ML20028C283

Interim Rept of Potential Deficiency 82-13 Re Fabrication & Detailing of Structural Steel Connections.Initially Reported on 821115.Shop-fabricated Fillet Welds Undersized.Qa Audits Will Be Increased to Assure Effective Reviews Are Performed

ML20028C283
Person / Time
Site:	Clinton
Issue date:	12/20/1982
From:	Hall D ILLINOIS POWER CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
10CFR-050.55E, 10CFR-50.55E, 1605-L, 82-13, U-10013, NUDOCS 8301070294
Download: ML20028C283 (5)

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. 16 05-L ILLIN018 POWER COMPANY y.10013 CLINTON POWER STATION, P.O. BOX 678 CLINTON, ILLINOIS 61727 December 20, 1982

' Docket Number 50-461 Mr. James G. Keppler Regional Administrator Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137

Subject:

Potential Deficiency 82-13

. 10CFR50.55(e)

Fabrication and Detailing of Structural Steel Connections

Dear Mr. Keppler,

On November 15, 1982, Illinois Power Company notified Mr. F.

Jablonski, NRC Region III, (Ref: IP memorandum Y-12935,'1605-L,

dated November 16, 1982) of a potentially reportable deficiency per 10CFR50.55(e) concerning' drawing details and fabrication of structural steel connections provided by Bristol Steel and Iron (Structural Steel Fabricator) for use at CPS. Our-investigation into this matter continues,-and this letter represents an interim report in accordance with 10CFR50.55(e)(3).

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! Statement of Potentiallv Reportable Deficiency 3 i

i As a result of structural steel reinspection efforts conducted

as part of an Illinois Power Structural Steel Recovery Plan, the

adequacy of certain structural steel connections in meeting engi-neering requirements is questioned. These concerns result from the following conditions:

1. Shop-fabricated fillet welds on the top horizontal leg.of connection angles (welds between connection angles and beam webs) for certain structural ~ steel beams were found to be undersized. The resulting weld may not be adequate to support design service loads designated by the Archi-tect/ Engineer.

8301070294 821220 21 T01 DEC gDRADOCK0500 6} 7

• Mr. James G. Keppler December 20, 1982 NRC Page 2 of 5

2. Installation and inspection criteria was not provided for minimum length of thread engagement in " drill and tap" structural steel connections detailed by Bristol Steel.

Inspection criteria utilized during the' inspection of field erected drill and tap connections may not be ade-quate to verify adequacy of connections in meeting engineering requirements.

B_ackground/ Investigation Results CONCERH 1 As a part of an Illinois Power Structural Steel Recovery Plan, an overinspection of installed and accepted structural steel was performed by Illinois Power Quality Assurance to assure and demon-strate that previously assembled structural steel met regulatory requirements. As a result of tha overinspection effort, two (2) nonconfermances were generated (NCR 50,002 and 50,004) which addressed inadequacies in welding performed by Bristol Steel. Of primary concern were certain undersized shop fillet welds on the top horizontal leg of connection angles which attach the angles to the beam webs. In investigating this matter, it was determined that the undersized welds were caused by connection detailing errors by Bristol Steel. Certain connection drawings show coped beam details which have insufficient clearance allowed between the top of the connection angles and the bottom of the cope, to provide the required size fillet weld. Also, there was a lack of fabrication tolerances for coping beams, which would prevent a cope from being cut excessively deep during fabrication. This lack of tolerance could result in insdequate clearance to provide the required size fillet weld.

Illinois Power's investigation of this problem is continuing in order to determine the scope and significance of the potential deficiency, and its impact on installed plant structural steel. A review of shop connection detail drawings has identified approximately 35 beams which indicate insufficient clearance to provide the required fillet weld. An additional review of detail drawings is presently being performed to tabulate all coped beams, including beams with top and/or bottom copes, calculate the clear-ance available for perforning the top and/or bottom fillet welds, and calculate the capacity of the connection without the top and/or bottom fillet weld in those cases where insufficient clearance exists. Upon completion of this review, the resultant connection capacity will be compared to the expected service loads in order to determine the adequacy of the as-built connection. An evaluation will then be made to determine corrective action necessary to correct and prevent identified hardware / software inadequacies, and to determine the safety implications of the potentially reportable deficiency.

'Mr Janes G. Keppler Dec enber 20, 1982 NRC Page 3 of S CONCERN 2 As part of an Illinois Power Structural Steel Recovery Plan (Phase 2A-1), a reinspection of installed structural steel in five

, (5) areas of the containment building was performed by Baldwin Associates (IP contractor) Quality Control in order to replace lost documentation in those areas. During the inspection of certain beam-to-box girder connections utilizing " drill and tap" connections (i.e. structural bolts installed directly into side plates of girders which have been drilled and tapped to receive the bolts) the inspector questioned the applicability of the in-spection for thread engagement. This question was raised, as inspection criteria for thread engagement was not provided. Past

inspection practices were reportedly to "N/A" the thread engagement

inspection point, to assure that no threads were in the shear plane, and assure that installation torque (as required by the AISC Manual) was met. A review of approved shop drawings for the drill and tap connections was performed, which specify grade, diameter, and number of bolts required, but did not specify bolt length or installation / inspection criteria for thread engagement. Bolt lists were provided as erection aids by Bristol Steel which specified bolt length, but were found to contain discrepancies; and, as unapproved documents, could not be used by Quality Control for

inspection. The facts that the bolt list was in error and that thread engagement and bolt length were not originally inspected or recorded, indicate that insufficient information exists to assess i the adequacy of the installed connections for sufficient thread engagement.

Bristol Steel has subsequently provided, with supporting calculations, the minimum theoretical thread. engagement, by bolt '

grade and diameter, necessary to assure adequate bolt strength.

The calculations have been reviewed by the Architect / Engineer and i found to be acceptable.

Illinois Power's investigation into this matter has determined

! that fourty-four (44) drill and tap connections are affected by this potential deficiency, of which seven (7) have not yet been completed. An inspection of the installed connections for bolt length and thread engagement is a part of Phase 2A-2 of the Struc-tural Steel Recovery Plan, whose implementation is pending NRC (Region III) approval and release. This inspection will determine i

the as-built condition of the drill and tap connections, after which the adequacy of the connections in meeting engineering requirements can be evaluated, and significance of this potential deficiency can be determined.

In addition to the 44 drill and tap connections detailed by

, Bristol Steel, a review is being performed to determine if other drill and tap connections exist. Additionally, the Architect /'

Engineer and safety-related steel vendors supplying material f s l

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• Mr. James G. Keppler December 20, 1982 NRC Page 4 of 5 to CPS have been directed to review their drawings to determine if non-standard connections exist which require special installation and inspection criteria.

Corrective Action (Interim)

Illinois Power is presently investigating corrective action necessary to prevent recurrences of the problems identified in this investigation. As the receipt of materials from Bristol Steel is

, complete, and future orders for material have not been placed, nor i vill future orders be placed with this vendor, future occurrences of an identical nature have been prevented. Therefore, corrective action to prevent recurrence has focused on preventing occurrences of a similar nature, as follows:

1. The scope of Illinois Power Quality Assurance audits will be increased to specifically include Sargent & Lundy's process of reviewing vendor design drawings to assure that effective reviews are being performed, to minimize

vendor design drawing errors.

2. Enhancements have been made to the Baldwin Associates vendor surveillance program. Important program enhancement include, but are not limited to, the following:

a. intensified in-shop vendor surveillances in both scope and number.

b. a reevaluation of Baldwin Associates vendor 1 surveillance inspection points was performed, with more hold points established.

c. a reorganization of the vendor surveillance department from the Quality Control to the Quality Assurance Department was made, to increase overall program effectiveness.

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Safety Implication / Significance ph l An investigation of this potentially reportable deficiency M ~

continues to determine the adequacy of affected structural steel in meeting engineering requirements. A detailed analysis of the significance of this potentially reportable deficiency cannot be performed, until the scope of the concerns have been

, fully ! identified, reinspection of as-built hardware is complete, and evaluation of the impact of these concerns on performance is

' determined. It is anticipated that approximately ninety (90) days will'be necessary to complete the investigation, determine reportability, and to file our final report on this potentially reportable s

deficiency.

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Mr. James G. Keppler December 20, 1982 URC Page 5 of 5 He trust that this interin letter provides you sufficient background information to perform a general assessment of this potential reportable deficiency and overall approach to resolution of the problem.

Very truly yours,

. . Hall Vice President cc: H.H. Livermore, NRC Resident Inspector Director, Office of I&E, Wasnington, D.C. 20555 Illinois Department of Nuclear Safety Director - Quality Assurance l

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