ML20002B032
| ML20002B032 | |
| Person / Time | |
|---|---|
| Site: | Yellow Creek  |
| Issue date: | 12/01/1980 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, YC-C-80-03, NUDOCS 8012090369 | |
| Download: ML20002B032 (3) | |
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400 Chestnut Street Tower II December 1, 1980 Mr. James \\. O'Reilly, Director Office of I pection and Enforcement U.S. Nuclear gulatory Comission 3
Region II - Sui 3100 101 Marietta Str t Atlanta, Georgia 303 Dear Mr. O'Reilly YELLOW CREEK NUCLEAR PLANT UNITS 1 AND 2 - CONSTRUCTION QA AUDIT -
SIGNIFICANT LEFICIENCIES - YC-C-80 FINAL REPORT The subject deficiency was initially reported to NRC-0IE Inspector M. Thomas en April 21, 1980, in accordance with 10 CFR 50.55(e). Interim reports were submitted on May 21, July 9, August 20, and October 21, 1980.
Enclosed is our final report.
1 If you have any questions concerning this matter, please get in touch with D. L. Lambert at FTS 857-2581.
Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mills, Manager Nuclear Regulation and Safety Enclosure Mr. Victor Stello, Jr., Director (Enclosure)/
cc:
Office of Inspection and Enforcement U.S. Nuclear Regulatory Comission Washington, DC 20555 M!
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80120003(o?
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a ENCLOSURE YELLOW CREEK NUCLEAR PLANT UNITS 1 AND 2 CONSTRUCTION QA AUDIT - SIGNIFICANT DEFICIENCIES YC-C-80-03 10 CFR 50.55(e)
FINAL REPORT Description of Deficiency The following are Construction Quality Assurance audit deficiencies which are considered significant conditions adverse to quality.
1.
Sampling and Reduction of Sa=ple - The central =ixing plant was found not to have provisions for procuring aggregate samples directly from the scale discharge which are representative of the =aterial being batched as required by General Construction Specification No. G-2.
Therefore, the sa=ple is being obtained by opening the discharge gates aci catching soce of the discharged material in a shovel. This sa=pling method is contrary to ASTM D-75.
Also, ASTM C-702 establishes approx 13 ate =inimum mass of field samples, and requires that the field sa:ple be mixed and reduced by quartering. Nencompliance to these requiremente was also observed. This item has been designated NCR YC-064 2.
Oradation - Observatiens indicate that gradation, including weighing, is being perfer=ed in accordance with the require =ents of QCI C-204.
Review of ferm TVA 10141 - Sieve Analysis of Concrete Aggregates, and of form TVA 10249 - Screen Analysis of Aggregate Combination and Sieve Analysis of Aggregates, revealed that during the period February 19, 1980, through March 26, 1980, the 3/8" aggregate in the mixing plant storage bins was out of specified limits numerous ti=es.
This review and subsequent investigation revealed six areas of noncompliance with the CA program requirements. This item has been designated NCR YC-065.
3 Tests of Cylindrical Concrete Specimens - The auditors observed concrete test cylinder molding, curing, unit weight determination, verification of dia=eter and perpendicularity, capping, and compressive strength determination. With the exception of compressive strength determinatien perfor:ed on March 24, 1980, using equipment number TVA 43970, all observed activities appeared to be in accordance with the applicable portions of the QA program. On March 24, 1980, the load was applied to the cylinders in excess of the 20-50 psi /s limits, and no special note of the type of failure and the appearance of the concrete was taken. This item has been designated NCR YC-063 Safety Implications 1.
Although the sampling of the aggregate was in question, the aggregate gradation was tested and acceptable. The principal purpose of correct aggregate gradation is to secure a workable, economical mix. The final acceptance criteria for concrete is the compressive strength. The established program for testing compressive strength of all concrete ensures the final acceptability /rejectability. Thus no safety concern exists.
W 2.
Although gradation test results show some of ths gradations slightly coarse, the principal effect would be some harshness in the concrete mixes...The final acceptance criteria for concrete is the compressive strength. The established program for testing compressive strength of all concrete ensures the final acceptability /rejectability. Thus no safety concern exists.
3 The effect of the increased loading rate can be determined from the relationship below which was obtained from Concrete, Froxell and Davis.
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a = s) (1 + k log R) s = Strength at a given rate of loading (R psi per sec.)
g = Strength at a rate of 1 psi per second s
k =' Constant, approximately 0.08 for 28-day tests 73 = 1.149064 a
= 1.0115 i
3 1.13592 50 The strength obtained at a loading of 73 psi /see would be slightly l
more than one percent higher than that obtained at 50 psi /sec. A review of the strength tests cited revealed that no breaks were on the border line and a 1-percent error would not affect the acceptance of the concrete, and no safety concern exists.
Corrective Action 1.
QC-M&C e=ployees have been instructed to obtain the =aterial correctly.
A pan is being used to collect the full cross-section of the flow.
Sample size has been increased to the correct amount.
2.
QCI C-204 has been revised and now rtquires a retest to be performed before an aggregate combination. A retest is made and, if necessary, a mathematical combination computed to determine acceptability.
Unacceptable samples are handled individually on a QCIR and evaluated and dispositioned by the materials engineer.
I 3.
QC-M&C employees have been instructed in the new requirements. A sign reminding employees of the requirements has been attached to the test 4
equipment.
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