ML18003A654

Interim Rept Re Deficiencies in Procurement,Fabrication & Insp of Engineered Plates for Concrete Embedment & Support of safety-related Loads.Caused by Misinterpretation of Design Documents by Site & Vendor Personnel

ML18003A654
Person / Time
Site:	Harris
Issue date:	09/04/1979
From:	CAROLINA POWER & LIGHT CO.
To:
Shared Package
ML18003A653	List: ML18003A652 ML18003A654
References
NUDOCS 7909190433
Download: ML18003A654 (5)

Text

CAROLINA POWER & LIGHT COMPANY SHEARON HARRIS NUCLEAR POWER PLANT UNIT NOS ~ 1 y 2p 2p 4 DEFICIENCIES IN THE PROCUREMENT, FABRICATION AND INSPECTION PROCESS ASSOCIATED WITH ENGINEERED PLATES FOR CONCRETE EMBEDMENT AND SUPPORT OF SAFETY RELATED LOADS INTERIM REPORT SEPTEMBER 4, 1979 REPORTABLE UNDER 10CFR50.55(e)

PREPARED BY: CAROLINA POWER & LIGHT COMPANY

INTRODUCTION Engineered plates are detailed on design drawings which specify dimensions, materials and weld symbols. The associated structural steel specification covers general requirements including welding inspections and documentation submittals. These plates usually consist of plate with threaded bar stock welded to the plate and anchor plates connected to the threaded bar stock ends with nuts. Plate anchor bolts are embedded in concrete with the plate flush with the concrete surface for attachment of structural members asso-ciated with pipe hangers, equipment, structural steel or any other item with a design load greater than allowed on standard strip plates utilizing concrete anchor studs. These plates are field procured items DESCRIPTION On or about July 6, 1979, during the repair of a damaged engineered plate, it was discovered that the anchor bolts were welded with a fillet weld rather than a full penetration weld with a reinforcing fillet weld as required by the weld symbol on the design drawing. The resulting investiga-tion revealed that all of the 238 engineered plates received from the same fabricator on four (4) purchase orders were welded with fillet welds of the size specified for reinforcing welds. The investigation also identified missing documentation associated with fabrication and nondestructive examination (NDE) ~

The findings of the above investigation prompted an investigation of field procured items requiring welding. This investigation revealed missing documentation associated with fabrication and nondestructive testing of engineered plates from two (2) additional fabricators Plates were fabri-cated (welded) in accordance with design re'quirements but in many cases nondestructive testing was not accomplished or not documented. Approxi-mately 130 engineered plates from these two (2) additional fabricators were missing some documentation Of the required NDE.

SAFETY IMPLICATIONS Engineered plates were not fabricated and/or tested in accordance with design requirements. Engineering evaluation of 46 plates installed prior to problem being identified is in progress (refer to PW-C-789, PW-C-866, PW-C-867 and PW-C-869). At this time it has been determined that a fillet weld of proper size will develop the full strength of the associated anchor bolts but the detailed analysis of assigned design loads as compared to "as built" condition continues.

Three (3) engineered plates identified on PW-C-789 have been analyzed by Ebasco. One (1) plate is satisfactory and two (2) are overstressed rela-tive to the allowable design stress. In the worst case one plate was overstressed 17X from that allowed by the applicable standard review plan.

The standard review plan requires a cross section l. 6 times the normal section calculated from A.I.S AC. The normal code calculation utilizes approximately .6 of the yield strength for tension and .45 of the yield

strength for shear. The standard review plan provides approximately 300X safety margin relative to the material yield strength. The 17X overstress is an encroachment into this required design safety margin.

Destructive tests were conducted in a tensile test machine to sample a typical plate fabricated with fillet welds Test results are documented in PW-C-789 and have been forwarded to the A/E for evaluation.

Design calculations by Ebasco allow additional design safety margin to pro-vide a tolerance of +2" in the load attachment point. Refer to CAR-2168-

'G-6091. Analysis shows that the plates discussed above will not be over stressed relative to allowable if this tolerance is not usedo CORRECTIVE ACTION The cause of the problem is due to misinterpretation and misapplication of design documents by both site and vendor personnel.

Each engineered plate installed prior to problem detection has been identified and is being evaluated relative to design requirements The required correc-tive action will be taken on an individual plate basis Engineered plates not installed prior to problem detection were placed on QA hold. As a secondary check to the QA hold, special interim procedures were implemented with the concrete placement activities to ensure individual engineered plates were in accordance with design requirements. - These interim procedures require the field construction inspectors to identify each engineered plate and obtain written confirmation from QA that documentation, NDT, and/or repair work is complete.

Site inspection and field procurement personnel were made aware of the problem. Training on weld symbol identification and weld inspection was conducted.

Site specifications utilized to procure fabrication steel have been reviewed in detail and changes were initiated to ensure fabricators and inspectors could readily ascertain welding and NDE requirements.

Fabricators working on site structural steel orders were individually con-tacted to ensure specifications were understood and change orders were issued where necessary to clearly define requirements.

Site personnel associated with procurement or inspection have been instructed to ensure that vendor requests or questions are properly documented and processed through purchasing to site engineering in accordance with standard procedures. Site personnel have been cautioned to use standard project pro-cedures (RCI) for requesting clarification of design requirements on an individual basis.

Ebasco has reviewed engineered plate details associated with identification nomenclature and welding symbols and initiated changes where required to minimize any confusion that may have existed.

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Ebasco has provided an alternate fillet weld design to repair existing fabricated plates. This detail requires increasing the fillet weld size to develop the full strength of the associated anchor bolt.

DETAILED REFERENCES The following detailed references are on file at the project site:

(1) PW-C-866, 8/23/79 (2) PW-C-867, 8/23/79 (3) PW-C-868, 8/23/79 (4) PW-C-869, 8/23/79 (5) QA-1213, 8/07/79 (6) MS-6513, 8/06-79 (7) FCR-AS-102, 8/01/79 (8) FCR-AS-101, 7/31/79 (9) FCR-AS-97, 7/17/79 (10) FCR-AS-95, 7/16/79 (11) FCR-AS-94, 7/13/79 (12) DDR No. 269, 7/13/79 (13) PW-C-789$ 7/12/79 (14) FCR-AS-91, 7/12/79 (15) FCR-AS-90, 7/ll/79 (16) FCR-AS-84, 6/25/79 (17) FCR-AS-79, 5/23/79 (18) FCR-W-011, 3/09/79 (19) FCR-AS-40, 1/16/79 (20) Associated Inspection Records (21) Associated Purchase Orders (22) Associated Data Packages