ML19262C622

Third Interim Rept Concerning Improper Anchor Bolt Matl. Caused by Failure of Const Quality Procedures to Require QC Personnel to Verify Correctness of Info on Matl Requisitions.Stop Work Order Issued to Change Procedures

ML19262C622
Person / Time
Site:	South Texas
Issue date:	12/31/1979
From:	HOUSTON LIGHTING & POWER CO.
To:
Shared Package
ML19262C620	List: ML19262C619 ML19262C622
References
NUDOCS 8002140734
Download: ML19262C622 (9)

Text

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FIELD FABRICATED ANCHOR BOLT IMPROPER MATERIAL DEFICIENCY It!TERIM REPORT I.

SUMMARY

A. Synopsis of the Incident On February 8,1979, HL&P notifed the NRC of a potentially report-able deficiency under 10CFR50.55(e). This deficiency concerned the installation of anchor bolts manufactured from improper materials.

Written reports were forwarded to the NRC on March 8,1979 and June 5,1979. This constitutes the third interim report of the improper material deficiency relative to the field-fabricated anchor bolts.

The discovery of the use of improper material was made during a pull test on a B&R manufactured anchor bolt. The purpose of this test was to confirm that the anchor bolt would fail prior to the plate attachment. The plate, however, failed before the bolt, but at a stress much higher than the yield strength of the ASTM A36 bolt material. A subsequent investigation of the bolt material re-vealed that a mix-up had occurred in the bar stock material used to fabricate some of the anchor bolts et the South Texas Project site. Some of the anchor bolts manufactured from improper rod stock material are installed in various safety related applications in the Reactor Containment Building, Mechanical-Electrical Auxi-11ary Building and the Fuel Handling Building.

B. Postulated Cause of Incident The deficiency was caused by the failure of Construction Quality Procedures to adequately require Quality Control personnel to verify the correctness of all information on material requisitions.

As a result, material other than specified was released for in-s tallation.

C. Synopsis of Corrective Action The immediate response by Quality Assurance to this incident was to issue a stop work notice to prevent further use of site manu-factured bolts until the deficiency could be corrected. The con-struction procedure governing storege of materials was revised to provide for additional marking of the received material. Also, all site manufactured bolts and rod material were subjected to a hardness test program to verify material type for all material received through September,1979. For material received since September,1979, the certified material test reports have been

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verified and the material has been permanently marked. To assure these corrective action measures are properly implemented, a resi-dent lead Quality Assurance inspector has been assigned on a full-term basis to the fabrication shop to supervise all operations.

Finally, a training program has been instituted to instruct site personnel in the proper procedure for identification of storage and traceability of bulk materials received.

D. Synopsis of the Results of the Safety Evaluation As the result of the fielu test and inspection program, non-con-forming anchor bolts were found in safety-related applications.

In most cases, ASTM A-193 Gr B7 bolts were found installed in lieu of the specifiec ASTM A-36 Grade. Because the ASTM A193 Gr B7 bolts are of a higher strength than the A-36 bolts, substitution of the higher strength material is considered acceptable. In other locations, however, the installed bolts are of a lesser grade material than originally required. In one case, Reactor Coolant System (RCS) hot and cold leg pipe support brackets, anchor bolt torque requirements were re-evaluated by Westinghouse and the lesser grade bolts were found to be acceptable. The re-maining locations are currently being evaluated by Brown & Root Design Engineering. If the installed anchor bolts are not found to be acceptable, they will be replaced with ASTM A-193 Gr B7 bolts or additional design measures will be taken to meet the correct load requirements.

II. DESCRIPTION OF INCIDENT A. Component Identification A large quantity of anchor bolts were manufactured at the South Texas Site by Brown & Root to offset an inadequate supply of vendor manufactured anchor bolts. The primary function of these elements

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is to secure structural steel members or machinery bases to their concrete foundations. Anchor bolts classified as Type I, II, III, IV, and V conform to ASTM A36 material. Classification Type VI conforms to ASTM A193.Gr B7 material. A sketch of the Type I thru VI bolts is shown in Figures 1 through 3. The bolt config-uration is designed based upon the loading, tensile stress area, and the yield strength of the bolt. A design allowable strength of 22 ksi was used for ASTM A36 bolts and 48 ski was used for ASTM A193 Gr B7 bolts. These design allowable strengths contain a considerable safety margin since the minimum yield strengths are 36 ksi and 115 ksi for the A36 and A193 material, respectively.

B. Source of the Incident The incident was discovered during an anchor bolt pull test on a B&R manufactured anchor bolt. The purpose of this test was to confirm that the bolt would fail before the plate. The plate, however, failed before, but at a stress much higher than the yield strength of the ASTM A36 bolt material. Investigation revealed that the bolt material was ASTM A193 steel instead :,i the ASTM A36 material that was specified for the bolt. A subsequent in-vestigation revealed that a mix-up had occurred in the bar stock material that was used to manufacture the bolts.

C. Date and Means by Which Incident Information was Obtained -

On February 1,1979, Quality Assurance was notified of the results of the pull test which indicated that material had been mixed. On February 8,1979, HL&P notified the NRC of a reportable deficiency under 10CFR50.55(e).

D. Unusual Circumstances Fabrication of anchor bolts at the STP site was not anticipated or intended for the Project. Original plans called for all anchor bolts to be furnished by vendors contracted for furnishing fabri-cated iron and steel. Production delays at several fabricators' facilities resulted in an inadequate supply of anchor bolts being shipped to the job site. In order to maintain job schedules, it was decided that site fabrication was the only viable alternative in obtaining anchor bolts.

E. Status of Construction at Time of Incident At the time of the incident, approximately 7,000 anchor bolts of various sizes and configurations had been manufactured at the STP job site. Of these, approximately 50% were installed in concrete.

The remainder of the bolts were located in the storage yard.

F. Procedures in Effect to Avoid Incident at Time of Incident The procedures in effect at the time of the incident required material verification by heat number at the receipt of the ship-ment and the assignment of a heat code to the material. Material identification from that time fonvard was maintained through fabrication by the heat code assigned. The verification of issued equipment consisted of a verification of the heat code transfer to the requisition to provide traceability throughout fabrication.

III. CORRECTIVE ACTION A. Immediate Response by Quality Assurance to the Incident Site Quality Assurance issued a non-conformance report on February 1, 1979 to reflect the results of a documentation review concerning rod stock material used in the manufacture of anchor bolts. As a 3

result of further investigations, Site Quality Assurance issued a stop work notice on the fabrication of anchor bolts at the job site.

B, Description of All Imediate Actions Taken to Correct the Deficiency Quality Assurance requested and obtained a revision to the Con-struction Procedure governing storage of materials to provide for additional marking of the received material. This additional marking was in the form of color coding and permanent marking of all Category I material. In addition, the revision to the pro-cedure required Quality Control to verify the heat codes of the material to the certified material test report for all material received.

C. Long Range Actions Taken to Correct the Deficiency The initial extent of this deficiency was determined by a review of the documentation associated with the rod stock used for site manu-factured anchor balts. The material heat numbers were taken from the warehouse requisitions and compared with the certified material test reports to determine if a mix-up had occurred.

After discovering the inconsistencies in the identification of anchor bolt material, a decision was made that all installed and uninstalled site manufactured bolts would be subjected to surface hardness testing as a means of verifying material type. A three phase program was initiated which consisted of (1) identification of all work orders issued for site manufactured anchor bolts, (2) the location of the bolts and determination of material type using a telebrinnell portable hardness kit, and (3) reporting of the results for engineering design evaluation.

The basic points of the field testing program included (1) the testing and verification of all material using the portable tele-brinnell hardness testing kit, (2) the verification and QC wit-nessing of the measurements taken by Construction Engineering, (3) the verification of the material type against the requirements of the design drawings, and (4) the identification of non-con-forming conditions. Field measurements were taken and independ-ently verified by Site Quality Control. The data forms, following verification by Quality Control, were submitted for engineering evaluation. A sample data form is shown in Figure 4.

The initial step in the hardness testing program was to inspect and test those bolts which had been fabricated and not yet in-stalled (approximately 3500). All field fabricated anchor bolts located in the miscellaneous steel laydown area were tested and documented. Approximately 460 non-conforming anchor bolts were found and Nonconformance Reports were issued. All of the bolts identified on these nonconformance reports were scrapped with the exception of 103 bolts, which were A193 material used in lieu of A36 material for Type V anchor bolts. A decision was made to use these colts in their intended location as the A193 material provides i higher strength than the original design requirements.

Once the colts in the storage yard were checked and verified, field personnel proceeded to locate and test the remaining field fabri-cated bolts installed in concrete (approximately 3900). Top priority was given to bolts needed for concrete pours. These items were tested, reviewed, and accepted (or rejected) by Construction Engineering and Quality Control personnel prior to pouring of concrete. Inspection data sheets were submitted for engineering review and final dispositioning.

Approximately 150 non-conforming anchor bolts were found in the Reactor Containment Building, Mechanical-Electrical Auxiliary Build-ing and Fuel Handling Building. In the Mechanical-Electrical Auxi-liary Building, higher strength A193 material was used in lieu of A36 material. In the other locations, the material installed was of a lesser grade than that required by the design drawings. The use of A36 material in these locations is presently being analyzed by Brown & Root Engineering.

The remaining items to be verified at the job site consisted of bulk material rod stock that may be used in future fabrication of anchor bol ts . All rod stock received prior to October 1,1979 has been hardness tested, bterial received after the date has been veri-fied against certified material test reports, marked with heat codes by QC Receiving, color coded, and segregated by safety classi-fication and material type in the storage yard. All bulk material has been properly identified and is in compliance with specifica-tions and procedures. The inspection data sheets for all bulk rod material have been submitted for final engineering review and dis-positioning.

All rod stock material and fabricated anchor bolts have been tested at the job site with the exception of pieces that are inaccessible.

There are approximately 400 bolts, both safety and non-safety re-lated, which are inaccessible at this time due to equipment place-ment, form work, etc. Testing will be accomplished as each area is made accessible.

Approximately 12,000 pieces of material b' c t- been tested at the South Texas job site. These figures ic.# alt safety related and non-safety related rod stock anf rw w oolt material.

IV. RECURRENCE CONTROL In order to preclude recurrence of this deficiency, five actions have been taken. These actions are:

A. Inspection Quality Assurance has assigned a resident lead inspector to the fabrication shop for supervision of all operations.

B. Material Identification Procedures have been instituted to require permanently stanying of the heat code on all Category I materials.

C. Verification Quality Control is required by procedures to verify all material heat code numbers identified in the heat code log back to the certified material test reports contained in the Quality Assurance

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va u i ts .

D. Receiving Inspection Procedural revisions have been incorporated to provide a systematic program for the identification and marking of material upon receipt at the job site prior to releasing for storage or fabrication.

E. Training Program A training program has been initiated in which site personnel are instructed in the proper procedure for identification, storage, and traceability of bulk materials received at the job site.

V. SAFETY ANALYSIS A. Niture of the Incident Anchor bolts manufactured from improper bar stock material are in-stalled in various safety-related applications in the Reactor Con-tainment Building, Mechanical-Electrical Auxiliary Building, and the Fuel Handling Juilding. The failure of specific anchor bolts could, under certain conditions, create a safety hazard.

B. Results of Investigations In seven locations, material has been installed that is of a lesser grade than required by the design drawings. In all other non-con-forming conditions, ASTM A193 Gr B7 material was installed in lieu of the ASTM A36 material specified on the design drawings. The substitution of the higher strength A193 B7 material for the A36 material is considered satisfactory in all cases for Type V anchor bol ts . In two locat'ons, ASTM A193 B7 material was used to fab-ricate Type II anchor bolts and is n>t considered satisfactory.

An evaluation is underway by Brown & Root Design Engineering to determine the significance of the cases in which improper substi-tution has been made. If the rese'ts of this evaluation are un-acceptable, the anchor bolts will , <eplaced or additional design measures taken to meet or exceed existing load requirements.

An extensive safety analysis will not be accomplished. All installed anchor bolts have been tested and identified and meet or exceed the design requirements, with the exception of the locations previously identified and presently undergoing evaluation.

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