IR 05000413/1984015

Insp Repts 50-413/84-15 & 50-414/84-11 on 840201-02.No Violation or Deviation Noted.Major Areas Inspected: Structural Concrete

ML20129K274
Person / Time
Site:	Catawba
Issue date:	03/16/1984
From:	Conlon T, Harris J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:
Shared Package
ML20129K242	List: IR 05000413/1984007 IR 05000413/1984015 IR 05000413/1984030
References
50-413-84-15, 50-414-84-11, NUDOCS 8507230541
Download: ML20129K274 (4)

Text

EriCLOSURE 3

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Report Nos.: 50-413/84-15 and 50-414/84-11 Licensee: Duke Power Company 422 South Church Street Charlotte, NC 28242 Docket Nos.: 50-413 and 50-414 License Nos.: CPPR-116 and CPPR-117 Facility Name: Catawba Inspection at Catawba site near Rock Hill, South Carolina Inspec ga ~

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Signed Approved . #m F-/F FY T. E. Conlon, Section Chief Date Signed Engineering Program Branch Division of Engineering and Operational Programs SUMMARY Inspection on February 1 - 2, 1984 Areas Inspected This special, unannounced inspection involved 14 inspector-hours on site in the area of structural concret Results Of the one area inspected, no violation or deviation was identifie I I

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r Enclosure 3

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REPORT DETAILS Persons Contacted Licensee Employees

• L. R. Barnes, Planning and Control Manager J. Warren, QC Engineer, Civil R. McCrary, Civil Engineer Construction M. Green, Civil Engineer, Design L. Hodges, Civil Engineer, Construction C. Arnold, Civil Engineer, Construction H. Nekooasl, Junior Field Engineer

• Attended exit interview Exit Interview The inspection scope and findings were summarized on February 2,1984, with those persons indicated in paragraph 1 abov . Licensee Action on Previous Enforcement Matters (0 pen) Unresolved Item (413, 414/80-33-01) Identification of Concrete Honeycom Licensee provisions for identifying and tracking repair of honeycomb that occurred prior to 1979 are not clea Discussions with responsible engineers indicated that the licensee is doing a 100 percent reinspection of concrete surfaces in Unit 1 and Unit Reinspection of Unit 1 is schedu?ed for completion by March 1,1984, and Unit 2 reinspection ;

is expected to be completed by April 198 During this intpection the inspector examined the nonconformance log and final concrete inspection logs for pour numbers 2532, 2741, 2978, 2972, 3013 and 206 Examination of these records showed that honeycomb is now being identified and repaired in accordance with procedures and specification The inspector also examined a memo by I. W. Pearce of Duke design engineering concerning review of nonconforming item reports on honeycomb occurring at the Catawba site from May 1977 to October 1980. The memo discussed the probable causes of honeycomb and suggested measures which could be taken to minimize honeycomb. Suggestions included: vibration of rebar where vibrators could not reach the concrete, use of small diameter .

vibrators (pencil vibrators), use of form vibrators and use of special mixes !

incorporating a puper plasticizing admixtur i Because of a concern raised in the Catawba licensing hearings that honeycomb might occur internally and not be visible at the surface, the inspector discussed the cause and occurrence of honeycomb with the U. S. Army Corps of l

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Enclosure 3

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f Engineers Waterways Experiment Station in Vicksburg, Mississippi and the Portland Cement Association in Skokie, Illinoi Discussions confirmed this inspector's observations that the probability of honeycomb occurring internally without any surface manifestation is highly unlikel Experience has shown that the reinforcing steel located near the outer faces of the structures interferes with the flow of the plastic concrete and causes a separation of mortar and coarse aggregate. Inadequate vibration in the area adjacent to the reinforcing steel sometimes results in honeycomb occurring in the space between the reinforcing steel and concrete surfac Discus-sions with the U. S. Army Corps of Engineers Watemays Experiment Station concrete technologists also indicated that numerous concrete cores taken by them from concrete structures have not shown any honeycomb. The only type of voids identified were occasional small air holes commonly referred to as bug holes. Discussions with Portland Cement Association concrete technolo-gists and a NRC Region III civil inspector indicated that nondestructive tests were performed on concrete structures at the Marble Hill Nuclear Plant to determine if any internal honeycomb was presen Numerous surface honeycomb areas were present but testing showed no internal honeycom Based on the experience of this inspector and observations and testing done by the above referenced testing laboratories and NRC experience at the liarble Hill site, the inspector concluded that the presence of any significant internal honeycomb in the Catawba structures is highly unlikel Some minor air holes or bug holes resulting from entrapped air may be presen It is not considered that the presence of scattered air holes or bug holes would have any effect on the integrity of the structure This unresolved item remains open pending NRC's review of the licensees final inspection report on honeyccmb at Catawba Unit . Unresolved Items Unresolved items were not identified during this inspectio . Bulging of Concrete Forms in Decontamination Pit CONCERN Concern was expressed indicating that improper bracing of forms caused the forms to sag three inches during a concrete placement in the decontamination pit. The three inch sag in the forms resulted in a three inch bulge in the hardened concrete wal DISCUSSION The decontamination pit is not necessary for the safe operation or safe shutdown of the plant. The decontamination pit is located in the spent fuel building and is used to wash radioactive contamination from the exterior of casks containing spent fuel prior to loading of the casks on a truck for shipment to a waste storage area. The pit consists

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Enclosure 3

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L of reinforced concrete walls lined with stainless steel. The stainless steel liner serves as a leak proof barrier to conta'a the contaminated water resulting from the cleaning proces Following cleaning, the contaminated water is drained and processed to waste storage. The main purpose of the concrete walls is to support the stainless steel line ' Any bulge in the concrete walls resulting from a bulge in the concrete forms would not have any affect on the structural integrity of the concrete walls. The effect of the bulge in the wall would only be that the stainless steel liner could not be installed until the bulge was remove The inspector examined the decontamination pit and discussed the placement of the concrete walls with responsible construction and design engineers. Discussions disclosed that the forms did break loose during placement of the lower walls and a 2 to 3 inch bulge was caused in a four foot square area of an inner wall. The resulting bulge was chipped away to the lines shown on the drawings so that the steel liner could be installed. Observations by this inspector confirmed that .the wall dimensions were restored to the dimensions shown on the drawing and that the steel liner was also installed as shown by the drawing FINDINGS - The forms did break loose during placement of walls in the decontamination pit and a 2 to 3 inch bulge occurred in the hardened concrete of an inner wall of the decontamination pi However, the buckling of the forms and resulting bulge in the hardened concrete did not affect the strrctural integrity of the concrete wal The main effect was the additional cost required to remove the bulge in order to allow placement of the steel liner. Concrete formwork is not nuclear safety-related. Failure from improperly braced forms results in aesthetially unacceptable appearances or results in expensive repairs to remove the bulg !

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