ML20030C508
| ML20030C508 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 07/09/1981 |
| From: | Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | Faulkenberry B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, ANPP-18369-BSK, NUDOCS 8108260181 | |
| Download: ML20030C508 (12) | |
Text
50.55(e) Report Docket Nos. 50-528/529/530 40D32'2KDi1A IFLUEEElKO QLTJIFULYil @@TEIIMDSST P, O. D O X 2166 6 PHOENIX, ARIZON A 85036 July 9, 1981 ANPP-18369-BSK/ JAR U. S. Nuclear Re.gulatory Commission b1 ts,
Region V g
[h> gg Walnut Creek Plaza - Suite 202
[(k N
d 1990 North California Boulevard Ti Walnut Creek, California 94596 Attention:
Mr. B. H. Faulkenberry, Chief d
j Reactor Construction and
^
Engineering Support Branch
Subject:
Final Report A 50.55(e) Reportable Condition Relating to a Concrete Void in Unit #2 Control Building Sump File:
81-019-026 D.4.33.2
Reference:
(1) Telephone Conversation between J. Eckhardt and B. S, Kaplan on November 25, 1980 (DER 80-37)
(2) Interim Report, ANPP-16957-BSK/ JAR, dated jN f'4 December 24, 1980 gs5 (3) Letter ANPP-17257-BSK/ JAR, dated February 24 SY y
3 1981
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(4) Interim Report, ANPP-17758-BSK/ JAR, dated n 3 #8.od S s --
April 10, 1981
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Dear Sir:
Attached, is our final written report of the reportable deficiency i
under 10CFR50.55(e) referenced above.
Very truly yours I
CLll
/ILLL I
E. E. Van Brunt, Jr.
APS Vice President j
Nuclear Projects ANPP Project Director EEVBJr/BSK:ske
&Y Attachment y
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1Hl1
U. S. Wuclear Regulatory Commission Attention:
Mr. B. H. Faulkenberry, Chief ANPP-18369-BSK/ JAR July 9, 1981 Page 2 cc: Victor Stello, Jr., Director Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, D. C.
20555 A. C. Gehr Snell & Wilmer i
R. L. Robb D. B. Fasnacht W. E. Ide A. C. Rogers J. M. Allen J. A. Brand W. H. Wilson W. G. Bingham W. J. Stubblefield R. L. Patterson R. W. Welcher D. R. Hawkinson Bruce Myerson, Esq.
Arizona Center for Law in the Public Interest 112 North Fifth Avenue Phoenix, Arizona 85003 Ms. Patricia Lee Hourihan 6413 South 26th Street Phoenix, Arizona 85040 l
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FINAL REPORT REPORTABLE DEFICIENCY 50.55(e)
ARIZONA PUBLIC SERVICE COMPANY (APS)
PVNGS UNIT NO. 2 1
I.
Description of Deficiency In Unit #2 Control Building basemat, northwest corner, approximately 16' east of Column Line JA and 11' south of Column Line J1, a void was found around a sump, designated as Sump No. 1 on Enclosure 1.
The void was discovered because it retained water when the sump was filled and released water when the sump was emptied. A plan of the approximate void found from core holes is shown on the sketch attached to Enclosure 2.
The grout-ing operation employed to correct the condition indicated that the void volume was approximately six (6) cubic yards.
4 Twenty-three (23) core holes were drilled around the sump.
Some of the core holes cut rebars in the basemat which were documented on FCR #18921-C. The basemat was reanalyzed to account for the cut rebars, and it has been verified that the structural integrity was not jeopardized.
The void around Sump No. 1 is attributed, in part, to the configuration of the reinforcing steel which allowed con-crete to bridge across the very dense reinforcing steel and resulted in lack of proper consolidation of the concrete.
The subject void was not found and corrected during inspec-tion and acceptance of the concrete placement because the defect was not apparent from the surface condition of the sump face.
i To demonstrate that this void is an isolated condition, I
three (3) core holes were drilled around another sump approximately 75' to the east of the same base slab (see, Sump No. 2).
The results indicated solid concrete existed in this location. A review of the corre-spondingaplacement criteria for Units #1 and #3 provides i
assurance that this condition does not exist on either Unit #1 or #3 as follows:
a.
The base slab and bottom of sump were poured in two i
separate placements on Unit #1.
b.
For Unit #3, rebar was spaced both ways to provide pour at 4' on centers. This allowed for easier vibrator access as well as allowing freer movement of concrete through the rebar.
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Final Report Page 2 11.
Analysis of Safety This condition is considered to be reportable since, if left unrepaired, the basemat may not have been struc-l turally adequate to. serve its safety-related function, j
In addition, there existed a possibility for corrosive liquids to leak into the basemat.
i i
III. Corrective Action 1
l Bechtel engaged a grouting consultant, John C. King, to I
develop a procedure in conjunction with Bechtel personnel l
for grouting the subject void. This procedure is attached as Enclosure 2.
Mr. King recommended a specific grout material, reviewed Bechtel's equipment and suggested i
methods to inspect the void.
Af ter preparation of the draf t procedure, a meeting was held with NRC representatives at the PVNGS jobsite on April 29, 1981, to discuss the subject void. The meeting i
was dccumented in ANPP Conference Notes CN-E-850 which is l
attached as Enclosure 3.
Later, after additional explora-l tion cores, a final procedure was issued and the void was filled with grout. This grouting operation was witnessed i
by the NRC's Resident Inspector, the Bechtel consultant, and the appropriate Bechtel Construction and APS personnel.
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u E nc Los u RE 2 7.ATERIALS, EQUIPMENT, AND PROCEDL*RES FOR GROUTING UNIT 2 CONTROL BUILDING BASEMAT VOIDS by John C. King, PE 101 East 252nd St.
Cleveland, Ohio 44132 (261)-731-0977 for BECHTEL POWER CORPORATION P. O. BOX 49 Palo Verde, Arizona 85343 1
DATE: June 11, 1981 Rev.: 1 (6-11-81)
Rev.:
2 (6-12-81) s
HATERZALS. EQUIPMENT. AND PROCEDURES FOR GROUTXNG UNIT 2 CONTROL BUILDING BASEMAT VOIDS MATERI ALS : IN-PAKT Construction Grout manufactured by Concrete Chemicals Company, Cleveland, Ohio.
MIX: Grout for the contained voids shall be mixed with sufficient water to attain a fluid consistence of 24 t 3 sec. flow cone, CRD-C 79.
MIXER: ChemGrout, double tub, vertical shaft mixer or approved equol.
PUMP: Moyno air driven.
PREPARATION FOR GROUTING: Interconnection of holes shall be determined by water pressure testing. Mapping shall indicate any connections.
Flush voids with air and water in combination to remove as much laitance and other loose material as possible into sump.
When voids are as clean as practical, erect venting forms over the openings in the sump as indicated on the sketch. A venting form may be made from 1/2 in, or thicker plywood through which 1/4 in, holes have been drilled at 6 inch centers.
Place expan 'ed metal lath against the wood, then wire screening (1/16 to 1/4 in mesh), and finally cloth.
Erect by placing cloth against the opening to be formed.
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a.PROCEDURE: As grout is discharged from tha mixar, it shall pass through
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a 1/4 or 3/8 inch screen placed over the pump hopper.
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Grouting shall follow the sequential numbering of core holes shown on Sketch 1 unless otherwise directed by John King, Consulting Engineer.
Grouting.
Begin grouting using the IN-PAKT Grout mix.
Connections shall be made to the holes using a grout packer inserted to sufficient depth to effect a tight connection. When grout flows from holes not yet grouted, these holes shall be plugged at a point below higher voids. The plug shall be removed and grout pumped into the hole, if in the opinion of the Grouting Consultant, it is necersary. Pumping shall continue until the void is full and the pump pressure rises to 10 psi. Stop punping and observe i
gage.
If pressure drops rapidly, in the opinion of the Grouting Consultant, resume grouting and report pressure observation.
Repeat for a maximum of 5 cycles, if necessary.
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Core holes found solid and any recerses lef t on removal of packers shall be grouted with IN-PAKT grout from the bottom up to flush with the floor. Recesses lef t by removal of plugs af ter the grout has stiffened shall be damp-packed flush with the floor.
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6 M c L O S U R E.
d B:chtel Job 10407 Date: May 12, 1981 i
File:
C.21 ANPP CONFERENCE NOTES NO. CN-E-850 DATE OF MEETING:
April 29, 1981 LOCATION:
PVNGS Jobsite ATTENDEES:
ANPP Bechtel N3s D. Wittas J. Black J. Eckhardt W. Ide S. Jain J. Burdoin P. Houseknecht D. Haavik J. Roedel J. King *
- k. Kic=el
- Consultant engaged by Bechtel.
SUBJECT:
Unit 2 Control Building nase Slab Voids FURPOSE: To discuss areas of concern and method to repair the voids In the meeting, the cause for the voids, extent of voids, cutting of rebars, and repair of voids were discussed and specific questions rais.d by NRC vere answered as noted below.
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QUESTION 1: What is the confidence level of Bechtel that there are no more voids in the subj?ct base slab?
ANSWER: Bechtel replied that at selected spacings, core holes were made to define the extent of voids at the present location. In addition, a similar area was selected around the sump on the east part of the same base slab and where three core holes were made which indicated solid concrete. Therefore, it is our belief that there are no other voids in the base slab except for the voids referenced j
in NCF C-J-2315 The cause of these voids is attributed to congestion of rebars and improper placement of concrete.
QUESTION 2: What 'is the density of rebars in this area?
ANSWER: There is apprcximately 700-800 lbs of rebar/cu.yd of concrete.
QUESTION 3: What about the possibility of voids in the Unit 1 Control Building base slab?
ANSWER: In Unit 1, the base slab and bottom of sump were placed in two separate placements thus assuring proper placement whereas in Unit 2, tha base slab and bottom of sump were placed in one Around the su=p in the northwest corner of base slab placement.
the concrete was not vibrated properly, thus creating the void.
In Unit 3, rebars were placed in a manner such that at every 4 feet a pour pocket was made for concrete placement and vibrator t
.ess to aid in the placement of the concrete.
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ANPP Confersnce Notes No. CN-E-850 Bzchtel Job 10407 Muy 12, 1981 Page 2 QUESTION 4: What are the rebar sizes and their spacing in base slab?
ANSWER: The engineering drawings were discussed indicating rebar sizes and their spacings. Copies of the engineering drawings and placement records for Unit 1 and Unit 2 control buildings were requested by Jim Eckhardt of NRC and the following documents were given to him the next day:
Dwg. 13-C-ZJS-100 (Rev. 12), Dwg. 13-C-ZJS-106 (Rev. 7), and placement records for Unit 1 and 2 Control Building base slab.
QUESTION 5: Discuss how these voids will be repaired.
ANSWER: Pechtel stated that a consultant, John C. King, who has an extensive ar.ount of experience in grouting, including recent experience in grauting on the South Texas Project, has been engaged to develop a procedure for grouting for this application.
It was also mentioned that we de not anticipate that the voids will be repaired by 100% but following Mr. King's procedure we anticipats about 95% of the voids will be grouted. Engineering calculations have been performed to indicate that this is acceptable.
QUESTION 6: Will eny additional holes be drilled?
ANSWER:
Yes, additional holes will be drilled for adequate pu= ping of the grout and venting purposes.
QUESTION 7:
Have you documented all the rebars which were cut due to core drilling and how does that effect design of base slab?
ANSWER: The rebars which were cut are documented on as-built FCR's.
The calculations have been made with these cut rebars and are part of the calculation package to indicate that the integrity of the base slab is not jeopardized.
QUESTION 8: How was the void determined?
ANSWER: During off working hout s a temporary water service line broke which filled the sump with water. When the water in the sump was pumped out, it was noticed that the water was seeping out from the walls of It was then decided to chip the concrete from the face of the su=p.
the sump to investigate the reason for seepage, which revealed the voids.
What was the reason for a separate void on the top of the base QUESTION 9:
slab just below the bottom of the tcp rebars?
ANSWER:
It is assumed that the craf tsman did not properly vibrate concrete in this area.
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B2chtel Job 10407 May 12, 1981 Page 3 QUESTION 10: How do you feel about the water seal between existing concrete and the grout that will be used to repair the void?
ANSWER: The repair procedure vill address this problem to provide in-place concrete which vill become nonolithic with the grout. The seal should be better near the surface of the sump due to the pressurized method of grout inj ection.
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Recorded by:
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S. K. Jain Reviewed by:
o, WI G. lin'ghW '
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