ML20092N216

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Forwards Suppl to Rept on Byron QC Inspector Reinsp Program.Related Correspondence
ML20092N216
Person / Time
Site: Byron  Constellation icon.png
Issue date: 06/28/1984
From: Furse M
COMMONWEALTH EDISON CO., ISHAM, LINCOLN & BEALE
To: Callihan A, Cole R, Smith I
Atomic Safety and Licensing Board Panel
References
ALAB-143, NUDOCS 8407020543
Download: ML20092N216 (72)
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THREE FIRST NATIONAL PLAZA CHICAGO iLUNot$60002 T um 2sa M Ljk ~hCQ8ent Avthu .N W June 28, 198 *^5"'",ffg&C 2=

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BR:NCH Ivan W. Smith, Esquire Dr. Richard F. Cole Administrative Judge and Administrative Judge Chairman Atomic Safety and Atomic Safety and Licensing Licensing Board Board U.S. Nuclear Regulatory U.S. Nuclear Regulatory Commission Commicsion Washington, D.C. 20555 Washington, D.C. 20555 Dr. A. Dixon Callihan Administrative Judge Atomic Safety and Licensing Board c/o Union Carbide Corporation P.O. Box Y Oak Ridge, Tennessee 37830 Re: In the Matter of Commonwealth Edison Company (Byron Nuclear Power Station, Units 1 and 2)

Docket Nos. 50-454 and 50-455 Gentlemen:

In accordance with the requirements of Duke Power Co. (William B. McGuire Nuclear Station, Units 1 and 2) ALAB-143, 6 AEC 623 (1973), Commonwealth Edison Company is providing the Atomic Safety and Licensing Board and the parties with the Supplement to the Report on the Byron QC Inspector Reinspection Program. A typeset version of this report will be available on Monday, July 2, and will be mailed to the Board and the parties at that time.

1 Very trul yours, j C7m ark C. Furse One of the Attorneys for Commonwealth Edison Company MCF: reg Enclosure cc: Service List

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SUPPLEMENT TO REPORT ON THE BYRON QC INSPECTOR REINSPECTION PROGRAM DOCKET NOS. 50-454 AND 50-455

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SUPPLEMENT TO REPORT ON THE BYRON QC ,

INSPECTOR REINSPECTION PROGRAM CONTENTS

1. INTRODUCTION SI-I II. SUPPLEMENTAL INSPECTIONS AND EVALUATIONS S 11- 1 FOR SUBJECTIVE WELD ATTRIBUTES FOR HATFIELD EL-ECTRIC AND PITTSBURGH TESTING 111. SUPPLEMENTAL INSPECTIONS AND EVALUATIONS FOR Sill-1 OBJECTIVE ATTRIBUTES FOR HATFIELD ELECTRIC ,

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I. INTRODUCTION .

The Byron QC Inspector Reinspection Program was established to verify the effectiveness of former certification practices and QC Inspector Qualification programs by reexamining, on a sampling basis, inspections performed by QC Inspectors l certified prior to September,1982. The Reinspection Program was completed and confirmed the adequacy of inspector activities at the Byron Station.

Although the Reinspection Program focused on an assessment of individual inspector

, . qualifications and contractor certification practices, a significant amount of work quality data was accumulated. Observed discrepancies were evaluated for their significance to the design and the quality of construction work at Byron was determined to be adequate. l This supplement provides the results of supplemental inspections and evaluations ,

which Commonwealth Edison committed to in the Report on the Byron QC Inspector Reinspection Program, Feburary 1984 (hereinaf ter referred to as the Reinspection Program Report). These supplemental inspections and evaluations covered subjective - ,

l weld attributes for Hatfield Electric Company and Pittsburgh Testing Laboratory and objective attributes for Hatfield Electric Company. [

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. 5 11- 1 II. SUPPLEMENTAL INSPECTIONS AND EVALUAT,10NS FOR SUBJECTIVE WELD ATTRIBUTES FOR HATFIELD ELECTRIC AND PITTSBURGli TESTING A. INTRODUCTION Appendix C to the Reinspection Program Report included commitments to perform supplemental inspections and evaluations (see Exhibit C-2, pages 10 and 13). These supplemental inspections included highly stressed welds for Hatfield

, . Electric and Pittsburgh Testing and welds with overlap for welds inspected by .

Pittsburgh Testing. The engineering evaluation of weld discrepancies noted in these supplemental inspections and evaluations followed the same process described in Exhibit C-2 of Appendix C in the Reinspection Program Report.

B. HATFIELD ELECTRIC Two sets of supplemental inspections were performed. One set of evaluations ,

involved identifying highly stressed welds from the population of Hatfield Electric subjective weld discrepancies identified in the Reinspection Program. The other set of inspections involved highly stressed welds inspected by inspectors whose work was not reinspected in the Reinspection Program. The supplemental inspections and evaluations completed for Hatfield Electric show that the highly stressed welds are capable of carrying the design loads even with the presence of weld discrepancies.

l. Highly Stressed Welds Within Reinspection Program This evaluation considered the highly stressed connection welds from the entire population of Hatfield Electric weld discrepancies in the Reinspection Program. The type of supports which have the highest stressed welds are cable tray supports. Cable tray support connections fall into four basic groups:

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o auxiliary steel connections to in-place building steel, o top connections for supports to auxillary or in-place building steel, o internal connections for support members to vertical members, and o cable tray hold down connections to horizontal support members.

The cable tray supports associated with the discrepant welds shown in Table C-1 of Appendix C to the Reinspection Program Report were identified. The design margins for the connections in each group were then tabulated. Then at least 15 supports having highly stressed connections from each of the four groups were selected for weld mapping and evaluation. The weld maps were used to determine the reduction in weld strength based on the mapp.ed weld discrepancy. The results of the engineering evaluation are shown in Table SCE-9.

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'U. Stressed Cable Tray Welds - Hatfield Electric -

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.? No ' Strength Weld Wel'd Strength Weld i m No. of Weld Structural Reduced Rcduced Rejected Weld Type Discrepancies. Impact by < 10% .by 2 10% (Cracks)

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connections 21  ! O 4 17 0 T6p connections for' supports 16 0 3 ,

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tions ior supports 17 0 4 13 0 Cable tray' hold-down " 15" 0 8 .' .

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1. 'The format of Table ~SCE-9 corresponds to Table,CE-9 in Exhibit C-2 of Appendix i C of thd Reinspectied Program Report. -

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' SII-4 The results of the engineering evaluation showed that each-weld is capable of carrying the design loads; thus, str6ctural integrity is not impaired.

This evaluation demonstrates that 69 highly stressed cable tray [

connections with weld discrepancies are capable of carrying the design loads.

2. Highly Stressed Welds Outside the Reinspection Program This inspection addressed highly stressed welds for the 10 Hatfield weld inspectors whose work was not reinspected during the Reinspection

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Approximately 60 highly stressed welded connections from the four groups of cable tray support welds were reinspected for the 10 Hatfield inspectors' work. A total of 187 welds were mapped. The types of weld discrepancies identified were similar to the discrepancies in the welds identified in the Reinspection Program.

The results of the engineering evaluation of these connections are shown in Table SCE-9A.

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Results of AWS Weld Discrepancy Evaluation for Highly Stressed Cable Tray Welds Outside the Reinspection Program - Hatfield Electric Weld Discrepancy Category

'A B1 B2 C Weld Weld No. No Strength Strength Weld of Weld Structural Reduced Reduced Rejected Weld Type Discrepancies impact by < 10% by 210% (Cracks)

Auxiliary steel connections 40 0 19 21 0 Top connections for supports 29 0 11 18 0 Internal connect-tions for supports 30 0 12 18 0 Cable tray '

hold-down 88 0 48 39 1 3

TOTAL 187 0 90 96 1 in the case where a cracked cable tray hold-down weld was found during these additional inspections, the other welds in the connection were capable of carrying the load. The engineering evaluation of these highly stressed welds showed that each weldment is capable of carrying the j design loads even with the presence of weld discrepancies. .

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3. Conclusion l The results of the supplementary evaluations complement the results of the Reinspection Program and give a total of 356 weld maps of discrepant welds which have been evaluated (50 randomly selected weld maps and 50 i

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' S 11- 6 weld maps containing the most weld discrepancies from the Reinspection Program; 69 weld maps from highly stressed cable tray support welds; and 187 weld maps for highly stressed welds for weld inspectors not included in the Reinspection Program). These evaluations, which revealed no design significance, result in a reliability of better than 99% which is consistent with the previous conclusions reached concerning the quality o,f Hatfield Electric's work.

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4. Additional Inspections and Evaluations As noted p.aviously, none of the weld discrepancies in the Reinspection Program or in the supplemental inspections and evaluations described herein impair the structural integrity of any structure or component.

However, there were three types of discrepancies which resulted in a considerable reduction in load-carrying capacity. Even though these conditions were found to be acceptable for the highly stressed elements reviewed in the program, additional inspections and evaluations were performed to provide assurance of the adequacy of the entire plant. The three types of discrepancies for which additional inspections were undertaken are categorized as follows:

T o Conduit support weldments o Cable tray support connections with fit-up gap .

s o Cable tray support internal diagonal member connection

a. Conduit Support Weldment The Reinspection Program identified two cases where a portion of the weld was omitted from a weldment for a conduit support connection.

The weldment consisted of four individual welds of which two welds were omitted. In order to assess the effect of such an omission

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anywhere in the plant, a sampling plan was developed.to inspect this type of weldment. A randomly s lected sample of 489 of these weldments out of an approximate total population of 3,000 were examined to determine if all required welds had'been made. In this examination, two supports were identified where the specified welds had been omitted. Based on the as-built conditions of these supports, an evaluation was made and it was determined that the conduit loads could be accommodated by the discrepant supports or by redistribution of loading to adjacent supports. Therefore, it has been demonstrated, with greater than 99% reliability at a 95% confidence level, that the

<- structural integrity of the conduit system is adequate. ,

These favorable engineering' evaluation results are due to the fact that the original conduit and conduit support design have design margins.

Conduit supports are generally spaced closer than the maximum conduit span requirements because of physical limitations in the plant.

Furthermore, the supports are initially selected from typical details.

The typical details are designed using peak seismic responses for a given area of the plant. Support selection is also based on loads which assume maximum cable loads in each conduit. When individual s

supports are reviewed using actual cable loads and more exact seismic analysis, there is sufficient design margin available to accommodate the weld discrepancy.

b. Cable Tray Support Connections with Fit-Up Gap The supplemental Hatfield Electric inspections identified recurring cases of welds with a fit-up gap. The engineering evaluations of these discrepancies conservatively assumed a considerable reduction in the load-carrying capacities of these connections. To assess the actual effect on weld c.'pacity due to a fit-up gap, a supplemental test program was established. Ten fillet welded sp2cimens with representative fit-up gap were prepared using the applicable Hatfield

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Electric weld procedure. These specimens were strength tested, and the test results indicated that therb was no reduction in strength of the weld due to the fit-up gap. Therefore, it was concluded that the fit-up gap that was identified in the Reinspectfon Program had no effect on the capacity of similar cable tray connections in the plant.

c. Cable Tray Support Internal Diagonal Member Connection

< r In the Reinspection Program and the supplemental Hatfield inspections, some of the connections for cable tray support diagonal .

member connections did not conform to the design configuration. In the worst case, a partial penetration weld was used instead of the specified fillet weld. The engineering evaluation of this case assumed that this diagonal did not carry any load and demonstrated that the support could still accommodate the design loads. Although the support was adequate, in order to address the effect of this type of discrepancy on the entire plant, the actual strength of this weld was investigated. The diagonal member with the welds in question was removed from the cable tray support and cross-sections of the welds were macroctched to determine the depth of weld p.enetration. Based T

on the results of this supplemental test, it was determined that the as-built welds had less than a 10% reduction in capacity from that calculated for the original fillet welds. Therefore, this type of discrepancy has no design significance and can be accepted for other such cases in the plant.

C. PITTSBURGH TESTING The supplemental evaluations and inspections completed for Pittsburgh Testing show that: (1) highly stressed welds inspected by Pittsburgh Testing are capab!c of carrying the design loads and (2) weld discrepancies involving overlap do not mask other discontinuities or reduce the weld capacity.

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1. Highly Stressed Welds This evaluation considered the highly stressed connection welds from the entire population of welds inspected by Pittsburgh Testing with weld discrepancies in the Reinspection Program.

The design margin for each of the 905 welds shown in Table C-1 of Appendix C of the Reinspection Program Report was determined using tiie design loads and weld properties. Forty-three highly stressed welds were identified, and detailed weld map were prepared showing all weld discrepancies. The results of the evaluations for the discrepant welds in the highly stressed connections are shown in Table SCE-II.

Table SCE-11*

Results of AWS Weld Discrepancy Evaluation for Highly Stressed Welds Inspected by Pittsburgh Testing Weld Discrepancy Category A B1 B2 C Weld Weld No Strength Strength Weld  ;

No. of Weld Structural Reduced Reduced Rejected Discrepancies impact by < 10% by 1 10% (Cracks) .

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, Note: The format of this table corresponds to Table CE 11 in Exhibit C-2 of Appendix C of the Reinspection Program Report.

I The results of the engineering evaluation showed that each weld is capable of carrying its design load. The results of this evaluation complement the results of the Reinspection Program and give a total of 107 weld maps of discrepant welds inspected by Pittsburgh Testing which have been .

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51I-10 evaluated (14 randomly selected weld maps and 50 weld maps containing the most weld discrepancies and 43 highly stressed welds). None of the discrepancies had design significance.

2. Welds with Overlap These supplemental inspections were initiated to address Pittsburgh Testing's failure rate for the inspection of welds with overlap. The presence of overlap may make visual weld quality inspection more difficult since overlap can mask other discontinuities. The third-party inspector identified the 51 welds from the 905 weld discrepancies which had the most severe cases of overlap. The overlapped portion of these welds was removed by grinding and the weld was then reinspected. In all  :

cases, the remaining weld was at least the size specified by the design.

These welds revealed no other discrepancies.

Because it was found after grinding that no other discontinuities were masked by overlap and that the weld size remained within the specified limit, it -is concluded that the amount of overlap present on welds inspected by Pittsburgh Testing has no impact on the capacity of the welds.

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5 111- 1 III. SUPPLEMENTAL INSPECTIONS AND EVALUATIONS FOR OBJECTIVE ATTRIBUTES FOR HATFIELD ELECTRIC A. INTRODUCTION Appendix D to the Reinspection Program Report included commitments to do additional inspections for Hatfield Electric objective attributes where the sample size was not statistically significant. These supplemental inspections are described in Note 5 to Table DE-5, in Exhibit D-1 of Appendix D of the ,

Reinspection Program Report, and include equipment setting, equipment modifications, A325 bolting, and conduit support bolting. l B. EQUIPMENT SETTING ~ >

The work reinspected as part of the Reinspection Program did not include any reinspection of equipment setting. In order to complete the data base, the setting of 50 randomly selected pieces of safety-related electrical equipment from a ,

total population of approximately 250 have been reinspected. A total of 778 items were inspected and 34 discrepancies were identified. An evaluation was made to determine whether or not the observed discrepancies have any design significance. The result of this evaluation is that none of the observed discrepancies has design significance. The majority of the discrepancies consist of equipment anchoring details with weld length and weld spacing deviations. The equipment anchoring details were determined to be adequate because of the conservatism 'which was used in the determination of design anchorage loads.  !

The only deviation which resulted in a significant reduction of strength was a hold-down weld detail for 4160 volt switchgear. In this detail, welds on the two short sides of a four-sided weld were omitted. In order to evaluate the overall effect of this discrepancy it was assumed that all of the 4160 volt switchgear had this discrepancy. Because of the conservatism in the original equipment anchorage loads, it was determined that the as-huilt condition was adequate to support the required loads. .

5 111- 2 A few discrepancies involved discontinuities in the equipment grounding connection. The discontinuities were determined to be acceptable because of the presence of an alternate grounding connection in each case.

C. EQUIPMENT MODIFICATION The work reinspected as part of the Reinspection Program included reinspection of 27 items associated with equipment modification. This sample was too small j to permit meaningful reliability calculations. In order to expand the data base, an additional random sample of 50 pieces of safety-related electrical equipment out

,. of a total population of 250 have been reinspected. Equipment modification work -

is, in large part, not recreatable. Several modifications may be made to the same equipment. A subsequent modification may alter a previous modification.

Modifications may be made by the electrical contractor, the equipment supplier, Commonwealth Edison Operational Analysis Department, or Commonwealth Edison Byron Station personnel. .

To accomplish the supplemental reinspection of equipment modification, a 100%.

wiring inspection was made. A total of 1,850 items covering a considerably larger number of inspection points were inspected and '!4 discrepancies were identified.

An evaluation was made to determine whether or not the observed discrepancies had any design significance. The result of the evaluation is that none of the observed discrepancies has design significance. The discrepancies are primarily minor wiring variations that do not affect the functioning of the equipment.

s D. A325 BOLTING ,

In the Reinspection Program only eight cases of A325 bolting in electrical supports were reinspected. In order to expand this data base, an additional random sample of 51 supports out of a total population of 169 supports using A325 bolted connections were reinspected. The engineering evaluation established an acceptance criteria taking 'into account bolt relaxation and measurement accuracy. Of the 295 bolts which were reinspected on these supports,46 bolts did i

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SIII-3 not meet this acceptance criteria. The design of the associated connections was reviewed, and it was determined that these connections are adequate as bearing i rather than friction type connections. Although these discrepancies have no design significance, because of the number of discrepancies found, a retorquing of all Hatfield A325 bolting installation has been initiated. Any discrepant conditions will be corrected.

E. CONDUIT SUPPORT BOLTING The work reinspected as part of the Reinspection Program did not include checking the torque level of conduit support bolting. Conduit support bolt torque was deemed not recreatab!c because it could not be associated with an individual inspector. In order to resolve questions concerning conduit support bolting, 305 randomly selected supports were reinspected from a total of approximately 25,000. A total of 1,008 bolts were inspected. Torque values were recorded for any bolt with torque less than the minimum installation criteria. The engineering evaluation established an acceptance criteria taking into account bolt relaxation and measurement accuracy. Thirty-four bolts did not meet this acceptance criteria. These conditions were evaluated and found to have no design significance because the loads would be carried by the adjacent supports.

In this process of inspecting conduit support bolt torques, two clamps with four bolts were found missing. Based on our concern for missing clamps and bolts, a walkdown of the critical clamps was undertaken. A critical clamp is typically located where' a conduit terminates. There were 8,532 cas;es included in this initial walkdown and ten cases were found with missing bolts or clamps. The walkdown of the remaining accessible conduit is continuing to ensure that conduit clamps and bolts are in place. Any missing bolts or clamps will be restored.

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i F. CONCLUSION 4

i The suppidmental inspections and evaluations which have been conducted for

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Hatfield Electric objective attributes confirm the adequacy of the quality of -

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ERRATA AND ADDENDA TO THE REPORT ON THE BYRON QC INSPECTOR REINSPECTION PROGRAM insert the fo!!owing page behind the first title page, O

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ERRATA AND ADDENDA

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TO REPORT ON THE BYRON [

QC INSPECTOR  ;

REINSPECTION PROGRAM The fo!!owing pages contain errata and/or addenda:

Page Numbers ES-4, 6 VI-5, 6 Vil-2,9,10,11,12,13 Exhibit Vil-1 page 3,5 L A-6  :

B-6 k C-1,2,4,

'i Exhibit C-1 page 3,4 Exhibit C-2 page 2,7,3,9,11 l F-6 ,

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ERRATA AN!) ADDENDA TO TiiE REPORT ON Tile BYRON QC INSPECTOR REINSPECTION PROGRAM Page ES-4 Table ES-1 Reinspection Program Summary Line Indica:ing Revision Change 76,663 to 27,$3S Change 92.04 to 92.Sc6 Change S6,905 to 37,733 Line Indicating Revision e Change 44,950 to 45,833 Change 201,906 to 202,784 (The revised page for the Reinspection Program Report follows.)

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l L D. BYR_ON REINSPECTION PROGRAM RESULTS The results of the Reinspection Program are summarized by contractor in Table ES-1.

[ This table also delineates the number of reinspections performed as part of the Program.

l Table ES-1 l

Reinspection Program Summary Total Objective Subjective Objective No.of Inspection No.of Inspection and Objectise Results Subjective Results Subjec tive Contractor inspections

  • Acceptable I Inspections *
  • Acceptable2 '3 Inspections B'ount Brothers 2,390 98.8% NA NA 2,390 4

Johnson Controls 7,812 99.4%" 1,459 95.5 % 9,271 Hunter 69,624 99.0% 3,725 97.0 % 73,349 NISCo 2,792 99.6% 229 100.0 % 3,021 Hatfield Electric 60,245 96.5% 27,338 92.8% 87,7S3 R1

! Powers-Azco-Pope 8,047 96.3%" 6,607 86.2%" 14,654 f 4  ;

Pittsburgh Testing 6,016 98.9 % 6,137 85.3% 12,153 5

Peabody Testing 0 NA 163 75.5 % 163 l

l TOTAL 156,926 45,858 202,784 R1  ;

l l From Appendix D, Table D-1. >

  • From Appendix C, Tabic C-1.

t r Notes for Table ES-1:

1. Program acceptance criterion is 95%.  :
2. Program acceptance criterion is 90%.
3. Includes concurrence by third-party inspector.
4. 100% of inspectors sampled; 100% of accessible work for inspectors not meeting i

acceptance criterion reinspected. ,

5.100% of inspectors sampled; 100% of accessible work reinspected.  !

As can be seen from Table ES-1, over 200,000 reinspe:tions were performed as part l of the Byron Reinspection Program. All seven contractors performing objective ,

inspections exceeded the acceptance criterion. Four of seven i

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  • r ERRATA AND ADDENDA TO Tile REPORT ON THE BYRON QC INSPECTOR REINSPECTION PROGRAM Page ES-6 Section 3. - Plant _ Quality inferred From the Reinspection Program Line Indicating Revis:en Change 64,930 to 45,33S Change 4,132 to 4,001 (The revised page for the Reinspection Program Repart follows.)

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ES-6 surveillances, and evaluations implemented as part of 11 quality program further assure us that the results of the Reinspection Program are representative of the overall plant quality.

2. Plant Quality inferred From int.pector Qualification The Reinspection Program validates the adequacy of the inspector training ,

and certification programs in use prior to September 1982 for six out of eight contractors reviewed. These contractors are responsible for SS% of l the total work at Byron. This ensures that all work performed by these contractors was adequately inspected, from which it can be inferred that the contractors' construction work is of good quality.

3. Plant Quality inferred From the Reinspection Program For the objective inspections, a total of !$6,926 items were reinspected, and 3,247 discrepancies were noted. For the subjective inspections, a total of 45,S53 items were reinspected, and 4,001 discrepancies were noted. The R1 evaluation of these subjective and objective discrepancies showed that many of the discrepancies are insignificant or do not affect the design (e.g., chipped paint, documentation, measured dimensions different than those of the original inspector but still within design tolerance, etc.). The remaining discreparcies which had potential for affecting the design were evaluated further. This engineering evaluation showed that these discrepancies had no design significance. This provides direct evidence of the quality work at the Byron Station.

F. CONCLUSIONS

1. The Byron Reinspection Program has been completed in accordance with the agreement reached with the NRC staff.
2. The Program verified that the vast majority of inspectors whose work was l

reinspected passed the established acceptance criteria and were qualified (see Table ES-2).

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ERRATA AND ADDENDA TO T11E REPORT ON Tile BYRON QC INSPECTOR REINSPECTION PROGRAM ,,.

j Page VI-5 Line Indicating Revision Change 2,117 to 1,986

- Change i! to 3 Change 2,064 to 1,936 Line indicating Revision Change I to 10

  • Change 887 to 378 Line Indicating Revision Change 4,132 to 4,001 Change 233 to 239 Change 3074 to 2937 Line Indicating Revision Change 233 to 239 L

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VI-5 C. RESULTS OF ENGINEERING EVALUATION

1. Subjective Discrepancy Evaluation The results of the subjcctive discrepancy evaluations for each contractor )

are summarized in Table VI-1.

~ Table VI-l Summary of Subjective liiscrepancy Evaluation Results No.of Category X Category Y Category Z No. with Discrepancy No. Within No. Acceptable No. Acceptable Design Contractor Evaluations Parameters by Judgment by Calculation Significance Blount Brothers" 0 N/A N/A N/A N/A Johnson Controls 65 15 12 38 0 Hunter 109 25 23 61 0 N!SCo 0 N/A N/A N/A N/A Hatfield Electric 1,986 8 1,936 42 0 R1 Powers-Azco-Pope 914 201 77 636 0 Pittsburgh Testing 905 10 878 17 0 R1 Peabody Testing 22 0 11 11 0 TOTAL 4,001 259 2,937 805 0 R1

  • Inspection of Blount Brothers was performed by Pittsburgh Testing. Inspection results are reported under Pittsburgh Testing.

Table VI-l shows that 259 of the discrepancies (6%) identified in the R1 Reinspection Program are not " valid" discrepancies and represent work that is within current design parameters. The Category X discrepancies result primarily from design parameters that have been expanded since the

  • time of the original inspection. Therefore, the observed discrepancies are actually within current design limits.

ERRATA AND ADDENDA TO Tile REPORT ON Tile BYRON QC INSPECTOR REINSPECTION PROGRAM Page VI-6

'Line Indicating Revision Change 3,074 to 2,937 Line Indicating Revision Change 19% to 20%

(The revised page for the Reinspection Program Report follows.)

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The Category Y evaluation covered 2,937 of the weld discrepancies (74%) R1 i

wherein weld capacity was reduced by approximately 10% after accounting for the weld discrepancy. In all cases the margin remained within the specified design liniits.

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The Category Z evaluation covered 303 of the weld discrepancies (20%). R1

' The reduction in weld capacity varied after accounting for the weld

. discrepancy. - However, in all cases the design margin remained within the specified design limits.

The engineering evaluation of subjective discrepancies has shown that none have design significance.

A detailed presentation of subjective discrepancy evaluation is contcined

.in Appendix C.

2. Objective Dir.crepancy Evaluation The results of the objective discrepancy evaluations for each contractor are summarized in Table VI-2.

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ERRATA AND ADDENDA TO THE REPORT DN THE BYRON r QC INSPECTOR REINSPECTION PROGRAM Page VII-2 Line Indicating Revision Added phrase and changed 136,926 to 160,857 Line Indicating Revision Change 44,980 to 47,676 Line Indicating Revision Added word " objective" Line Indicating Revision Added sentence Line Indicating Revision Added footnote Add Page Vil-2A l

P (The revised pages for the Reinspection Program Report follow.)

VII-2 uniformly effective, performed most of his work after September 1982.

The vast majority of the work performed prior to September 1982 was reinspectable, and 100% of that reinspectable work for all inspectors failing to pass the Program acceptance criteria was reinspected. Because no discrepancy of design significance was identified, the quality of work was shown to be good. Peabody Testing had too little reinspectable work from which conclusions on certification program effectiveness could be drawn. However, this contractor had a very limited scope of work (0.2% of j the site total), most of which was overinspection of other contractors or inspections overseen by Commonwealth Edison personnel. Inasmuch as 100% of this contractor's reinspectable work was reinspected and no discrepancy with design significance was found, the good' quality of this contractor's work can be inferred.

3. The Reinspection Program and supplemental inspections subsequent to R1 the Reinspection Program resulted in a total of 160,857 objective inspections and a total of 47,676 subjective inspections being repeated by R1 currently qualified inspectors. These reinspections ranged over a wide variety of plant work items. Engineering evaluation of all observed objective discrepancies showed that none had design significance. R1 Engineering evaluation of all subjective discrepancies for six contractors R1 and a representative sample of discrepancies for Hatfield Electric and

. Pittsburgh Testing Laboratories showed that none had design significance.

This data supports the inference that the quality of work for all eight contractors in the Reinspection Program was good. l l The remainder of this chapter elaborates upon and substantiates these points. ,

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, B. MANAGEMENT APPROACH TO ENSURE QUALITY OF CONSTRUCTION 1

Commonwealth Edison has implemented a comprehensive quality program to assure that the Byron Station is constructed properly and is of high quality. The program begins prior to award of contracts by requiring that procurement documents include commitments to specific quality requirements and it continues These supplemental inspections were performed as a result of commi to the R1 NRC staf f.

1 3

VII-2A throughout the construction phase. The essence of the approach is the provision b of many independent layers of inspection and review of field installations to

. assure compliance with requirements and, thereby, to ensure quality construc-

tion.

i 1

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A m.

4 T

=

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ERRATA AND ADDENDA TO Tile REPORT ON Tile BYRON QC INSPECTOR REINSPECTION PROGRAM Page VII-9 Lines indicating Revision Added and modified sentences (The revised page for the Reinspection Program Report follows.)

Vil-9 acceptance criteria, and no observed discrepancies were determined to have design significance. The quality of their work is inferred from the reliability calcualtion presented in Section D below.

D. INFERENCE OF WCRK QUALITY FROM Tl!E REINSPECTION RESULTS R1 In this section, the detailed reinspection data given in Appendix B and, the

+

engineering evaluation data given in Appendixes C and D and the supplemental RI inspections and evaluations presented in Section !! and !!! of the Suppicment to the Reinspection Program are combined to obtain reliability estimates for each of Y the eight contractors' work. These reliabilities are intended to address the quality levels for v.Erk that was not reinspected.

1. Applicability of Data to Plant Quality inferences R1 The data from the Reinspecticn Program and the supplemental data R1 s provide s'ieasonabic basis for estimating plant quality when samples are adequate,in ' size and scope, and the entire Reinspection Program is of

. m ,e..

' sufficient technical scope. . s

, .y .

g'. The qcestion of' sample size and adequacy of representation for sampled

' ' inspectors in the. overall inspector. population is discussed in section C

%.  ? -s above. The sampling of inspectors' work was not entirely random in that it

q. ,

concentrates entlicly_on each inspector's first 3 months of work. However, R1 l 1, . the selection of the l'nspectors was random, and thus the work reinspected was largely random from a plan't' quality viewpoint. It should be noted

~

~

3 "that the calculation of the reliabilit;cs presented below is based on a formal statistical methodology which assumes random selection of RI y , ,- .

samples. Ik,we'ver, the biases introduced by the samp!c selection J /

. procedure are conservative and the results of the formal calculation are w thus justified in that they are underestimates of the true reliabilities.

- j - ,

Thh50fficiency'of technir;al scope is an engineering judgment that relates

, > to 16e televan'i'o of inspected attributes to work quality. Based on the QC procedures and their associat*J checklists used in the Reinspecion

. .d '

Progranf, it is our evnclusion that the Reinspection Program did have sulfiet*cnt technical sccpe to yield information on construction quality.

4 v .,/ e .

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  • -m=~-s- _.J_-_______--__< _

ERRATA AND ADDENDA TO Tile REPORT ON Tilli BYRON I QC INSPECTOR REINSPECTION PROGRAM Page Yll-10 Evaluation of Re:iabilities Line Indic:tingllevision Change Sentence Line Indicatirg Revision Change 44,900 tc 45,US ,

Line Indicating. Revision Change 4,132 to 4,C01 Change Paragrcph Add Pcre VII-10A (The revised pages for the Reinspection Pregram Report follow)

- . . - - , . e VII-lQ

[  % m

2. Evaluation of Reliabilities in the Reinspection Program, for objective inspections, a total of !$6,926 R1 items were reins'ected p and 3,24,7 discrepancies were noted (Appendix D).

I2or the sub'jective inspecdo,ns, a. total of 43,858 items were reinspected, R1 and 4,001 ~ discrepancies s'ere noted (Appendix C). All the objective R1

~

discrepancies which had potential for, affecting the design were evaluated. This engineering evaluation showed that none of these discrepancies had design significance. Engineering evaluation of all subjective discrepencies 'for sid co'otractors and a representative sample of discrepancies for Hatfield Electric and Pittsburgh Testing R1 4 Laboratory showed'that;none .had design significance. Subsequent to the Reinspection Program; objective inspections for an additional 3,931 items and subjective inspections for an additional 1818 welds were performed.

l All the discrepancier; which had a potential for affecting design were l evaluated. This evaluation showed.thht rione of these discrepancies had design significance. These evaluations Semonstrate the good quality of the work performed by the contractors reviewed at the Byron Station.

Tables Vile-1 through'v!!E-3-of h.xhibit Vil-1 list the number of anspected items, the number of discreparicies of design significance, and calculated reliabilities for each of the eight contractors. Objective and subjective attributes are listed separately. ,

The reliability for each attribute can be defined as the proportion of work items in the total popniation of work for.' th'a't attribute which have no discrepancies with de2ign~ significance. St'atistical estimates of the l reliability can be made from inspections and engineering analyses of f random samples froni thb population. The precision of these estimates, of course, increases with the sample size.

s 1

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s

. . . . a- .

Vil-10A A' generally accepted statistical method for calculating such reliabilities is to compute reliabilities at 95% confidence level from the sampled data.

Such a reliability represents a conservative estimate of the true reli-ability. It is conservative in the sense that there is a 95% chance that the true reliability is greater than the estimate. In the case v.here na discrepant items are observed in a random sample from a large populatien, the reliability at 95% confidence level can be calculated from the formula" E:

  • Reference 1: Miller, I., and Freund, J.E., " Probability and Statistics for Engineers,"

Prentice Hall, Inc.,1977, Chapter 9.

ud.

ERRATA AND ADDENDA TO T}lE REPORT ON Tile BYRON QC INSPECTOR REINSPECTION PROGRAM Page Yll-ll Line Indicate Revision i' Change 25 to 29 Line Indicating Revision Change 30 to 31 (

Change 21 to 24  :

Line Indicating Revision Change four to five Line Indicating Revision  !

Change five to two i Line Indicating Revision  ;

Change five to two Page Vil-12 Line Indicating Revision Change 5 to 6 l Deletes part of a sentence Page VII-13 Line Indicating Revision Change sentence 6

i i

i

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4

. (The revised pages for the Reinspection Program Report follow.) j e

.._ , ,,n-n-7 -

y . , - - - --

- - ---,p - ~ ,, , - . . - - -

, y v

VII-11 9955 R=1 Eq. VII-I n

where R = Reliability at 95% confidence level n = number of inspections in the random sample In Exhibit VII-1 and Tables Vile-1 (Blount), VI!E-2 (Johnson Controls),

Vile-3 (Hunter), Vi!E-4 (NISCo), VI!E-5 (Hatfield), VIIE-6 (Powers-Arco-Pope), VIIE-7 (Pittsburgh Testing), Vile-S (Peabody Testing), which fo!!ow, the reliabilities presented are based on Eq. Yli-1, i.e., they represent reliabilities at 95% confidence level based on samples which contained no discrepancies of design significance. It should be emphasized that, when a sample size is small, the true reliability is likely to be much greater than indicated.

Tables VIIE-1 through Vile-S show better than 95% reliability for 29 of the R1 31 attributes reinspected. In 24 of these cases, the calculated reliabilities R1 are better th'an 99%. For five cases, the reliabilities are computed in the R1 96% to 99% range. For the remaining two cases, in these tables no R1 reliability estimate at 95% confidence level is projected because Equation Vll-1 requires at least 60 observations to provide 95% reliability. For these two cases, the sample sizes were too small to obtain meaningful R1 reliabilities based on Equation Vil-1. This does not prevent us from concluding, on the basis of calculated reliabilities, that all contractors ,

performed good work. This conclusion remains valid because all inpectors within a contractor organization were qualified under the same program and good reliability demonstrated in one objective attribute'provides a valid basis for inferring the reliability in another objective attribute where

VII-12 sampling was limited. In Table Vile-6, three out of five attributes have R1 better than 95% reliability, therefore it is inferred that the reliabilities not listed in the tables would also be better than 95%. Note that for attributes where the number of items reinspected is large (>300), the computed reliabilities are better than 99E This is indicative of good quality work.

The above discussion of reliabilities indicates that better than 95%

reliability is expected for the work of all eight contractors. This component level reliability is considered to be high enough to conclude that work quality is good.

E. CONCLUSIONS The evaluation of Commonwcalth Edison management approach to ensure quality of construction and the successful completion of the Reinspection Program leads us to conclude that:

1. The good quality of construction at Byron is ensured because of the comprehensive quality program implemented by Commonwealth Edison management. The many layers of inspections, overinspections, audits, surveillances, and evaluations impicmented as part of this quality program further assure us that the results _ of the Reinspection Program are representative of the overall plant quality. -
2. With limited exceptions, the Reinspection Program verified the effectiveness of QC inspector certification programs prior to September 1982. This ensures that work performed by the contractors whose -

programs were effective was adequately inspected, from which it can be inferred that the contractor's construction work is of good quality. The quality of work for the contractors whose QC inspector programs were not verified has been confirmed through additional reinspection and evaluatien.

9

Vil-13

3. The adequacy of construction quality for a!! eight contractors is supported by 'he Reir.spection Prograni results, the results of the supplemental R1 inspections subsequent to the Reinspection Prograrn, and by inferences drawn from these results.

4 9

t ERRATA AND ADDENDA TO THE REPORT ON THE BYRON r QC INSPECTOR REINSPECTION PROGRAM  :

Exhibit VII-l Paee 3 of 5

. Item A. - Obiective Attributes >

Line Indicating Revision - t

.f - - Change 0 to 773 and add 99.6 i Line Indicating Revision  ;

Change 8 to 295 and add 98.9  !

Line Indicating Revision  !

Change 27 to 1350 and add 99.S Line Indicating Revision  :

-Added item 9 Line Indicating Revision Change footnote ,

i Item B. - Subjective Attributes '

- Lin'e Indicating Revision  :

Change 26,660 to 27,53S and 99.9 to >99 i Line Indicating Revision.

Added Footnote  ;

t i

1 b

i i.

4 $

(The revised page for the Reinspection Program Report follows.)

t 4

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, _ .-- ,,-v m,, ,- ,-y-,- , - ..-.,_,._---_~,.,.,_.,.,-,.-,-.-,y _,-_- ,y, .- - , _ - , ., ,_ , -y . .- .. _ ..m.., - _ - - . -

Exhibit Yll-1 Page 3 of 5 Table YllE-5 Calculated Reliabilities for Work of Hatfield No. of Reliability No. of Discrepar cies  % at 95%

Inspected with Design Confidence items Significance Level A. Objective Attributes

1. Conduit 2,793 0 99.9
2. Terminations 7,784 0 >99.9
3. Equipnient setting" 778 0 99.6 R1
4. A325 bolting' 295 0 9S.9 R1
5. Equipment modification
  • 1850 0 99.8 R1
6. Conduits as-built 44,777 0 >99.9 7.' Pan hangers 4,776 0 >99.9
8. Pan 80 0 96.3
9. Conduit support bolting
  • 1,008 0 99.7 R1 Subjective Attributes

! B.-

1. Visual welds 27,538 0** >99 R1 Supplemental inspections subsequent to the Reinspection Program. R1 i ..

Inferred from the engineering evaluation presented in Appendix C. R1 e

D i

ERRATA Af2D ADDENDA TO Tile REPORT ON Tile BYRON QC IN5PECTOlt REINSPECTION PROGRAM Exhibit VII-I Page 5 of 5

_ Line Indicat:ng Revision Added " Work Inspected By" Line Indicating Revision Changed 99.9 to >99 *

  • Line Indicat: .g Revision Added Footnote (The revised page for the Reinspection Program Report follows.)

Exhibit VII-I Page 5 of 5 Table VIIE-7 Calculated ReliaEIInties for V!ori: Inspected by R1 Pittsburgh Testing No. of Reliability No.of Discrepancies  % at 9390 Inspected with Design Confidence items Significance Level A. Objective Attributes

1. Concrete expansion .

anchor 6,016 0 > 99.9 B. Subjective Attributes

1. Visual welding 6,137 0** >99** R1 Inferred from the engineering evaluation presented in Appendix C. R1 Tabic Vile-8 '

Calculated Reliabilities for Work of Peabody No.of Reliabilty No. of Discrepancies  % at 95%

Inspected with Design ' Confidence

~A. Objective Attributes items Significanc e Level i None B. Subjective Attributes .

1. Visual welding
  • 163 0 98.2
  • 100% of accessible and recreatable work was rcinspected.
  • ERRATA AND ADDENDA TO THE REPORT ON Tile BYRON QC INSPECTOR REINSPECTION PROGRAM Page A-6 Item A. - Results by inspection Type Line Indicating Revision Change 89.9% to SS.6%

Change 92.1% to 92.S%

Line Indicating Revision Change (23,978/26,660) to (24,402/27,538)

Change (24,543/26,660) to (25,552/27,53S)

Under item B. - Results by inspection Attribute Line Indicating Revision Change 92.1% to 92.S%

Line Indicating Revision Change 2,6S2 to 3,136

%w (Thr- revised page for the Reinspection Program Report follows.)

. l A-6

?

Table A-5 Reinsnection Results liaTfTeid lflectric A. Results by Inspection Type Reinsp:ction Results (Acceptabte/ Total)

Type Level 11 Reinyection Third-Party Review Subjective 88.6 % 92.8 % R1 (24,402/27,53S) (25,552/27,53S) R1 Objective 96.5% (2)

B. Results by inspection Attribute Initial Samole Period Expansion Samo!e Period No. of People Final % No. of People Final %

Attribute Reinsnected AccenttNe Reinmc:ed Acceotah!e

1. Visual weld (Subjective) 8 92.8% (1) (1) R1
2. Conduit 6 97.6 % (1) (1)
3. Terminations (Objective) 5 99.9% (1) (1)
4. Equipment setting 0 0% (1) (1)

(Objective)

5. A325 bolting 1 100.0 % (1) (1)

(Objective)

6. Equipment modification 3 100.0 % (1) (1)

.(Objective)

, 7. Conduit as-built 8 95.9 % (1) (1)

(Objective)

8. Cable Pan

~

hangers 2 95.5 % (1) (!)

(Objective)

9. Cable Pan 1 100.0 % (1) (1)

(Objective)

Notes for Table A-5:

'Results are cumulative. 3,136 observed discrepancies were reinspected by RI

' third-par 1y inspectors.

(1) Not required (2) Not applicable 1

s

{

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ERRATA AND ADDENDA TO Tile REPORT ON Tile BYRON QC INSPECTOR REINSPECTION PROGRAM  ;

Page B-6 i All entries under Table B-5 Detailed Inspector Results Hatfield Electric - Attributes All items under Attrwute No. I have been revise ~c. .

Change item A 82S/365 to 833/S63 [

Change item C 60S/69S to 630/712 -

Change item E 10221/11312 to 10554/11501 Change item G 724/771 to 1132/1211 Change item 14233/4439 to 4462/4701 Change item N 3309/3404 to 33S1/34S9 Change item O 31/51 to 50/50 [

Change item W 4569/5070(3) to 4510/501 h3) l t

p Change total 24543/26C60 to 25532/27538 i

i

[

l I

a f

I I

L  :

i 1-i (The revised page for the Reinspection Program Report fol!ows.)

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B-6 Table B-5 Detailed Inspector Rc_su_Its Hatfic!d Electric Attributes Inspector No. I No.2 No.3 No.4 No. 5 No.6 No.7 No. 8 No.9 A 833/863 - - - - - - - -

R1 B- - - - - - -

4795/4974 - -

C 630/712 - - - - - - - -

R1 D -

80/80 638/638 (1) 8/S - - - -

E 10554/11501 187/183 48/4S - - - - - -

R1 F -

178/179 72/72 - -

2/2 - - -

G 1132/1211 386/401 544/546 - -

1/1 - - -

Rt H - - - - - -

3985/4112 - -

1 4462/4701 - - - - - - - -

R1 3 -

639/661 - - - - - - -

K -

1256/1284 - - - - - - -

L - - - - - - -

705/742 -

M - - - - - -

10952/11457 - -

N 33SI/34S9 - - - - - - - -

RI O $0/50 - - - - - - - -

R1 P - - - - - -

2001/20S1 - -

Q - - - - - -

4818/5055 - -

R - - - - - -

11734/12205 - -

S - - - - - -

2753/2S79 - -

T - - - - vi - -

1917/2014 - -

U - -

6473/64S0 (2) -

24/24(2) - - -

V - - - - - - -

3854/4034 SO/SO W 4510/5011(3) - -

R1 TOTAL 25552/27535 2/26/2793 7775/7784 -

8/8 27/27 42955/44777 4559/4776 80/30 Ri Notes for Table B-5:

No expanded sampling was required; a substitution (W) was made for (C) in Attribute No. I because (C) failed the first 3-month period but had no further inspections to reinspect.

Attribute ! - Visual weld -

Attribute 2 - Conduit Attribute 3 - Terminations Attribute 4 - Equipment setting Attribute 5 - A325 bolting Attribute 6 - Equipment modification

' Attrib'ute 7 - Conduit as-built Attribute 8 - Pan hangers Attribute 9 - Pan (Notes for Table B-5: Continued on the following page)

ERRATA AND ADDENDA TO Tile REPORT ON Tile BYRON QC INSPECTOR REINSPECTION PROGRAM Page C-1 Appenriix C EgineerinL Evaluatien of Subjective Disq;pancies Item B. - Quantity of 5 :bjectise (Weld) Inspection Discrepancies Line Indicating Revision Change 4,132 to 4,001 Line Indicating Revision Change 44,930 to 45,SSS Table C Summary of Weld Discreper,cies by Centractor Line Indiccting llevision Change 26,660 to 27,533 Change 2,117 to 1,986 Line Indicating Revis:en Change 44,9S0 to 45,333 -

Change 4,132 to 4,001 (The revised page for the Rein.,pection Program Report follows.)

C-1 APPENDIX C ENGINEERING EVALUATION OF

~ SUBJECTIVE D15CREPANCllCS-A. INTRODUCTION This appendix has been reformatted from the Appendix C submitted with the January 12, 1934, Interim Report. A sample of the subjective (weld) dis-crepancies was evaluated for the Interim Report. All weld discrepancies have been evaluated and tabulated for this report. The tables which form part of this appendix tabulate discrepancies by type and by method of engineering evaluation.

B. QUANTITY OF SUBJECTIVE (WELD) INSPECTION DISCREPANCIES The Reinspection Program identified 4,001 wc!d discrepancies associated with R1 visual weld quality inspection out of 45,S$3 welds inspected. Table C-1 R1 summarizes the number of welds inspected and weld discrepancies for each contractor.

Table C-1 Summary of Weld Discrepancies by Contractor No. of Welds No. of Weld Contractor inspected Discrepancies Blount Brothers " 0* N/A Johnson Controls 1,459 65 Hunter 3,725 109 NISCo 229 0 Hatfield Electric 27,53S 1,9S6 R1 Powers-Azco-Pope 6,607 914 Pittsburgh Testing 6,137 905 ,

Peabody Testing 163 22**

TOTALS 45,858 4,001 R1

  • Inspection of Blount Brothers was performed by Pittsburgh Testing. The inspection results are reported under Pittsburgh Testing.
  • 40 discrepancies were identified; IS were located in non-safety related structures.

ERRATA AND ADDENDA TO Tile REPORT ON Tile ilYRON QC INSPECTOR REINSPECTION PROGRAM Page C-2 Category Y Delete last sentence in paragraph I

-(The revised page for the Reinspection Program Report follows.)

8

C-2 r

C. CATEGORIZATION OF SUBJECTIVE DISCREPANCIES An engineering evaluation has been performed for each observed subjective (we!d) discrepancy. The eva! cation methods used can be divided into three categories.

These three categories are related to the acceptance criteria for visual weld inspection. The acceptance criteria consists of inspecting we!ds for arc strike, spatter, . convexity, crater, incomplete fusion, overlap, porosity, undercut, underrun, and cracks. The presence of these weld inspection items are con;idcred .

as weld discrepancies. These weld discrepancies vary in degree as to their effect on weld capacity.

Category X - Evaluation by comparison with current design parameters and tolerances.

Category X contains weld discrepancies that do not reduce the ,

weld capacity. Arc strikes and spatter are cosmetic indications that relate only to appearance. Convexity relates to weld metal on the face of a weld in excess of the weld metal necessary for the required weld size. Convexity has r.o effect on weld capacity (see Exhibit C-2 Section C.1).

Category Y - Evaluation based on engineering judgment by comparison of the discrepancy with design margins.

Category Y contains some of the following weld dis-crepancies: crater, incomplete fusion, overlap, porosity, undercut, or underrun. Portions of the weld with these discrepancies are considered ineffective, and weld capacity is ~

based on a reduced weld length. Engineering judgment is used to evaluate the weld discrepancies based on the availab'c design margin in the weld and the reduced weld length, which .

accounts for the assumed ineffective portions.

RI k

ERRATA AND ADDENDA TO THE REPORT ON THE BYRON QC INSPECTOR REINSPECTION PROGRAM

_Page C-4 Table C Summary of Subjective Discrecancy Evaluation Results Line Indicating Revision Change 2,117 to 1,936 Change 1i to S Change 2064 to 1936.

Line Indicating Revision Change I to 10 Change 887 to S78 Line Indicating Revision Change 4,132 to 4,001 Change 253 to 259 Change 3074 to 2937 Lines Indicating Revision

- This paragraph has been revised.

Add Page C-4A Line Indicating Revision Change 13% to 20%

(The revised page for the Reinspection Program Report follows.)

9 .

%_____. _ _ fl

L e

Cm Tabic C-2 Summary of Subjective Discre;Ency Evaluation Results Category 2 No. with Category Y Design No. of Category X No. Acceptable No. Acceptable Sienificance No. % tihin Discrepancy by Judgment bv Calcu!ation Evaluations Parameters Contractor 0 N/A N/A N/A N/A 0 3S Blount Brothers * ' 15 12 65 0 61 Johnson Controls 25 23 109 0 0 Hunter 0 0 R1 0 0 42 NISCo 8 1,936 1,9S6 0 Hatiield Electric 77 636 o 201 0 R1 914 17 Powers-Azco-Pope 87S 10 0 905 Pittsburgh Testing 11 11 22 0 Peabody Testing 0 R1 2,937 805 4,001 239 TOTAL h Testing. Inspection

  • Inspection of Blount Brothers was performed by Pittsburg results are reported under Pittsburgh Testing. tion Table C-2 shows that 6c5 of the discrepancies k thatidentified is in the Program as Category X are not " valid" discrepancies and within current design parameters. i the time of primarily from design parameters that have t design limits. been expanded s n l the originct inspection and therefore are within curren b d The Category Y evaluation in Tab!c C-2 indicates Powers-Azco- Pepe that 7495 o weld discrepancies, wherein for Johnson Controls, i tely Hunter, 10% after .

and Peabody, the weld capacity was reduced by approx mall cases, the accounting for the weld discrepancy, are acceptable. In aFor H ies > .

margin remained within design limits. J Testing, the remaining weid discrepancies, beyond j dged to be the 100 w R1 mapped for Hatfield Electric and 64 for PittsburghIt Testing,

!d discrepancies. were acceptable by comparison of the number and types of wc of welds are the weld discrepancies in the mapped set was found that f Hatfield E!ectric representative of the entire group of weld discrepancies c*

and Pittsburgh Testing.

C-4A The Category Z evaluation in Table C-2 indicates that 20% of the observed weld R1 discrepancies are acceptable. The reduction in weld capacity varied af ter accounting for the weld discrepancy. However, in all cases, the design margin remained within the specified design limits.

e

ERRATA AND ADDENDA TO TiiE REPORT ON THE BYRON QC INSI)ECTOR REINSPECTION PROGRAM EXHIBIT C-1, Page 3 of 4 Line Indicating Revision Change 2117 to 19S6 Change 11 to S Change 2046 to 1936 l

c

. I I

(The revised page for the Reinspection Program Report follows.) l

Exhibit C-1 Page 3 of 4 Table CE-3 Summary of Subjective DiWepancy Evaluation Hatfield IIie'ctric Type of Category X Category Y Category Z No. with Discrepancy Total No. W tthin No. Acceptable No. Acceptable Design By Attribute Quantity Parameters by Judgment by Calcula: ion Sicnifica ce Visual weld 1986 8 1936 42 0 R!

Note for Table CE-3:

'l. Categories X, Y, and Z are defined in Section C of Appendix C.

Table CE-4 Summary of Subjective Discrepancy Evaluation Powers-Azco-Pope -

Type of Category X Categorv Y Category Z No. with Discrepancy Total No. R ithin No. Acceptable No. Acceptable Design By Attribute Quantity Parameters by Judgment by Calcu!ation Significance Visual weld

1. Instrument 608 167 77 364 0 tubing supports ,
2. Socket welds 44 1 0 43 0 (NC)
3. Socket welds 24 11 0 13 0 (ND)
4. Support 34 0 0 34 0 welds (NF)
5. Socket welds 204 22 0 182 0 (B31.1)

TOTAL 914 201 77 636 0 Note for Table CE-4:

1. Categories X, Y, and 2 are defined in Section C of Appendix C.

ERRATA AND ADDENDA TO Tl!E REPORT ON Tile BYRON QC INSPECTOR REINSPECTION PROGRAM EXHIBIT C-1, Page 4 of 4 Line Indicating Revision Change i to 10 Change SS7 to 878 l

l' i

l^

l I

(The revised page for the Reinspection Program Report follows.)

I

-'N- ' 1 ' - - - -- - - -

______s-- _ _------

Exhibit C-1 Page 4 of 4 Table CE-5 Summ:iry of SubjeEtivBiscrepancy Evaluation Pittsbuigh Testing Type of Categorg Category Y Category Z No. with Discrepancy Total No. Within No. Acceptable No. Acceptable Design By Attribute Quantity Parameters by Judgment by Calcu!ation Significance Visual weld 905 10 878 17 0 I L Note for Table CE-5:

1. - Categories X, Y, and 2 are defined in Section C of Appendix C.

Table CE-6 Summary of Subjective Discrepancy Evaluation Peabody Testing Type of Category X Category Y Category Z No. with Discrepancy Total No. Within No. Acceptable No. Acceptable Design By Attribute Quantity Parameters by Judgment by Calculation Significance Visual weld 22 0 11 11 0 Note for Table CE-6:

1. Categories X, Y, and Z are defined in Section C of Appendix C.

O e

L ERRATA AND ADDENDA TO Tile REPORT ON TliE

- QC INSPECTOR REINSPECTION PROGRAM EXHIBIT C-2, Pege 2 of 13 Paragraph Indicating Revision This paragraph has been revised Add Exhibit C-2, Pcae 2A of 15 (The revised page for the Reinspection Program Report follows.)

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- >- s s

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Exhibit C-2 Page 2 of 15

~ " '

~

- .. N therefore_have no design significance. These are limited to arc strike,

<~7 -

convexity, and spatter.

Catqop B Weld disci @ancies that result in a reduction of the size, length, or r

capscity of,the weld. These include craters, incomplete fusion,

,/ ~

e overlap, porosity, undercut, and underrun. Category B v. eld dit-

~

x ,crepancies are further subdivided into Categories Bl and B2 to qua!!!y

$ th'esignificance of the.te weld discrepancies as follows:

r ,

.1 Category Bl Weld discrepaEcles that have capacity reductions of less than 10:6.

e

% 4

~ Category B2 Weld discrepancies that have capacity reductions of equal to or gre.ater than 10%

_CategoFy C '^ Weld discrepancies that are assumed unsuitable for load transfer and

.' result in total weld r' ejection. Cracks are the only case for this scategory. ..

AccordiNg' td-the American Welding Society, a weld discrepancy is defined as "An interruption of thd typich! structure of a weldment, such as a lack of homogeneity in

-the mechanical, metallurgical ' or physical characteristics of the material or weldment. - A discontinuity is not necessarily a defect" (Reference C2).

6

.~

The terms Cathory X, Category Y, and Category Z have been used to categorize the c evaluation metidds 6 sed for the AWS weld discrepancies in Chapter VI and in this

appendix. Categories A, B, and C have been used to categorize the significance of the a Wold discrepancy'.- The evaluation methods and weld discrepancy significance are

,. related. Categ'ory X is equivalent to_ Category A, and Category 2 is equivalent tc

  • Categories B2 and C; Cabgory.Y is equivalent to Category BI for Johnson Controls, R Hunter, Powers-Azco-P6pe, and
  • Peabody. For Hatfield Electric and Pittsburgh sTesting, the results of the enginee' ring, evaluation of 100 mapped weld discrepancies

,.,.for Edtfield Electric and 64 for Pittsburgh Testing indicated no design significance.

aThe . mapped welds for Hatfield Electr>ic and Pittsburgh Testing were biased by

, includirg'.at least $0 welds that the tNrd-party inspector identified as having the most m .

~ weld. quality disc (epan^cies. This was done by reviewing all the reinspectic recer is for dibrepant weldIwEiich were previously examined in the field by the same third-

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Exhibit C-2 Page 2A of 15 i

party inspectors. For the remainder of the weld discrepancies for Hatfield Electric and Pittsburgh Testing, a detailed review of the reinspection records was made to assure that the number and types of discrepancies in the mapped welds were representative of the entire group. Based upon the ,

results of the engineering calculations for the mapped welds, the review of the reinspection records including discussions with the third-party inspectors, and the knowledge of the conservative design process, it was inferred that the remaining population of weld discrepancies is acceptable. On this basis, the remaining Hatfield Electric and Pittsburgh Testing weld discrepancies were placed in Category Y.

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_ ERRATA ANif 5DDENDA TO Tile REPORT ON Tile BYRON QC INSPECTOR a .,

REINSPECTION ..

PROGRAM s

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-EXHIBIT 03-2, Paco 'of 15

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Paragriph 3 - Ilatfi Id $lectric avaluation Results - ATS We:d Discrecanc:es L.ine Indicating Revision, Change 26,660 to,27,53S , '

Change 2,117 to 1,936, ,~

Line Indicating Revision .

Change 2,117 to 1,936 ,,

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(The revised page for the Reinspection Program Report follows.)

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. Page 7 of 15 Table CE-8 Results of AWS Weld Discrepancy Evaluation Hunter Weld Discrepancy Category A B1 B2 C Weld Weld No Strength Strength Weld No. of Weld Structural Reduced Reduced Rejected Weld Type- Discrepancies Impact by < 10% by 1 10% (Cracks)

' Pipe supports and pipe whip restraints ' 60 19 18 23 0 The results of the engineering evaluation of Hunter AWS welds indicate : hat each of the components are adequate to carry the design loads with the obser.ed discrepancies present. ,

Based on the small number of discrepancies and the evaluation which deterrained that no discrepancy had design significance, the AWS welding performed by  ;

- Hunter has been determined to be of good quality.-

3. Hatfield Electric Evaluation Results - AWS Weld Discrepancies The inspection work performed by Hatfield included conduit supports, junction box supports, cable tray supports, cable tray hold-down welds and auxiliary stee!

for electrical supports.' A total of 27,53S welds were reinspected and 1,916 v.e:d R:

discrepancies were identified.

A detailed review of the reinspection records for all 1,936 discrepancies was Ri made. This review indicated that there were only.two cracked welds. In order to achieve 95% reliability with 95% confidence, a statistical sampling plan was chosen in accordance with Military Standard 10$D. The resulting sample sitt fer the engineering evaluation was 100 welds. The sample was conservatively biased by including the 50 welds that the third-party inspector identified as having the most weld quality discrepancies. The two welds with cracks were part of that group. The remaining 50 welds were randomly selected.

ERRATA AND ADDENDA TO Tile REPORT ON Tile BYRON QC -

INSPECTOR REINSPECTION PROGRAM  ;

EXHIBIT C-2, Page 3 of 15 Line Indicating Revision Change 35 to 36  :

Change.15 to 16

_ Line Indicating !!cvision .

Change 36 to 34 . '

Change 17 to 16 Change IS to 17 Line Indicating Revision - '

Change 29 to 30 ' ,

Change 19 to 70 l i

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EXIIIBIT C-2 Page 8 OF 15 The results of the engineering evaluation for the sample of 100 Hatfield weld.; are shown in Table CE-9.

Table CE-9 Results of AWS Weld Discrep.3ncy Evaluation llatfield Electric Weld Discrepancy Category A B1 B2 C Weld W eld No Strength Strength No. of Weld Structural Reduced Reduced Rejected Weld Type Discrepancies Impact by < 10 % by 2 10% (Cracks)

a. . Conduit /
-junction box supports and associated auxiliary steel' 36 2 17 16 1** R1
b. Cable tray supports and associated auxiliary steel 34. 1- 16 17 0 R1

. c.~ Cabic tray hold-down 30 2 20 7 1* R1 TOTAL 100 5 53 40 2'**

One of the two ho!d-down welds attaching the cable tray to its support was cracked. It was found that, after subtracting the entire length of the cracked weld, the other weld was sufficient to transfer the design loading.

    • Temporary tack weld used to aid cons *ruction was cracked. The tact: weld is not required by design. There is no crack in the design weld.
      • The potential of crack propagation into the base metal was evaluated. For the two' reported cases, based on the fracture toughness of the materiais, it was determined that the cracks will not propagate into the base meta! under the maximum design loading and minimum plant operating temperatures.

Design margins exist in conduit and junction box supports and associated auxiliary steel because the initial design conservatively assumed maximum O

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ERRATA AND ADDENDA TO Tile REPORT ON Tile BYRON QC INSPECTOR REINSPECTION PROGRAM P

Exhibit C-2, Page 9 of 15

-Line Indicating Revision Change 36 to 34 Line Indicating Revision Change 13% to 14%

Line Indicating Revision Change 29 to 30 (The revised page for the Reinspection Program Report follows.)

EXHIBIT C-2 Pege 9 of 15 cable weight in each conduit. In addition, the supports and auxiliary steel are conservatively designed for peak seismic acceleration. When a more exact calculation was performed using actual cable loads and actual seismic acceleration, the design margin exceeded a 1.5 factor. This design margin is representative of the highly stressed conduit and junction box supports and associated auxiliary steel in the plant. The we!d strength reduction for all but the two lowest quality welds was applied to all of the components with weld discrepancies and the weld stresses remained within design basis allowables. The two lowest quality welds were evaluated and ,

those supports have a design margin greater than one.

A design margin exists in welded connections for cable tray supports and cable tray support auxiliary steel because the initial design was conservatively based on a maximum uniform cable load. In addition, the components are generally designed using simplified, yet conservative, techniques. By using actual cable tray loadings and more exacting methods of analysis, it was shown that the actual stresses are lower than the stresses from the original design. For the 34 cases where a detailed R1 engineering evaluation of the weld discrepancy was performed, the welds are adequate to carry the loads. The average value of the we!d strength reduction for cable tray supports and auxiliary steel is approximately 14% This reduction is not significant to the overall behavior of the R1 support system.

A design margin exists for cable tray hold-down welds because the initial design conservatively assumed maximum cable weight, maximum cable tray span and peak seismic acceleration. When a more detailed calculation is performed for any particular cable tray hold-down weld using the .

seismic values for that particular location, actual cable tray loads and actual cable tray spans, there is additional design margin. There is additional design margin for the 30 cases where a detailed engineering RI

- evaluation was performed, and the welds are adequate to carry the design loads.

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ERRATA AND ADDENDUM TO Tile REPORT ON Tile BYRON QC INSPECTOR REINSPECTION PROGRAM t

EXHIBIT C-2, Page 11 of 15 Line Indicating Revision Change Twenty-eight to Thirty-one (The revised page for the Reinspection Program Report follows.)

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Exhibit C-2 Page 11 of 15 An engineering evaluation of all 603 AWS weld discrepancies was completed. In all cases, the design of the component was acceptable with the observed discrepancy present. The results are categorized in the Table CE-10.

Table CE-10 Results of AWS Weld Discrepancy Evaluation Powers-Azco-Pope Weld Discrepancy Catecory A B1 B2 C Weld Weld No Strength Strength No. of Weld Structural Reduced Reduced Rejected Weld Type Discrepancies impact by < 10% by 110% (Cracks) r Instrument tubing supports 608 167 77 364 0 The supports installed by Powers-Azco-Pope typically have a large design margin.

The supports are designed for peak seismic accelerations. These supports are selected from generic design tables which envelope the various design considera-tions and use standard member sizes. Thirty-one of the supports associated with R.

the 608 discrepancies had a design margin of 1.1 or less. This is representative of the highly stressed supports installed by Powers-Azco-Pope. The maximum weld strength reduction based on the lowest quality weld was applied to all of the supports associated with the 608 discrepancies. In all cases, after performing a more exact analysis, the design margin remained greater than one and had no design significance.

The results of the engineering evaluation of Powers-Azco-Pope AWS weld discrepancies indicate that the Reinspection Program has captured a representative sample of highly stressed elements with lowest quality welds and that'there is no design significance.

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, ERRATA AND ADDENDUM TO Tile REPORT ON TliE BYRON QC

. INSPECTOR REINSPECTION PROGRAM Page F-6 Paragraph deleted e

a (The revised page for the Reinspection Program Report follows.)

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F-6 Evaluation of fifty welds from the entire population of discrepant welds with the lowest factor of safety. Another method would be to select the worst weld in each category and the weld with the lowest factor of safety in each category. Then perform a detailed engineering evaluation to determine if the worst weld would meet the design intent for the weld with the lowest factor of safety."

Response

As stated in the response to Q4, all weld discrepancies have been evaluated. Refer to Exhibit C-2, Sections D.1 through D.6, for the erigineering evaluation of highly stressed welds and their compliance with design criteria.

. QS. " Provide a summary regarding the number and type code (ASME) and AWS) rejectable items found during the reinspection for each contractor. Further, with regard to the number of rejectable ASME Code items, please explain how you are going to assure that the items that have not been repaired are acceptable. This

-includes both items that have and have not been reinspected."

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