ML17208A315

Final Const Deficiency Rept:On 790903,Chicago Bridge & Iron Guyed Derrick Collapsed During Hurricane David,Damaging Reactor Auxiliary & Concrete Shield Bldgs.Caused by Inadequate Securing.New Derrick Will Be Erected 800107

ML17208A315
Person / Time
Site:	Saint Lucie
Issue date:	02/01/1980
From:	FLORIDA POWER & LIGHT CO.
To:
Shared Package
ML17208A314	List: ML17208A313 ML17208A315
References
NUDOCS 8003190685
Download: ML17208A315 (17)

Text

~yl~Final Construction Deficienc Resort Dama e Resultin From Derrick Failure Durin Hurricane David Name of Station: Owner: Architect/Engineer:

Date of Def iciency: Interim Report Piled: Supplement to Interim ,Report Filed: Final Report Piled: S t.Luc ie Plant-Unit Pi 2'lorida Power&Light Company Ebasco Services, Incorporated September 3, 1979 October 4, 1979 December 7, 1979 February 1, 1980 Table of Contents I Summary II Description III Assessed Damage IV Corrective Actions V Saf ety Implications VI Conclusion Tables'Table 1-Dispositioned Concrete Nonconformance Reports Table 2-Dispositioned Electrical Nonconformance Reports Table 3-Concrete Design Change Notices~Fi ures I-Reactor Auxiliary Building-Location of Pulse Echo Testing (Elevation

+43 ft)2-Reactor Auxiliary Building-Location of Pulse Echo Testing (Elevation

+62 ft)Attachment

,'ketches SK 2998'G 7'5.01 to 7'5.06 I-Slk2fARY On Monday morning, September 3, 1979, at approximately 10:45 a.m., the.Chicago Bxidge&Iron guyed derrick buckled, twisted, and collapsed during Hurricane David.The lower portion of the derrick (below'Elevation

+192 feet)did not collapse and was leaning at a slight angle from the vertical, remaining braced to the containment shield wall by virtue of the horizontal strut braces.The upper portion of the derrick became dismembexed and, four major sections came to rest in or on the Reactor Auxiliary Bui ding.A portion of the boom remained suspended by guy wir'es from the top of the containment shield wall.The guy wires pexformed,their intended function and did not fail.Per the requirements of 10CPR50.55(e)

>the event was deemed reoortable because'I the derrick failure caused significant.

damage to safety-related structures, ,which, were it to have xemained uncorrected, could advexsely affect the safety of operations of the plant, and did requixe extensive evaluation and repaix'.Notification of the incident was telephoned in to the NRC Inspection and Enforcement Office on September 4, 1979 (approximately ll:45 a.m.)by Mr N Weems, Florida Power&Light Company's Assistant Manager, QA Construction.

Via numerous onsite inspections by the Architect/Engineer and engineering review of onsite confirmatory destructive and nondestructive testing, all damaged areas wexe identified and coxrective'actions were issued.IX.DESCRIPTION The concrete Shield Building.and the Reactor Auxiliary Building were at the.following stages of construction when the huxricane passed the jobsite: The concrete Shield Building cylinder had been completed to Elevation+191.42 feet and the Reactor Auxiliary Building, being constructed in a staggered manner, had walls and columns completed to the underside of floor slabs at Elevations

+43 feet,+62 feet and+82 feet.Actions taken to Identif Dama e A storm damage team was assembled to determine and document the extent of.damage resulting fxom the derrick failure.The team consisted of the Ebasco Civil Site Support Engineer and two civil construction office engineers.

In DESCRIPTION on')conjunction, the Architect/Engineer visited the jobsite, both before and after derrick removal and cleanup, to observe the damage and to confirm and task force findings.Nonconformance reports were prepared for observed damage to concrete and reinforci ng, and corrective actions for removal and initial repair were issued with Architect/Engineer review and approval.Architect/Engineer directed construction to proceed with two,testing pro-grams to confirm the extent of damage within the Reactor Auxiliary Building and Shield Building.The first program required testing of reinforcing steel samples removed from the damaged floor beams and slabs of the Reactor Auxiliary Building at Elevation+62 feet.Test results would'indicate if the rei nforci ng which extends into the surrounding sound concrete had been overstressed during missile impact.The second program required nondestructive testing of: P a)Reactor Auxiliary Building concrete members 1)adjacent to damaged'loor slab ax'eas at Elevations

++3 feet and+62 feet, including all the beams at Elevation+43 feet which were observed to have surface cracks, and 2)an exterior wall al'ong the north side of the building which had only five day concrete strength when a section of the derrick hit the top of the wall.b)Shield Building cylinder wall 1)at three locations on top of wall where dowels were bent and sheared off, and~2)at a gouged area on outside-face of wall at Elevation+112 feet.The pulse echo method was selected and was performed by ifuenow and Associates of Charlotte, North Carolina.The attached Pigures 1 and 2 show the concx'ete members which were investigated.

Areas completely unaffected by the derrick failure were released for continued planned cons truction.

.III.ASSESSED DAMAGE The initially observed damage to the containment shield wall was limited to bent and sheared dowels project'ng from the top of the cylinder wall and a small surface gouge on the exterior wall face.The initially observed damage within the Reactor Auxiliary Building was extensive and consisted of penetraLion of floor slabs, shattered floor beam, spalled concrete, and bent.and sheared dowels for columns and walls.The location of derrick and boom section resting positions, and details of observed damage to the Reactor Auxiliary Building are presented on Sketches, SK-2998-PG 75.01 to 75.06 (Attachment).

In addition to the noted damage on the sketches, cracks were observed on the surf'ace of a few elevation+43 feet floor beams.These cracks were ch'pped back to determine depth and were observed to be only surface shrinkage cracks.In addition to the above structural damage in the Reactor Auxiliary Building, the following is a listing of damaged equipment and supports: ,1)Conduit on Elevation+43 feet 2)Cable tray restraint on Elevations

+43 feet and+62 feet 3)4.16 kV Switchgear 2A3-1, 2, 3, 4, 5, 6, 7, 8 4)Station Service Transformer 2A2-5)480V Switchgear 6)Pressurizer heater buses-2A3 and 2B3 The destructive testing of reinforcing steel and nondestructive testing of concrete members proceeded in the following sequence with results as noted: Reactor Auxiliary Buildin Elevation+62 feet (floor slab, beams, girders, and supporting column and exterior wall)..All shattered and badly cracked concrete of beam 3B3 between Column lines 2RA1 and 2RA2 and adjacent slabs were removed.

I ASSESSED W~E (Cont'd)Samples of exposed beam and slab reinforcing were*removed and tested by.Construction Quality Control to determine if ASKS minimum requirements were met or if the reinforcing had'ecome overstressed upon impact.Test results indicated that the slab reinforcing (No.6 and 8 rebars)met all ASTi~f requirement and beam reinforcing (Ho.9 rebars)met all ASM requirement except percent elongation which indicated values as low as 3 percent vs a minimum allowable of 7 percent.-To check the field test results, samples of the field tested rebars and additional samples of the beam reinforcing were sent to the Architect/

Engineer for investigation and tensile testing.Hicroscopic inspection of the field tested rebars did not reveal the elongated grain which typify material exposed to plastic strain.Tensile testing of two rebar samples indicated that all AS'Bf requirements were met except for elongation in one sample.It was noted that both samples failed at surface indentations which were caused by nicks and gouges during concrete removal.The test-ing program concluded:

1)There is no evidence of rebar straining-due to the crane collapse.2)The New York Office tested rebars failed at the gouges (stress risers}(Copy of the report is contained within J Brodsky (Ebasco Materials Engineer)memo to L M Petrick{Chief Materials and Welding Engineer)dated-12-18-79.For additional information on the effects of loading of reinforcing steel past-yield, the Architect/Engineer requested field tensile testing of reinforcing of same size (No.9 rebars)and heat number as installed in Beam 383.Testing proceeded as follows: 1)Measure diameter, 2)Load to yield point and hold for 5-10 sec, 3)Slowly release load, 4)Measure elongation and diameter, 5)Load to ultimate and 6)Determine elongation, For all rebars tested all ASTi'!requirements were met.Nondestructive testing of visually sound concrete members adjacent to the impact area indicated the following:

1)Microcracking and loss of concrete bond to reinforcement in the top four inches of concrete within beams 3B2 and 3B4 adjacent t;o impacted Beam 3B3, and in Beam 3B3 south.of Column Line 2RA2.2),Microcracking in adjacent slabs.through out the one foot depth and for a distance of 3;5 feet past beams 3B2 and 3B4.3)Microcracking on exterior wall at support point of Beam 3B2 for a depth of less than three inches.To document validity of test results, nondestructive testing of concrete members-away from the damaged area was also performed and results indicated sound concrete.Reactor Auxilia Buildin~Elevation+43 feet (beams, girders and supporting columns)Shattered and badly cracked concrete of slab east of column line RAG and between column lines 2RA2 and 2RA3 was removed.Samples of exposed slab reinforcing, were removed and tested, and were found to meet ASTi'l minimum xequirements.

Nondestructive testing was performed on all beams on which a portion of the derrick had come to rest and girders and support columns adjacent to the damaged concrete slab (beams 2B4-2B13 between columns lines 2RA2 and 2RA3).No microcracks were detec'ted and any visually observed surface cracks were found not to extend beyond two to three inches in depth.

III.ASSESSED DAHACE (Cont'd)Reactor Auxilia Buildin Walls between Elevation+19.5 feet to+43.0 feet Nondestructive testing of north exterior wall between column lines RAB and RAE indicated microcracking in the top two to three feet for a portion of the wall.Nondestructive testing of interior wall on column line RAE between column lines 2RA2 and 2RA3, around an area which had been damaged and unsound concrete removed, indicated no microcracking.

Reactor Buildinz Shield Wall Nondestructive testing, performed at Azimuths 70,130 and 160 degrees between Elevations

+191.42 and+186 feet, indicated microcracking up to six inches below top of wall for the complete thickness.

Nondestructive testing around a gouge located at Azimuth 160 degrees-.at Elevation+112 feet indicated surface microcracking for a four square foot area on the outside face of the shield wall.For complete description of nondestructive testing program, including technique and test results for all areas investigated, see ifuenow and Associates"Final Report On the NDE Evaluation of Concrete Damage at St Lucie Unit No.2" which is filed at the site;IV.CORRECTIVE ACTIONS Actions-Taken Florida Power&Light Company retained Cadcom, a division on<<fanTech of New Jersey Corporation, to investigate the cause of the derrick failure and to make recommendations concerning the erection of a.replacement derrick.The Cadcom Report concludes that the guyed derrick should have withstood the hurricane force winds had different securing precautions been taken.In CORRECTIVE ACTIONS (Cont'd)addition, the report recommends minor modifications that could be made to further enhance.the hurricane withstand capability of the crane.The Cadcom Report was subsequently reviewed by Chicago Bridge and Iron (CBI), who designed, manufactured and supplied the crane.CBI, concurred that the Cadcom Report provides a reasonable account of the derrick collapse, and that the recommendations for securing the derrick when hurricane winds are expected are technically sound." Following their own design review, and consideration of the Cadcom Report'BI has concluded that the following actions should be taken to secure the replace-ment derrick when hurricane winds are expected: l)Raise the boom as high as possible and allow the boom and mast to"weathervane." 2)Remove the spreader beam from the boom.3)Fix the mast-tower swivel joint to the tower with bolts or welded lugs.A duplicate replacement derrick will be erected at the site, with installation commencing January 7, 1980..Florida Power 5 Light Company's equality Control Department had the responsibility to prepare nonconformance reports (NCRs)where damage occurred to completed con-struct>on activities (i.e., after concrete placement) or equipment.

Table I contains dispositioned NCR's summarizing categories of structural members, types of damage and corrective action to be taken.Table 2 contains dispositioned NCR's summarizing the equipment damage and cor-rective action be taken.

IV., CORRECTlVE ACTIONS Table 3 contains design change notifications'DCN's) which were issued by the Architect/Engineer to repair damaged concrete and reinforcing as deter-mined from visual observations and from the resul'ts of the destructive and nondestructive testing programs.C Involvement The procedures'util'ized to identify damage, evaluate and disposition corrective action are the following:

1)Site Quality Procedure SQP-21"Corrective Actions" for the handling of NCR's.The Florida Power&Light Company's Quality Control Department has independently reviewed the damaged areas and issued NCR's to identify damaged areas and equip-ment.They follow-up the corr'ective action dispositioned by Engineering and apply the normal testing and inspection-requirements for final approval.In addition'to the above normal QC inspection and approval process and documenta-tion>the storm damage team has photographed and mapped the damaged areas to permit additional documentation on the extent of damage.V.SAFETY GPLXCATIONS The Chicago Bridge&Iron derrick failure caused significant damage to the Reactor Auxiliary Building structure which required extensive evaluation and repair to establish the adequacy of the, structure to perform its intended safety function and meet the criteria and bases stated in the Preliminary Safety Analysis Report.If it were to have remained uncorrected, the struc-tural damage could have possibly affected the safety of operations of the plant.VI.CONCLUSION The Chicago Bridge&Iron derrick failure was determined to be a potentially reportable accident on September 4,*1579"and such notification was made to the

~~I~~VI CONCLUSTON (Cont'd)NRC inspection and Enforcement Office the same day.Prior to any repair work or new construction in the affected areas, each area was specifically evaluated for structural soundness and repair measures approved.Adequate documentation on the structural evaluation and repair work is maintained at the site.As a result of the dispositioned corrective action described above, the damaged portions of the Reactor Auxiliary Building and Reactor Building shield wall have been restored to original structural soundness.

Table 1 ned Concrete NCRs Issued NCRs 830C 831C, 841C, 845C, 846C, 848C, 850C Cate oxies Covered b NCR Interior wall.and proj ecting reinfoxcing Columns, walls and projecting reinforcing T eof Damae Bent rebars Spalled concrete and bent rebars in walls-and columns Corrective Action Rebend rebaxs to original positions Chip concrete back 1'-6, cut off damaged rebars and mechanically splice rebaxs 835C 832C Columns and projecting rein-forcing Bent xebaxs Wall and projecting reinforcing Cracked concrete and ben" rebaxs Chip back 1 ft into sound concrete and mechanically splice'ebars Chip concrete back to specified elevation for full rebax lap splice and install new xebars.836C forcing Reactor Shield Building and pxojecting reinforcing 834C Slab, beams and girder at Elevation+62 feet (RAB)851C, Beams at Elevation+43 feet 860C (RAB)870C Exterior Wall (RAB)842C Slab and gixders at Elevation+43 feet (RAB)833C Columns and p'rojecting rein-Cracked near'loor level Microcracking at top of wall, and bent rebars Concrete micro-cracking and damaged xebars Superficial sur-face cracks.Superficial sur-face cracks..Cxacked concrete and bent xebars Chip concrete colum and replace dam ged reinforcing Chip back 1 ft into sound concrete and mechanically splice rebars.See DCN 550.203 and 513.609 None None Chip concrete and lap splice slab rebars an;.m chanically splice girder rebars.

t Table 2 Dis ositioned Electrical NCRs Issued NCRs E uioment Covered b NCR Dis osition 839E 84QE Conduits on Elevation+62 feet Remove damaged conduit and replace with new 838E Electrical Equipment Scrap and replace 837E Cable tray restraints on Elevations

+43 feet and+62 feet Two restraints are to be repaired by Construction to within AISC tolerances.

Balance to be scrapped.

Table 3 Concrete DCNs Issued DCNs 550.203 513.609 Cate pries Covered b DCN Slab, beams and girder at Elevation+62 feet (RAB)e of Dama e Concrete microcracking and damaged rebars Corrective Action Remove concrete and rebars, and lap splice and mechanically splice as specified.

550-208 Wall (RAB)Concrete microcracking Chip back into sound concrete as specified 550-207 Slab Elevation+43 feet (RAB)'racked concrete and damaged rebars Remove concrete and rebars, and splice as specified.

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