ML20002C908
| ML20002C908 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 08/15/1980 |
| From: | HOUSTON LIGHTING & POWER CO. |
| To: | |
| Shared Package | |
| ML20002C906 | List: |
| References | |
| NUDOCS 8101120393 | |
| Download: ML20002C908 (41) | |
Text
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O STATUS REPORT SOUTH TEXAS PROJECT CONCRETE VERIFICATION PROGRAM August 15, 1980 bO//o2OJ y3
PREFACE Based upon the review and investigation of the concrete placements in the Unit 1 Reactor Containment Building, there are no internal honey-combs or voids and the major reinforcing steel conforms to the design.
No areas requiring structural repairs were identified and no major deviations that are considered structurally significant were found.
Any deviations determined to be nonconforming are being documented and dispositioned by nonconformance reports.
The areas in the Unit 1 Reactor Containment Building where additional concerns were identified by B&R and HL&P audits, and the NRC Investi-gation Report, were investigated for the specific concern.
Both the visual inspections and subsequent testing concluded that the struc-tural qual'ty was more than adequate.
Further discussions of these areas are provided herein.
STP Con. St. Rpt. 8/15/80
STATUS REPORT SOUTH TEXAS PROJECT - CONCRETE VERIFICATION PROGRAM The review of safety-related concrete in the Unit 1 Reactor Containment Building intern &ls began on July 8,1980 and was completed on August 14, 1980.
The following report describes the four phases of this review and summarizes the results obtained. This review included detailed evaluations of five concrete placements within the RCB-1. Additional concerns regarding placements CIl-W90, CIl-W83, and CIl-W818 were also investigated.
As an attachment to this report, members of the consultant panel have written statements concerning the applicable portions of the review made to date, (see Exhibit A). Additionally, the consultants have reviewed the previous investigations conducted to evaluate the Reactor Contain-ment shells.
Their evaluation of these reports is also attached (Ex-hibit B).
SELECTION OF THE FIVE SAFETY-RELATED PLACEMENTS In order to have a range of samples and to ensure that all types of placements are represented, five generic types of placements have been selected. They are a thick slab, thin slab, thick wall, thin wall, and high lift.
The actual definition of the type is relative within each building and is not specified.
One placement of each type was selected.
This procedure has been used for the six major safety-related structures described in TRD 2A700GQ003.
Due to the accessibility of some of the placements, the conventional use of random samples was modified. A stratified sampling using engin-eering judgement was used as a basis for this statistical approach.
In order to assure conservative results, the selections came from those placements which were determined to be more critical to design engineering due to complexity of the pour, previously identified concerns, or any other reason.
The Task Leader (TL) obtained the pour number of three placements of each generic type from the RCB internals Cognizant Design Engineer (CDE).
The CDE completed this list from the placements which had been placed as of April 30, 1980.
He included in that list any placements which might have been of some concern to him as to potential problems in achieving design requirements.
The Task Leader, Cognizant Field Engineer (CFE) and Mr. Joe Artuso representing the consultant panel, then inspected each placement listed by the CDE and evaluated accessibility for subsequent inspection and testing.
If a given placement chosen by the CDE was not accessible,
-l-4 STP Con. St. Rpt. 8/15/80
an alternate was chosen based on the previously described requirements.
The amount of infomation available from a placement (such as more em-bedded plates, more exposed reinforcing steel) was considered in the final selection. With this in mind, the list was reduced to one place-ment of each generic type.
The review team used these 5 placements for their evaluation.
By following this procedure for the six major safety-related structures to be evaluated, a total of 30 placements will be used for evaluation, giving a broadly based conservatively selected sample.
The 5 placements of Unit 1 RCB internals were then evaluated by a four phase program, (e.g., Documentation Evaluation, As-Built Verification, Visual Inspection and Testing).
For the fourth phase, Testing, the placements were divided into equal areas of approximately 100 square feet.
Three of these areas on each placement were selected on a random basis for testing purposes.
This allowed for measuring variations within the placement, as well as within generic types and within the struc-ture. When all six structures are evaluated, within plant variations can also be measured.
Table I shows the placements selected in the RCB internals, its generic category and the location of the 100 square feet test areas.
The date listed under the placement number is the date the placement was made.
Attached is a statement by Dr. Albert W. Wortham which gives his evaluation of this statistical approach and method of sample selection (see Exhibit C). STP Con. St. Rpt. 8/15/80
DESCRIPTION OF SNtPLE AREAS TEST PLACEMENT GENERIC TYPE AREA APPROXIMATE LOCATION OF TEST AREA Cll-W20F THIN WALL 1
Entire Nortii Wall 2
Entire East Wall (Jan. 22, 1979) 3 Entire South Wall Cll-W41A, THICK WALL 4
14 ft. North of W.P. 9
- W26A, W26C 5
5 ft. Southwest of W.P. 9 (Aug. 8, 1978) 6 W.P. 10 CII-W83 HIGH PLACEMENT 7
5 f t. West of W.P.15 8
8 f t. Southeast of W.P.15 (Oct. 31,1979) 9 14 ft. Southeast of W.P. 15 CII-S14 THitK SLAB 10 20 f t. West of Centerline of Containnent 11 4 f t. East of Centerline of Containnent (Oc t. 17, 1977) 12 12 f t. East of Centerline of Containment CII-SSS THIN SLAB 13 6 ft. Northeast of South edge of Slab 14 17 f t. South of Elevator Wall (Apr. 6, 1979) 15 North Edge of Slab TABLE I STP Con. St. Rpt. 8/15/80
I.
Phase 1: Documentation Evaluation The purpose of the Documentation Evaluation effort is two-fold.
First: To define as-designed condition by identifying all appli-cable drawings, DCN's, FREA's, and NCR's.
Second: To assure that proper documentation was made on each of the selected placements.
The as-designed condition is the configuration documented by the drawings and DCN's that were in effect at the date of the place-ment, FREA's pertaining to that placement, NCR's submitted at any time concerning that placement, and any required work as a result of a FREA or NCR.
These documents have been evaluated to determine where every embedment, penetration, anchor bolt, construction joint, opening and dimension change should be located.
Also defined by these documents are the dimensions and location of the placement.
This information has been placed on a sketch and submitted to the Task Leader for comparison with the as-built sketches submitted by the as-built survey team.
To assure that proper documentation was performed, test reports, batch plant records, pour cards, inspection reports, drawings, DCN's, FREA's, and NCR's which pertain to the selected placements have been reviewed and evaluated as to their correctness and complete-ness.
Test reports have been evaluated for the cement, admixtures, aggregates and water used. Other test reports are the field tests which consist of slump, air content, compressive strength, unit weight and concrete temperature.
Each report is checked for completeness, compliance of test results, signatures or initials, and compliance with procedures for issuing the report.
Pour cards have been checked for QC signatures, listing of NCR's, FREA's, DCN's, and drawings, and any indication of. a nonconfaming situa-tion.
Preplacement, placement, and curing inspection checklists have been reviewed for signatures, time span between preplacement inspection and the date of pour, and any indication of a noncon-foming situation. Where available, punchlists were also evaluated for proper resolution of each item.
NCR's were reviewed for irregularities in their issuance or resolu-tion.
FREA's were reviewed to detennine signatures and actual issue date.
This helped detemine the as-designed condition as l
well as provide a basis for evaluation of the pour cards.
The Engineering Design Drawings and the DCN's were reviewed to de-temine the actual issue date and assure that the proper issuance occurred as it pertains to the placements.
The results of this evaluation were given to the Task Leader for his evaluation.
The consultant panel Aa evaluated any of the problems relating to concrete quality. Any items found to be outside of tolerance were subject to evaluation by the concrete i
(
technologist and the Cognizant Design Engineer to evaluate de-l sign acceptability.
l !
STP Con. St. Rpt. 8/15/80 t
Results:
The maior finding of the Documentation Evaluation Team was the lack of a definitive procedure for listing applicable drawings, DCN's, FREA's, and NCR's on the pour card.
Prior to November,1979, NCR's were not specifically required to be listed on the pour card.
Only those FREA's and DCN's that were written against the " principal drawings" and pertained to tne placement were required to be listed on the pour card prior to November, 1979.
Prior to May,1978, procedures did not require any of these documents to be listed on the pour card. The newest revision of this procedure appears to have eliminated this problem.
No other major concerns were identified.
One minor concern identified was the omission of three FREA's on a pour card (CIl-W83).
Conversations with Construction, En-gineering, and Site QC personnel indicate that the inspection and placements were made with the FREA's in mind even though they were not listed on the pour card.
This deviation is being documented by an NCR.
II.
Phase 2: As-Built Verification The "as-ouilt" inspection program consisted of obtaining field measurunents for alacement locatiors and dimensions (thickness, openings, and plunbness), embedment and penetration locations, including identification, if availabl.e, and blockout location and dimensions (plumbness, squareness, and size).
Horizontal and vertical control for each placement was established using existing references in the Unit 1 RCB.
In placements where an adjoining placement was not made, reinforcing steel was checked for size, spacing, cover, projection and solice lap.
For any embedded item which had a visible identification number, the number was recorded in the field books.
Resul ts: Once the "as-built" condition was documented, it was compared to the "as-designed" condition.
Over 90% of the apparent deviations (outside of tolerance) related to locations of embedded plates, penetrations, floor drains, conduits, etc., which are l
generally not considered structurally significant. Only five l
areas were noted where the dimensions of the member were outside of tolerance, which ranged from -1/8" to +1/2".
The average surface variations identified as being outside of tolerance were -1/2" and
+5/16".
Nonconfonning conditions are being documented and dis-positioned as required by Project procedures.
II.
Phase 3: Visual Insoection A visual inspection was performed by the Special Consultants Panel and selected examiners from the Task Force and addressed the following areas: general appearance of the surface, the nature and extent of cracking, evidence of volume change, evidence of l
cement / aggregate reactions, secondary deposits on surfaces l
(efflorescence, exudation, incrustation), secondary-deposits in cracks or voids (efflorescence, leaching, incrustation), construc-I i
i :
STP Con. St. Rpt. 8/15/80
tion joint alignment, construction joint cleanliness, control joints (expansion, contraction), the nature and extent of deflec-tions, the nature and extent of dislocations resulting in joint movement, tilting, shearing or misalignment of structural elements, apparent effectiveness of curing, the extent and significance of surface characteristics, (such as scaling, spalling, peeling, popouts, pitting, or construction scarring, dusting, staining or discoloration, cold joints, pour lines, corrosion of reinforce-ment, soft spots, sand streaks or pockets, honeycomb, air / water voids, segregation or stratification), indication of inadequate consolidation in general, indications of adequate consolidation behind embedments, the adequacy of repairs based on soundness and appearance (tie noles, cosmetic, structural), satisfactory embedment of penetrations, based on appearance and sounding as applicable, dislocation or misalignment of embedded plates, satisfactory embedment of plates based on appearance and sounding as applicable, apparent consolidation surrounding anchor bolts, general appearance of seismic joints, and evidence of grout leakage.
The Consultants Panel indicated areas on the selected placements in which destructive tests (cores or probe holes) were performed to verify the sonic test results.
The Cognizant Design Engineer reviewed and approved the location of core holes with regard to the potential of cutting reinforcing steel and subsequent con-sequences thereof.
Only cores drilled in placement CIl-S55 cut reinforcing steel, nowever, prior approval had been obtained from the Cognizant Design Engineer to verify that structural integrity would not be affected.
The Consultants Panel also visually examined cores to evaluate the quality of consolidation and unifomity of the concrete. The Consultants Panel directed the drilling of probe holes and, utilizing fiberoptics, visually examined the cleaned holes to evaluate the quality of consolida-tion.
In addition to the visual examinations of the cores, selected cores were examined using petrographic and microscopical techniques.
The Consultants Panel also addressed previous un-resolved concerns and allegations by visually inspecting such areas and recommending specific tests where such methods would resolve specific concerns or allegations.
Resul ts : The visual inspection has been completed for the five selected placements of the Unit 1 RCB.
The overall condition of the concrete was judged by the Consultants Panel to be good with only minor discrepancies noted.
The visual inspection revealed that all of the selected placements were sound and properly con-solidated and do not require any structural repairs.
A quality rating was given for each of the items inspected. The quality rating was categorized as (1) Excellent, (2) Good, (3) Fair, or (4) Poor, and as being either substantial or minor in structural significance.
The overall " checklist" rating was between 1 and 2 for all the placements, and there is a 957, confidence level that STP Con. St. Rpt. 8/15/80
that over 85% of all items inspected for the other placements of the RCB 1 would equal :r exceed a rating of 2 for the structural significant items.
Attached is a statement from Mr. A. W. Wortham concerning the confidence levels achieved from these five place-ments, (see Exhibit C). A verification of the overall rating was confimed by cores, probe holes, and testing with sonic methods as discussed later in this report.
A visual inspection of the cores indicated an overall excellent appearance and a nomal or less than normal amount of entrapped air, which would verify good consolidation.
There were no signs of honeycomb or segregation of the coarse aggregate within the matrix and a unifom distribution of the aggregate was noted throughout.
Attached is a petrographic examination report by Dr. R. C. Mielenz of two cores taken from this structure, (see Exhibit D).
Only one existing nonconformance report was applicable to the visual inspection where the concrete free fall exceeded the speci-fication limits. The reported location of the free fall was examined and there were no signs of segregation or improper con-solication.
IV.
Phase 4: Testing Testing included Ultrasonic Testing (Pulse Through Method),
Petrographic Examination, Compressive Strength Tests, Unit Weight Evaluation, Pachometer for reinforcing evaluation in the appli-cable areas, and Windsor Probe for compressive strength indica-tion and correlation with Ultrasonic Testing data.
Each selected sample area has been tested by sonic methods on the smaller grid.
The sonic correlation and reference standards are developed on the sample areas utilizing cores or bore holes where possible.
The strength and unifomity as measured by Cores and Windsor Probe readings were made or, the selected sample areas.
The location and cover of the face reinforcing steel has been measured in the selected sample areas in which the rebar congestion did not affect the capability of the "R" meter (pachometer).
The sununary of the Ultrasonic Testing perfomed on the 15 sample areas is presented in Table II.
The correlation between the Sonic data and cores is also presented in Table II (see Exhibits E and F).
A petrographic examination of two representative cores were per-fonned by Dr. Mielenz.
Dr. Mielenz's report, (see Exhibit D), indi-cates that no concerns were identified and supports the visual inspection of the cores by Messrs. Artuso and Reading.
Compressive strength tests were conducted on representative cores from the 4000 and 5500 psi cencrete and were 8600 and 9900 psi, respec-tively.
The calculatec unit weight of the cores are in agreement with the visual examination made by Messrs. Artuso and Reading in STP Con. St. Rpt. 8/15/80
that no excessive amounts of entrapped air were evident.
Dr.
Mielenz petrographic report also indicates that the entrapped air was low. All the above factors indicate that the consoli-dation was more than adecuate.
The use of the pachometer was limited to areas in which there was no reinforcing steel congestion; i.e., only areas in which the bars are on a grid (no additional diagonal bars) and spaced such that interbar interference is not evident in the reading.
Two of the selected placements, i.e., CIl-W20F and CIl-514, were success-fully investigated as indicated in statement by J. F. Artuso, attached (see Exhibit G).
The Windsor Probe readings were obtained on all placements; however, it appears that the high strength of the concrete was in the vicinity of the probe limits.
See attached statement by J. F.
Artuso (see Exhibit H). STP Con. St. Rpt. 8/15/80
SUMMARY
OF TEST DATA TEST PULSE VELOCITY COMPRESSIVE STRENGTil AREA PLACEMENT n
y a
CV Sv Sc Sca CIl-W20F 1
57 14,777 352 2.4 7,300 2
88 15,113 320 2.1 8,100 3
83 15,399 320 2.1 9,200 AVERAGE 8,300 8,710 3,400 CIl-W41A 4
64 14,017 1,446 10.3 E'
W26A, W26C 5
73 12,456 1,807 14.5 6
69 11,606 1,192 10.3 AVERAGE CIl-W83 7
73 12,666 1,595 12.5 8
77 13,/49 1,762 12.8 9
110 13,112 1,536 11.5 AVERAGE n = Number of readings Sv = Correlated strength based on 9 v = Average velocity (fps)
Sc = Strength based on core tests o = Stand %-d deviation Sca = Acceptable core strength (.85 fc)
CV = Coefficient of Variation TABLE II STP Con. St. Rpt. 8/15/80
Suff1ARY OF TEST DATA TEST PULSE VELOCITY COMPRESSIVE STRENGTil AREA PLACEMENT n
v o
CV Sv Sc Sca CIl-S14 10 82 14,933 371 2.5 8,000
)
11 49 14,712 254 1.7 7,300 12 59 14,612 169 1.2 7,100 AVERAGE 7,500 8,490 3,400
,L CIl-SSS 13 72 14,684 640 4.4 7,200 O'
14 52 14,620 558 3.8 7,100 15 27 14,124 429 3.0 5,800*
AVERAGE 6,700 9,900 4,675 n = Number of readings Sv = Correlated strength based on v v = Average velocity (fps)
Sc = Strength based on core tests o = Standard deviation Sca = Acceptable core strength (.85 fc)
CV = Coefficient of Variation
- Extrapolated SW Cet S(L RaLldifBOL
REVIEW 0F ADDITIONAL CONCERNS The Task Force investigated NRC, HL&P and B&R Audits to detennine i
1 any unresolved previously identified concerns pertained to the Un tCIl-W These are:
Three were identified.
RCB Internals.
CIl-W90 (ADR 36.7); CIl-W818 (I&E 79-19).
CIl-W83 was one of the 5 placements evaluated in the main evaluation.
The ADR indicated that due to procedural violations, the quality ofTh Force and the Consultant Panel have determined that this placement is the placement was indetenninant.
In fact, in the area where excessive free fall was identified, the concrete was detennined to be of greater strength and structurally sound.
density than other areas.
CIl-W90 was investigated for underconsolidation in the area of the 42 d in the pipe sleeve, under the embedded plates in the top of the wall anVisua 5 square foot area of the form vibrators. indicated good sound concrete in all areas excep area to the side of the 42" D pipe.
The ADR inspected showed no porosity nor voids to exist in this area.
indicated that due to procedural violations, the quality of the place-The Consultant Panel and the Task Force have d
ment was indeterminant.detennined from this evaluation that the placeme Ul -
CIl-W81B was investigated for alledged over-vibration of concrete.
h This trasonic Testing was used to evaluate consolidation a f no concern.
Table III shows the results of the Ultrasonic Testing for the different areas tested under this effort. I l
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STP Con. St. Rpt. 8/15/80
ADDITIONAL C0riCERilS SUMt1ARY OF TEST DATA TEST PULSE VELOCITY COMPRESSIVE STREf1GTH fi/A AREA PLACEMENT n
v o
CV Sv Sc Sca Cil-W90 (ADR 367)
Form Vibration Internal Form Spacings 96 13,960 1,021 13.7 CIl-W90 2.
Consolidation Y
Under Embedded Plates 83 12,250 1,613 7.6 i
CIl-W81B Uest Pressurizer South Wall Excessive Vibra-tion 29 14,914 469 3.2 1
l l
n = Number of readings Sv = Correlated strength based on v v = Average velocity (fps)
Sc = Strength based on core tests i
o = Standard deviation Sca = Acceptable core strength (.85 fc)
CV = Coefficient of Variation TABLE III STP Con. St. Rpt. 8/15/80
ADDIT 10tlAL C0flCERNS
SUMMARY
OF TEST DATA TEST PULSE VELOCITY COMPRESSIVE STREliGTil N/A AREA PLACEMENT n
y a
CV Sv Sc Sca Cll-W83 Excessive Drop 28 14,816 706 2.1 4
CIl-W90 Consolidation at Pipe Support Plates 36 12,041 1,365 8.8 Cll-W83 fonn Tie Repairs 5
13,926 1,320 10.6 i
l n = Number of readings Sv = Correlated strength based on G y = Average velocity (fps)
Sc = Strength based on core tests o = Standard deviation Sca = Acceptable core strength (.85 fc)
CV = Coefficient of Variation VGm1T IIR (memR'd) sTP rnn st ont 9 /16 /nn
EXHlBlT A UNIT 1 REACTOR BUILDING INTERNALS A study of the documentation, visual inspection and test data of the five generic type placements and placements of additional corcern was completed to evaluate the structural integrity.
1.
The rev'ew of documentation was made to detect any special con-ditions or deviations which would affect this evaluation.
"hese were included in the study and conclusions.
2.
The visual insjections and manual sounding indicated that concrete integrity was better than average construction and was classified between good and excellent.
3.
A review of the test data indicated high strength and proper struc-tural integrity throughout.
(a) The strength data indicated strengths considerably higher than required.
(b)
The sonic testing indicated that a good level of uniformity was attained throughout. There were several localized areas within a one foot grid which had transmission times on the high side of the range which were attributed to a subsurface condition.
Oscilloscope curves were provided at random.
The criteria of the evaluation is two fold - one is relative time and the other energy inputs depicted by the curves.
Studies on the calibration block indicated both a high time (double the nomal) and a flat curve when transmitting around an 18" void in a four foot wall.
(This would be a relative relationship for thinner walls and smaller voids). Also, curves of similar configuration but somewhat flatter are considered nomal because thn amplitude condition is a function of surface or subsurface condition. The criteria of either (not necessarily both) shape or similar time would mean similar quality concrete.
The test data on the five placements evaluated did not indicate any voids by this criteria, d.
Additional Concerns:
(a)
Fonn Tie Evaluation Various fann ties were tested at random using the sonics technique.
Test results indicate soundness throughout and indications of high strength dry packed mortar.
(b) W90 Wall (Form Vibration-Vibrator Spacing)
The area of form vibration and locations of larger than specified internal vibrator spacings were tested sonically.
Test results indicate a high degree of uniformity of dense concrete. There were several localized spots within the one foot grid that were lower velocities but this is attributed to subsurface condition.
There were no voids located. STP Con. St. Rpt. 8/15/30
Exhibit A Page 2 (c) W90 Wall (Pipe Support Plates)
Sonic tests indicate proper and unifom consolidation at the area of the plates.
However, the streng*.h indication is some-what lower than the other placements which is normal for loca-tions at the top of the wall of a high placement.
(d) W41 (Back Wall of Elevator Shaft) - Outside Face of East Secondary Shield Wall Elev. 29 The cold joint detected on this wall was tested sonically across the plane of the joint.
Proper velocities were achieved and therefore proper bond was developed.
(e) W83 (NCR 2174 Excessive Drop)
The area where the excessive drop was reported was sonically tested. Test results show a large degree of unifonnity and consolidation.
Two of the lower velocity readings were cored and visually examined and this indicated proper consolidation.
The sonic correlations to other areas and core tests indicate that this concrete is of greater sgrength and density than other acceptable placements.
(f) W81B (West Pressurizer Wall)
This area was sonically tested to evaluate the concrete uni-formity and consolidation because of the reported over-vibration.
The test data indicates a high degree of uniformity and consolidation.
It appears to be better than normal in strength and structural integrity.
(g) W90 Wall (Pipe Embedment)
Sonic tests indicate a proper and uniform consolidation was achieved.
However, a localized area of about lis sq. ft. near the side of the pipe showed indications of porosity or a localized void.
This was checked thru probe holes at this area to visually classify the consolidation. A study of the probe holes indicated sound and properly consolidated concrete.
The readings are apparently due to subsurface pores.
August 13, 1980 Joseph F. Artuso STP Con. St. Rpt. 8/15/80
Exhibit A Paga 3 EVALUATION OF REVIEW BY T. J. READING The evidence - appearance of concrete surfaces, and previous reports on the defects and the repairs which have been made - indicates a good quality of concrete in place.
The strengths of concrete cores taken to date are very good - somewhat higher than the values for control cylinders made during construction.
Mr. Artuso is evaluating the results from the pulse velocity and Windsor Probe tests. Mr. Mielenz is examining the cores petrographically.
There is a problem of offsets at construction joints which should receive attention.
The offsets, which in some cases are as much as 1/2 inch or more, are the result of unsatisfactory formwork.
A wide band of concrete has been chipped and bush hammered and a thin mortar patch applied.
Minimizing these offsets 'and the associated chipping, grinding and thin mortar patches will improve the appearance and give better assurance that any needed repair at the joint is properly made.
No areas requiring structural repair were identified.
Continued efforts should be made to obtain the best possible consolidation in these complex placements.
August 13, 1980 h#
T. J. Reading v l
l STP' Con. St. Rpt. 8/15/80
EXHEBli ' B STATEMENT BY T. J. READING AND J0E ARTUS0 ON STATUS OF INVESTIGATION OF REACTOR CONTAINMENT SHELLS 1 AND 2 The existence of voids in the Reactor Containment shell for Unit I was first reported in October 1978.
Since that time, about 80% of the con-crete adjacent to the steel liner in this Unit and in the completed portion of Unit 2 has bee.1 investigated, with particular emphasis on areas believed to be prone to voids. As an estimate, the investigation included about 90% of the accessible area.
The liner plate, generally 3/8 inch thick, was first sounded by tapping with a hamer.
Drummy areas were then drilled to detennine whether voids existed and their extent. A number of voids were found.
Some were significant; however, in most cases, they were only a few thousandths of an inch thick and probably resulted from shrinkage and temperature changes.
Several holes were drilled at locations where the 3/8 inch liner plate was not drummy, and no voids were found; however, minor surface honeycomb (unconsolidated concrete) was found in some areas where the quality of the concrete was questioned because of difficult placing conditions.
It was also found that in areas where the liner plate was much thicker, tapping with a hamer could not be depended upon to locate defects; therefore, a standard pattern of holes was drilled through the thickened plate where a potential for voids existed.
The exterior of the shell was also carefully inspected and holes were drilled as needed.
Voids and honeycomb here were much less prevalent than for the inner face.
A few additional holes were drilled to provide vents for later grouting.
In all,1,589 holes were drilled.
621 of these holes were drilled into 105 determined voids, some of which contained honeycomb around their periphery.
Their total volume was 17.7 cu. yd., (the volume of grout required to fill the voids), which amounts to approximately 0.1% of the volume of the concrete.
Certain areas were found to be particularly prone to voids.
These were areas of difficult consolidation - the bracket embedments for the polar crane rail in Lift 15, below penetrations through the shell and below the 8 inch channel and plate stiffeners where the reinforcing steel is congested.
Although a few conventional concrete repairs were made, the great majority were made by pressure grouting, using a comercial, highly fluid, nonshrink grout.
The grout "take"for Unit 2 was only about 1/5 of that for corresponding areas in '; nit 1 --the result of better consolidation.
The investigation and repairs made to date on concrete placed in the Con-tainment shells give assurance of good quality concrete near the inner and outer portions of the shell. The drilling and grouting of these areas should also have reached any voids which extended to the central 36dm~3A ML JMM
Exhibit B
Pags 2 portion of the shell; additional voids in this region (not indicated at the surfaces) are unlikely because it is readily accessible for vibration and the placing procedure involved depositing concrete into the middle portion of the walls and moving it outward to the formed or liner surfaces.
It is believed that the investigation has located and repaired all except a few small voids and areas of honeycomb such as those found in the area behind the removed liner bulge portion which was approximately 15"x12" in area and tapered to a depth of about 6".
The quality of construction is consistent with the present state-of-the-art on the consolidation of concrete in very congested members.
In a letter dated Feb. 18, 1980, HL&P advised the NRC that "the investi-gation and repair of the deficiencies for both Unit 1 (Lift 1 through Lift 17) and Unit 2 (Lift I through Lift 6) have been completed except for the area in Unit 2 where the liner bulged", (which is being handled by separate correspondence).
h
- .J
).
August 13, 1980 r
seph F. Artuso
? h.
't T. J. Meading STP Con. St. Rpt. 8/15/80
EXHZBZT C d.9k 9hMam andducciales August 13, 1980 Mr. Gerald Murphy Brown & Root, Inc.
Post Office Box 3 Houston, Texas
Dear Mr. Murphy,
Attached are three sumary documents which cover selected portions of my effort in the investigation on the South Texas Project. More specifically, these documents cover:
o The sampling methodology and philosophy.
(Attactment1)
The preliminary evaluation of the visual Inspection Quality o
Ratings for RCS 1.
(Attachment 2)
The regression analysis and interrelations of thi:kness, time, o
and velocity measurements obtained from the sonic testing methods for the placements in RCB 1.
(Attachment 3)
In addition to this, support was given in other areas of the investi-gation.
Such support was in sampling, computations, and computational methods development.
As of this time, to the best of my knowledge, the statistical approaches being used are satisfactory and in accordance with the requirements of the investigation.
The methods are being used in an appropriate scientific and engineering fashion and should produce satisfactory decision making information.
Sincerely,
./
A. W. Wortham AWW/rj STP Con. St. Rpt. 8/15/80
Exhibit C Page 2 ATTACHMENT 1 Sample Assessment The samples used in the evaluation were stratified to assure good engin-eering representation of ai; placement ( all buildings, and all generic types. To achieve this, the five generic types were defined as thin wall, thick wall, high placement, thick slab, and thin slab. Of the 150 total potential placements in the Reactor Building, five were selected (one for each of these generic types).
The placements so selected were then partitioned by area into equal areas of approximately 100 square feet.
Since placements varied in size, the number of potential sample areas within each placement varied from a minimum of 3 to a maximum of 10.
These areas were then numbered for identification and sample selec-tion purposes.
Using tables of random numbers, three samples were then selected from each placement.
This procedure gives a total of 15 sample areas representing five generic types within the Unit 1 RCB. When the evaluation is complete, six structures will have been evaluated giving a total of 90 sample areas representing the five generic types, six buildings and thirty placements.
The investigations planned,in the utilization of these sample areas are the pulse transmission times (the number of readings varies depending upon the accessibility of points - typically the number of readings are.in the range of 40 to 80 values), and Windsor Probe Strengths (typically three on each sam'ple area).
From a sampling standpoint, the number of data points varies depending upon the particular investigation.
For example, for assessing quality rating, there will be 30 points, for assessing velocity characteristics within a placement, there may be as few as 40 points, and for assessing velocity thickness relations for a given building, there may be more than 500 data points.
The visual inspection rating system covers 22 major categories with four rating levels on each placement.
Two of these levels are further sub-divided for more complete assessment.
Thus, the number of data points varies depending upon the characteristic being investigated and the anticipated variation in the characteristic.
As a general guide, if a sample of size 90 is selected, we can say with
.95 confidence that 90% of the measurements in the population will exceed or be equal to the 5th smallest observation.
Similarly, one can say with
.95 confidence, that 97% of the measurements in the population will equal or exceed the smallest observation in the sample.
This guide will be used in the overall requirement of 90 sample areas.
The number of data points within the sample areas was detennined after the sample was selected and the number taken was based on what was freely available for observation and/or testing.
In general, the number of data points far exceeds the normal three to five per sample used in scientific and engin-eering investigations.
This strategy of over sampling is taken to assure l
STP Con. St. Rpt. 8/15/80
. - =.
A%2achment 1 Page 2 Exhibit C adequate data availability to assess within building, within generic type characteristics.
Even the normally accepted 25 samples for assess-ment was exceeded, generally by a factor of 2.
This approach overall should yield adequate and meaningful results. As stated in the original plan of effort, if there is an indication that the evaluation needs a
additional samples, they will be considered.
Based on the preliminary evaluation of data collected at the time of publication of this request, such additional samples will not be necessary.
1 i
i i
l i
STP. Con. St. Rpt. 8/15/80
Exhibit C ATTACHMENT 2 Visual Inspection Preliminary results of the statistical analysis of the visual inspec-tions are shown in the following table.
These results were derived from the visual inspection records as illustrated in the fom for Bldg.
RCB 1 Placement CIl-W20F, The results are based on the pooling of the quality ratings for all factors having the same classification of im-portance(substantialorminor). This pooling, though slightly biased since all factors are not independent, still gives an indication of the visual quality character of the generic types and the building.
The tabular results may be interpreted as follows:
o For placement CIl-W20F substantial important factors.
There is
.95 confidence that 83% of the ratings will exceed (be better than) or equal to a factor of 2.
o For RCB 1 minor important factors.
There is.95 confidence that 94%
of the ratings will exceed or equal a factor of 3.
Overall, the results are based on a relatively small amount of data (only 1/6 of the total set).
Thus, these results will be expected to change as the investigation progresses.
Even with this reservation, the overall results for the building are considered satisfactory.
STP Con. St. Rpt. 8/15/80 Page 2 OVERVIEW - VISUAL INSPECT 10N Exhibit C 95% Confident Bldg. RCBl:
Factor Equal or Placement Importance Percent Exceed Rating CIl-W20F Substantial 83%
2 Minor 84%
3 CIl-W41A Substantial 83%
1 Minor 84%
1 CIl-W83 Substantial 74%
2 Minor 54%
2 CIl-S14 Substantial 78%
2 Minor 84%
3 CIl-S55 Substantial 60%
2 Minor 54%
2 B1dg.
Substantial 85%.
2 Minor 94%
3 These results are preliminary and are based on the pooled observed data from only one building.
They are presented to show that from a quality rating standpoint, the results at this point should be con-sidered favorable.
STP. Con. St. Rpt. 8/15/80
4 C-DATE OF POUR
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i STP Con. St. Rpt. 8/15/80
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STP Con. St. Rpt. 8/15/80
Exhibit C ATTACHMENT 3 Statistical Analysis - Time, Thickness, Velocity Since the relation between time, thickness, and velocity is anticipated to be of the form t=hT where T is thickness, V is velocity, and t is time, a regression analysis using the model t=ST+c was perfomed.
For RCB 1 data, the results established were t = 75.575 T with s /T = 29.01 t
.95 confidence limits on s are then 74.899 and 76.251 These valuas, when transfomed to velocity, become Y =.0132318 or 13231.8 ft./sec.
with the confidence limits for overall average velocity as
.0131146 and.0133513 or 13114.6 and 13351.3 ft./sec.
The regression methods may be used to assess velocity for any thickness.
For 2' placements, the estimated average velocity is still.0132318.
Confidence limits for individual tests are
.0096142 and.0212148 or 9614.2 and 21214.8 ft./sec.
These values are satisfactory at this stage of the investigation. As with all other pursuits, the results may change as more information becomes available from other placements and other buildings.
STP Con. St. Rpt. 8/15/80
EXH181T 0 RICHARD C. MIELENZ, P.E., INC.-MATERIALS AND PETROGRAPHY PETROGRAPHIC EXAMINATION OF SAMPLES OF DRILLED CORES OF PORTLAND-CEMENT CONCRETE, SHOW CAUSE EFFORT, SOUTH TEXAS PROJECT INTRODUCTION In accordance with the letter of transmittal dated July 5, 1980, from Mr. Gerald R. Murphy, Discipline Project Engineer, Show Cause Order, South Texas Project, Brown & Root, Inc., I have examined by petrographic methods two drilled cores of port-land-cement concrete that were received by priority United States mail on August 9, 1980.
The samples were identified as follows:
Core No. 3 From 2-ft. wall placement Core No. 14 From 1-ft. slab placement It was requested that the samples be investigated and that a report be prepared and submitted.
The samples were examined visually and in detail under the stereoscopic microscope.
Euch core was sawed twice along the length so as to produce two cross sec?. ions of the concrete in an undisturbed condition.
The sections were prepared by lapping so as to allow determination of the air-void content in accordance with ASTM C 457, Standard Recommended Practice for Micro-scopical Determination of the Air-Void Content and Parameters of the Air-Void System in Hardened Concrete.
CONCLUSIONS Core No. 3 1.
The concrete represented by Core No. 3 is homogeneous, hard, and well consolidated.
Air-void content was determined to be 2.33 l
per cent, of which the greater part is in voids less than 1.0 mm. in size.
Occasional air voids are as large as 10 mm.
Moderate bleeding of the fresh concrete is shown by narrow separations occurring beneath particles of coarse aggregate; however, in my opinion, such features l
are without structural significance.
Core No. 14 2.
The concrete represented by Core No. 14 is hard and ade-quately consolidated.
The air-void content was determined to be 3.69 per cent, of which slightly more than one half is in voids larger STP Con. St. Rpt. 8/15/80
Exhibit D RICHARD C. MIELENZ P.E., INC.-MATERIALS AND PETROGRAPHY South Texas Project Page 2 than 1.0 mm.
Occasicnal sir voids are as large as 10 mm.
3.
Pronounced bleeding of the fresh concrete is shown by carrow separations and accumulations of weak to soft laitance beneath particles of coarse aggregate and reinforcing steel.
Such accumulations and separations are commonly 0.25 to 1.0 mm. wide.
31eeding tendency of the fresh concrete probably was aggravated by relative coarseness of the cement employed.
However, in my opinion, the separations and laitance accumulations are not of critical structural significance insofar as they are represented by the sample.
DESCRIPTION OF THE SAMPLES Core No. 3 The sample was a 3-3/4 in. diameter drilled core of portland-cement concrete.
The section was 8-1/4 in. long.
The outer end is a formed surface that is coated by a trowelled application of portland-cement and sand mortar.
The inner end is a sawed cross section.
No reinforcing steel is present in the sample.
The surfacing mortar is about 2 mm. thick and is underlain by a bond coat of portland cement-sand mortar that contains a finer sand than that present in the surfacing mortar.
The outer one half of the surfacing mortar is poorly compacted and so includes numerous, small, irregular cavities.
The outer part of this coating is spalled at the perimeter of the core.
The bond coat is poorly compacted and includes irregular cavities and granular zones in contact with the substrate This interface also is partially separated at the perimeter concrete.
of the core.
The surface treatment evidently was used to cover air-bubble holes in the formed surface.
The concrete is hard and well consolidated.
No segregation of the fresh concrete is _eparent.
However, moderate bleeding is shown by frequent separations beneath particles of coarse aggregate, where water accumulated before setting of the concrete.
The separations are usually 0.025 to 0.050 mm. wide.
The concrete is not air entrained but air voids are sparsely distributed through the mortar matrix.
They are usually spherical or nearly so and empty of secondary chemical deposits such as commonly develop as a result of cement-aggregate reactions or aggressive-attack on cement paste by substances from external sources.
They are-usually 0.2 to 1.0 mm. in diameter and occur singly.
However, occasional grape-like clusters of air voids are present in masses up to 10 mm.
across.
Entrapped air voids usually are 1 to 3 mm. across and spherical to ovoid in shape.
Rare voids are up to 10 mm. across.
STP Con. St. Rpt. 8/15/80
Exhibit D RICHARD C. MIELENZ, P.E., INC.-MATERIALS AND PETROGRAPHY South Texas Project Page 3 The coarse aggregate is a natural gravel, the apparent nominal maximum size being 3/4 in.
The main constituents are chalcedonic and quartzose cherts, quartz, quartzites, quartzose sandstones, and occasional particles of microcline feldspar.
The fine aggregate is a natural, highly quartzose sand.
No deleterious cement-aggregate reacti,ns were detected.
The cement paste matrix is very firm, compact, and vitreous in appearance on fresh fracture produced in the laboratory by breaking the concrete by light blows of a small hammer.
The cement paste matrix is homogeneous in appearance and physical characteristics.
Sound particles of fine aggregate, suen as quartz, commonly are broken across on fresh fracture, a fact indicating good quality of bond of the matrix to the aggregate.
Incompletely hydrated granules of portland-cement clinker are common in the matrix.
The cement is not undesirably coarse.
Calcium hydroxide, a normal product of hydration of portland cement, is present in usual amounts and occurrence.
The cement paste is uncarbonated or slightly carbonated as a result of slow penetration of the hardened concrete by carbon dioxide from the atmosphere.
No mineral admixture, such as fly ash, is present.
Core No. 14 The sample is a 2-3/4 in. diameter drilled core of portland-cement concrete.
The section was 6 to 6-1/2 in. long.
One end is a sawed cross section.
The other end is a fracture surface along which the core was broken from the concrete remaining in place.
One side adj,acent to the sawed end is intersected by a 1-in. diameter steel reinforcing rod.
The rod passes diagonally along the core and emerges on the same side of the core 1-1/2 to 2-3/4 in. from the sawed end.
The concrete is hard.
No evidence of segregation of the fresh concrete was apparent.
Pronounced bleeding of the fresh concrete is shown by separations and accumulation of soft laitance and weak mortar of very high water-cement ratio beneath particles of coarse aggregate.
These separations and accumulations are usually 0.25 to 1.0 mm. wide.
An extensive development of such separations and accumulations occurs beneath the reinforcing steel.
The concrete is not air entrained but entrapped air voids are common.
These voids are spherical to irregular in shape and occasion-ally are as large as 10 mm.
The air voids are empty of secondary chemical deposits.
STP. Con. St. Rpt. 8/15/80
Exhibit 0 RICHARD C. MIELENZ, P.E., INC.-MATERIALS AND PETROGRAPHY South Texas Project Page 4 The coarse and fine aggregate are like those in Core No.
3, except that the apparent nominal maximum size is 1/2 in.
No evidence of cement-aggregate reactions was detected.
The cement paste matrix is mottled in appearance in shades of dark gray, medium to light gray, and off-white.
The darker portions predominate.
They are very firm and vitreous in appearance on fresh fracture.
Sound sand grains, such as quartz, commonly are broken across by such fractures, a fact indicating good quality of bond of the matrix to the aggregate.
The lighter colored portions are less firm to weak or soft, and subvitreous to lack-luster in appearance.
Sound sand grains frequently are not broken across on fresh fracture in these portions.
The various phases of the cement paste matrix are intimately intermingled but the weaker portions often are localized beneath particles of coarse aggregate, as noted above.
Patches of the weak matrix usually are 1 to 5 mm. across and are embedded in the more firm matrix.
The cement paste matrix is uncarbonated or slightly carbonated as a result of slow penetration of the hardened concrete by atmospheric carbon dioxide.
Incompletely hydrated granules of portland-cement clinker are abundant.
The cement is relatively coar,se, especially in the proportion of granules that are larger than 25 micrometres.
Granules larger than 45 micrometres are common.
No mineral admixture, such as fly ash, is present.
AIR-VOID CONTENT OF THE SAMPLES The air-void content was determined in accordance with ASTM C 457 by the point-count method on sections sawed lengthwise from the cores.
For Core No. 3, three sections were prepared along the length for separate determinations.
For Core No.
2, two separate sections were prepared.
The results are summarized in Table 1.
In order to further describe the air-void system, the air-void I
content is reported separately for air voids 1.0 mm. or less in maximum l
cross section and air voids that include at least one dimension that l
is greater than 1.0 mm.
For purposes of description, the former air voids are classified as " entrained" air voids, whereas the latter are classified as " entrapped" air voids.
This classification is not recognized by ASTM C 457, but the literature commonly identifies j
entrained air voids as those less than 1.0 mm. in size, in contrast l
to the larger entrapped air voids.
STP. Con. St. Rpt. 8/15/80
Exhibit D RICHARD C. MIELENZ, P.E., INC.-MATERIALS AND PETROGRAPHY South Texas Project Page 5 RICHARD C. MIELENZ, P.
E.,
INC.
$Y
^ w!
x-1 Richard C. Mielenz, P.
E.
President August 11, 1980 Route 1, Box 103 Brigham Road Gates Mills, Ohio 44040 STP. Con. St. Rpt. 8/15/80
Exhibit 0 RICHARD C. MIELENZ, P.E., INC.-MATERIALS AND PETROGRAPHY TABLE 1.
AIR-VOID CONTENT OF CONCRETE CORES South Texas Project 1/
Core No. - Per Cent By Volume Classification of Air Void 3
14 Outer end Entrained air voids 1.19 1.69 Entrapped air voids 0.86 2.33 Total air voids 2.05 4.02 Intermediate section Entrained air voids 1.63 Entrapped air voids 1.33 Total air voids 2.96 Innor end Entrained air voids 1.30 1.71 Entrapped air voids 0.68 1.65 Total air voids 1.98 3.36 Average Entrained air voids 1.37 1.70 Entrapped air voids 0.96 1.99 Total air voids 2.33 3.69 1/
Each result is based on 1,550 to 1,957 counts spread over 14.7 to 17.9 sq. in. of prepared surface.
STP. Con. St. Rpt. 8/15/80
EXHfBET E STUDY OF SON!C VAR!ATIONS The average standard deviations of pulse velocities ranged from 265 to 1631 for the five generic placements.
The average pulse velocities ranged from 12,693 to 15.096 which is considered a very good range for high quality concrete.
This is particularly significant because greater variations are expected in highly congested and thick reinforced s crete sections. Our calibration studies indicate that there will be a reduc-tion of about 50% of pulse velocities when an 18" void is encountered in a 4 foot wall with the same reduction for correspondingly reduced void size encountered in thinner walls.
Out studies of the generic areas did not indicate this type of void in any area.
The average standard deviations of pulse velocities for the concerned areas ranged from 269 (2 foot walls) to 1613 (3.5 foot walls).
The average pulse velocities ranged from 12,041 to 14,914 feet per second which is the very good range for high quality concrete. The same evaluation applies to the concerned areas as given for the generic placements above.
Voids were not found in any areas and all of the con-crete appears to be above average in proper consolidation and uniformity.
August 13, 1980 erse?
pn F. Artuso STP Con. St. Rpt. 8/15/80 l
EXHfBIT F i
COMPRESSIVE STRENGTH EVALUATION OF THE GENERIC PLACEMENTS (3)
Based on the standard deviations of correlated strength values and ACI Standard Recommended Practice for Evaluation of Strength Test Results of Concrete, the following analysis is developed:
COMPRESSIVE STANDARD REQUIRED 99% PROBABILITY PLACEMENT STRENGTH DEV.
V CORE STRENGTH OF EXCEEDING, CIl-W20 8300 149 1.8 3400 psi 7968 psi CIl-S14 7500 135 1.8 3400 psi 7200 psi CIl-SS5 6700 247 3.7 4675 psi 6164 psi Under the worst conditions, 99 oercent of the strength values will be greater than 7200 psi for the 4000 psi concrete design and greater than 6164 psi for the 5500 psi design.
This indicates an extraordinary quality since ACI 318 Evaluation of Concrete Strength allows the 99% probability for any single strength to be only 3500 psi for the 4000 psi concrete and 5000 psi for the 5500 psi concrete and allows acceptability when any three consecutive strength equal the 4000 psi to 5500 psi designs, as applicable.
Also, ACI 214 considers a rating of Excellent General Construction when the standard deviation is below 400 psi. The highest standard deviation detennined is 247 psi.
Auoici. 13, 1050 sepn F. Artuso STP Con. St. Rpt. 8/15/80
EXHIBIT G REBAR PLACEMENT EVALUATI0tl The magnetic device sensitivity enabled a relatively accurate deter -
mination for location of rebars only in placements which were not congested and where diagonal and other supplementary stirrups and dowel rebars are not encountered.
The two locations which met these conditions were the CIl-S14 slab and the CIl-W20F wall.
In both cases, it could be conservatively concluded that the outer rebars contained the minimum amount of steel spe:ified.
August 13, 1980 eM eph F. Artuso STP Con. St. Rpt. 8/15/80
EXHIBIT H STRENGTH CORRELATIONS OF CORE STRENGTHS VERSUS WINDSOR PROBE AND PULSE VELOCITIES Attached is the curve indicating relationships between actual strength of cores in compression and corresponding values of pulse velocities and Windsor Probes. Additional data is necessary for a more compre-hensive study, but there appears to be a reasonable correlation for pulse velocity versus compressive strength. However, the Windsor Probe capa-city has apparently been exceeded because of the high strength concrete.
A unifom projection of about 2.2 inch occurrs for a range of compressive strengths of 6500 to 9900 psi.
Therefore, no conclusions will be stated regarding the Windsor Probe detenninations since all concrete tested to date exceeded 6500 psi.
August 13, 1980 t'
M-frepn F. ' Artuso i
STP Con. St. Rot.
S/15/80 t
CORRELATION OF CORE COMPRESSIVE STRENGTHS g
TO PULSE VELOCITIES AND WINDSOR PROBES X = U.T.
0 = W.P.
000 '
I
,,000 ;
A 000 -
1,
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x
,000.$
=
a b
l 000!
3 I
l l
t e
000
- 2 000 t 5,000 6,000 7,000 8,000 9,000 10,000 11,000 12',000 COMPRESSIVE STRENGTH (ps1)
STP Con. St. Rpt.
8/15/80