ML20235S166

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Rev 1 to Comanche Peak Response Team Results Rept:Issue Specific Action Plan Ii.E, Rebar in Fuel Handling Bldg
ML20235S166
Person / Time
Site: Comanche Peak  Luminant icon.png
Issue date: 09/03/1987
From: Beck J
TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:
Shared Package
ML20235S157 List:
References
NUDOCS 8710080350
Download: ML20235S166 (26)
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{{#Wiki_filter:,. l a O \\ COMANCHE PEAK RESPONSE TEAM i RESULTS REPORT l ISAP: II.e'

Title:

Rebar in the Fuel Handling Building 1 REVISION 1 l i I i O I .{ M 6/t9 Iss5e Coordinator Dafe f ~J A, 9hin Refiew" Team Leader v Date I i %.O. L n i rhh 7 J p W. Beck, Chairman CPRT-SRT Date l 4 l O g4ga6%? a i 

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4 j Rivisions 1 Pag 9 1 of 25 RESULTS REPORT ISAP II.e { Rebar in the Fuel Handling Building

1.0 DESCRIPTION

OF ISSUE IDENTIFIED BY NRC Issue II.e was identified in Supplement 8 to the Safety Evaluation Report (SSER-8) for the CPSES (Reference 9.1, page K-89) as follows: Allegation AC-15 identifies a specific instance of the i possible unauthorized cutting of rebst. In this case, a i former Brown & Root employee stated he possibly drilled holes through rebar in a concrete floor without a component modification card (CMC) or a design change authorization (DCA). He explained that in January 1983 he drilled j approximately 10 holes about 9 inches deep while installing 22 j taetal plates with a core drill. He said the' metal plates were used to secure the trolley process aisle rails located on the i j 810-foot, 6-inch floor level in Room 252 of the Fuel Handling ) Building. The TRT inspected the trolley process aisle rails and its l anchoring system and observed no violations of project pi drawings or specifications. The TRT reviewed the

g reinforcement drawings (2323-S-0800 and 2323-S-0820) for the Fuel Handling Building to determine the location of rebar.

j The drawing showed three layers of reinforcement in'the upper part of the mat, which consisted of a No. 18 bar running in { { the east-west direction, in the first and third layers, and a .j Ho. 11 bar running in the north-south direction, in the second layer [See Figure 1]. { The review of the reinforcement drawingsL (2323-S-0800 and 2323-S-0820) revealed that the layout of the east-west reinforcement and the trolley process aisle rails was such ) that only one bar of the east-west reinforcement could be cut by drilling holes for rail anchors. However, if 9-inch holes l were drilled, both layers of the No. 18 reinforcing bar would be cut. Design Change Authorization (DCA) No. 7041 was written for authorization to cut the uppermost No. 18 bar at only one rail, but it did not reference the authorization to cut the lowermost No. 18 bar. The DCA (No. 7041) also stated that the expansion bolts and baseplates could be moved in the 3 i east-west direction to avoid interference with the No. 11 reinforcement running in the north-south direction. The information described in DCA No. 7041 was substantiated by Gibbs & Hill calculations. 3 The DCA approval was based on the understanding that only the uppermost No. 18 reinforcement would be cut. If the 10 holes were actually drilled 9 inches ( deep, then the allegation that reinforcement was cut without proper authorization may be valid. I m

4 R:visien 1 Pcgo 2 of 25 4 RESULTS REPORT ISAP II.e -() (Cont'd) 2.0 ACTION IDENTIFIED BY NRC The NRC (Reference 9.1, page K-91) indicated that the following action should be taken on this issue: TUEC shall Provide: 1. Information to demonstrate that only the No. 18 reinforcing steel in the first layer was cut, or 2. Design calculations to demonstrate that structural integrity is maintained if the No. 18 reinforcing steel on both the first and third layers was cut.

3.0 BACKGROUND

The base mat (slab) at elevation 810'-6" of the Fuel Handling Building is approximately 5 feet thick with reinforcing steel (reba:) layers near both the top and bottom surfaces of the slab. Reinforcing steel at the top of the slab consisted of three layers, No. 18 bar in the first and third layers, spanning east-west, and V) No. 11 bar in the second layer, spanning north-south (see figure l 1). To install a pair of rails, holes were drilled into the slab in order to insert Hilti bolts that would hold rail clips. This rail installation (which according to the operational ~ traveler for this activity (Reference 9.2) actually occurred in Septsaber 1982, not in: January 1983 as stated by the alleger)~will be referred to i in the following as "the subject case".. It was alleged that in the subject case ten holes were drilled approximately 9 inches deep, 3 inches deeper than required for the Hilti installation. Drilling to 9 inch depth may have resulted in cutting through both the 1st and 3rd layers of the east-west No. 18 reinforcing steel along a line next to the northern-most rail at the top of the mat. Design Change Authorization (DCA) No. 7041 Rev.- 7 (Reference 9.3) concerning drilling for the subject installation authorized cutting of only the first layer of rebar. The DCA required that the rail clips be so located in the east-west direction that. cutting of the 2nd layer of (No. 11) rebar running north-south would be avoided. A field inspection verified that the location and length of the Hilti bolts installed is such that rebar in both the let and 3rd layers could have been cut in several locations aloag the east-west line next to the northern-most rail (Reference 9.4). 1 k ) I a l 1

l Rsvision: 1 Pega 3 of 25' i RESULTS REPORT I O ISAP II.e () (Cont'd) j t 4.0 CPRT ACTION Pl.AN l 4.1 Scope and Methodology The objectives of this action plan were to: Assess the structural adequacy of-the slab in the subject case. I Evaluate whether in other cases where cutting of reinforcement bar was authorized for the installation 3 of Hilti bolts structural adequacy was compromised due to potential. unauthorized cutting of additional bars. The CPRT tasks implemented to achieve these objectives are described in the following paragraphs. Design calculations (Reference 9.5) were generated'to evaluate I structural adequacy of the concrete mat at elevation 810'-6", assuming one No. 18 bar in the 1st layer and one in the 3rd layer are each cut along the east-west line Both bars were' modeled as being completely ineffective (i.e., omitted) in the analysis. g Procedural controls governing rebar cutting for Hilti installation drilling as well as for core drilling were-reviewed. The review focused.on requirements for engineering authorizations and inspections of drilling as well as~on. craft procedures and control of rebar cutting equipment. All cases from units 1 and 2 where rebar cutting was requested for installation of Hilti bolts were identified (Reference 9.6). The possibility of additional (i.e., unauthorized) i rebar cutting was determined for these cases, based on the design reinforcement pattern in the slab or wall. I An evaluation of structural adequacy (Reference 9.7) was performed by postulating that the additional rebar was cut-in all cases for which the possibility for unauthorized rebar cutting existed. Ultrasonic inspection was conducted in some-of these cases to verify actual installed embedded length of Hilti bolts (Reference 9.8). In addition, following a review to identify other work processes in which rebar could have been cut, installations of pipe supports in units 1 and 2 that utilize shear lugs were investigated for the possibility of rebar cutting while drilling holes for the lugs (Reference 9.9). , O

Revisions' 1-Pega 4'of?25 4 - RESULTS REPORT 7"** - 15AP II.e (Cont'd) ~ 4.0 CPRT ACTION PLAN (Cont'd) A review of the NRC conclusions regarding the number'of diamond drill bits that could have been'used for unauthorized-rebar cutting was performed..This also involved comparison of the alleged unauthorized rebar cuts and the Project documentation on cut authorizations. 4.2 Participants Roles and Responsibilities The organizations'and personnel that participated in this effort are described below with.their respective scopes of work. 4.2.1 TUGC0 Nuclear Engineering (TNE) - Civil / Structural ~ Discipline 4.2.1.1 Scope Prepared design calculations documenting the adequacy of the slab at:elev'ation 810'-6". 3 ( Identified rebar cuts by review of all DCAs and CMCs, and evaluated . cases where potential for unauthorized cuts existed. 4.2.1.2 Personnel Mr. C. R. Hooton TNE Civil / Structural. Discipline- -Supervisor-Mr. D. G. Patankar Civil / Structural Lead Engineer Mr. S. A. Raz Structural Engineer 4.2.2 Gibbs & Hill (G&H) - Site Design. Review Team 4.2.2.1 Scope i Performed design review of l-calculations performed by TNE. l() 3 1 1

f.; s 1Revisiont 1 4 .Page 5'of.25i ( RESULTS REPORT a - (3 H ISAP II.e ' () - (Cont'd) i 4.0 TUEC ACTION PLAN (Cont'd) 1 4.2.2.2 Personnel Mr.-B. Wilcoxson . Design Review Group Supervisor: Mr. B. K. Bhujang Structural Group Lead ,.,4 Mr. R. P. Shah-Principal Engineer l 'w 4.2.3 Stone & Webster Engineering Corporation (SWEC) . ? ~ i Lead Contractor responsibility for this task was' i transferred by TU Electric from G68 to SWEC on October 13, 1986. After that date, SWEC participated in the execution of this action plan.as described be. low.- 4.2.3.1 Scope Assessed the extent of pote'ntial unauthorized rebar' cutting by reviewing: ~ .the diary of the foraman of the crew a. that performed drilling'for most of the Hilti installations;:this-individual made allegations'that unauthorized rebar cuts were-made and documented in his diary; l b.' Project design change documents to I determine whether the rebar cuts listed in~the. alleger's; diary were. or were not authorized; and Project documents to determine ' the l c. number of diamond drill bits that are capable'of cutting rebar and to determine the total' number of rebar at the plant.- 4.2.3.2 Personnel Mr. T. W. Houston Principal Structural . Engineer-Mr. M. P. Holland. Group Leader, Structural' Division

Revisien 1~ Peg 2 6 of 25 l '+ RESULTS REPORT i e s ISAP II.e (Cont'd) -I 4.0 TUEC ACTION PLAN (Cont'd) 4.2.4 Third-Party Activities 4.2.4.1 Scope I Reviewed design calculations performed by TNE to verify adequacy l of the slab at elevation 810'-6". -j 8 Reviewed procedural controls for rebar cutting. ) Reviewed Project identification and 1 evaluation.of Hilti installations where potential for unauthorized: rebar cutting existed.- ( Determined actual lengths of Hilti { bolts by Ultrasonic testing for j cases where rebar cutting was 7s -required for Hilti bolt installation l and the possibility of additional.' l rebar cutting exists. l Reviewed Project evaluations of.the rotal extent of potential rebar cutting. Prepared Results Report. 4.2.4.2 Personne1' Mr. H. A. Levin TERA - Civil / Structural Review Team Leader Dr. J. Honekamp TERA - TRT Technical Manager l Mr. J. Miller TERA - TRT Issues Manager Dr. J. Arros TERA - Issue Coordinator . O V L

i 6 Revision:

1 Paga 7 of'25 RESULTS REPORT O'

ISAP II.e V (Cont'd) 4.0. CPRT ACTION PLAN '(Cont'd) Mr. G. Lagl' der Southwest Research e Institute - UT measurement of Hilti bolt lengths 4.3 Personnel Qualification Requirements Where inspections required the use of certified inspectcrs, a qualifications at the appropriate level were to the-requirements of ANSI N45.2.6,~" Qualification of Inspection, Examination, and Testing Personnel at Nuclear Power Plants". i Third-party inspectors were certified to the requirements of.- the third-party employer's quality assurance program and '{ trained to the applicable inspection procedures. 1 Third-party participants in the implementation of this Action Plan meet the personnel qualification and objectivity j requirements of the CPRT Program Plan and its implementing i procedures. Other participants were qualified to the requirements of the CPSES Quality Assurance Program or to the specific i requirements of the CPRT Program Plan. Activities performed { by,other than third-party personnel were governed by the i applicable principles of Section III.K, " Assurance of CPRT Program Quality", of the CPRT Program Plan. 4.4 Procedures Calculations and evaluations performed by TNE, Gibbs & Hill, and SWEC were performed in accordance with-the procedures 4 i normally applicable to those activities for CPSES. Third-party. activities were conducted in accordance with applicable CPRT guidelines. i i Procedure SWRI-NDT-800-103, Revision.1, " Ultrasonic Length Measurements of Bolting",(Reference 9.8) was specifically developed by Southwest Research Institute to provide guidance for ultrasonic length measurements of. bolting in place. This procedure describes the responsibilities of SWRI personnel and the techniques and equipment to be utilized during the performance of ultrasonic length measurements of bolting and establishes the method of recording the results of field inspections. This procedure was approved by TNE and TERA. l O

~ T.- R3 vision .1. <Pega 8 of 25 1 RESULTS REPORT I b .ISAP II.e (Cont'd) All 4.0 CPRT ACTION PLAN (Cont'd)'

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'4.5 Standards / Acceptance Criteria 1. ACI-318-71, " Building Code Requirements for Reinforced Concrete", land' stipulations of FSAR Section 3.8' formed the. basic standards and design criteria for the f original design of the concrete mat at El. 810'-6"'in { the Fuel Handling Building. The acceptance criteria i for calculations generated within this action plan were consistent with.the original design criteria. j i 2. Adequate controls of activities related to rebar { cutting, such as engineering. authorization, equipment use, and QC inspections must be defined in the Project procedures. 3. DCAs and CMCs associated with identified rebar cuts i j must be supported with appropriate. analyses.to evaluate { and qualify the changed condition.. J 5.0 IMPLEMENTATION AND DISCUSSION OF RESULTS The implementation of this action plan involved:.. preparation'of

f design calculations for the Fuel Handling Building concrete mat i

postulating that the unauthorized rebar cutting had occurred;. review of procedures for drilling for Hilti installations and core drilling to determine the controls for rebar cutting; identification and evaluation of Hilti installations where a,rebar cut was authorized and the possibility of cutting underlying rebar, existed; and ultrasonic measurement of the. length of some Hilti bolts. These tasks are discussed in'the following sections. Additional sections discuss a review of the NRC conclusions, an- ) i evaluation of the potential safety significance, and root cause and j generic implications of this issue. Figure 1 provides a sketch of the subject Hilti bolt installation and rebar placement in the concrete mat. The activities that were performed by.the Project were reviewed by the Third Party. }~ 5.1 Fuel Building Concrete Mat at Elevation 810'-6" I i In order to respond to the NRC request regarding the possible rebar cutting in the subject-case, as stated in Section 2.2 above, a field walkdown of the. area was performed by Projects. The walkdown consisted of's determination of the location of~ O V I 'l

1 Revision: 1 Pags 9 of 25 . RESULTS REPORT ISAP II.e (Cont'd),}.c 8 5.0 IMPLEMENTATION AND DISCUSSION OF RESULTS (Cor,t'd) the bolts and a UT measurement of the length of the installed Hilti bolts (Reference 9.4). It was determined that soce of t 'X the bolts were'long enough:(greater than 7 inches) to hi e required holes to be drilled deep'enough to potentially cut a rebar in the third layer. In addition TNE performed calculations, assuming that a section of rebar in the first and third layers was cut (Reference.9.5). The calculations established that even if rebar.in both the'first and third layers had been cut alcng the ~aet-west 1ine next to one of e ~ the rails, the mat satisfies the requirements of the design criteria.(i.e., ACI-318-71). DCA-7041 was revised to- . incorporate authorization for cutting both the first and third layers of rebar, The new calculations and DCA-7041. Rev.- 10 were reviewed by the C6H Site Design Review Team and also by1 the third party. In the subject case, and in the 62 other Hilti installations where potential for additional unauthorized. rebar cutting was determined to exist (see Section 5.3), it has not been p confirmed that additional rebar was actually cut because i removal of the Hilti to allow inspection would lead to the l . destruction of the bolt or the concrete around the hole. Instead, it was conservatively assumed for evaluation purposes that the'rebar was cut in all instances where'it may have been. ~ cut as a consequence of drilling deeper than the design documents authorized. Even if any rebar was actually cut by drilling in any of these - cases, it is unlikely that the rebar was completely cut. It is probable that the drill bit and the rebar were not aligned perfectly and, further, in several cases.'the diameter of the drill bit was less than the diameter of the rebar. For example, the diameter af a No. 18 bar, potentially cut in the subject case, is 2.25 inches, while the diameter of the Hilti bolt was 1/2 inch, for which a 1/2 inch drill bit is used. As l a result, the potential drilling into the 3rd Inyer No. 18 bar l could not totally sever the bar, but could only reduce the cross-sectional area by 28 percent. However,' in all evaluations, it was conservatively assumed that every rebat-that could have been partially: cut, was totally ineffective. Thene two assuriptions provide a significant margin of consr.rvatism in the results of the;4 valuations. 5.2 Review of Procedural Controls for Rebar__ Cutting Procedural controls for cutting rebar either while drilling for Hilti installations or by core drilling were reviewed by; the third party. -( b 1 =L

-n z. Lf y;-)]- R 'k ,~ .f .Rsvision:- 1 $x, 'N Page 10.wf 25. [f _1 n j_ Q./ I, g. s ) .i s "r 'RLSD8TS REPORT N y.' . (~] JISAP Iy e (). e i (Cont'd) ij .I 5.0 4 IMPLEMENTATION AND DISCUTSIOF.Ol' RESUI.TS (Gtic'd) t 1 l ] e..T Hilti bolts range intsto;s from 1/hindh in diameter to 1 14 s s inch in diameter. F41tfdo.!esite"installedbydrillingjnto-concrete using kill bits ei the same-ncminal diameter au 'tbe bJit and.by inserttng the bolt into the hole, qWhen the nut is i' tightened, the wedges arcyc.d the bolt exqstid ynd the bolt is anchored. ? ' / ,s l Core dr11%g' {ciso pdantimes called cord, boring) is performed using special'Jrtvea did co~re bits to drill an annular void and to remove he. core of materia 2 from within the void. 7 The precedurea'. relevant to rebar cutting.activitie.s in'the I contant of Ht'ici installations veie Nr.dtifia66s the 'f 4 f olicving: i a Construction procedure CEI-20, " Installation of 'Hilti' Drilled-in Boles", e Craft pr-edure CCl-47, " Requests for Rebar Cutting", r3

s i

t Quhlity Control Frocedure CP-QP-11.2 " Inspection of a i Concrete Anche:h. Bolt Installation", I QualityC Instruction QI-C?-11.2-1, " Installation of l 'Bilti"i Dr{11er'-in Eolts*'. p a s e r ,Theproceduresrelevan'ttoIoredrillingwereidenttfiedas the following:. .{. / j l a Craft procedure MCP-1.), " Requests for Core Drilling", y Quality Instruction QI-QA-11.0-6, " Inspection of i N i Grouting". - s l The procedures were revieue'd for t[he following asaectt,\\ relavant to rebar cu'tting: r( l The requiretdr;ts for engineering approvals fa rebar cutting; , lr / ,f ' /, i .i the method'of drillin3, including any details thst f relate to the possibility.of cutting rebar; e.g., i specification of' equipment to.be used; p, f 3 .b / y X,6 a y)' 3, '3.\\ 8 s / e l_ -Q V W.. -_-O

aW 4

Rsvision
.

'l Pags 11'of 25 i i RESULTS REPORT

  1. 'p -

ISAPL11.e' 1 1 (Cont'd) i i 5.0 IMPLEMENTATION AND DISCUSSION OF RESULTS-(Cont'd) "0 the requirements for QC inspection of the drilled holes ..i to verify that either no rebar was cut or that.rebar 1 was cut in accordance with a DCA authorizing rebar cutting; and the control of drilling equipment capable of cutting rebar. 5.2.1 Procedures for Hilti Installations 1 Construction Procedure CEI-20 " Installation of 'Hilti' Drilled-In Bolts" -j This procedure established the guidelines-and requirements for the field installation of 'Hilti' l ij i l drilled-in expansion anchors..The provisions of the-procedure apply to Hilti bolts used for installation of { safety-related equipment', and for the installation of non-s.afety-related equipment located in safety-related' i structures. Revision 0 of this procedure was issued on -j May 31, 1978. ( ) iy Section 3.2.1 of the procedure, states, in part, " Expansion bolt holes shall not.be drilled into concrete reinforcing steel unless approved by the Gibbs & Hill resident i engineer or his representative. Holes for the i expansion bolts shall be drilled into concrete by the use of suitable power dril,1s l using 'Hilti' carbide masonry bits of< the same nominal size as the bolt and which are designed and recommended by the Hilti Corporation specifically for this purpose." I' 1. These requirements have been repeated in all subsequent .,'s 1 revisions of the procedure. It is noted that the i carbide masonry bits are not capable of cutting through 4 t rebar (' Reference 9.10). b s } . Revision 7 of the procedure, issued on February 11, s t ~ w 1981, added in its Section 3.1.2.3. s r. \\\\ i i', y "Where cutting of structural reinforcing I I A,4 steel is permitted by the engineer, Drillco t ) l' d 1. ~ 1 6 g s, O , /,

1 1 7 ' Revision: 1' y Pege 12 of 25

/

.RESULTS REPORT j f ISAP II.e- \\, (Cont'd) i 5.0.. IMPLEMENTATION AND DISCUSSION OF RESULTS (Cont'd) l water cooled carbide / diamond bits or equal. l' shall be used. Once the structural. I reinforcing steel is cut,- the remainder of. the hole'shall be drilled with a 'Hilti' - carbide masonry bit per 3.1.2.1."- (Paragraph i ~ 3.1.2.1 of Revision 7 corresponds to Paragraph 3.2.1 of Revision 0.] j Section 3.1.2.4 of Revision 7 further added., ~ i "In limited access ~ areas it may,be difficult-to-drill. holes for; expansion bolts using. equipment as required by 3.1.2.1. For this situation, a flexible ^ drive drill with drill-press / vacuum base;and Drillco water cooled l carbide / diamond bit or approved equal: may be - l used. Caution shall be used when drilling:to-avoid the cutting of ' structural reinforcing steel. 'In no case'shall structural O reinforefng steel be (.t;without prior approval of the Engineer." l l The requirements of Sections 3.1.2.3 and 3.1.2.4, have been repeated in the subsequent revisions of the-procedure. When drilling is performed, whether'using carbide masonry bits or diamond drill bits,'it is obvious to an i operator when a rebar is encountered. Thus, the-caution in Section 3.1.2.4 affords a practical means of controlling rebar cutting. Revisions 1 and 2 of CEI-20 specified QC inspection-requirements for Hilti bolts. In-process surveillance' inspections. performed at a frequency (once per shift) specified in the procedure were intended to verify that. Hilti installations were performed in accordance with~ the guidelines of the procedure. All unsatisfactory. i conditions were to be reported on an Inspection Report.' However, the Inspection Report for these inspections did not include specific' requirements for a check'of l l 0

R: vision: 1 Pegs 13 of 25 RESULTS REPORT (]/ /~ ISAP II.e (Cont'd) 5.0 IMPLEMENTATION AND DISCUSSION OF RESULTS (Cont'd) the hole drilled for the Hilti to determine whether any ) rebar was cut, or to verify that rebar cutting was in { accordance with design change documents. This observation was transmitted to the QA/QC Review Team for their consideration in collective evaluation. Since Revision 3 of the procedure (dated January 11, 1979), QC inspections have been addressed by reference to applicable.QC procedures and instructions. Craft Procedure CCP-47 " Requests for Rebar Cutting" l Revision 0 of this procedure was issued on June 17, 1981, and is still the current revision. This procedure provides a method for controlling the requests for cutting of structural reinforcing steel embedded within structural concete by requiring that a document, Rebar Cut Request Uz:R), be used to communicate a rebar cut request co the Project Civil (m) Engineering. It is noted that prior to June 1981, rebar cut requests were communicated to engineering by v' phone calls or memoranda (Reference 9.11); however, the requests were still to be dispositioned with engineering approvals documented in DCAs or CMCs. Section 2.3 states, I "The project civil engineer or his designee shall review the RCR to ascertain its correctness, determine the specific { reinforcing steel being encountered, review the cutting criteria and rebar maps to determine the acceptability for cutting. If acceptable for cutting, a Design Change Authorization (DCA) will be issued indicating rebars to be cut." Also, engineering approval was required before issuance of the DCA. Quality Control Procedure CP-QP-11.2, " Inspection of, Concrete Anchor Bolt Installation" and Quality Instruction QI-QP-11.2-1, " Installation of Hilti Drilled-In Bolts" o

i Rsvision: 1 j Pegs 14 of.25 j RESULTS REPORT O i ISAP II.e \\, (Cont'd) .I i l i 5.0 IMPLEMENTATION AND DISCUSSION OF RESULTS (Cont'd) - i Revision 0 of CP-QP-11.2 and QI-QP-11.2-1 were issued l on December 14, 1979 and December 13, 1979, respectively. Before.this time, the requirements for-Hilti installation inspections were specified in CEI-20.. The generic inspection requirements are identified in CP-QP-11.2 while more detailed requirements are addressed in QI-QP-11.2-1. CP-QP-11.2 and QI-QP-11.2-1, Revision 0 and later a .) revisions required inspections to be performed at a. specified frequency to verify that Hilti installations. were performed in accordance with the requirements of the CEI-20. Section'3.1 of QI-QP-11.2-1 specifically. stated that concrete anchors were not to be drilled into reinforcing steel without written, engineering-approval. However, the Inspection Report for these inspections did not include specific requirements for a check of the hole drilled for the~Hilti to determine whether any rebar was cut or to verify that rebar cutting was in accordance with design change documents. This observation is the same as was observed with respect to CEI-20 and was also transmitted to the-QA/QC Review Team for their consideration in collective evaluation. 5.2.2 Procedures for Core Drilling Construction Procedure MCP-13, " Requests for Core Drillina" Revision 0 of this procedure was issued on September 1 27, 1977, and provides a method for controlling the request for core drills and obtaining required approvals. It applies to all core drilling in the plant. Core drilling is typically performed for installing wall / slab penetrations and installations of i through or. grouted-in anchor bolts. Section 2.4.2.1 contains instructions for correct placement of core drill holes to prevent damage to embedded plant items. Sections 4.1.1 and 4.1.2 require the engineer-responsible for the craft requesting the cutting of rebar to. initiate a Core Drill Request (CDR) j O

I Rcvision: 1 Pegt 15 of 25 RESULTS REPORT o ( ISAP II.e (Cont'd) 5.0 1 IMPLEMENTATION AND DISCUSSION OF RESULTS (Cont'd) detailing the size and location of the hole to be drilled. "The request form is then routed for review and approval through the B&R Engineering Department and the owner." The approval signature block on the CDR form includes a sign-off by civil engineering personnel as well as representatives of other disciplines. if appropriate. According to Section 4.2.1, "QA/QC notification of core drilling is required. The witness of work is a QA option, work may proceed if the QC inspectors are not available unless otherwise notified by QA/QC Department." 3 Later revisions of the procedure have maintained all of the requirements of Revision 0 and have added guidelines on chipping of concrete where needed for locating rebar. The requirement for QA notification was deleted in the second (May 28, 1980) and later I revisions of the procedure. However, core drilled holes were inspected prior to grouting as discussed in Section 5.2.3 below. ,s IV) 5.2.3 Quality Instructions Quality Instruction QI-QP-11.0-6, " Inspection of Grouting" i Revision 0 of this procedure was issued on July 28, 1976, and outlines the methods and criteria used to inspect grout pre-placement, pincement and post-placement. The instruction is relevant to the subject issue through the fact that core bores except for special cases, e.g., in block-outs, are grouted. Revision 1, June 13, 1977, of procedure CCP-16, " Grouting of Base Plates, Bearing Places, and Equipment Bases", which also applied to grouting of core bores. established the grout card as the place where the QC inspector documents his pre-pour checkout and acceptance by a signoff in accordance with the requirements of the QI-QP-11.0-6. The grout card required verification of " structural steel" but not of "rebar cutting" as a line item. Observed notations addressing rebar on the grout cards pertaining to pours involving rebar cuts indicated awareness of rebar cutting considerations. However, the formal inspection /3 requirements did not address inspection of core bores U for possible rebar cutting.

a Ravision: 1 1 Pega 16 of 25 RESULTS REPORT r~' (,,) ISAP II.e (Cont'd) 5.0 IMPLEMENTATION AND DISCUSSION OF RESULTS (Cont'd)- 5.2.4 Results of Review It was concluded that the procedure for Hilti installation, CEI-20, and the procedure for core drilling requests, MCP-13, established strict .) requirements for obtaining engineering approval prior. to any rebar cutting. d i l For Hilti installations, since its original issue in. j May 1978, CEI-20 cautioned against drilling into J reinforcing steel and specifically required the use of a carbide masonry bit which is not capable of cutting j through rebar (Reference 9.10). If rebar needed to be cut, an engineering evaluation and a DCA were required. Hilti installations were inspected by QC under a Hilti surveillance program for conformance with CEI-20 requirements; however, inspections for.rebar cutting were not documented. l In the subject case, the requirements of CEI-20 were t followed to the extent that when the first layer of no. 18 East-West rebar was encountered, an engineering evaluation was performed and a DCA was issued that authorized cutting of the first layer..However, if the rebar in the third layer was cut as alleged, authorization to cut a rebar in both the first and third layers would have.been required. a For core drilling, since its original issue in September 1977, MCP-13 cautioned about not damaging items embedded in concrete and required engineering evaluation and approval for every core bore. Pre-grouting inspections in accordance with j l QI-QP-11.0-6 required the involvement of Civil Engineering QC inspectors for every core bore that was

grouted, i.e., essentially every core bore.
However, inspection to verify that either no rebar was cut,or that rebar was cut in accordance with engineering authorization was not specifically required.

No procedures were identified that would establish controls on equipment used for rebar cutting, i.e., 7.-

y Ravision

-1 zv .Pags-17 of 25 3-h RESULTS REPORT c, -ISAP II.e (Cont'd) 5.0 IMPLEMENTATION AND DISCUSSION.0F RESULTS (Cont'd) core bore drill machines, diamond. drill bits or core bore drill bits. Such procedures 'were not essential to L preclude unauthorized rebar cutting,'since the procedure on Hilti drilling (CEI-20) and. core drilling -(MCP-13) provided adequate controls...However,. procedures controlling equipment.would have added.to the control;of rebar. cutting activitiesLand reduced the possibility of unauthorized rebar cutting. It-is concluded that while the procedural controls-governing drillingcoperations.were adequate,; additional requirements for QC. inspections for all rebar cutting-and controls of rebar cutting tools lwould'have strengthened them. Current procedures have been strengthened in these respects as discussed in Section 8.0. 5.3 Review of Documentation of'Rebar Cuts for H11ti Insta11ations and Evaluation of Postulated Rebar Cuts All Civil / Structural concrete outline and reinforcement drawings were reviewed by TNE to identify all DCAs and CMCs regarding'rebar cuts for Hilt 1' installations-in units 1 and 2 (Ref. 9.6). :A-total of 189 such rebar cut cases were identified (113 DCAs and-76 CMCs).. For.each of these cases. design drawings were reviewed.to determine whether there was rebar beneath the bar authorized for cutting that could potentially:have been cut'if a hole had been drilled deeper than implied by the authorization using:aldiamondtdrill bit. It was determined that in 62: cases such underlying ^rebar was specified in the design. TNE evaluated these'62 cases to determine' structural' adequacy,' postulating that the additional rebar, not. authorized.to'be cut, was cut,- regardless of the. length of the Hilti bolt installed. In all-62 cases the structures were found adequate. Therefore, it' was.not necessary from a structural point of view to determine if the additional'rebar thatlcould have been cut while drilling in the authorized locations, were in. fact cut. ' Identification of'DCAs and CMCs regarding rebar cuts.and the structural evaluations performed by TNE were reviewed and; 'found acceptable by the_ third' party (References.9.12 and- .9.13).. O

Rsvision: 1 Pass 18 of 25 RESULTS REPORT '[~ ' \\ ISAP II.e-(Cont'd) 5.0 IMPLEMENTATION AND DISCUSSION OF RESULTS (Cont'd) 5.4 Results of Ultrasonic Measurements Within this Action Plan two methods.were originally identified to evaluate and disposition Hilti installation cases where it was determined that the potentia 1' existed for cutting more ) rebar than. authorized:

1) to determine whether the drilled hole was deep enough to possibly cut rebar and evaluate 3

accordingly, or 2) to evaluate'the structure, postulating that if a rebar was authorized for cutting, any underlying rebar was also cut. As discussed in.Section 5.3, all cases with potential for unauthorized cutting were evaluated using the j latter. alternative. 'However, during the'early execution of I the Action Plan, the length of the Hilti bolts was determined-by ultrasonic measurement (as discussed in Section 5.1).in nine additional cases (Reference 9.8)..In six out of'the nine. 'j cases the Hilti bolt was found to be'long enough that rebar underlying the rebar that was authorized to be cut could also have been cut. In the other three cases the length of the Hilti was such that only the authorized cut should have been (~" (,)S made (assuming the hole is, in accordance with the procedures, only one half' inch deeper than the length of the Hilti bolt.) Based on these findings, the Hilti bolt length was not relied upon in dispositioning cases with potential unauthorized ) cutting. Instead, all of the 62 cases where there was rebar underlying the rebar authorized for cutting were evaluated postulating that the unauthorized cutting had occurred as discussed in Section 5.3. ) l 5.5 Shear Lugs l 4 An investigation to determine whether there were other work i processes that might have caused rebar cuts revealed that j i rebar cutting also could have occurred when holes were drilled for shear lugs used in some_ pipe supports. A shear lug is a piece of round steel bar, up to nine inches long, with a diameter from one to two inches, welded at the back of a support base plate to increase the shear capacity of the pipe I support anchorage. All pipe support drawings were reviewed to identify the supports utilizing a. shear lug (Reference 9.9). Twenty-four (24) such supports were identified, one of which I had QA documentation. Therefore an evaluation was performed for the concrete slab or wall where each of the remaining twenty-three (23) supports was installed assuming rebar was cut (Reference 9.14). In all cases, the structure was found to meet the design criteria. _ _ _ _ _ -. _ _ _ _ _ _ - _ _ _ _ _ _ = _ _ -. - _ _ - - _ _ - -. - - - _ -. _ _. = _ _ _.. . - - - -. A

7 l Ravision:l il; { + Paga 19'of 25 .) a. RESULTS REPORT .l -t IS AP. ' II. e 1 -(Cont'd) 5.0 IMPLEMENTATION AND DISCUSSION OFlRESULTSf(Cont'd) 5'.6. Review of'NRC Conclusion. i An issue that was addressed:in the SSER'(Reference'9.1), ,I concerned.the fact that'the number of. diamond' drill bits of. i the diameter sizes used:for.Hilti. installations purchased'for .the plant' appeared to be significantly larger'than-should,haveL been needed based on the extent of rebar cutting documented in the DCAs authorizing ~rebar cutting. This raised questions-concerning' potential unauthorized _use of diamond drill bits. The possibility.that such use.could.have resulted in unauthorized rebar cuts..was concluded by.the NRC to be of "... inconsequential effect..." (Reference 9.1). i This issue.was reopened in a meeting between NRC. staff'and.the' third party in October 1985, and the NRC: staff indicated that' an investigation of unauthorized use of diamond drill bits should be conducted. The NRC staff based their origina'l conclusion of: / inconsequential effect on an analysis that assumed a maximum. .j of 5000 diamond drill bits had been used on the project by the 1 time of the TRT investigations. The upper limit estimate of 5000 bits was arrived at by researching the purchase documents [.- for drill bits. 'NRC further assumed, in accordance.with-the I statements made by an individual who made allegations about-unauthorized rebar cutting, that.as many'as 20 percent of the diamond drill bits may have been.used in an unauthorized-manner, and that up to five reb'ars'could be cut with one drill bit. These assumptions combined with the estimate of approximately 800,000 to 1,200,000 rebars installed in the j concrete structures of the plant, led to the NRC's' conclusion 1 that approximately 0.6 percent"of the' total rebar in the plant could have been cut in'an unauthorized manner. It was further noted (Reference 9.1) that if every one of the 5,000 drill bits were used to cut'rebar (5 bars per. bit),:only 3 percent of the total rebar at the plant could have been' cut. In response to the NRC staff's request to reconsider the diamond drill bit issue, the Project investigated all diamond drill bit purchase documents. After screening for those sizes of bits used for Hilti installations, and deducting the number of bits used for cuts through non-structural embedded steel, e.g., steel templates, and.the bits in stock as'of late-1986, it was estimated that the number of diamond drill bits that O were available for rebar cutting was less than 2000 (Reference 9.15) rather than the 5,000 conservatively estimated by the; NRC, as. discussed above. i

Ravision: 1 i c Psgs 20 of 25 i RESULTS REPORT l r~" ()3 ISAP II.e j (Cont'd) 5.0 IMPLEMENTATION AND DISCUSSION OF RESULTS (Cont'd) A further added margin of conservatism to the numbers ) presented by the NRC in the S3ER is provided by the fact that the Project estimated the total amount of rebar in all j j concrete structures to be in the order of 2,000,000 (Reference 9.15) rather than the 800,000 to 1,200,000 assumed by the NRC. i Two crews, the steel fabrication department drilling crew and~ a millwright crew were assigned to perform drilling using diamond drill bits. The steel fabrication drilling crew typically drilled the small holes (2 inches or less in i diameter) and the millwright crew did the larger core borus I (Reference 9.16). (Drilling of concrete for Hilti installations using carbide masonry bits which could not cut rebar was not limited to the two special drilling crews.) After the termination of his employment, allegations about unauthorized rebar cuts at unspecified locations were made by the foreman of the steel fabrication department drilling crew j 'i that performed most of the drilling involving rebar cutting for Hilti installations.1 g (Reference 9.1).- The foreman had jj maintained a diary about the drilling activities of his crew. b He had stated that the diary included documentation of rebar cuts that had not been authorized and documented in appropriate design change documents. To assess the accuracy and implications of the allegations, the Project obtained a copy of the diary and thoroughly reviewed it. By comparing every rebar cut identified in the diary for seismic Category I j buildings with the authorizations. in the project documents, j the Project determined that there were no more than ten rebar cuts that had not been authorized by the Project (Reference 9.17). All ten cases were for installations for which other rebar cuts had been authorized. -{ An estimate of the number of potentially unauthorized cuts performed by the drilling crew during the total construction period was extrapolated by multiplying the number of unauthorized cuts during the foreman's employment by the ratio j l of the number of design change documents authorizing cuts issued during the total construction period to the number of authorizations issued during the period ~of the foreman's-employment (September 1978 - October 1979). This resulted in an estimate of a total of 22 potentially unauthorized rebar cuts in the concrete structures. This led to an estimate that at most 0.0013 percent of the approximately 1,650,000

} R2 Vision: IL Pag 21'of 25' I RESULTS REPORT j ' ~ ~ ISAP II.e (Cont'd) l 5.0 IMPLEMENTATION AND DISCUSSION OF RESULTS-(Cont'd) rebar in the seismic Category lI buildings of the. plant-(as compared to 2,000,000 in the total plant) have been subjected to some. amount of cutting (Reference 9.18). This.is significantly less,than the NRC estimate of 0.6' percent that was stated in the_SSER-8 for all concrete structures j ~ .j (Reference 9.1).- This estimate of.0013 percent is: judged to be reasonable..in part,~b'ecause the controls on rebar. cutting-j became more rigorous during.the. time frame.following.the-q foreman's employment. ~ Considering the fact that the steel fabrication. department drilling crew performed' practically all drilling for Hilti l installations that required rebar cutting'-(Reference 9.10):(a l millwright crew performed-core' drilling for holes with' larger 'l diameters) using special' heavy dr1111ng equipment providing water cooling to the drill bit, and the fact that the. diary. appears to be an accurately maintained' log'of the crew's activities, it-can be judged that the. diary provides strong j .1 evidence that the. total' number of unauthorized rebar cuts is well below the upper bound estimate presented by NRC-in' - SSER-8. Further, nine individuals, who-allegedly had knowledge of potential use of diamond drill bits by personnel other than the crew assigned to perform drilling requiring rebar cutting, gave sworn statements denying any knowledge'of unauthorized rebar cutting (Reference 9.1). Collectively, the evidence supports the NRC's conclusion about the " inconsequential effect on the safety of the structures" of the issue of unauthorized cutting of rebar. i 5.7 Summary of DIRs Two DIRs concerning potential unauthorized rebar cutting in the Fuel Handling Building were written during implementation ~ of the ISAP II.e. Both of these DIRs (E-0986 and E-1050) were-written to document the. concern expressed on the subject case in two separate NRC Reports. Based on the evaluation of the subject case, the two DIRs were classified as deviations, j 1.e., the possible (not confirmed) unauthorized rebar cutting l represents a violation of a design criterion.. The subject case was resolved by implementation of this Action Plan ISAP i II.e, and'the two DIRs were closed. O

Revision: 1 Paga 22 of 25 RESULTS REPORT l ISAP II.e l (Cont'd) 5.0 IMPLEMENTATION AND DISCUSSION OF RESULTS (Cont'd) 5.8 Safety Significance Evaluation The evaluation of the Fuel Building mat concluded that the l structural design. criteria are met even if a rebar in the I third layer was cut as alleged. The evaluation of the 62 cases where rebar cutting was authorized but underlying ) rebar could also have been cut, concluded that e"en if the underlying rebar had been cut, the structural design criteria were met. The same conclusion was reached in the evaluations of the ten potentially unauthorized cuts identified in the alleger's diary.. Based on these evaluations, and the fact I that the potentially unauthorized cuts identified in.the diary j are at scattered locations, there is a reasonable assurance j that other unauthorized rebar cuts would not present a safety This conclusion is in agreement with j significant deviation. i the conclusion of " inconsequential effect on the safety of structures" presented in the SSER (Reference 9.1). In conclusion,~no deficiencies were identified in the investigations for this ISAP. OQ 5.9 Root Cause and Generic Implications Assessment I The investigations. performed under this action plan did not identify any deficiencies or adverse trends, thus an i evaluation of root cause and generic implications.is not. required by the CPRT Program Plan.

6.0 CONCLUSION

S 1 The concrete mat at the 810'-6" elevation of the' Fuel handling 1 Building was found to be structurally adequate even if the second layer of No. 18 rebar was cut as alleged. The.other identified locations where the possibility of unauthorized rebar cutting existed were also found to be structurally adequate assuming rebar The procedures specify requirements to perform drilling was cut. for Hilti installations and drilling core bores in such a way that, if they are followed, unauthorized rebar cutting cannot occur. This investigation did not identify.any deficiencies. 7.0 ONGOING ACTIVITIES There are no ongoing activities. f~ l

.. + Revision: 1 Pags 23 of 25 4 RESULTS REPORT I I ISAP II.e (Cont'd) 8.0 ACTION TO PRECLUDE OCCURRENCE IN THE FUTURE Procedures CEI-20 and QI-QP-11.2-1 were revised to strengthen the controls of rebar cutting ~in order to minimize the possibility of future occurrences of unauthorized rebar cutting when drilling for Hilti installations. The revised procedures require that if rebar cutting is performed, a construction traveler be used and that a QC i inspector inspect the bolt holes to ascertain that the rebar is cut in accordance with the issued design change authorization. The QC inspection for rebar cutting will be documented. Procedures MCP-13 and QI-QP-11.0-6 were revised to require that if rebar cutting is performed, a construction traveler be used with a i " hold point" for QC inspection'to verify that any rebar cutting is completed in accordance with the issued design change authorization. This strengthens procedural controls of. rebar cutting due to core boring. MCP-13 was further revised to establish controls on the diamond drill bits and core bore bits; new requirement will restrict issuance of those bits only to the cognizant craft foreman- / responsible for core drilling against the rebar cutting traveler. \\s_, The General'Mechanica) Superintendent or his Assistant signs on the traveler for his approval of issuance of the drill bit.

9.0 REFERENCES

'I 9.1 NUREG-0797, Supplement No. 8. " Safety Evaluation Report 1 i Related to the Operation of Comanche Peak Steam Electric Station, Units 1 and 2", pages K-89-91, February 1985. 9.2 Operation Traveler HE-82-1454-6000. 9.3 Design Change Authorization, DCA-7041 Revision 7. i 9.4 Memorandum, J. Arros to ISAP II.e File, August 25, 1987, i 9.5 Comanche Peak Project Civil Engineering Calculation SFB-102C, Set 1, Revision 10 with supplementary information. 9.6 TNE-CPSES Calculation Sheet, "TRT-Issue II.e, Investigation into Possibility of Additional Rebar Cuts - Other Than Those Previously Authorized - for Hilti Bolt Installation" M. M. Kamble, June 12, 1986, with supplementary information. C\\ V

t Revists : 1 Page 24 of 25 RESULTS REPORT [ ISAP II.e j b (Cont'd) J

9.0 REFERENCES

(Cont'd) 9.7 TUGC0 Memorandum, C. R. Hooton to B. K. Bhujang, " Comanche Peak Steam Electric Station, TRT Issue II.e, Evaluation of Rebar Cuts", March 6, 1986, with supplementary information. 9.8 Final Report " Ultrasonic Length Measurement of Selected i Bolting at the CPSES Units 1 and 2", Rev.1 Southwest Research Institute, September, 1985. l 9.9 Memorandum to ISAP II.e File " Project Identification of Pipe Supports Utilizing Shear Lugs", G. Braun, August 20, 1987. ~ 9.10 TERA Contact Log, Ben Hauser, Bob Prather, J. Arros, August 12, 1987. 9.11 TERA Contact Log, J. Arros with S. McBee, August 3, 1987. 9.12 TENERA Notes, "TRT Issue II.e, Review of Project's Identification of CMCs and DCAs Related to Hilti Rebar Cutting", F. Ramezanbeigi, July 14, 1986. 9.13 TENERA Notes, "TRT Issue II.e, Review of Project's Evaluation of Postulated Additional Rebar Cuts due to Hilti Installations", F. Ramezanbeigi, July 14,'1986. 9.14 TENERA Notes, " Review of Shear Lug Calculations TRT-Issue II.e", F. Rameranbeigi, June 12, 1986. l 9.15 STIR CPRT-S-004, Rev. O, "Rebars Improperly Drilled / Cut During Hilti Expansion Anchor Installation" June 12, 1987. 9.16 Letter, USNRC to TUGCO, G. L. Madsen to R. J. Gary, September 29, 1983. 9.17 Memorandum, F. Ramezanbeigi to J. Arros, " Third Party Check of SVEC's Review of Messerly's Diary", September 1, 1987. l 9.18 Memorandum, F. Ramezanbeigi to J. Arros, " Third Party Check of SWEC's Estimate of Total Number of Rebara Received at CPSES", September 1, 1987. 1

Paga 25 of 25 RESULTS REPORT ISAP II.e (Cont'd) Figure 1 Fuel Building Slab at Elevation 810'-6" Partial Plan Shcwing Process Aisle Rail Hilti Bolt Location and Positions of Upper Three Layers of Rebar N-11.2- .L _ !._ 1._ _ l_ _ _. _ l - l_ _L 1 7' l l t l _..,_ pRail Base .l l l l.e l Centerline (TYP.) ( L O L __ _ E _ 9_ _! t _ _+_ _.4_ . _.). Q __ 1 l I l l A rocess Aisle P ._. 7.,. . _ _ 1 _ +l _. 7 _ J b l l l Rail (TYP.) ,.u l ,. _l l il l l_ e _. 4 _ _ l __ _.lj_. - T - 7 ~ l I I.

  • t--Hitti Bolt b

4 L (TYP.) "'~ g. __9 N l l t i i l l I l I #18 @ 1*-0" 1 CC layers 1 & 3 C 7_ ___q_ - (TYP.) a Li J l i i I i i b -yrf--t-~r --t --f mm-jt,,,, 3. o. l l l CCla _.1 _ l _ pl ,._ g fTYP.)yer 2 o g l W l I l l l l I I o i _%g __ j p_.4_ _.9 _.l_ 4_ l I l l_ l e l i t "~ -l 4 _. l -p_ l__._p_ _A p i ll l t i y __ 4 . __p._..;I i T-_ ;_ __.t 4 e m 4

g

__t, :,..;I I I l _. .I ._ __.L __ .__ __1- __ E l. p l '-t (TYP.) 3'* 3' i l I -y t-2'73/4" 2'73/4" s 5 CENTERLINE CENTERLINE CENTERLINE RAIL PROCESS AISLE RAll N n, yTop ot Floor b #18 O SECTION A-A j l 1}}

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