ML20212H103
| ML20212H103 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 01/13/1987 |
| From: | TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML20212G828 | List: |
| References | |
| 215.9-(B), 215.9-(B)-R01, 215.9-(B)-R1, NUDOCS 8701210281 | |
| Download: ML20212H103 (14) | |
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i, TVA EMPLOYEE CONCERNS REPORT NLMBER: 215.9 (B)
SPECIAL PROGRAM REPORT TYPE: REVISION NUMBER: 1
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SEQUOYAH ELEMENT TITLE: CIVIL / STRUCTURAL DESIGN Structural Steel Connection Design PAGE 1 0F 13 REASON FOR REVISION:
- 1. Incorporated SRP's and TAS' comments. I.dded ciironology, corrective action, and CATD list.
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- TVA EMPLOYEE CONCERNS REPORT NUMBER: 215.9 (B)
SPECIAL PROGRAM REVISION NUMBER: 1 PAGE 2 0F 13
- 1. CHARACTERIZATION OF-ISSUE:
Concern: Issue:
IN-85-297-003
" Structural steel connections Bolts and welds are used in the same (I-Beam to embed plates) are both connection to transfer loads welded and bolted. One method from structural steel members to is for vibration and the other concrete walls. These are not is for dead loads. Both type supposed to be mixed.
connections are being used on the same I-Beam and these 'are not supposed to be mixed.' . . . " l
- 2. ' HAS ISSUE BEEN IDENTIFIED IN ANOTHER SYSTEMATIC ANALYSIS? YES X NO Identified first by WBN Problem Identification Report and then by Generic Applicability Review, SON Significant Condition Report and Related Engineering Report q Dates: December 10, 1985, January 10, 1986, and February 11, 1986 Documentation Identifiers:
PIR WBN CEB 8573, SCR SQN CEB 8601, and CAQ Engineering Report for SCR SQN CEB 8601,
- 3. DOCUMENT NOS., TAG NOS., LOCATIONS, OR OTHER SPECIFIC DESCRIPTIVE IDENTIFICATIONS STATED IN ELEMENT:
No specific area, numbers, or identifications were referenced. The issue in question ' general and addresses structural steel framing where both bolting and welding were used on the same connection.
- 4. INTERVIEW FILES REVIEWED:
The interview files for concern IN-85-297-003 were reviewed on 10/02/86 as indicated by RFI SQN #607 (10/02/86). The files
- contain only the K-Fom and Generic Applicability Sheets.
0025D - 12/30/86
c.
TVA EMPLOYEE CONCERNS REPORT NUMBER: 215. 9 - ( B )
SPECIAL PROGRAM REVISION NUMBER: 1
[ PAGE 3 0F 13
- 5. DOCUMENTS REVIEWED RELATED TO THE ELEMENT:
See Appendix A.
- 6. WHAT REGULATIONS, LICENSING COMMITMENTS, DESIGN REQUIREMENTS, OR OTHER APPLY OR CONTROL IN THIS AREA?
See Appendix A.
- 7. LIST REQUESTS FOR INFORMATION, MEETINGS, TELEPHONE CALLS, AND OTHER DISCUSSIONS RELATED TO ELEMENT:
See Appendix A.
P. EVALUATION PROCESS:
- b. Identified SON investigation on this topic.
j c. Selected SQN design drawings where bearing-type bolts and
(. welds were used in the same connections.
- d. Performed walkdown in reactor building and verified that
. " mixed" connections exist.
- e. Reviewed drawings and calculations for cases of " mixed" connections.
- 9. DISCUSSION, FINDINGS, AND CONCLUSIONS:
The discussion, findings, and conclusions in this section address structural steel connection design for miscellaneous steel supports including those for commodities such as electrical raceways, HVAC ducts, and instrument tubing but excluding mechanical system piping. The same subject, but for another concern related to piping, has been investigated under Report Number 222.5 (B) entitled Pipe Support Weld Design - Bolts Replaced by Weld.
Chronology:
02/78: A generic detail for mixed connections was issued.
05/85: The concern was submitted to TVA on a K-form.
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0025D - 12/30/86
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- TVA EMPLOYEE CONCERNS REPORT NUMBER: 215.9 (B)
SPECIAL PROGRAM
' REVISION NUMBER: 1 PAGE 4 0F 13 12/85: TVA identified the issue at WBN 01 /8 6 : TVA identified the issue at SQN 02/86: TVA issued engineering report for the SCR SQN CEB 8601 09/86: TVA issued policy memorandum PM 86-17 addressing the issue Discussion:
Sequoyah FSAR Section 3.8.4.5.2 and the Design Criteria SQN-DC-V-1.3.2 and SQN-DC-V-1.3.3.1 commit to the American Institute of Steel Construction's (AISC) " Specification for the Design, Fabrication and Erection of Structural Steel for Buildings" as the design code for the structural steel and its connections.
Section 1,15.10 of this specification gives design criteria for use of bolts in combination with welds. It states:
. . . A307 bolts, or high strength bolts used in
.g bearing-type connections shall not be considered as
$4' sharing the stress in combination with welds. Welds, if used, shall be provided to carry the entire stress in the connection."
Policy memorandum PH 86-17 (CEB), issued in September 1986 by the TVA civil branch chief, recognized and addressed this issue .( App.
A, 5.e). The instructions clearly require that AISC requirements be followed.
Occasionally in steel construction, a beam will have a welded connection at one end and a bearing-type bolted connection at its other end. AISC does not preclude this type of construction and does not consider this to be a " mixed" connection as described in Sec . 1.15.10.
Because the evaluation team had found that the access platform framing around the WBN steam generators has " mixed" connections, similar framing at SQN was reviewed. The review of the drawings
( App. A, 5.f) and a plant walkdown at SQN revealed that the beams are framed into steam generator support columns; therefore, the condition of " mixed" connections for the steam generator platform framing does not exist at SQN.
k 002ED - 12/30/86
i TVA EMPLOYEE CONCERNS REPORT NUMBER: 215.9 (B)
SPECIAL PROGRAM l REVISION NLHBER: 1 PAGE 5 0F 13 Miscellaneous steel beams frequently have welded end plates. These end plates are, in turn, surface-mounted on concrete walls and secured with mechanical expansion anchors installed per TVA Specification G-32. Mechanical expansion anchors do not produce friction-type connections; thus, they must be considered as bearing-type connections.
In areas with embedded plates in concrete walls, where configuration considerations require that a surface-mounted plate for a steel beam partially overlaps an embedded plate, potential for a " mixed" connection exists. Typically, the plate has two or three expansion anchors with welding along the overlapping lengths. Where a surface-mounted plate has three expansion anchors and only a limited amount of weld at the fcurth corner, the weld initially resists all the load until it reaches yield and slips; then the expansion anchors take over the load-resisting function.
However, at this point the weld is no longer functional, and the ancnors must be able to resist all the load considering the asymmetry of the connection. This is an acceptable approach for the reanalysis.
$."' Significant Condition Report (SCR) SQN CEB 6601 was prepared for the Sequoyah plant on January 10, 1986, based on a similar condition at the Watts Bar Plant. The condition is described as follows:
" Note II-2 on TVA Drawing 47A050-2 R5 allows substitution of fillet welds in place of bolt anchors when a surface mounted plate overlaps an embedded plate such that one or more of the anchors cannot be installed. Design calculations justifying this note do not exist. The apparent assumption, that the load distribution between the weld and anchor bolts are
[ sic] equivalent, has not been substantiated and may result in an unconservative design on the weld to the embedded plate."
The SCR states that this condition has existed since February 19, 1978.
SQN drawing series 47A050, 47A051, 47A052, 47A054, 47A055, and 47A056 cover general notes for all seismic Category 1 support structures for piping, electrical conduits and trays, HVAC ducts, and instrument tubing. All of these drawings have a similar note allowing substitution of welding when embedded plates are encountered (App. A, 5 9). Original Sequoyah calculations ( App. A, 5.h) backing up the general notes were reviewed, but they did not
( address the mixing of bolting and welding.
! 002ED - 12/30/86
TVA EMPLOYEE CONCERNS REPORT NUMBER: 215.9 (B)
SPECIAL PROGRAM REVISION NUMBER: 1 PAGE 6 0F 13 The evaluation team also reviewed recent TVA assessment calculations ( App. A, 5.1) which were prepared to support the SCR '.
conclusions that:
o All systems will be able to perform their intended design functions o No failures will occur as a result of this note o No plant modifications will result from this CAQ The calculations addressed two hypothetical sample plates subjected to weld substitution arrangement, and a detailed finite element analysis was performed.
The evaluation team reviewed the latter calculations and made the following observations:
- a. In establishing the adequacy of the connection, the maximum 1
allowable shear load for four bolts was applied to the entire
- connection. This is acceptable as it will envelope the actual loads for connections at SQN.
- b. The load established in a. above was shared between the expansion anchors and the weld. This is contrary to the AISC code and TVA policy memorandum PM 86-17.
- c. The analysis demonstrated several cases where the stresses exceeded the yield stress (one case exceeded the ultimate stress) of the weld. This is contrary to FSAR Tables 3.8.4-1 through 3.8.4-18.
. d. In determining the ultimate load carrying capacity of the weld, the capacity of the base metal, which could be j governing, was not considered.
The evaluation team reviewed TVA preliminary calculations ( App. A, l 5.j, 5.k, 5.1, and 5.m) in September 1S86 for specific mixed connections and determined that DNE had adequately addressed the issue. Moreover, the preliminary conclusion of one calculation
( App. A, 5.m) requires a modification to qualify the mixed connection welding.
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- TVA EMPLOYEE CONCERNS REPORT NLMBER: 215.9 (B) .
SPECIAL PROGRAM REVISION NUMBER: 1 PAGE 7 0F 13 During a plant walkdown in the SQN reactor building, several mixed connection conditions were noted by the evaluation team. These connections support a large duct at El. 710' circling the reactor cavity wall in the annulus area approximately at azimuths 330 ,
350*, and 10*. Observations during the walkdown indicate that there are additional supports with mixed connections.
Findings:
The issue is valid that a combination of welds and expansion anchor l bolts has been used for transferring shear loads from structural steel members to concrete walls. Calculations performed for the mixed connections on drawings 47A050, 47A051, 47A052, 47A054, 47A055, and 47A056, and for SCR SQN CEB 8601 do not satisfactorily comply with the design commitment.
Conclusion:
The evaluation team concludes that the issue of mixed connections is valid. Some related calculations do not demonstrate SQN conformance to FSAR commitments and TVA's policies and design
- y. criteria.
1
- 10. CORRECTIVE ACTION:
To comply with the design requirements, TVA has ccomitted to the folicwing corrective action plan (CAP) (TCAB-049, App. A, 5.n).
TVA will use a statistical method with randomly selected samples to establish adequacy. A minimum of 60 samples will cover a variety of Category I systems located in different structures and will irclude end plate connections supporting piping, HVAC ducts, electrical conduits and trays, and platforms. The mixed-connection samples subject to the actual design loads will be structurally assessed in accordance with the AISC Specification Section 1.15.10.
The maximum actual design stresses in welding will be computed and compared with the allowable stresses. Connections found deficier.t in welding will be strengthened. If necessary, the sample size will be expanded until TVA can demonstrate with a 95 percent confidence level that at least 95 percent of the as-built mixed connections at SQN meet the design requirements.
0025D - 12/30/E6
TVA EMPLOYEE CONCERNS REPORT NUMBER: 215.9 (B)
SPECIAL PROGRAM REVISION NUMBER: 1 PAGE 8 0F 13 L(l~
To preclude recurrence of this problem, TVA has issued a policy memorandum instructing engineers to follow the AISC specification section dealing with the mixed connections and explaining its
- ( rationale.
Application of statistical methods are an acceptable means of assessing as-built installations. TVA's CAP based on this statistical method will provide detailed calculations for establishing the adequacy of the randomly selected samples, which -
in turn, will give a 95 percent confidence level to the entire population of the mixed connections. As a result, TVA will meet
- its FSAR commitment for the Category I components at SQN. The evaluation team concludes that the stated CAP is an acceptable resolution of the concern and should also preclude recurrence of
, the problem.
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l 00?50 - 12/30/86
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- TVA EMPLOYEE CONCERNS REPORT NtMBER: 215.9 (B)
SPECIAL PROGRAM REVISION NUMBER: 1 PAGE 9 0F 13 APPENDIX A
- 5. DOCUMENTS REVIEWED RELATED TO THE ELEMENT:
[B41851220 016]
- b. TVA memo from R. O. Barnett, " Potential Generic Condition Evaluation - Problem Identification Report (PIR) PIR WBN CEB 8573 - Bolt Replacement Welds for Surface - Mounted Plates,"
[B25 860103 300] (12/20/85)
- c. TVA memo from R. -0. Barnett to J. P. Vineyard, "SCR SQN CEB 8601 - Unsubstantiated Design Assumption on Weld of Surface Mounted Baseplate to Existing Embedded Plates,"
[B41860304 009] (03/04/86)
[S01 860211 952]
/ e. TVA memo from R. O. Barnett, " Policy Memo PM 86-17 (CEB) -
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_ Structural Steel Connections Combining Welds and Bolts (Including baseplate connection)," [B41 860911 011] (09/11/86)
o 48N905 (R24) Reactor Building Units 1 & 2 - Misc. Steel -
S.G. , R.C. Pump and Press. Rel. Tnk. - Access Platform -
Sh. 1 o 48N906 (R12) Reactor Building Units 1 & 2 - Misc. Steel -
S.G. , R.C. Pump and Press. Rel. Tnk. - Access Platform -
Sh. 2 o 48N908 (R10) Reactor Building Units 1 & 2 - Misc. Steel -
Steam Generator - Access Platfonn o 48N908-1 (R7) Reactor Building urots 1 & 2 - Misc.
Steel - Steam Generator - Access Platform o 48N908-2 /.R6) Reactor Bai.1intq . Its 1 & 2 - Misc.
Steel - Steam Generator - Access Platform
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00250 - 12/30/86
.~ TVA EMPLOYEE CONCERNS REPORT NUMBER: 215.9 (B)
SPECIAL PROGRAM REVISION NUMBER: 1
( - PAGE 10 0F 13 APPENDIX A (continued) o 48N908-3 (R3) Reactor Building Units 1 & 2 - Misc.
Steel - Steam Generator - Access Platform o 48N908-4 (R1) Reactor Building Units 1 & 2 - Misc.
Steel - Steam Generator - Access Platform o 48N908-6 (RO) Reactor Building Units 1 & 2 - Misc.
Steel - Steam Generator - Access Platform
- g. TVA SON Drawings:
o 47A050-1 (R2, 3, and 6) Seismic Class I Structures -
Mechanical Hanger Drawing General Notes o 47A050-16 (Rl) Seismic Class I Structures - Mechanical Hanger Drawing General Notes o 47A050-16A (R1) Seismic Class I Structures - Mechanical
.r' Hanger Drawing General Notes
(- o 47A051-21 A (R1) Seismic Class I Structures - Mechanical Seismic Support Instr. Sensing Lines o 47A052-1 (R9) Seismic Class I Structures - Mechanical Seismic Supports - Radiation Monitoring and Sampling o 47A054-1 (R7) Seismic Class I Structures - Mechanical Seismic Supports - Control Air Lines o 47A055-1B (R3) Seismic Class I Structures - Mechanical Heating, Ventilating, and Air Conditioning Duct Supports
? o 47A056-1 A (R14) Seismic Class I Structures - Mechanical Seismic Supports - Conduits
o 48W904 (R36) Miscellaneous Steel - Lower Ice Condenser -
Access Platform El. 745.0 o 48W904-1 (R10) Miscellaneous Steel - Steam Generator Access Platforms 0025D - 12/30/86
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TVA EMPLOYEE CONCERNS REPORT NtMBER: 215.9 (B)
SPECIAL PROGRAM REVISION NUMBER: 1 PAGE 110F 13 APPENDIX A (continued) o 48W904-2 (R8) Miscellaneous Steel - Steam Generator Access Platforms o 48W904-3 (R14) Miscellaneous Steel - Steam Generator Access Platforms
< 8601," [P25 860904 300]
$ j. TVA DNE Calculations, " Support 47A 920-8-2," [B25 860811 323]
Prelim. Rev. 1, (09/20/86)
- k. TVA DNE Calculations, " Attachment to AB emb. MKICPLI 48N1277, El . 748'-0," Preliminary, (09/20/86)
- 1. TVA DNE Calculations, "Gual . Attach. to aux. bldg. embed MK y 23 C below El. 749'," Preliminary, (0S/20/86)
- m. TVA DNE Calculations, " Cable tray support qualifications MK-3 Aux. Bldg. El . 734'," Preliminary, (09/20/86)
- n. TVA letter from G. R. McNutt to G. L. Parkinson, " Employee Concern Evaluation Program - SQN Restart Program - Corrective Action Plan," TCAB-049 (12/30/86)
- 6. WHAT REGULATIONS, LICENSING COMMITMENTS, DESIGN REQUIREMENTS, OR OTHER APPLY OR CONTROL IN THIS AREA?
- a. SNP FSAR update through Amendment 3 Section 3.8.4.5.2 " Structural Steel" and Tables 3.8.4-1
~
through 3.8.4-18
- b. TVA SQN " Detailed Design Criteria for Miscellaneous Steel Components for Class I Structures," No. SQN-DC-V-1.3.2, Rev. 8 i c. TVA SQN, General Design Criteria for " Additions af ter November 14, 1979 - Reinforced Concrete, Structural and Miscellaneous Steel," Design Criteria No. SQh-DC-V-1.3.3.1, Rev. 4 k
0025D - 12/30/86
TVA EMPLOYEE CONCERNS REPORT NUMBER: 215.9 (B)
SPECIAL PROGRAM REVISION NUMBER: 1 PAGE 12 0F 13 APPENDIX A (continued)
'd. TVA, " Design of Structural Connections," Civil Design Guide DG-C1.6.4, Rev. O
- e. Merican Institute of Steel Construction ( AISC),
" Specification for the Design, Fabrication, and Erection of Structural Steel for Buildings," adopted February 12, 1969
- f. TVA, General Construction Specification No. G-32, " Bolt Anchors Set in Hardened Concrete," Rev.11
- 7. LIST REQUESTS FOR INFORMATION, MEETINGS, TELEPHONE CALLS, AND OTHER DISCUSSIONS RELATED TO ELEMENT:
- a. Documents reviewed were obtained in visits to the SQN site on August 20 through August 24, 1986, and September 16 through September 20. Contact was made with Messrs. F. S. Taylor and J. W. Morgan of TVA DNE, who made the documents available.
- c. RFI SCN #580, (09/22/66)
- e. BLT 037, (09/05/86)
- f. Walkdown in the Sequoyah Unit 1 Reactor Building, by the
. evaluation team on 09/18/86 i
0025D 12/30/86
- [* TVA EMPLOYEE CONCERNS REPORT NtMBER: 215.9 (B)
SPECIAL PROGRAM REVISION NUMBER: 1
- PAGE 13 0F 13 CATD LIST ,
The following CATD identifies and provides corrective action for the finding included in this report:
215.09 SQN 01 (12/24/86) 4 f
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~) i REFERENCE - ECPSI20J-ECPS121C TENNESSEE VALLEY AUTHORITY PAGE '- 85 FREQUENCY - REQUEST OFFICE OF NUCLEAR POWER RUN TIME -- I2:57:19 '
3 ONP - ISSS - RHM EMPLOYEE CONCERN PROGRAM SYSTEM (ECPS)- RUN DATE --12/02/86 LIST OF EMPLOYEE CONCERN INFORMATION CATEGORY: EN DES PROCESS & OUTPUT SUBCATEGORY: 21509 STRUCTURAL STEEL CONNECTION DESIGN I S GENERIC KEYHORD A H APPL QTC/NSRS P KEYHORD B CONCERN SUB R PLT BBSH INVESTIGATION S CONCERN KEYHORD C "
HUMBER CAT CAT D LOC FLQB REPORT R DESCRIPTION KEYHORD D
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IN 297-003 EN 21509 N H3N NNYY SR STRUCTUAL STEEL CONNECTIONS CI-BEAMS HELDING T50227 REPORT TO EMBED PLATES) ARE BOTH HELDED AN DESIGN RELATED D BOLTED. ONE METHOD IS FOR VIBRATI. HELDING I ON AND THE OTHER METHOD IS FOR DEAD BOLTING-LOADS. BOTH TYPE CONNECTIONS ARE BE ING USED ON THE SAME I-BEAM AND THES E "ARE NOT SUPPOSED TO BE MIXED". C
' ONSTRUCTION DEPT. CONCERN. CI DECLI NED TO PROVIDE FURTHER INFORMATION.
1 CONCERNS FOR CATEGORY EN SUBCATEGORY 21509
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