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VIRGINI A ELECTRIC AND POWER CCWP ANY, RICMMOND, VIRGINI A 23261

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January 17, 1980

Mr. James P. O'Reilly, Director Serial No. Il53AOffice of Inspection & Enforcement PSE&C/CES:VML: wangU. S. Nuclear Regulatory CommissionRegion II Docket Nos. 50-339101 Marietta Street, Suite 3100 50-404Atlanta, Georgia 30303 50-405

Dear Mr. O'Reilly:

On December 18, 1979, NRC Region II was notified under the provisions of10CFR50.55(e) concerning a significant breakdown in the Quality ControlProgram relative to verification of the calibration of the Forney CompressionTesting Machine. This notification was followed g a five day report onDecember 20, 1979 in accordance with reporting requirements of 10CFR21.

The report stated that it has been determined that the Forney CompressionTesting Machine has not been calibrated in the range from 0 to 25,000 lbs.(lower 10% of the total range of the machine). The machine has been used todetermine compressive strengths of grout cylinders (2 in. diameter), groutcubes (2 in, square), concrete core samples (3 in. diameter) and full sizeconcrete cylinders (6 in. diameter). The majority of the grout and concretecore samples broke in the 0 to 25,000 lb. range due to the smaller area towhich the compressive force was app 9 d. The concrete cylinders which brokein this range would be the 7-day breaks in the low strength (1,000 psi)backfill concrete. ASTM E4-72 provides a procedure for calibrating in thelower 10% range of the machine.

It was also stated in the report that the diameter of the suspendedspherically seated blocks used on the machine ior testing the various sizedsamples is larger than that specified in ASTM C39-72 and C109-73 for groutsamples. The diameter of the blocks used on the machine is 6 1/2 in. ASTMC39-72 specifies that the diameter of the upper spherically seated bearingblock shall not exceed 4 in for a 2 in. diameter test specimen. ASTM C109-73specifies that "The diagonal or diameter of the bearing surface shall be onlyslightly greater than the diagonal of the face of the 2 in. or 50 m cube inorder to f acilitate accurate centering of the specimen."

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Calibration runs on the Forney Compression Testing Machine in the loadtest range from 5,000 lbs. to 25,000 lbs. were performed by J. W. RichardsonCalibration Service, Chalfont, Pa. on January 9,1980. A copy of thecalibration report is included as Attachment "A" to this report. Thecalibration runs performed on that date indicated the following r a ts for Othe subject test load range: y\

1. The normal calibration run consistently demonstr ted that the machinegauge conservatively understates the actual load in the subject testload range.

Ib 80 0 2 36 o 625 8Q91. .. _ ,Omag egW

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2. A special calibration run, which permitted the red follower needle tobe pushed by the black load indicator needle (not the usualcalibration practice), demonstrated that the machine understates theactual load by an additional amount in the subject test range due tothe resistance of the follower needle.

3. The machine gauge error at 25,000 lbs. satiefies the requirements ofASTM E4-72 for accuracy but conservatively understates the actualload.

Engineering investigation of the subject of this report has revealed thefollowing additional facts:

1. Records of past calibrations show that the machine gauge has neverindicated an unconservative error at the low end of the previouslycalibrated load range. The low end of the previously calibrated loadrange corresponds to a value of 25,000 lbs.

2. The machine gauge has never been known to be significantly out ofcalibration while in use at North Anna Power Station and all theprevious calibrations were performed not subject to interaction ofthe red follower needle. These points of information have beenconfirmed by Mr. J. W. Richardson who personally performed all buttwo of these previous calibrations.

3. The lowest load of interest in the 0 to 25,000 lb. range is 9,000lbs. since this load corresponds approximately to that which isrequired to produce 3000 psi compressive stress on the 2 in. diametergrout cylinders. At that load, the machine gauge error recordedduring the January 9,1980 calibration is -2.5 divisions (-1250lbs.). When combined with the effect of the resistance of the

- follower needle, -1.0 division (-500 lbs.), the calibration.

corresponds to a conservative error of 19.4 percent.

From the above information presented in this report, it can be concludedwith a high level of confidence that the compression test results in the 0 to25,000 lb. range were conservative. To further reinforce this conclusion,consideration will be given to the remote event that the January 1980calibration runs would have indicated a gauge error measured in thenonconservative direction by the same magnitude, that is, +2.5 divisions(+1250 lbs.) at a 9000 lb. test load. Combining the constantly conservativeeffect of the resistance of the follower needle, -1.0 division (-500 lbs.),the net effect would result in a +1.5 division (+750 lb.) error,-or less than8.5 percent error. Grout which was accepted on the basis of compression testsof 2 in diameter cylinders, which could have included such an error had itpossibly existed, would still be acceptable if tested in place today due tothe additional strength gained by continuing cement hydration after the 28 daytest period.

Based on the above information, it is co. ' <jed that the lack ofdocumented calibration and the failure to sativ,y the accuracy requirements ofASTM E4-72 in the O to 25,000 lb. load range has had no detrimental effects oncompressive test reports recorded from the Forney Compression Testing Machine.

'927 217

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The incorrect use of the 61/2 in diameter block for smaller diametergrout cylinders and concrete core samples could not have produced a breakstrength higher than that produced by use of the specified proper equipment.The requirement for using a smaller diameter block recognizes the potentialfor eccentric load which may be introduced if a larger block is used. This isnot to infer that any error must have been introduced by use of a largerblock, but only that the net result of any such error would always beconservative resulting in a lower recorded compressive strength than may haveotherwise been indicated.

To assure that future tests are performed in accordance with thespecifications of ASTM C39-72 and C109-73, Construction Quality Control hasbeen instructed not to perform any further testing on the Forney CompressionTesting Machine in the O to 25,000 lb. load rance. A new compression testingmachine with a load range of 6,000 to 60,000 ;os. will be procured andinstalled prior to the restart of the concrete program at North Anna. Inorder to preclude a recurrence of this type the purchase order for thecalibration of the compression testing machines has been modified to specifythe exact load range calibration required for each machine. Additionally, thecalibration program checklists have been modified to verify the calibration ofeach machine within its load range of operation. Construction Quality Controland Stone & Webster Field Engineering are reviewing the ASTM requirements forthe concrete production and testing program to insure full compliance. Thisreview will be completed by February 15, 1980.

Since the lack of documented calibration and the use of improper equipmenthas had no detrimental effects on compressive test y eports, we anticipate nofurther correspondence on this subject. Therefore, this letter is consideredto be a final report and completes all reporting requirements under provisionsof 10CFR50.55(e) and/or 10CFR50.21.

/ / ~

Ve rul you ,,

.{[f^ o/

S C. Brown, Jr.Senior Vice resident-Powerpyation

Engine ring and Construction

Attachment

cc: Mr. Victor Stello, Director' ~'

Office of Inspection & Enforcement

Mr. Harold R. Denton, DirectorOffice of Nuclear Reactor Regulation

1927 218\

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