ML19329E506
| ML19329E506 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 05/21/1976 |
| From: | Howell S CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | |
| References | |
| NUDOCS 8006160303 | |
| Download: ML19329E506 (9) | |
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Tj j' Stephen H. Howell Vice Presodent
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f General Offices: 212 West ulchigan e.<enue. Jackson, Machigan 49201 May 21, 1976 THIS DOCUMENT CONTAINk P00R QUALITY PAGES m,i 3_. '.
s Dr. Ernest Vogenau, Director C'
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Office of Inspection Enforcement
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f 6; MIDIAID PIANT - AUXIIIARY BUILDING g/'f' 4
MISSING REBAR DOCKE'Is #50-329 aim #50-330 4
On April 21, 1976, we sent you a report relative to three instances of deficient rebar placement in the Auxiliary Building at the Midland Site.
At that time, we indicated that Consumers Power Company did not consider two of the instances to be reportable per 10 CFR 50 55(e). The third instance has now been evaluated and, as the attached report indicates, has been determined that this instance would not have affected the safety of the plant had it remained undetected. Therefore, Consumers Power con-siders this third instance of deficient rebar placement to be not reportable per 10 CFR 50.55(e) and is a final report on this topic.
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Off of Management Information & Program Control USNRC, Washington, DC JGKeppler(w/ enc-2)
USNRC, Glen Ellyn, IL l
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4 INVESTIGATION OF MISSING HORIZONTAL REINFORCING STEEL FOR MIDLAND AUXILIARY BUILDING WALLS 29, 31 and 30, 32 AT WALLS 7.4 & 5.6 RESPECTIVELY (NCR 260)
Prepared by:
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BECHTEL ASSOCIATES PROFESSIONAL CORPORATION Revision No: 0 Date: May 18, 1976 MAY 131976 MIDLEiB PROJECT MANAGEliENT Page 1 of 7
.r TABLE OF CONTENTS 1.
STATEMENT OF THE PROBELM 2.
DESIGN PROCESS FOR THE WALLS 3.
JUSTIFICATION OF TIIE ADEQUACY OF WALL REINFORCEMENT WIT!!OUT ADDITIONAL HORIZONTAL PIBARS
- 4. ~ CONCLUSION APPENDICES A.
LIST OF REFERENCED DOCUMENTS B.
DESIGN VERIFICATION SIDDIARY 4
Page 2 of 7
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INVESTIGATION OF MISSING HORIZONIAL REINFORCINO STEEL i
FOR t'
MIDLAND AUXILIARY BUILDING WALLS 29, 31 and 30, 32 AT WALLS 7.4 & 5.6 RESPECTIVELY (NCR 260) 1.0 STATEMENT OF THE PROBLEM 1.1 Th'e areas of the auxiliary building under consideratica
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are the intersection of wall line 7.4 with walls 29 and 31 and wall line 5.6 uith walls 30 & 32, between elevation 591'-0" and 599'-0".
The condition reported in NCR 260 in the subject areas was that 16 additional #8 horizontal dowels were left out for each of the walls 27 through 32.
Subsequent review of as-built conditions revealed that only 12 - #8 rebars were left out from each wall 29 and 30 and 14 #8 rebars were left out from each wall 31 and 32, between elevations 591'-0" and 599'-0".
1.2 For the subject walls, the requirements for the placement of rebars are shown on Drawing 7220-C-283 Revision 4 and 7220-C-284 Revision 3.
The location of these walls in plan is shown on Drawing 7220-C-203 Revision 3.
1.3 The purpose of this report is to investigate the adequacy of the subject walls _ and show that they are structurally i
adequate without the aforementioned horizontal rebars and 4
meet the design requirements.
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2.0 DESIGN PROCESS FOR THE WALLS 2.1 DESIGN BASES 2.1.1 Design Philosophy and Codes The analytical methods used to design the walls in i
the auxiliary building is described'in Section 5.2 of Midland PSAR. The loading conditions are listed in Appendix SA of the PSAR.
Page 3 of 7
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2.1.2 Maximum stresses at the ' locations of concern were determined to occur under the following loading conditions:
U = 1.0D + 1.0L + 1.0E' + 1.0Tg + 1.0HA + 1.0R Where '
D = Dead Load L = Live Load E'= Design Basis Earthquake Load (Safe Shutdown)
TA = Thermal load due to temperature gradient through wall under accident condition HA = Force on structure due to thermal expansion of pipes under accident condition.
R = Force or pressure due to rupture of any one pipe
.2.2 CONSTRUCTION MATERIAL SPECIFIED The specified concrete strength is 5000 psi (Reference 3) and the yield stress of the reinforcement is 60,000 psi.
(Reference 2) 2.3 METHOD OF ANALYSIS The original design of these walls was based on worst-case loading information provided from preliminary high energy line break analysis (HELBA) data.
Latest design calculations are based apon up-to-date loading information from the ongoing HELBA. Based upon these new loads, the design calculations show that all code requirements are met for all design loading combination enumerated under Section 2.1 when the' horizontal dowels are assumed omitted.
The use of updated loads from ongoing HELBA are justified since these loads are more realistic as compared to the conservative loads used in the original analysis from the L
preliminary HELBA.
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2.4 DESCRIPTION
OF SPACE FRAME FOR HELBA LOADS The loads from the high energy lines will be supported by a space frame. The loads to the walls are transmitted through horizontal and vertical members of this space i
frame at elevation 599'-0_ (refer to Drawing C-191 Revision 1
'for space frame). The layout and geometry of the space frame has not been finalized.
Thus for this analysis conser.vative loads from the space frame are used.
I Page 4 of 7
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.3.0 JUSTIFICATION OF ADEQUACY- 0F ASSUMED REINFORCEMENT 3.1 RALL NORMAL REINFORCEMENT (WITUGUT ADDITIONAL HORIZONTAL REBARS)
For simplicity, the reinforcement used for the current analysis does not include any of the additional #8 horizontal rebars from each of the valls 29 through 32.
This current analysis has shown that the regular horizontal rebars in
~ the walls satisfies ACI 318-71 code requiroments for the bend.ing, shear and torsional forces imposed by the specified loading conditions (Section 2.1.2).
Therefore, the rein-
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i forcement is adequate.
3.2 STRESS IN WALL NORMAL REINFORCEMENT 4
The stress in the reinforcement was found to be less than the yield stress and hence satisfies the requirements of Appendix 5A of the PSAR.
4.0 CONCLUSION
This analysis has indicated that the walls (29 through 32) referenced in NCR-260 are adequate without the additional horizontal #8 bars at 12" c/c (each face) spaced vertical from elevation 591-0"+ to 599'-0" at wall line 5.6 and 7.4 and satisfy all the requirements specified in the governing documents. Therefore the omission of j
these bars is not a deficiency "---which were it to have remained uncorrected, could have affected adversely the safety of operations of the nuclear power plant at any time throughout the expected d
lifetime of the plant-- " (Reference 10).
Nevertheless, since it did not require extensive rework' NCR 260 was dispositioned'such that 12 #8 dowels for each of the walls 29 4
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and 30 and 14 #8 dowels for each of the walls 31 and 32 were
_ drilled and grouted into wall line 5.6 and 7.4.
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- APPENDIX A LIST OF REFERENCES 1.
ACI 318-71 " Building Code Requirements for Reinforced Concrete"
'2.
lBAPC Technical Specification _7220-C-39, Rev. 7, " Furnishing, Detailing,. Fabricating and Delivering Reinforcing Steel:
3.
BAPC Technical Specification 7220-C-230, Rev. 6, " Operating On-Site Batch Plant and Furnishing Concrete" 4.
BAPC Drawing 7220-C-140, Rev. 8, " Concrete Standard Details and General Notes" 5.
BAPC Drawing 7220-C-203, Rev. 3, " Floor Plan at Elevation 599"-0".
6 Midland Plant Preliminary Safety Analysis Report (PSAR) Section 5.2 and appropriate appendices.
7.
Nonconformance Report Number 260.
- 8.'
BAPC Drawing 7220-C-283, Rev. 3, " Interior Wall Elevations at Walls 27 and 28.
9.
.BAPC Drawing 7220-C-284, Rev. 2, " Interior Wall Elevations at Walls 29 through 32".
' 10.
10 CFR 50.55(e) l l
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APPENDIA B DESIGN VERIFICATION SUSD'ARY The various calculations in support of this report, were verified in conformance with Dcchtel Engineering Procedures (EDPs 4.34 and 4.37).
Specifically, this verification included the following steps:
C-1 A check of the referenced materials and criteria (i.e.
PSA2 and specification requirements) used in the design.
C-2 Verification that this criteria was properly input to the design process, that the input was correct, and that the results were accurate and properly interpreted.
In addition to the design verification, a thorough review of the written report by the checker, civil design group supervisor, the Midland Project engineer and by the Chief Civil Engineer was performed.
This review also confirmed that appropriate documentation of this review had been prepared (i.e. signoff of calculation sheets and design review notices).
Revision 0:
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50-3293 30 NRC DISTRIBUTION FOn PART 50 DOCKET MATERIAL
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FiiOM:
DATE OF DOCUMENT N
CONSUMERS POWER CbMPANY 5/21/76 MR. ERNEST V0GENAU JACKSON, MICHIGAN g,7cnfb4'/76 g
STEPHEN H. HOWELL S
'ISLETTER
.C N O TO n tz E D PROP INPUT FORM NUMUEn OF COPIES RECCtVED RfoniclN At.
$U NC LASSIFIC O OcOPY ONE SIGNED cesCnteTION ENCLOSU RE p
.I LTR. RE THEIR 4/21/76 REPORT TRANS THE INVESTIGATION OF MISSING HORIZONTAL REINFORCING FOLLOWING:
STEEL FOR MIDLAND AUXILIARY BUILDING WALLS 29, 31 AND 30, 32 AT WALLS 7.4 AND 5.6 RESPECTIVELY (NRC 260)
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NOTE: SAME DISTRIYUTION AS CONTROL #4041
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DATED 4/27/,76 C((Q]
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