ML20214V832
| ML20214V832 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 05/14/1987 |
| From: | Beck J TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | |
| Shared Package | |
| ML20214V785 | List: |
| References | |
| NUDOCS 8706120313 | |
| Download: ML20214V832 (42) | |
Text
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O COMANCHE PEAK RESPONSE TEAM RESULTS REPORT ISAP:
VII.b.4
Title:
Hilti Anchor Bolt Installation REVISION 1 O
b,k1wOs /
cht/A 7 Issue C 4rdinator g Date
/
JY $7 1ew Team Leader Date/
/
- k. fL s%vh7 Jo p. Beck, Chairman CPRT-SRT Date O
070 m oata e7060e PDR ADOCK 05000445 h
Rsvision:
1 Pego 1 of 41
-RESULTS REPORT
-s ISAP VII.b.4 Hilti Anchor Bolt Installation
1.0 DESCRIPTION
OF ISSUE IDENTIFIED BY NBC (NUREG 0797, Supplement No. 11, Pages 0-293 and 0-297)
The TRT inspected Hilti anchor bolt installation on pipe, supports and electrical raceway supports to the requirements of QI-QP-11.2-1, Installation of Hilti Drilled-In Bolts.
The TRT found the following deviations during its inspection:
1.1 Cable Spread Room 133 Inspections "Hilti Kwik bolts (concrete expansion anchors) as installed did not meet minimum effective embedment criteria (Reference QI-QP-11.2-1, Section 3.5.1, Revision 16.)"
Three of the twenty-four bolts inspected did not meet the minimum embedment requirements.
1.2 Electrical Raceway Support Inspections O(,/
"CTH-6742 (Auxiliary Building) anchor bolt torque was not verified (paragraph 3.5 of the procedure). Hilti bolts were not marked in accordance with Attachment 1 of the procedure, nor was the length of these bolts verifiable (paragraph 3.2)."
"CTH-5824 (Containment Building) base plate bolt holes had violated minimum edge distance--edge distance cannot be less than 1 7/8" (Attachment 2 of the procedure). Actual distance was 1 5/8" to 1 3/8" from the nearest plate edge. This condition affected five of the eight Hilti anchor bolt holes in the base plates for this hanger."
"One Hilti bolt was skewed to more than 15 degrees.
Maximum allowable skew was 6 degrees without corrective bevel washers (paragraph 3.1.2)."
"The Hilti bolt torque on this hanger CTH 6741 (Auxiliary Building) was not documented as being verified by QC (paragraph 3.5)."
O
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1 Pegs 2 of 41 7-~g RESULTS REPORT U
ISAP VII.b.4 (Cont'd) 2.0 ACTION IDENTIFIED BY NRC NUREG 0797, Supplement No. 11, Pages 0-293 and 0-297 Evaluate the TRT findings and consider the implications of these findings on construction quality. "... examination of the potential safety implications should include, but not be limited to the areas or activities selected by the TRT."
" Address the root cause of each finding and its generic implications..."
" Address the collective significance of these deficiencies..."
" Propose an action plan... that will ensure that such problems do not occur in the future."
3.0 BACKGROUND
The primary function of Hilti anchor bolts at CPSES is to provide s
l baseplate anchorage, with both tensile and shear loads being distributed to the anchor bolts. Hilti bolts were installed by s.
Brown & Root craftsmen and inspected by TUGC0 and Brown & Root inspectors in accordance with the applicable procedures, with the exception of HVAC duct supports.
For HVAC duct supports, installations and inspections were performed by Bahnson Service Company. The Bahnson craftsmen and QC inspectors were trained to Bahnson procedures, which have the same essential requirements as those procedures that were used by Brown & Root craftsmen and TUGC0 inspectors.
Since Bahnson was a completely separate organization, the results from the reinspections.of HVAC duct supports are discussed separately in Section 5.3.3.
The TRT findings for Hilti bolts identified in Section 1.0 were predominately deviations on cable tray hangers. Other issues related to cable tray hangers led to the implementation of a TUGC0 corrective action program as described in DSAP VIII. DSAP VIII also describes the third-party overview to be performed on this corrective action program. Because efforts conducted under the auspices of the corrective action program include the reinspection of cable tray hangers (including Hilti bolts), they are not included in this Action Plan.
This Action Plan for Hilti bolts utilized the results of the reinspections and documentation reviews performed under Issue Specific Action Plan (ISAP) VII.c, " Construction Reinspection / Documentation Review Plan", to evaluate the severity i
l Revision:
1 Pags 3 of 41
=.
RESULTS REPORT ISAP VII.b.4 (Cont'd)
3.0 BACKGROUND
(Cont'd) and extent of the Hilti bolt concerns for all applications (except cable tray hangers). A separate torque verification program conducted as part of this Action Plan addressed the major support populations, including cable tray hangers.
4.0 CPRT ACTION PLAN 4.1 Scope and Methodology The objective of this Action Plan was to assess construction quality with respect to Hilti bolt installations.
Implications resulting from the TRT findings were addressed through reinspections conducted under ISAP VII.c and evaluated
.in this Action Plan. Reinspections were performed for the safety-significant characteristics for Hilti bolts installed at CPSES (with the exception of cable tray hangers, which are being addressed in the Corrective Action Program described in DSAP VIII).
The following tasks were implemented to achieve these
, objectives:
Review specification and procedures for safety-significant characteristics, Ensure inclusion of safety-significant characteristics for Hilti bolts in the ISAP VII.c inspection procedures, Review the requirements among various project (discipline) documents for commonality and for adequacy.
Evaluate sample size for adequacy, Initiate Hilti bolt torque verification program that supplements the documentation review for setting of Hilti bolts with actual field results.
,3 The specific methodology is described below:
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4.1.1 A review of the specification and procedure 4
- c requirements was performed to identify safety-significant characteristics.
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Revision:
1 Page 4 of 41 RESULTS REPORT O
5 I
s_s ISAP VII.b.4 (Cont'd) 4.0 CPRT ACTION PLAN (Cont'd) 4.1.2 A review of the CPRT Quality Instructions for ISAP VII.c was performed to verify the consistency of Hilti bolt characteristics in the reinspection of different populations. The review also provided assurance that the CPRT Quality Instructions covered all safety-significant characteristics required for Hilti bolt installation.
4.1.3 A review of the specification, installation procedures, QC inspection procedures, and training procedures for craftsmen installing Hilti bolts for various items, i.e., electrical raceway supports, pipe supports, HVAC supports, equipment supports, etc., for Units 1, 2 and common was performed to determine consistency and adequacy.
4.1.4 The sample size and samples chosen from the ISAP VII.c were evaluated for their adequacy in supporting the f"*
objectives of this Action Plan.
D 4.1.5 Reinspections and documentation reviews were performed under the auspices of ISAP VII.c.
The specific results are discussed in Section 5.2 of this Results Report.
4.1.6 To provide additional assurance in the results from the ISAP VII.c document review for the non-recreatable characteristic of " setting" (expanding the wedges by torquing) of Hilti bolts, the physical condition of a group of Hilti bolts was checked through a torque verification program developed and implemented under this action plan. The program consisted of checking torque for a number of Hilti bolts from electrical raceway supports, pipe supports, and HVAC duct supports.
1 4.2 Participants Roles and Responsibilities i
The organizations and personnel that participated in this effort are described below with their respective scopes of work.
4.2.1 CPSES Project l
4.2.1.1 Assisted in determining the number of items
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with Hilti bolts to be covered in the VII.c
(
population.
l
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1 Page 5 of 41 RESULTS REPORT ISAP VII.b.4 (Cont'd) 4.0 CPRT ACTION PLAN (Cont'd) 4.2.1.2 Processed NCRs that were generated due to this Action Plan.
4.2.1.3 Personnel Mr. C. R. Hooton TUGC0 Coordinator 4.2.2 CPRT-QA/QC Review Team 4.2.2.1 All activities not identified in 4.2.1 above were the responsibility of the QA/QC Review Team.
4.2.2.2 Personnel (Prior to May 1,1986)
Mr. J. Hansel QA/QC Review Team Leader Mr. S. H. Popper Issue Coordinator Mr. J. Adam Supervisor, SSEG 4.2.2.3 Personnel (Starting May 1, 1986)
Mr. J. Hansel QA/QC Review Team Leader l
Mr. C. Beasley Issue Coordinator P
I Mr. J. Adam Supervisor, SSEG 4.3 Qualifications of Personnel Where tests or inspections required the use of certified inspectors, qualifications were to the requirements of ANSI N45.2.6 at the appropriate level. Third-party inspectors were certified to the requirements of the third-party employer's Quality Assurance Program and were specifically trained to the requirements of the CPRT quality instructions and CPRT procedures generated to implement this action plan.
Other participants were qualified to the requirements of the CPRT Program Plan.
n v
Revision:
1 Pegs 6 of 41 RESULTS REPORT ISAP VII.b.4 (Cont'd) 4.0 CPRT ACTION PLAN (Cont'd) 4.4 Procedures This Action Plan was conducted in accordance with instructions developed for CPRT Action Plan VII.c and an instruction developed for the torque verification program identified in 4.1.6.
See Table i for the appropriate instruction numbers.
4.5 Sampling Plan The sampling plan for Hilti bolt reinspections was developed in accordance with ISAP VII.c.
When selecting items for the random sample, it was required that at least 60 sample items be reinspected for each attribute pertaining to each population. However, for Hilti bolts this requirement was not considered practical for each construction work category (CWC) because of the large number of items in each population that would have to be examined in O
order to locate the appropriate number of items with Hilti bolts. On this basis it was decided that proportional sampling across populations of items with Hilti bolts would be used to obtain the required total number of sample items with Hilti bolts.
In each population the installation of the Hilti bolts was subject to similar procedural requirements and was performed by craft with similar training. The minimum number of items with Hilti bolts randomly selected from each of the populations was proportional to the estimated number of items potentially containing Hilti bolts in the population. The proportional sampling process employed is described more fully in ISAP VII.c.
Hilti bolts were chosen on an engineered basis for the torque verification program for three support groups (pipe supports, KVAC duct supports, and conduit supports) from the ISAP VII.c samples and an additional sample of cable tray hanger bolts.
The process is discussed further in Section 5.4.
4.6 Acceptance Criteria Acceptance criteria were based on the following:
Reinspection and documentation reviews were performed in accordance with instructions developed for ISAP VII.c.
Inese instructions include acceptance criteria for Hilti bolts taken O
from Project Procedure CEI-20. " Installation of Hilti
Rsvision:
1 Page 7 of 41 RESULTS REPORT ISAP VII.b.4 (Cont'd) i 4.0 CPRT ACTION PLAN (Cont'd)
Drilled-in Bolts." which was used in conjunction with project documents (drawings, Component Modification Cards (CMCs),
Design Change Authorizations, etc.) to perform the reinspections.
For torque verification the torque acceptance value, selected on the basis of an engineering evaluation, was 80 percent of the original setting torque. This percentage'is a criterion used at other projects where verification programs have been performed.
Since data on Hilti type bolts show that they relax in-place, the attainment of this level of torque would be a strong indication that the anchor had been previously set to the required value. The acceptance criteria also covered
[
bolt nut rotation occurring prior to achieving the 80 percent
~
torque value.
In such cases, attainment of 100 percent of the original torque value within one full turn of the nut was acceptable. This second criterion was also used at other projects and is based on the phenomenon that if the wedges had O
been set and relaxation had occurred, only a small amount of' expansion would be required to reapply the initial installation torque.
5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS 5.1 Summary of the Action Plan Implementation This Action Plan consisted of a series of reviews of applicable procedures and specifications, a reinspection program of a sample of Hilti bolt installations with a companion documentation review in accordance with ISAP VII.c, and a torque verification program.
The following project documents were reviewed to identify those characteristics relating to the Hilti bolt installation that had safety significance:
Gibbs & Hill project specification no. 2323-SS-30 Revision 1. dated February 10, 1984, " Structural j
Embedmonts";
I i
Brown & Root procedure CEI-20, Revision 9, dated i
December 16, 1983, " Installation of Hilti Drilled-In Bolts"; and i N i
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Revision:
1 Page 8 of 41 RESULTS REPORT l
ISAP VII.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd)
TUGC0 Instruction QI-QP-11.2-1, Revision 18, dated June 7, 1985, " Installation of Hilti Drilled-In Bolts" Note: These were current revisions at the time of QI development.
The safety-significant characteristics identified were compared to procedures used at other projects to assure all safety-significant characteristics were included. This review is discussed further in Section 5.2.
As ISAP VII.c was intended to provide the majority of the data for this Action Plan, the Quality Instructions used in ISAP VII.c were reviewed to determine that they covered all the safety-significant characteristics required for Hilti bolt-installation. In addition, the sample size and samples chosen for the reinspection program under ISAP VII.c were evaluated to ensure that the sampling was in accordance with the sampling plan discussed in Section 4.5 of this Results Report.
Implementation of ISAP VII.c included the reinspection of a sample of Hilti bolt installations utilizing the verified 3
list of inspection characteristics: bolt size, type and quantity, embedment depth, spacing, angularity, concrete damage, nut engagement and nut bearing. Note that edge i
distance is normally covered in ISAP VII.c populations as a separate attribute or characteristic of a bolted item.
In addition, a documentation review of original QC inspection reports was performed to ascertain whether the appropriate 3
i non-recreatable characteristics had been satisfactorily j
inspected.
l To provide additional assurance that the bolt installation process was executed properly, the setting of a selected group of Hilti bolts was verified by a torque verification program.
This program included Hilti bolts from three major areas:
electrical raceway supports, pipe supports, and HVAC duct j
supports.
Exclusion of other populations was based on the low j
frequency of use or the predominant use of smaller size bolts on supports with lower design stress.
I i
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Rsvision:
1 Pags 9 of 41 RESULTS REPORT b
ISAP VII.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd) 5.2 Review of Procedures A review of the installation and inspection procedures was performed to verify that the appropriate characteristics were included. During the review it was determined that the procedures lacked the requirement of maintaining 1:20 bearing for nut and washer. Also, the installation procedure was not specific in the spacing criteria to penetration sleeves or chaefered concrete corners. Further discussion of these inadequacies is provided later, along with recommendations for resolving the resulting concerns.
5.3 Reinspections and Documentation Reviews Conducted under CPRT Action Plan VII.c Reinspections and documentation reviews.of Hilti bolts installed by Brown & Root were conducted for nine populations.
Table 2 provides a list of the populations along with information regarding the number of samples with Hilti bolts from each of the populations.
Each population used the same Hilti characteristics for the reinspections and documentation reviews. -The characteristics used are listed in Tables 3 and 4 Documentation review was conducted on the original QC inspection reports for non-recreatable characteristics.- From the reinspection and documentation reviews, nonconforming conditions were documented on deviation reports. These deviations were evaluated to determine if they were safety-significant. The deviations were also categorized and evaluated for adverse trends.
5.3.1 Reinspection Results The reinspection program reviewed the in-place condition of approximately 3,000 Hilti bolts of varying i.
diameter involving approximately 45,000 individual inspection points. From this total, 174 deviations were identified during the reinspections. Table 5 i
contains a tabulation of all reinspection deviations.
This section provides, by characteristic, a discussion of the reported deviations, an analysis of the effect of the deviations on the functional capability of the j
Hilti bolts, and an analysis for the presence of j
trends. The function of Hilti bolts is to transfer tensile and shear loads to the concrete structure in
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which the bolts are installed.
I
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1 Page 10 of 41 7-~
RESULTS REPORT ISAP VII.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd)
Size, Type and Quantity Hilti bolts were reinspected to verify that the size, type and quantity of bolts installed were as specified on the installation documentation.
In defining the inspection for Hilti bolt length it was determined that the marking on the end of the bolt would be an adequate indication for length. This was judged to be adequate based on the findings of an extensive ultrasonic testing (UT) program performed on site during the period 1980 to 1981, when some 10,000 Hiltis were examined. The results of the test program showed that only 13 bolts were found to have been modified prior.to installation. From this study it can be concluded that the marking on the bolt would be a highly reliable indicator of the bolt length, based on the low incidence of these discrepancies.
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There were 51 deviations for size, length, o'r type of f
bolts identified during the reinspections. None was identified for quantity of bolts.
Eighteen of the deviations were due to the bolt not being stamped with an identification mark that indicates bolt type and length. Ultrasonic examinations performed on these bolts revealed that 15 of the bolts were the type and length required by the installation drawing. These deviations were determined to be not safety-significant. For the three remaining deviations, the bolts were 1/2-inch short of the specified length. The documentation records for these bolts indicate that the bolts had been previously verified as the correct length. Based on review of the Hilti catalogue, the longest length of this diameter was the one specified and the next length in size is 2 1/2 inches less than the one specified.
It is concluded that the appropriate size bolt was installed though it has been modified.
However, overall length is not significant provided embedment is adequate and, in all three cases, the bolts provided the required embedmont. These deviations were determined to be not safety-significant.
v
Revision:
1 Page 11 of 41 RESULTS REPORT ISAP VII.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd)
Twenty-six of the deviations were due either to the bolt being longer than required or a " super" Hilti bolt (two sets of wedges) being used rather than a regular Hilti bolt (one set of wedges). Project procedures allow these type of substitutions for rework if bolt modifications are required. Evaluations indicate that these types of substitutions provide at least the same capacity as that provided by the originally required bolts.
These deviations were determined to be not safety-significant.
One of the deviations was due to a Richmond insert being substituted for a Hilti bolt.
Evaluation d
indicates that the insert provides at least the same capacity as that provided by the originally required bolt. This deviation was determined to be not safety-significant.
i Two of the deviations identified were due to markings on the bolts that indicated that the bolts were shorter l
than the drawing-specified length. One of these deviations was for a bolt that had been modified, as a CMC instructed, " rethread the bolt as required", which indicates that the bolt was cut.
Review of the inspection report determined that the bolt had been inspected with the modified length documented on the inspection report. However, the support drawing had not been revised to show the modified length. The other deviation occurred due to the bolt being stamped
^
incorrectly, as ultrasonic examination revealed the bolt was the length specified on the drawing. Based on j
the bolts providing the required embedmont, these deviations were determined to be not safety-significant.
i i
i Four deviations occurred on the same support, where l
1/2 inch diameter bolts were used where 3/4 inch diameter bolts were specified. The deviations resulted from the bolts being installed to revision 1 of the detail drawing, which specified 1/2 inch' diameter l
bolts. However, revision 2 and subsequent revisions specify 3/4 inch bolts. An NCR was written that i
j approved the 1/2 inch bolts as acceptable, but a CMC
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was never issued to document the exception for the detail drawing.
Because the bolts were acceptable per the NCR, these deviations were determined to be not safety-significant.
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Pag 2 12 of 41 RESULTS REPORT ISAP VII.b.4 l
(Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd)
If deviations similar to these were to occur in the uninspected portion of the Hilti bolt population, it is unlikely that a construction deficiency would result, since the installed bolt in each instance met the applicable design requirement. Therefore, no adverse trend was identified.
Embedmont Depth Hilti bolts were reinspected to verify that the embedment of the bolts met the minimum required. There were 15 embedment deviations identified during the i
reinspections. The deviations ranged from 1/32 inch to 1
3/4 inch less than the required minimum embedment.
Evaluation of all these deviations determined that even with these reduced embedmonts, the resulting installed 4
capacity of each bolt still maintains a design factor of safety against ultimate tensile failure of 4.0.
Should similar deviations occur in the uninspected portion of the Hilti bolt population, it is conceivable that the factor of safety against ultimate tensile failure of some of these bolts could drop below the design factor of safety. However, the ability of the 3
bolt to sustain the design load would not change; that is, it would still be able to perform its function.
The difference would be that a bolt with less than the required embedment would be able to achieve an ultimate tensile capacity somewhat less than the capacity it would have achieved with the required embedmont.
Review of the manufacturer's test data indicates that the amount of load to cause initial slip in the anchor i
decreases but not significantly when the embedment I
depth is decreased in the range of the magnitude of the identified deviations.
i j
Additionally, the ultimate values used in the design i
criteria are based on a concrete strength at 28 days of 4000 psi. The test results reviewed in ISAP II.b.
i
" Concrete Compression Strength" indicate, however, that the concrete strength at 28 days for CPSES is typically much higher. This increase would add additional conservatism in the design of Hilti bolts.
O i
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Rsvision:
1 Pcg3 13 of 41 RESULTS REPORT ISAP VII.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd)
The trend evaluation concluded that, in the limiting case where the actual embedment was 25 percent less than required, the bolt's ability to carry the full allowable load would likely be unchanged, and such a deviation would be not safety-significant. Therefore, no adverse trend was identified.
Spacing The spacing between Hilti bolts on one attachment and those on an adjacent fixture and/or other embedded items was teinspected to verify that the spacings are in accordance with design requirements given in drawings or approved procedures. There were 63 spacing deviations identified during the reinspections. The worst case resulted in an estimated 50 percent reduction in the bolt's ultimate tensile capacity.
O Project procedures require that prior to installing a
()
bolt that will result in a spacing violation, the installation is to be evaluated and approved by Engineering.
For each of these deviations an Engineering Evaluation of Spacing Violation (EESV) could not be located.
Review of the program for performing EESVs found that there was not a central tracking system, as each discipline had its own tracking system.
It could not be determined whether the identified files contained all the EESVs that had been performed. Hence, it could not be determined whether these spacing violations had been previously identified and evaluated or not.
Evaluations of these 63 deviations determined that the as-installed capacity of each bolt still maintains a design factor of safety against ultimate tensile failure of 4.0.
Therefore, all of these deviations were determined to be not safety-significant.
Should the uninspected portion of the Hilti bolt population have similar spacing deviations, it is conceivable that an attachment that uses a single or double-bolt pattern could have its ultimate tensile capacity reduced sufficiently to jeopardize its ability to perform its safety function.
Based on this
(
observation and the indeterminate nature of prior U
engineering evaluations (i.e., the EESV problem
R:vicion 1
Peg 2 14 of 41 RESULTS REPORT ISAP VII b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd) described above), spacing violations were determined to constitute an unclassified trend. A root cause and generic implications evaluation for this unclassified trend is provided in Sections 5.6.1 and 5.7.
Angularity Hilti bolts were reinspected to verify that the bolts were installed with less than six degrees in angularity from the perpendicular axis to the concrete surface.
There were three valid deviation reports describing deviations where the angularity was 6.5, 6.6 and 12 degrees, respectively.
Evaluation of the three deviations determined that the as-installed capacity of each bolt is greater than the design loads such that they provide a factor of safety greater than 4.0.
Should other deviations of similar f'h magnitude, including the 15 degree deviation noted by l
Ns the NRC, occur in the uninspected portion of the Hilti bolt population, it is expected that they would also be not safety-significant. This is based on an evaluation that concluded that any increase in shear loads due to angularity would be offset by the conservatism that exists in bolt design for allowable shear and that the amount of increased tension would be negligible.
Therefore, no adverse trend was identified.
Concrete Damage Hilti bolts were reinspected to verify that the structural concrete surrounding the fixture was not spalled in a manner that could significantly reduce the capacity of the Hilti bolt. There was one deviation that involved an abandoned hole with a spall 1/2 inch in depth located close to an existing Hilti bolt.
Evaluation of the deviation determined that, even with the reduction in the bolt capacity due to the amount of concrete damage that exists, the resulting installed capacity of the bolt still maintains a design factor of safety of 4.0 against ultimate tensile failure.
Therefore, this deviation was determined to be not
/-'s safety significant. No adverse trend was identified (j
for this characteristic.
R:ivision; 1
Pcg3 15 of 41 RESULTS REPORT ISAP V11.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd)
Nut Engagement and Bearina Each Hilti bolt was reinspected to verify that the nut on the bolt was fully engaged, that the nut was not bottomed-out, that the nut had a washer and that the nut was properly bearing with a bearing angle not greater than 1:20. There were 41 deviations for these characteristics identified during the reinspections.
There were seven deviations due to the nuts not having washers under them. The absence of washers is expected to have little effect on the bolt setting, since the washer material and the plate material provide similar bearing surfaces. While some increase in bearing friction may be anticipated, tests performed by the Project have shown that lesser amounts of torque than those specified at CPSES are capable of setting the anchor properly. Any galling that may take place where O
nuts are tightened directly against the connected part d
is not detrimental to the static or fatigue strength of the joint. Review of these deviations shows that the nuts obtain adequate bearing for the as-designed hole size without the washers. Therefore, these deviations were determined to be not safety-significant.
There were two deviations that occurred on the same base plate due to the washer not completely covering slotted holes.
Review of these deviations shows that adequate bearing of the washer exists without covering the entire slot. Therefore, these were determined to be not safety-significant.
There were four deviations, including one of the items with an angularity deviation, that occurred due to the bearing angle of the washer with the base plate being greater than 1:20.
Review of the specification and procedures indicates that 1:20 was not a requirement for Hilti bolting at CPSES. This missing requirement issue was transmitted to the Design Adequacy Program (DAP) for their consideration. Evaluation of the deviations determined that they were not safety-significant.
O
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1 Pass 16 of 41 RESULTS REPORT ISAP VII.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd)
There were nine deviations due to nuts not being fully engaged.
In each case a minimum of three threads was engaged. Evaluation of the deviations determined that the bolts had sufficient engagement to develop adequate bolt strength. These deviations were determined to be not safety-significant.
There was one deviation where the nut was loose on the bolt. Torque verification determined that the bolt was set, although it was not in tension. Published tests have shown that loss of preload does affect the amount of deformation or displacement of the anchor but does not reduce the anchor's ultimate tensile capacity.
Thus, the evaluation of the deviation determined that it was not safety-significant.
There was one deviation where a bolt had an indication of an arc strike. Analysis of the are strike O
determined it to be minor and not to affect the capability of the bolt. Therefore, this deviation was determined to be not safety-significant.
Should other deviations similar to any of the preceding six types occur in the uninspected portion of the Hilti bolt population, it is expected they would also be not safety-significant, since the deviating bolts were concluded to be set and have sufficient nut engagement and nut bearing to perform their intended function.
Therefore no adverse trend was identified.
There were 17 deviations in which it was determined by measuring bolt projections that the nut had possibly bottomed-out on the threads. Six of the deviations were determined to be not bottomed-out, based on using measured thread lengths of stock bolts of the same size as those identified with deviations instead of using the minimum thread lengths that are in the procedures used for the reinspections. The measurements determined that the bolts have sufficient threads to have been properly torqued. Seven of the deviations were determined to be not bottomed-out by removing the nuts and determining that the bolts had sufficient threads to have been properly torqued.
Revision:
1 Page 17 of 41 RESULTS REPORT 5
ISAP VII.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd)
.For one of the deviations (involving one bolt), it was determined that additional threads beyond the minimum had to exist based on the current position of the nut.
Further review of the documentation indicates that this bolt was documented as being properly installed and torqued to the appropriate value to set it.
Therefore, it is concluded that sufficient threads were available to properly torque the bolt.
Two of the deviations occurred on two pieces of rotating equipment (one deviation per piece of equipment). Review of documentation indicates these pieces of equipment were installed during a period when only limited frequency inspections were performed on' Hilti bolt installations. Since no documentation exists that these bolts were inspected it is concluded that they were not inspected. The documentation also indicates that these pieces of equipment were reworked with the equipment being removed which required the O-Hilti bolt connections to be broken.
In addition, the rework required removal of existing grout and replacement with new grout. The bolts on one piece were torque-verified with all six bolts requiring additional nut rotation (3/4 to 1-1/2 turns) to reach the installation torque, with two bolts not meeting the torque verification criteria.
Evaluation of the deviations that' conservatively assumed that two of the six bolts were not present, determined that the deviations were not safety-significant.
l The vibration from rotating equipment could potentially I
cause loosening of Hilti bolts, and such uses are not recommended in the manufacturer's data. From this
)
review it could not be determined, however, if the condition of the bolts resulted from the rework or possibly resulted from the vibration of the equipment when the fan and motor were operated. Thus the available evidence is insufficient to substantiate loosening due to vibration. Therefore, these i
deviations (including torque deviations to be discussed under "Hilti Bolt Torque") were determined to be an l
unclassified trend for rotating equipment using Hilti bolts. A root cause and generic implication evaluation for this unclassified trend is provided in Sections i ()
5.6.2 and 5.7.
1 I
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1 Page 18 of 41 b
RESULTS REPORT ISAP VII.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd) j The remaining deviation was also determined to be a nut bottomed-out. Evaluation of the deviation that conservatively assumed that the bolt was not present determined that the deviation was not safety-significant.
Should the uninspected portion of the Hilti bolt population have similar deviations for bottomed-out nuts, it is conceivable that an attachment that uses a single or double bolt pattern with the bolt not properly set prior to the nut bottoming-out could result in sufficient displacement of the attachment under design loading conditions to jeopardize its I
ability to perform its safety function. Since the
)
determination that such a bolt has been properly set cannot be determined from the inspection data, this type of deviation was determined to be an unclassified trend. A root cause and generic implication evaluation
,O for this unclassified trend is provided in Sections 5.6.3 and 5.7.
lI i
5.3.2 Documentation Review Results i
Documentation reviews were conducted for
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non-recreatable characteristics identified in Table 4 for approximately 500 support packages. There were 59 j
support packages that did not contain proper Hilti bolt j
torque documentation identified during the reviews.
~
i Table 6 provides a tabulation of these results. The following is a discussion b~y characteristic of the document review deviations and an analysis of the effect of the deviations on the ability of the collected evidence to provide reasonable assurance that the Hilti bolts were properly installed.
Hilti Bolt Torque i
l Documentation reviews were conducted to verify that the i
inspector had noted that the bolts were satisfactorily l
torqued, that the torque value used was recorded, and that the torque wrench used was calibrated. These reviews identified 59 support packages with deviations.
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19 of-41 RESULTS REPORT 1-1 ISAP VII.b.4 (Cont'd) i 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESUI.TS (Cont'd)
Twenty-six of the deviations occurred because inspection reports could not be found.
In 14 cases the traveler for the item had an operation step for installing the Hilti bolts with a QC inspector's 2
signature indicating the bolts had been inspected and were properly installed. Because the inspector's signature was on the traveler, these deviations were determined to be not safety-significant.. In another nine cases, bolts were torque-verified and found to meet the torque verification acceptance criteria, which indicates that the bolts were properly set during the i
installatiun. Based on confirmation of bolt setting, these deviations were determined to be not safety-significant.
In three cases the bolts were installed during a period e
l when only limited-frequency inspections were performed I.
on Hilti bolt installations; as a result, a torque inspection had not been performed for these items. One I
of the cases was previously addressed in Section 5.3.1 for nut bottomed-out where an unclassified trend for Hilti bolts used on rotating equipment was identified. The j
six bolts involved in this case were torque-verified, j
and two bolts failed the torque check; the deviation for the missing inspection documentation is included in the unclassified trend evaluation.
l The other two cases could not be torque-verified because the bolts are covered by grout that made them j
inaccessible.
Since the bolts meet the program requirements of the time period that they were f
i installed, they do not represent a violation of i
requirements. However, since no documentation e::ists j
for the bolts the condition of the bolts is indeterminate; therefore, further review is a
recommended. These deviations'are included in the j
unclassified trend for unacceptable bolt torque identified below.
l In 15 cases the number of bolts on the inspection j
reports was less than the number reinspected. In 12 of l
these cases the bolts that were reinspected were torque-verified, with all the bolts meeting the torque verification acceptance criteria.
In one of the cases i
the bolts had multiple inspection reports, but it was j
not clear if all bolts were included. Field I
verification determined that the bolts in question had v.
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1 Pags 20 of 41 4
RESULTS REPORT ISAP VII.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd) torque sealant, which indicates that the bolts were torque-verified though not properly documented.
Therefore, the deviation was determined to be not safety-significant.
In the other two cases the bolts were torque-verified and found to have one bolt in each that did not meet the acceptance criteria. Evaluation of these two deviations determined that they were not safety-significant. However, should the uninspected portion of the Hilti bolt population have similar deviations for not fully set bolts, it is conceivable that sufficient displacement could occur to jeopardize the attachment's ability to perform its safety function. Since it cannot be determined if the bolts were properly set during installation and have related or were not properly set these deviations were determined to be an unclassified trend for unacceptable O-bolt torque. See Section 5.6.3 and 5.7 for root cause and generic implication evaluations for this unclassified trend.
I In 12 cases the number of bolts indicated as being torqued on the inspection reports was more than the number of bolts that had been reinspected.
In these i
cases it was concluded that some of the inspection reports were for the retorquing of bolts previously installed and inspected. Therefore, these deviations were determined to be not. safety-significant.
Two of the deviations identified were due to the bolt size shown on the inspection report not matching the bolt size of the detail drawing. During reinspection these bolts were determined to be the size specified on the detail drawing. The bolts were torque-verified and found to meet the torque verification acceptance criteria. Therefore, the deviations were determined to be not safety-significant.
Two of the deviations occurred when the verification of calibration for the wrench used in the original inspection could not be made.
In one case the wrench was used on the day of its recalibration. Review of calibration records for the wrench indicates it was in O
calibration. The other deviation occurred due to the wrench number not being recorded on the inspection
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Pcgo 21 of 41 RESULTS REPORT (s)
ISAP VII.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd) report for a conduit support. Review of the inspection report for the conduit system that the support is a part of, showed that it was prepared by the same inspector on the same day as the Hilti bolt inspection report for the conduit support. A torque wrench number was listed on the conduit system inspection report.
It is concluded to be the one used in the Hilti bolt inspection for the conduit support. Review of the calibration record for this wrench indicates it was in calibration. Based on the above discussions, these deviations are considered to be a result of an oversight by the inspector and were determined to be not safety-significant.
One deviation occurred when the torque value recorded on the inspection report was for 1 inch diameter bolts where the support had both 1 inch and 1-1/4 inch diameter bolts.
Evaluation of the deviation determined if the bolts had been torqued to the lower value the
(~'l bolts would have been set sufficiently to perform their (s /
intended function. Therefore, this deviation was determined to be not safety-significant.
One deviation occurred when no torque was recorded on the inspection report.
The attribute was checked satisfactory, indicating that the bolts had been inspected and met the torque requirements. However, an oversight by the inspector had apparently occurred in not recording the torque value. One of the bolts was torque-verified in the torque verification program and found to meet the acceptance criteria. Therefore, this deviation was determined to be not safety-significant.
Surveillance Characteristics Since individual population item documentation reviews could not comprehensively include surveillance type characteristics (Characteristics 2, 3, 4, and 5 on Table 4) these characteristics were reviewed separately from the ISAP VII.c document reviews. A specific time period was chosen for the review of these characteristics, yielding approximately 23 hole drilling inspection reports that include the surveillance characteristics for review. This review
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did indicate that inspection surveillance for Hilti q,j bolts was documented at a frequency that appeared reasonable for surveillance. The level of installation activities occurring at the time of the inspection surveillances could not be determined. Therefore,
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1 Pcg3 22 cf 41 RESULTS REPORT V
ISAP VII.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd) a definitive assessment of the overall adequacy of this surveillance program could not be performed. The appropriate characteristics were noted as inspected, with the results being satisfactory. This review also determined that due to the method used to track surveillances and the fact that the number of holes drilled per shif t could not be determined, a comprehensive review could not be performed. Based on this evaluation and the existence of the unclassified trend already identified for unacceptable bolt torque (which includes deviations for bolts not inspected, but installed when inspections were performed on a surveillance basis), this concern was included in the evaluation of the unclassified trend for unacceptabi's bolt torque.
Inspector Certification Q
The certification status of all QC inspectors who had
(,/
performed or signed off inspections on the documentation reviewed for any of the CWCs that include Hilti bolts was reviewed by reference to personnel certification files. A comparison was made to determine if the personnel had been certified in appropriate disciplines / procedures prior to performing inspections or examination activities. Separate identification of personnel inspecting Hilti bolts specifically was not made. Construction Deviation Reports were initiated to document inspectors for whom evidence of appropriate certification could not be located. These DRs have been reviewed and validated by the ISAP I.d.1 Issue Coordinator, in accordance with QA/QC Review Team procedures. The results of the evaluations of these deviations will be discussed in the Results Report of ISAP I.d.1, "QC Inspector Qualifications".
5.3.3 HVAC Duct Supports Reinspections of Hilti bolts for HVAC duct supports installed and inspected by Bahnson identified 17 deviations in approximately 3,800 inspection points.
All of these deviations were determined to be not f3 safety-significant.
Torque verification was performed on a group of 60 bolts from duct supports, with the results discussed in Section 5.4
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1 Pcgo 23 of 41 RESULTS REPORT m
ISAP VII.b.4 (Cont'd) l 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd)
In SDAR CP-85-54, the Project identified a number of 1
findings associated with HVAC duct supports. A Project corrective action program (TE-FVM-CS-029) has been proposed that includes reinspection of the safety-significant characteristics of Hilti bolts.
This corrective action program, when it is finalized, will be responsive to the corrective action recossendations for HVAC duct supports in the Action Plan VII.c Results Report. Therefore, no further evaluation of Hilti bolts used on duct supports was performed in this Action Plan.
5.4 Torque Verification Proaram The torque verification program identified in Section 4.1.6 of this report consisted of application of a specified torque to three groups of 60 Hilti bolts each chosen from populations of pipe supports, electrical raceway (cable tray and conduit) supports, and HVAC duct supports.
Except for cable tray hangers, which were not reinspected, the bolt selection process utilized a portion of the supports already chosen for reinspection under ISAP VII.c. to provide specific torque verification information about a group of bolts for which other Hilti bolt characteristics were known.
4 Torque verification for these 180 Hilti bolts (three groups of 60 each) was performed. All bolts tested set the acceptance criteria of Section 4.6.
Of these bolts 111 achieved the specified 80 percent of original installation torque without 1
nut rotation. The remaining 69 bolts exhibited rotation of J
the nut prior to achieving the 80 percent torque value, but were able to be torqued to 100 percent of the original i
installation torque well within the allowed one full l
additional turn. The maximus amount of additional rotation i
was 1/2 full turn.
i No deviations were found during the course of the torque verification program.
i
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P:go 24 of 41 RESULTS REPORT
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ISAP VII.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACT101 PLAN AND DISCUSSION OF RESULTS (Cont'd)
As discussed in Section 5.3.2, additional bolts were torque-verified to collect evidence useful to resolve documentation deviations. Of approximately 400 bolts that were torque-verified for this reason, four bolts did not meet the acceptance criteria. Two of these were determined to constitute an unclassified trend.
5.5 Related Issues During the implementation of ISAP VII.b.3 " Pipe Support Installations", two deviation reports describing six deviations involving Hilti bolts were issued. Review of the deviations found that all six deviations were due to the Hilti bolts not having star stamps identifying them as Super Hilti bolts.
These bolt deviations were also identified during the implementation of a TUGC0 corrective action in which UTs were performed to verify the type of bolts installed.
In both cases, the bolts installed were the type specified by the
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design drawing. Therefore, these deviations are considered to s_
be not safety-significant and do not affect the conclusions m
drawn in this Action Plan.
5.6 Root Cause Evaluation This section provides a root cause analysis for 1) the unclassified trend for spacing violations, 2) the unclassified trend for bottomed-out nuts and unacceptable bolt torque on rotating equipment, 3) the unclassified trend for bottomed-out nuts and 4) the unclassified trend for unacceptable bolt torque.
5.6.1 Spacing Violations Root Cause The unclassified trend identified for Hilti bolt spacing is based on spacing violations that occurred in different populations. These violations also represent seversi different physical situations (spacing from Hiltis to embeds, to concrete edges, to Richmond inserts or to adjacent Hiltis). The Hilti bolts involved were installed by Brown & Root craftsmen working to a single construction procedure with a 7-~
single set of spacing criteria. The inspections were (j
performed by Brown & Root inspectors for ASME installations and TUCCO inspectors for non-ASME installations.
Because the deviations that constitute
I j
R visiont 1
Pcg3 25 of 41 RESULTS REPORT ISAP VII.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd) the unclassified trend involve a variety of physical situations, each deviation is likely to have a different set of contributing causes. A number of possible causes were considered in this evaluation to ensure that the corrective action defined from the root causes and contributing causes would correct all the situations encountered. The following possible causes were evaluated Congestion of components at the concrete surfaces Lack of detailed instruction in the installation procedure to detect and resolve potential spacing violations Failure of engineering to identify spacing conflicts of engineered supports to embedded items Less-than-adequate inspection procedures Insufficient inspector qualification / training Failure of personnel to perform tasks in accordance with the spacing requirements of the procedure.
The spacing criteria at CPSES are specified in Project Document CEI-20. " Installation of Hilti Drilled-In Bolts". Review of the deviations identified some cases where this installation procedure was not clear in detailing criteria for the spacing of a Hilti bolt to a penetration sleeve or spacing of a Hilti bolt to chaefered corners of concrete. This is a contributing cause to violations that occurred in these type of installations.
Review of the deviations identified some cases where the congestion of itees was such that when field run items such as instrument tube and conduit were installed, it was not possible to comply with the spacing requirement. However, personnel performing the O
installations are still required to do so in accordance with the requirements of the applicable procedures.
The craft should have called these situations to the
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1 Pcg3 26 of 41 RESULTS REPORT ISAP VII.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd) attention of their supervisors, who, in turn, should have obtained engineering approval for any situation that did not meet procedural requirements.
Review of the deviations identified some cases where an interference or spacing conflict existed due to engineered supports being too close to embedded items.
Since the Hilti bolt locations are specified on the design document, this would indicate a lack of interf ace between engineering disciplines, which resulted in the items being located in violation of spacing criteria. This is determined to be a contributing cause, as the primary responsibility of maintaining spacing is that of the installer.
Review of inspection procedures applicable during most Hilti bolt installations determined that they included the appropriate criteria in tabular form for inspecting O
Hilti bolt spacing and a summary entry for spacing in b'
the checklist. The inspection procedure did not, however, include criteria for spacing to penetration sleeves previously discussed concerning CEI-20 (except revision 18 of TUCCO Procedure QI-QP 11.2-1, dated 6/7/85, that does have the criteria for spacing to penetration sleeves) nor did it provide detailed criteria more precise than the installation procedure.
Review of inspector certification identified some inspectors with questionable qualifications to perform Hilti bolt inspections. Although not totally complete.
ISAP I.d.1 evaluations have not detected any significant problems regarding the capabilities of these inspectors to perform the required inspections.
These results afford a substantial amount of evidence interpreted to indicate that less-than-adequate inspector qualification and/or training did not contribute to this condition going undetected. A final conclusion will be reported in the ISAP 1.d.1 Results Report.
For those deviations where EESVs had been performed but can not be located in the support documentation files (i.e., not traceable), it is concluded that the lack of p
a central tracking system and the lack of an effective program to incorporate acceptable spacing violations into the appropriate support documentation is a primary root cause of undocumented spacing violations. There
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1 Pegs 27 of 41 e~s RESULTS REPORT ISAP VII.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd) is no way to determine which specific deviations fall into this category; however, it was determined that the documentation control provisions in this program were less-than-adequate.
If it is assumed that an EESV had not been performed, review of the deviations identified that in most cases the installation was apparently performed without adequate regard to the spacing requirements of the procedure. In soma cases the disregard of requirements could be based on the fact that the item being installed had a specified location with minimal location tolerance. However, as discussed previously, the primary responsibility of maintaining spacing requirements is that of the installer. Therefore, deviations that occurred in the spacius of Hilti bolts to other embedments are concluded to have occurred primarily due to personnel performing these
'O installations tasks without paying sufficient attention to procedural requirements for maintaining proper spacing. This is considered the primary root cause of those spacing violations that were never addressed in an EESV. No secondary root cause was identified in these cases.
Summary The unclassified trend for Hilti bolt spacing was evaluated with the following results:
For spacing violations that had an EESV performed but not retained, the primary and secondary root cause was an ineffective EESV program that resulted in failure to identify spacing violations and to incorporate the acceptance of the violation into the appropriate supporting documentation.
For spacing violations that did not have EESVs performed, if any, the primary root cause was personnel performing tasks without regard to the spacing requirements of the procedure.
Contributing causes were installation and inspection proceduren that lacked sufficient detail to prevent O
spacing violations and the failure of engineering personnel to identify spacing conflicts between engineered supports and embedded items.
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1 Pcga 28 of 41 RESULTS REPORT
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ISAP VII.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd) 5.6.2 Bottomed-Out Nut and Unacceptable Bolt Torque on Rotating Equipment Root Cause An unclassified trend was identified for bottomed-out.
nuts and unacceptable bolt torque for Hilti bolts installed on rotating equipment, since it could not be determined if the bolts were originally installed correctly or not. Hilti bolts were installed by Brown
& Root craftsmen and inspected by Brown & Root and TUGC0 inspectors as previously discussed in the root cause evaluation of spacing violations. These installations were performed to a single construction procedure that included criteria for avoiding bottomed-out nuts and for Hilti bolt torque. The deviations described above occurred on two pieces of rotating equipment installed during the time period r
when only surveillance inspections were performed. The
'(
two pieces of equipment were also reworked during the same time period with the bolt connections being broken, the grout removed and replaced with new grout.
The rework is considered to be a possible contributing cause to the nut bottomed-out condition, since thinner grout reinstallation can permit bottoming-out in what had been an acceptable installation.
Since no inspection documentation could be found, it was concluded that these pieces of equipment were not inspected originally nor after they had been reworked.
The practice of performing torque and nut bottomed-out inspections on a surveillance basis (permitted for about nine months at CPSES) is determined to be the secondary root cause of the found deviations as the nut bottomed-out condition should have been detectable after rework even if vibration was subsequently significant. These two pieces of equipment have been operated, which may have caused excessive bolt relaxation. Therefore, based on the limited amount of data and the lack of inspection documentation for the Hilti bolts the primary root cause for this '
unclassified trend is concluded to be indeterminate.
O
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Pega 29 of 41 RESULTS REPORT ISAP VII b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF.RESULTS (Cont'd) 5.6.3 Bottomed-Out Nut Root Cause An unclassified trend was identified for bottomed-out nuts since, for the deviation found, it could not be L
determined if the corresponding bolt was properly set or not. Hilti bolts were installed by Brown & Root craftsmen and inspected by Brown & Root and TUGC0 inspectors as previously discussed in the root cause evaluation of spacing violations. These installations were performed to a single construction procedure that included criteria for checking for a bottomed-out nut.
A number of possible causes were considered in this evaluation to ensure that the corrective action defined from the root causes and contributing causes would correct all the situations encountered. The following possible causes were evaluated:
)
Less-than-adecuate installation or inspection procedures Less-than-adequate training Failure of personnel to perform tasks in accordance with the requirements of the procedure.
In most cases a bottomed-out nut occurs either when setting the bolt as a result of the bolt not being installed deep enough prior to torquing the nut or when the bolt does not set when torquing the nut. The installation criterion allows pullout of the bolt equal to one nut thicknes when torquing or setting the bolt.
When this criterion is exceeded, the bolt is not setting and the nut would probably bottom out if torquing were continued. The installation procedure requires that such bolts either be cut off and abandoned with a replacement bolt installed or be removed and replaced with a larger bolt using the existing hole. When the bolts are inspected to verify torque the inspector applies the required amount of torque per the procedure.
If the bolt has relaxed the inspector is allowed to continue torquing the bolt O
until the required torque is reached.
It is conceivable that when the bolts had been torque
(
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1 Pago 30 of 41 RESULTS REPORT
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ISAP VII.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd) verified the inspector could have bottomed-out the nut attempting to achieve the required torque value. Based on the low frequency of occurrence (approximately 1 in 3000) and the limited amount of data, the primary root.
cause for bottomed-out nut deviations cannot be determined.
Review of inspection procedures applicable during most Hilti bolt installations determined that they included the appropriate criteria for inspecting Hilti bolts for bottomed-out nuts.
In addition, the procedure included direction to the inspector that if there was doubt concerning whether a nut had bottomed-out, the nut should be removed and available thread length verified.
Such checks, when performed, were not documented.
However, the procedure to which the inspection was performed, where a deviation was identified, did not have specific criteria for bottomed-out nuts.
Because the bottoming-out of a nut occurs when the bolt is being set, additional verification of a bottomed-out nut would occur in those cases where torque was separately verified. As discussed above it is possible the inspector bottomed-out the nut when performing this torque verification. However, review of the procedure indicates that the verification of torque was only required on a random basis, with not all bolts on an installation being torqued. Therefore, it is concluded that the inspection procedure included adequate criteria for detecting bottomed-out nuts. However, while the inspection procedure was thus found to be adequate, it appears to have been ineffective as applied in identifying the bottomed-out nut deviation at the very low frequency at which it occurred. No secondary root cause was identified.
5.6.4 Unacceptable Bolt Torque The unclassified trend identified for Hilti bolt torque is based on missing or inconclusive documentation for torque inspections of bolts that were found either to be unacceptable when torque was verified or to be inaccessible and hence indeterminate. The Hilti bolts O3 involved were installed by Brown & Root craft working to a single installation procedure that included criteria for setting the bolts. The inspections were performed by TUCCO inspectors.
j9 Rcvision:
1 r
Pags 31 of 41 RESULTS REPORT O
s.
ISAP VII.b.4 "
(Cont'd)
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1
' 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd)
A number of possible causes were considered in this evaluation to ensure that the corrective action defined from the root causes and contributing causes would j
sI/f correct all the situations encountered. The following possible causes were evaluated:
Less-than-adequate inspection procedures Less-than-adequate inspecto'r qualification / training Failure of personnel to perform the task in accordance with the setting requirements of l
the procedure.
Excessive bolt relaxation.
Review of the. inspection procedures applicable during most Hilti bolt installations determined that they included the requirement for verifying torque; however, I
these requirements did not 1cclude verifying all bolts on each item.
For early; installations, however, review-of the initial inspection procedure determined that bolts were inspected on a surveillance basis, with some
[.
items not being inspected. Therefore, it was determined that the frequencies required by the procedur's do not ensure that all installed bolts are properly set. This less-than-ade,quate inspection frequency is considered to be the primary root cause for incomplete documentation to provida assurance that the bolts had been properly set during installation.
~
As discussed previously the review of inspector certification identified some inspectors with questionable qualifications to perform Hilti bolt inspections. Although not totally complete, ISAP I.d.1 evaluations have not detected any significant problems regarding the capabilities of these inspectors to perform the required inspections. These results afford a substantial amount of evidence interpreted to l
indicate that less-than-adequate inspector qualification and/or training did not contribute to this condition going undetected. -A finci conclusion will be reported in the ISAP I.d.1 Results Report.
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1 Paga 32 of 41 i
s RESULTS REPORT ISAP VII.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd)
For bolts that were not properly set during installation, the responsibility for proper installation is that of the installer. Therefore, deviations that occurred due to improperly set bolts are the result of personnel performing these installations without sufficient attention to ensure that the bolts were properly set when installed.
However, based on the frequency of occurrence and the amount of nut rotation to reach the installation torque it cannot be determined if the bolts were properly set and have excessively relaxed or if the bolts were not properly set during installation. Therefore, the root cause could not be determined.
5.7 Generic Implications Review of the spacing deviations determined that spacing violations have occurred in all applications that incl'uded installed Hilti bolts.
Spacing violations do not have O-implications beyond Hilti bolt installations in that they involve multiple installations, i.e., distance of one installation to another.
Therefore, there are no generic implications to other activities.
Root causes for bottomed-out nut and torque deviations were not determined. However, these deviations occurred when setting the bolt, an operation which is unique to Hilti bolt installations. Therefore, *zplications beyond Hilti bolt installations are unlikely to exist.
5.8 Recommended Corrective Action Spacing Violations TUGCO should verify that site training for craft installing Hilti bolts provides emphasis on the fact that minimum spacing criteria for Hiltis to other embedded items must be maintained or engineering approval obtained to ensure proper performance of the installed bolt.
Responses to spacing violations arising during installation activities should be reviewed and refresher training should be provided as necessary.
TUGC0 should verify that site training procedures for QC inspectors who inspect Hilti bolts are adequate and include (g
emphasis on the specific requirements for completing
( _,)
inspection records that attest to proper installation of Hilti
_ = _ -
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1 Paga 33 of 41 4
RESULTS REPORT
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ISAP VII.b.4 (Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd) bolts. This should include emphasis on the importance of noting on inspection reports the existence of alternate documentation that approves deviations from inspection
- criteria, e.g., CMCs, EESVs, etc.
A room / area walkdown should be conducted to identify spacing violations.
Identified violations should be evaluated or reworked, as required. Applicable procedures should be revised to provide spacing requirements clearly with respect to penetrations and chamfered corners of concrete. An interface tracking system for EESVs should be established that includes all applications that include installed Hilti bolts.
Copies of EESVs or the appropriate acceptance document should l>
be filed with the applicable inspection report and noted on the inspection report.
Bottomed-Out Nut / Missing Documentation / Unacceptable Torque For the unclassified trend relating to rotating equipment identified in Section 5.3.1, it is recommended that an
_l Engineering review of the use of Hilti bolts for the anchorage of rotating equipment be performed and design requirements be updated, as necessury. The review should include reinspections and torque verification of the Hilti bolts used on rotating equipment to determine if excessive relaxation in the bolts has occurred.
If additional deviations are found that relate to inadequate bolt torque, an analysis of the deviations should be performed, including a root cauce and generic implications evaluation.
For Hilti bolts that lack documentation and are inaccessible
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due to grout or topping, evaluations of the installations should be performed to determine if the grout would compensate for any deviations that might exist in the Hilti bolts. The evaluations should include determination of corrective action to be taken to complete resolution, if necessary.
For the other installations using Hilti bolts, an evaluation of the current inspection procedure should be performed to determine what level of inspection (including surveillance characteristics) should be used to ensure that bolts have been properly set to provide the required support capacity. This evaluation should include an engineering evaluation of support types and configurations to determine the required number of bolts to be verified on an item. The evaluation should also O
develop torque-verification criteria to be used when torque needs to be verified.
This evaluation should consider the
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1 Page 34 of 41 RESULTS REPORT ISAP. VII.b.4 l
(Cont'd) 5.0 IMPLEMENTATION OF ACTION PLAN AND DISCUSSION OF RESULTS (Cont'd) l effect of retorquing bolts after they have been set as well as determine the amount of loss in preload that is acceptable.
An evaluation of previously performed surveillance inspections should be performed to determine if they provide adequate confidence that Hilti bolt installations were performed correctly. Where required, torque verifications with the appropriate documentation should be completed. Any field corrective action should include verification that the bolts do not have bottomed-out nuts.
6.0 CONCLUSION
S The NRC-TRT inspected Hilti anchor bolt installations on both pipe supports and electrical raceway supports and found deviations that raised concerns regarding the construction adequacy of Hilti anchor bolt installations. These deviations were not specifically verified by CPRT.
However, the results of the reinspections discussed in detail in Section 5.2 for Hilti bolts confirm that a small percentage of bolts did not comply with all of the specified installation requirements, some of which are in areas identified by the TRT.
Evaluation of these deviations identified unclassified trends for Hilti bolt spacing and nuts that were bottomed-out. The
-documentation reviews identified missing documentation for Hilti bolt torque. When investigated, a few of these bolts were found to be outside the inspection criterion, resulting in an unclassified trend being identified for Hilti bolt torque. Corrective action is required to assure construction adequacy for prior and future work.
Based on the results of the reinspections and documentation review, and satisfactory implementation of the above recommendations there i
will be reasonable assurance that the Hilti bolts are adequately installed.
7.0 ONGOING ACTIVITIES i
Although the reinspection portion of ISAP VII.c is essentially complete, the final evaluation of all data is incomplete. As a result, there exists a potential for the identification of construction deficiencies or trends applicable to issues addressed in ISAP VII.b.4 Initial reviews of the remaining O
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1 Paga 35 of 41 RESULTS REPORT ISAP VII.b.4 (Cont'd) 7.0 ONGOING ACTIVITIES (Cont'd) data indicate that no new issues involving Hilti bolts have been raised, and therefore additional impact on this Action Plan is not anticipated. A final review of the data after the completion of ISAP VII.c will be made to ensure that there are no additional issues to be addressed regarding Hilti bolt installation at CPSES.
8.0 ACTION TO PRECLUDE FUTURE OCCURRENCE Implementation of the recommended corrective actions will be sufficient to preclude future occurrence.
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Revision:
1 Pago 36 of 41 RESULTS REPORT Om i
ISAP VII.b.4 (Cont'd)
Table 1 VII.c Populations for which Reinspections and Document Reviews were Conducted for Concrete Expansion Anchors Population Quality Instruction Numbers Large Bore Pipe Supports - Rigid QI-027 and 028 Large Bore Pipe Supports - Non-Rigid QI-029 and 030 Small Bore Pipe Supports QI-019 and 020 Instrumentation Supports QI-055 and 056 Conduit Supports QI-053 and 054 Equipment Supports QI-066 and 067 1
l HVAC Duct Supports QI-035 and 036 Pipe Whip Restraints QI-051 and 052 Structural Steel
'QI-045 and 046 Mechanical Equipment QI-059 and 060 j
Torque verification was conducted in accordance with Quality Instruction (QI-063).
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1 Pags 37 of 41 f-x RESULTS REPORT U
ISAP VII.b.4 (Cont'd)
Table 2 Hilti Bolt Samples for Each Construction Work Category No. of Items Min. No. of Total No.
With Items with of Items Construction Population Sample Hilti Bolts Hilti Bolts with Hilti Work Category Size Size #
In Sample +
Required Bolts Insp.++
Structural Steel 1,656 227 14 1
31 Pipe Whip Restraints 652 161 3
1 3
Pipe Whip Restraint Support Structures 652 160 13 1
13 Small Bore Pipe Supports 7,947 69 34 28 40 es Large Bore-Rigid Pipe Supports 7,207 68 36 27 55 Large Bore-Non-Rigid Pipe Supports 2,182 65 36 9
50 Equipment Supports 1,439 175 51 4
55 Mechanical Equipment 466 10*
1 10
- Conduit Supports 53,022 60 60 146
- Instrument Tube Supports 1,024 60 60 114 Actual number of items in the population with Hilti bolts.
Not included in the calculation of minimum number of items required.
Total number of sample items selected to obtain 60 valid sample items.
)
+
Items that are accessible and QC-accepted.
++
Collectively these represent approximately 3,000 Hilti bolts.
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1 Page 38 of 41 RESULTS REPORT
,t ISAP VII.b.4 (Cont'd)
Table 3 Reinspection Characteristics - Action Plan VII.c 1.
Size. Type, and Quantity of Anchors included a verification check that anchor diameter, type, length, and total quantity of anchors correspond to the requirements of the applicable design drawing.
2.
Embedment Depth consisted of a verification check that the in-plate anchor embedment was as required by project documents.
3.
Spacing consisted of a verification check of the center-to-center spacing of anchors between adjacent attachment fixtures, and that the distances between the anchors and Richmond Screw Anchors, concrete edges, abandoned holes, cut-off Hiltis and embedded anchors, and embedded plates are as required by project documents.
4.
Angularity consisted of a verification check that the longitudinal axis of the anchor was within a prescribed degree of
)
perpendicularity to the concrete, a
5.
Concrete Damage consisted of a verification check that the concrete surrounding the fixture was not spalled beyond the project's maximum criteria.
6'.
Nut Engagement and Bearing included a verification check that each nut has full thread engagement on the anchor, that at least one washer was provided and that the nut and washer had proper bearing, that the nut had not bottomed-out on the anchor and that no welding j
was evident to the anchor or nut.
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1 Pega 39 of 41 RESULTS REPORT ISAP VII.b.4 (Cont'd)
Table 4 Documentation Review Characteristics - Action Plan VII.c 1.
Hilti Bolt Torque consisted of a verification check that the calibration period of _the torque wrench was effective at the time the wrench was used, and that_the torque value recorded was in accordance with project requirements.
2.
Spacing consisted of a verification check that notation was made that sufficient spacing between Hiltis and abandoned holes under the plate had been maintained or that notation was made that the holes had been filled in accordance with project procedures.
3.
Rework consisted of a vecification check that, if rework occurred.
the inspector noted correctness of thread fit requirements and the observance of any new length stamping.
4.
Hole Drilling consisted of a verification check that, if hole drilling was witnessed, no rebar cutting took place during drilling
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unless specifically permitted by project documents and that there
(
was no unacceptable spalled concrete under the fixture plate.
5.
Setting consisted of a verification check that the bolt setting was appropriately performed, including any redrilling of holes.
6.
Inspector Certification consisted of a verification that the inspector performing Hilti bolt inspections was certified to the procedure to which the inspection was performed.
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1 Page 40 of 41 f-~s RESULTS REPORT
_ t ISAP VII.b 4 (Cont'd)
Table 5 Reinspection Results'(VII.c)
REINSPECTION APPROXIMATE NUMBER TOTAL NUMBER CHARACTER-0F INSPECTION TOTAL NUMBER OF CONSTRUCTION ISTICS POINTS DEVIATIONS DEFICIENCIES Size, type, and quantity 9,000 51 0
Embedment Depth 3,000 15 0
Spacing 12,000 63 0
Angularity 3,000 3
0 Concrete Damage 3,000 1
0 Nut Engagement and Bearing 15,000 41 0
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l TOTALS 45,000 174 0
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1 Page 41 of 41 RESULTS REPORT f
1 ISAP VII.b.4 4
l (Cont'd)
Table 6 Documentation Review Results (VII.c) l TOTAL NUMBER TOTAL NUMBER OF PACKAGES OF CONSTRUCTION CHARACTERISTICS WITH DEVIATIONS DEFICIENCIES 5
{
Hilti Bolt Torque 59 0
I Spacing 0
0 Bolt Rework 0
0 Hole Drilling 0
0 i
Setting 0
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TOTALS 59 0
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