the forefront of the state of the art-Discussions with R. Muenow established that many of the discontinuities he observed were of small magnitude (i.e., less than the height of a r e i,n -
forcing bar def ormation).
In response to questions in regard to " apparent changes" in discontinuity characterizations, Mr. Muenow indicated that during the first weeks of inspection, the initial discr,tinuity characterizations were assigned before a site-specific designation was established.
There were no changes in interpretations, only a change in the designations.
To verify this information,we inspected concrete surfaces at seven locations where surface discontinuities had been designated as honeycomb.
The inspection verified at those seven locations that discontinuities desig-nated as honeycomb were entrapped air.
This confirmed the explanations given and was also consistent with the information in the SL-3753 Report, Revision 1.
The written procedure, Evaluation of Concrete (Pulse Echo Method),
required additional testing of the suspect areas at 6-inch intervals to out-line parameters of indications. When the discontinuities were interpreted by 13 l
Mr. Musnow to b9 of cuch cmall cize or cxpl sinzble, no extension of tests was deemed necessary.
The adequacy of the pulse echo method and equipment was demonstrated at Marble Hill with NRC observation on June 27, 1979. Confirmation of the preciseness of the Pulse Echo procedure was observed by the consultants through the demonstration on the test block and in several test areas within the structures.
NRC Report No. 50-546/7 9-07 ; 50-547/79-07, dated September 18, 1979, identifies the qualification of the above test method for Marble Hill.
The NRC report also has a Notice of Violation relating to quality control aspects and procedural parameters associated with the pulse echo testing. The report indicates that each of the identified non-compliances involved were completely corrected and resolved prior to the testing fcc record.
Discussions with the NRC and review of information identified that an approved procedure for pulse echo testing was obtained and used on July 6, 1979. This is the initial date of testing identified in the SL-3753 Report, Revision 1.
The through transmission testing was found to have been done in accordance with ASTM C597-71 except that a mechanical wave producer was used in lieu of an electrical c.,e.
Discussions with NRC determined that this would be an approved procedure for Marble Hill.
In the 58 test areas (omitting two areas related to grout placements)
I there were 1439 individual test readings obtained.
The number of readings where no discontinuities were observed (i.e., concrete was solid) was 1185.
Discontinuities were reported to be observed at 254 test locations, involv-ing 42 of the 60 selected test areas.
The SL-3753 Report Revision 1 attri-butes many of these to localized lack of bond between concrete and reinforc-ing steel or between concrete and embedded steel support frame. Some discontinuities were also attributed to the presence of construction joints or embedded pipes, etc.
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The identification of discontinuities was expected because of the fact that small structurally insignificant air voids are normally assoc-iated with embedded ma'.erials, construc tion joints, etc.
All identified discontinuities examined in accordance with all approved procedures demonst ra ted t hat all of the 60 test areas w're acceptable (i.e., al1 of the test areas were free of any structerally significant discontinui-tics).
On l'ch rua r y 12, 1981, the l icensee id en t i f i ed four t est areas win re the SL-3753 Report, Revision 1, ident if ied interpretat ions t hat discon-tinuities were attributable to construc tion joints. These joints were identified to be non-existent because t he conc rete was placed monol i t hic al l y.
This was an apparent error in the construc tion joint d ra w i ngs.
To further confirm the adequacy and accuracy of the discussions and conclusions of the SL-3753 Report, Revision 1, regarding t he changes in characterizations and designations of discontinuities discussed previnusly; and to examine coccrete where there were changes in interpretation attri-buted to construction joints; an investigation by line drilling and/or coring and visual inspection of surfaces was recommended.
Our let t er dat ed Ma rch 5,1981, requesting t he d r ill ing and /o r cor inr, is shown in Exhibit A.
The f ind ings report ed f rom the l ine d r ill iny, and coring of SL-3753 test areas indicate that discont inuit ies previously reported are of limited extent and st ruc tu rally inaign i f ictint.
These findings, along with our inspection of test locations verify that the designations and interpretat ions are consistent with t he conclusions of the Revision 1 Report SL-3753.
15
D.
Surface Defects The occurrence of surface defects is not uncommon in concrete construction. The situation at Marble Hill, however, is unusual in the number and extent of surface defects. However, the frequency of occurrence merely signifies that greater and more careful repair has to be made.
The identification, evaluation and repair of all nurface defects is covered under the Construction Verification Program No. SPP-5.
The program was found to involve an extensive and thorough documented visual inspec t ion and evaluation of all visible concrete surfaces.
The repair procedures were reviewed and found to be consistent with good construct ion practice.
Areas inaccessible due to formwork are required to be identified and then inspected as accessible areas when formwork is removed.
Areas inaccessible because of backfill are required to have interior surfaces inspected and evaluations made of the inaccessible services.
We recommended that repairs made of those concrete patches and repairs, evaluated as structural defects, be inspected and evaluated six months after their completion. This should determine if the integrity of the repair patching has been adversely af fected by either shrinkage of repair material or the dif ferential volume change of the new and old concrete. It is also recommended that the grout used in repairs of concrete patches and repair areas have concrete strengths as close as possible to the originally placed conct'te strength in order that new and old conc rete involved in the repair have similar moduli of elast ic it ies.
This is part icularly recommended for areas where strain compat ihi,l it y is desired because of the adverse ef fects f rom dif ferent strains.
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' Conclunirn, Based on the investigation made, the concrete structures at Ma rble
^
Hill Nuclear Generating Station, Units 1 and 2, were found to have been constructed of very good quality concrete material (of higher st rengt h than required or specified), but wit 1 concrete placement which failed to meet requirements.
Based on the numerous investigations made and a comprehensive review of the SL-3753 Report, Revision 1, along with the inspection of surfaces and the findings from the line drilling and/or coring of SL-3753 test areas, we are abic to verify that internal conc rete in t he saf ety-rela t ed Ca t er,ory 1 structures of the Marble Hill Nuclear Plant consists of homogeneous concrete with a 95% reliability and 95% confidence level.
This, combined with the localized critical structural strength demands yields, a confidence and reliability level above 95% for structural adequacy.
Thu s, the quality of the internal concrete in the structures is acceptablu.
Based on our investigation of a selected number of visible arface defects, identified by the licensee in the Construction Verification Program No. SPP-5, we are able to verify that the surface preparat ions made and repair of the concrete patch and repair areas observed were consistent with good construction practice.
l Lased on the review of information furnished
.ating to the exam-
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ination of concrete surfaces under the Construction Verification Program No. SPP-5, we conclude that, the program is very extensive and t horough l
and should identify all concrete patches and repair areas. Based nn review of procedures for repair and evaluation of cunerete patches and repair areas, we are able to verify that they are consistent witig good construction practice. Further, if the procedures are followed and high standards of workm.nship are maintained, the structural integrity and bio-l logical shielding requirements of the. concrete structures should be met.
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LOWEST 91-DAY STRENGTH TEST RESULTS Conersto No. 01 Specified Design Strength 3500 psi Individual Average cylinder Cylinder Cylinder Test of Test Sample Sample Ave. of 2 3 Cylinder No.
1 2
Samples Tests 2
3920 4270 409" 4582 184 4530 4670 4600 4932 185 4940 5190 5065 4877 229 4760 4940 4850 4843 233 4590 4550 4570 4927 235 4910 4910 4910 4988 243 5200 519J 5195 4958 276 5130 5190 5160 4990 300 4830 4880 4855 4990 3 02 5130 4990 5060 4997 549 4590 4710 4650 4972 550 4970 5200 5085 4838 554 5020 4670 4845 4893 555 5110 4620 4865 4783 612 4940 4710 4825 4942 j
613 5200 5060 5130 4832 622 4510 4390 4450 4778 l
623 5430 5540 5485 4832 l
l 684 4390 4500 4445 4987 i
I 685 3990 3930 3960 4610 1
68 6 4170 4100 4135 4180 687 4680 4700 4690 4262 688 4960 4940 4950 4592 68'9 5130 5260 5195 4945
tid STRENGTH TEST EVALUATION TABLE 3 -STANDARDS OF CONCRETE CONTROL Overall variation Standard deviation for different control standards, psi (kgf/cm!)
Class of operation Excellent Very good Good Fair Poor General construction below 400 400 to 500 500 to 600 600 to 700 above 700 testing (28.1)
(28.1) (35.2)
(35.2) (4?. 2)
(42.2) (49.2)
(49.2)
Laboratory trial below 200 200 to 230 250 to 300 300 to 350 above 350 batches (14.1 )
(14.1) (17.6)
(17.6 ) (21.1 )
(21.1) (24.6)
(24.6)
Within-test variation Coefficient of variation for different control standards percent Class of operation Eyeellent Very good Good Fair Poor Fiild control testing below 3.0 3.0 to 4.0 4.0 to 5.0 l
5.0 to 6.0 above ea Laboratory trial batches below 2.0 2.0 to 3.0 3.0 to 4.0 4.0 to 5.0 above 5.0 t
TABLE 4 LOWEST 9l-DAY STRENGTH TESTS Concrete Nos. 26, 27, & 28 Specified Design Strength 5500 psi Individual Average Cylinder Cylinder Cyl'nder Sample (Ave.
of Test Sample Sample of 2 3 Cylinder No.
1 2
Samples)
Tests 26 205 5170 5080 5125 6088 26 206 6200 6340 6270 6062 26 2 07 6420 6350 6385 5927 26 3 65 5100 4180 4680 6542 26 396 5560 5800 5600.
6018 26 400 5180 5100 5140 6017 l
27 17 5770 5710 5740 5842 27 20 6070 6420 6245 6045 28 77 4620 6070 5345 6600
EXHIBIT A March 5, 1981 United States Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, Illinois 60137 Atta: Mr. Ed Schveibinz Reactor Inspector (Projects) 1 Gentlemen:
We are enclosing a copy of related test records, meeting notes and grid layout l
sheets to identify arcas and test locations which have honeycomb and crack desig-l nations for some discontinuities found during nondestructive microseismic testing (Pulse Echo) of in-place concrete and which are inconsistent with discussions and conclusions in Revision 1 of Sargent & Lundy Report SL 3753 Also enclosed is a copy of meeting notes related to designations of discontinuities as major separa-l tion and a copy of Data Analysis Sheets which refer to discontinuities which can be attributed to construction joints that veyg,gdgnfj.fied by the liccinsee on February 12, 1981 as being noneriistent becauseAwas p' aced monothically. Meeting notes and Data Analysis Sheets related to da91:natinna of aeparation and uninter-pretable signal is also included.
Following is a listing of areas, test number locations, designations of disconti-nuity, document identifying inconsistent designation of discontinuity, and refer-ence photos involved:
(Test No. Locations noted with have been selected for investigation by drilling or coring to verify that discontinuities designated as honeycomb, cracks, major separation, uninterpretable signal or discontinuities which can be attributed to construction joints are not honeycomb or cracks or are or such small magnitude as to be insignificant and are consistent with the information in Revision 1 of Sargent & Lundy Report S13753)
Area Test No.
Designation of Discontinuity Document Reference
& Location Photo 1
- JS Honeycomb 8 3' Test Record b
of 6/27/79 Ill OK Slight Honeycomb Top 8-10" Do 5
Ill-6"N OK Slight Honeycomb Top 6" Do None I12 Slight Eoneycomb Do 6
33 Honeycomb Top 6-10" Do B
l 2
Al Honeycomb Top 6" Test Record 9
of 6/27/79
- A2 Crack (sic) 7" down(sic) from top Do 10 l
B2 Bottom Honeycomb Do 11 l
3 "B1 Discontinuity can be attrib-Sheet B-2 SA15 uted to Construction Joint k
"B3 Multi Cracks (sic)
Test Record SA178 of 7/17/79 Discont2nuity can be attrib-Sheet B-3 uted to Construction Joint
,/jh
Arca Test N3.
Designatica cf Dioecntituity Document Raforenes l
& locctico Photo i.
8
- AT Honeycomb Test Record None of 6/28/79
- A8 Honeycomb Do None 9
A2 Honeycomb near face, near 1/3 Meeting Notes kT inward and near backface, Crack of 8/23/79 near backside Honeycombing at surface, at Grid Layout Do 1/3 inward (sic), Crack and Sheet honeycombing 8 back Crack Test Record Do of 6/29/79
- A5 Cract Do kB "C1 Crack at reflecting face, Meeting Notes 18h Some honeycomb on surface of 8/23/79 C3 Crack Test Record 50 of 6/29/79 Ch Crack Do 51 "B3 Honeycomb (sic)
Do h9 10 A7 Slight Honeycomb Surface, OK Test Record None of 6/29/79 "L5 Honeycomb (sic)
Do 53
- J3 Honeycomb (sic)
Do None 13
B3 Possible Crack 8 Center of slab Meeting Notes 71 of 8/23/79 16
- D5 Cracks vay, 3/h, Honeycomb Grid Layout 61 at bottom face Sheet Honeycomb front and back Meeting Notes Do of 8/23/79 26 Honeycomb on both faces Do 62 2k eeA3 Crack 3/8 vay duirn, 3/h way Meeting Notes lh9 down, 7/8 vay down of 8/23/79 Ak Major Separation k" from bottom Do 150 C3 Crack way covn, 3/h way down Do 151 "El Major Separation k" from bottom Do 152 Discontinuities can be attrib-Sheet B-18 uted to Construction Joint "Fk Crack 3/8 vay down Meeting Notes 15h of 8/23/79 2B
*3 Crack 3/8'vay down Meeting Notes 11h of 8/23/79 5
Crack 3/8 vay down Do 115
- 6 & 6A Separation 4,5" in Do 116 & 117 Uniterpretable Signal Sheet B-20 Do Uniterpretable Signal Sheet B-3 of 26 & 27 2/9/81
- 22 Honeycomb Test Record 118 of 7/7/79 O
I l
Area Toct N3.
Designatico of Diccentinuity Docum2nt Rafaranca
& Location Photo 33
- 6"R of Ch Honeycomb Test Record None (CS) of 7/6/79 36
- 13 OK cracks (sic)
Test Record None of 7/6/79 40
- Ah Discontinuity can be attrib-Sheet B-28 SA251 & 252 uted to Construction Joint Drill locations should be adjusted to avoid first layer (s) of reinforcement and drilling should be terminated if significant structural weakening would occur. Ahy determination of structural weakening to be determined by Sargent & Lundy.
Inspection of surfaces shculd be made at the following to verify that discontinu-ities designated as honeycomb or cracks are not honeycomb or cracks or are of such small magnitude as to be insignificant and are consistent with the information in Revision 1 of Sargent & Lundy Reprot SL 3753:
Area 1 - Test No. Incation Ill, I11-6"N, I12, and B3 Area 9 - Core hole at Test No. Location A2 Area 28 - Core hole at Test No. Location 5 Investigation of crack designations at Area 9 at Test No. Locations C3 and Ch should be made if drilling at Test No. Locations A5 and C1 are not adequately definitive.
Investigation of crack designation at Area 2h at Test No. Location C3 should be made if drilling at Test No. Location A3 is not adequately definitive.
Inspection of surfaces at Area 9 at Test No. Location A2; at Area 10 at Test No.
Location A7; at Area 16 at Test No. Locations D.5 and E6; and at Area 2 at Test No.
Locations Al and B2 vere made by and verified that surface discontinuity desig-nated as honeycomb was entrapped d the discontinuities observed vere consistent 3
with explanations given and with the information in Revision 1 of Sargent & Lundy Report SL 3753 The above listing conforms to the request made at the meeting on March it,1981 at NRC Region III office and with the oral list given on March 3, h, and 5,1981.
The success of the above investigation vill enable us to remove the qualifying state-ment in the preliminary summary statement submitted orally on February 26, 1981 and discussed at the March 2,1981 meeting.
Very truly yours, Alfred L. Parme Rolland C. Hamm, P.E.
Enclosures:
As Listed l
CC: Parameter, Inc.
$6
-.