ML18017B043

Interim Deficiency Rept Re Omission of Rebar in Unit 1 Containmnent Bldg Exterior Wall.Caused by Unique Ref Notation of Addl Steel (25 Bars) on Main Reinforcing Drawing.Significance Not Fully Recongnized on Drawing

ML18017B043
Person / Time
Site:	Harris
Issue date:	04/16/1980
From:	Jackie Jones CAROLINA POWER & LIGHT CO.
To:
References
NUDOCS 8004280560
Download: ML18017B043 (7)

Text

REGULATOR NFORMATION DISTRIBUTION iEM (RIDS)

ACCKSSION NBR:8004280560 DOC DATE: 80/04/16 NOTARIZED! NO DOCKET ¹ FACIL:50 000 Shearon Harris Nuclear Power Planti Unit ii Carolina

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05000400 50-001 Shearon Harris Nuclear Power Plant~ Un,it 2r Carolina 05000401 50 402 Shearon Harris Nuclear Power Plant~ Unit 3i Carolina 05000002 AUTH INANE AUTHOR AFFILIATION JONKSgJ,A, Carolina Power 8 Light Co.

REC IP ~ NAME RECIPIENT AFFILIATION SUBJECT! Itenrim deficiency rept re omission of rebar in Unit 1 containmnet bldg esterior walli Caused by unique ref notation of " addi steei " (25bars) on mein reinforcing drawing, Significance not fully recognized on drawing..

DISTRIBUTION CODE: B019B COPIES RECEIVEDtLTR '+ ENCL o SIZE:

TITlE: Construction Deficiency Repoit (10CFRSO ~ SSE)

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ACTIONS 20 LAj ~~M & 1 15 BC 21 AD ~~~

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FILE 02 NRC PDR 07 EDO 3 'STAFF 08 MPA 09 DEPY DIR DPM 10 QAB 11 STANDRDS DEV 13F IELD COOR/IE 16 AD FOR ENGR 17 AD PLANT SYS 17 AD REAC SFTY 22 DIR DPM 23 OElD AD/RCI/IE AD/SITE TECH AEOD DIRECTOR DSE GEOSCIENCES BR HANAUERrS ~

ISC SYS BR MATL ENG BR MECH ENG BR POSER SYS BR STRUCT ENG BR EXTERNAL: 03 LPDR 00 NSIC 2Q ACRS 16 1

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April 16, 1980 ~ ~

Mr. James P. O'Reilly, Director Region II United States Nuclear Regulatory Commission 101 Marietta Street, Northwest Atlanta, Georgia 30303 SHEARON HARRIS NUCLEAR POWER PLANT~ UNIT NOSe 1 ~ 2~ 3~ AND 4 DOCKET NOS 50-400, 50-401, 50-402, AND 50-403 INVESTIGATION AND CORRECTIVE ACTIONS POLLOWING OMISSION OP REBAR IN CONTAINMENT BUILDING UNIT NO 1 EXTERIOR WALL

Dear Mr. O'Reilly:

This letter will provide supplemental information and commitments to the telephone conversations held between you and Mr. M. A. McDuffie, Senior Vice President, Engineering and Construction Group, on April 9, 1980 and April 10, 1980 regarding the omission of rebar from the exterior wall of Unit No. 1 Containment Building.

I. Investi ation of Event On April 9, 1980, Mr. M. A. McDuffie was informed by Mr. T. H. Wyllie, Senior Construction Manager, and Mr. Ashleigh Lucas, Senior Resident Engineer, SHNPP site, that the omission of 25 vertical and circumferential rebars scheduled for addition to and inside the seventh row of bars ad)acent to the construction opening for the equipment hatch on Unit No 1 Containment Building exterior wall had been detected by the CPtj'L Construction Inspector and reported to Mr Robert Bradley of your staff by Mr. Ashleigh Lucas, Senior Resident Engineer (CP6L SHNPP Site) ~

Mr. M. A. McDuffie directed the placement of Class I concrete containing rebar in the Unit No. 1 Containment Building exterior wall be discontinued pending resolution of this problem and approval of the NRC to resume such placements.

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Mr. McDuffie contacted Mr. Sheldon Smith, Vice President, Power Plant Construction Department and Mr. P. W. Howe, Vice President, Technical Services Department and discussed the matter with them. At this time, Mr, McDuffie requested Messrs. Smith and Howe to form a special investigation team to determine the cause for this omission and to develop recommendations to avoid a recurrence.

The investigative team was formed and consisted of: Mr~ Sheldon Smith, Vice President, Power Plant Construction Department (off-site), Mr. Pi W Howe, Vice President, Technical Services Department (off-site), Mr. T. H.

Wyllie, Senior Construction Manager (off/on-site), Mr. N. J. Chiangi, Manager, Engineering and Construction Quality Assurance Section (off-site), Mr Ashleigh Lucas, Senior Resident Engineer-SHNPP (on-site),

Mr. George Forehand, Principal Quality Assurance Specialist-SHNPP (on-site) ~

During the period of April 10-11, 1980, the investigative team performed an intensive and comprehensive investigation of the event including a thorough review of procedures, programs and controls, drawings, placement forms, technical competence of those personnel involved, and held interviews with the Construction Inspector (QC), the Construction Inspector Supervisor (QC), the Rebar Superintendent, the Rebar General Foreman-Wall Street, the Rebar General Foreman-Penetration Steel and the Quality Assurance Inspector.

Based upon this evaluation, it to is the opinion of the investigative team the rebar omission was the unique that the root cause leading reference notation of the "additional steel" (25 bars) on the main reinforcing drawing being used by all parties involved in the placement and inspection of the placement. The significance of the notation was not fully recognized due to its placement of the drawing and due to the complexity of the rebar design and its geometry This "human error" resulted in the omission of the forementioned rebarsi It is also the opinion of the task force that lack of technical competence, or lack of proper training were not contributory factors to this problem.

II. Audit of Previous Exterior Wall Placements An audit of previous exterior wall concrete placements with special emphasis on obscure notes and remote or unique details has been completed. One similar problem was found. Two bars which should have originated at the top of the base mat below pen'etration S151 in the eighth row were omitted These bars are unique in that they are the only bars originating at this elevation on any row. All other bars extending up through the base mat are shown on the dowel plan whereas these two bars are shown on the main reinforcing drawing, The 2-1/2 foot lift from

Mr. James P O'Reilly Elevation 216 to 218 ' was all base mat dowels except for these two bars DR 8267 was issued on April 15, 1980, to document and control this discrepancy. PW-C-1370 was issued to Ebasco on April 15, 1980. Ebasco has indicated the omission of these two bars does not compromise safety or structural integrity. It should be noted that the missing bars represent two bars out of a total of 2,749 vertical and diagonal bars at this elevation, III. Corrective Action A. Structural:

PW-C-1361 was submitted to Ebasco on April 10, 1980. The existing conditions were detailed and a reconfiguration of rebar was requested to satisfy design requirements. On April 12, 1980, the approved design fix was obtained from Ebasco, The fix for the 12 horizontal bars was to obtain the required embedment length by bending every other bar and extending down at the concrete interfacei Six bars were shortened by the amount of concrete encroachment. Eight horizontal bars were also added above the placed concrete. The fix for the 13 vertical bars was to add anchor plates and start bars at the top of existing concrete Eight additional vertical bars were added adjacent to the concrete Six diagonal bars were added to supplement both the vertical and horizontal bars omitted.

BE Administrative and Procedural:

1 A detailed tabulation of bars by type (vertical, horizontal, dowels, etc') and location (inside face, outside face, column 4M, etc ) will be prepared by the field engineers and construction inspectors from the design drawings in advance of the preplacement inspection. This effort will be done independently and in advance of the field inspectioni Differences in tabulations will be resolved in advance of field inspection. This tabulation will be utilized for bar count in the field. It is felt that this action is only required for the exterior wall of the Containment Building due to the increased complexity of rebar design and the geometry 2i The area engineer currently intiates the pour card and signs for design approval signifying that there are no last minute design changes. The procedure will be modified to require the area engineer to review the rebar drawing with .the C.I inspector before he signs design approvali This review will emphasize a search for details on referenced drawings that are obscure or unusual. Again, it is felt this action should only be required for the exterior wall of the Containment Building for the reasons stated in 1 ~

. Mr. James P. O'Reill 3~ The QiA. field audit program will be modified to monitor a few of the more difficult details of pours rather than 100 percent of selected pours. A special emphasis will be placed on columns and dowels since surveys and inspections show these areas to be troublesome. "Additional Steel" of various types will also be monitored. Methods will be developed to ensure work on different shifts and in different buildings is monitored since it is recognized that inspectors and crafts basically work in limited areas and samples from one area are not necessarily representative of the other.

4. A drawing review will be conducted to identify similar potential problem areas on the exterior walli (This has been completed for closely related rebar details but will be ongoing prospect as part of 1 and 2.)

A field engineer responsible for rebar verification has been assigned to the exterior wall on a full-time basis.

6~ The area rebar superintendent has been instructed to closely coordinate the activities of crews working various portions of the wall to ensure crews are aware of overlapping work.

7~ Administrative action will be taken to ensure first-line and second-line supervisors perform field audits on the people they supervisei The Contractors Production Manager, Senior Resident Engineer and the Principal Q.A. Specialist will establish methods to ensure the performance of individuals doing field installations and inspections is monitored. The emphasis of this program will be to get the more experienced individuals away from office and coordination duties on a x'outine basis to overview field performance and the end product.

8~ Ebasco design engineers who are familiar with and actually work C.B. rebar design will review drawings and problem areas with the area engineer A special emphasis will be placed on rebar details that may be obscure on the drawings and more complicated or intricate areas of installation. This practice will be modified to more or less frequent reviews as dictated by activity, (A designer will be on-site April 16 and rebax'nstallation 17, 1980, to initiate this action.)

9~ A report on the implementation of corrective action will be submitted to Seniox'orporate Management in 30 days.

It is our opinion that the omission of these bars from the exterior wall of Unit No. 1 Containment Building was a unique situation precipitated by an unusual mode of notation on the drawing and does not 'represent a breakdown in our program or controls. We further feel that the additional corrective action being implemented will offex'urther protection against recurrence of rebar omissions.

Mr. James P. O'Really We, therefore, request your approval to resume placement of Class I concrete containing rebar in the Unit No. 1 Containment Building exterior wall upon implementation of the corrective actions described in this letter.

We appreciate your cooperation in this matter; and should you have any questions, please contact Mr. M. A. McDuffie, (919-836-6663) urs very truly, JoA J s Senior xecutive Vice President Chief Operating Officer JAJ/mf