ML20028A329
| ML20028A329 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 09/08/1982 |
| From: | Wiedner K BECHTEL GROUP, INC., CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | |
| Shared Package | |
| ML20028A330 | List: |
| References | |
| ISSUANCES-OL, ISSUANCES-OM, NUDOCS 8211180348 | |
| Download: ML20028A329 (78) | |
Text
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I STATE w MIonca 09fdycED l
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'82 M)V 17 P1 :10 I
UNITED SMES T MERICA
'.- c : ~ %F tita.i A'KMIC SAFEIY AND LICENSING
$hkfifCH In 'Ibe Matter of
)
Docket Nos. 50-329 OL
)
50-330 OL OCNSlHERS POhTR (%EPANY
)
)
Docket Nos. 50-329 CM I
(Midland Plant, Units 1 and 2)
)
50-330 CM TESTIMONY OF KARL WIEDNER FOR THE MIDLAND PLANT DIESEL GENERATOR BUILDING
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SEPTEMBER 8, 1982 I
I I 8211180348 820708 I PDR ADOCK 05000329 I
T PDR PSa3
11 STATE OF MIQIIGAN 00WIY OF WAS!fIENAW UNITED STATES OF AME:RICA I
NUCIEAR REGUIATCM 00mISSIOi ATOMIC SAFTIY AND LI NSING BOARD I
In The Matter of
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Docket Nos. 50-329 OL
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50-330 OL I
CT)NSQERS POWER COMPANY
)
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Docket Nos. 50-329 OM (Midland Plant, Units 1 and 2)
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50-330 OM i
AFFIDWIT OF KARL WIERER My name is KARL WIEDER.
I am Chief Civil / Structural Engineer in Bechtel Power Management of Bechtel Power Cbrporation. I am residing at 504 Seaver Drive in Mill Valley, California, 94941. I have over 20 years experience in the nuclear pcuer industry. A resume showing my experience record is attached.
I graduated from the Technical University of Graz, Anstria in 1949 with a Bachelors degree in civil engineering and received a Masters degree in struc-tural engineering in 1952. Af ter graduation I worked as a teachirg assistant at the same university for two years.
I am a registered professional ergineer in the States of California and Oregon.
I have practiced civil engineering as a registered professional engi-neer in the Province of Alberta, Canada from 1955 to 1957.
My association with the Midland Plant began in 1973 while I was Chief Civil / Structural Engineer and continued frcxn 1976 to October 1979 while I was Ergineering Manager.
In Decarber 1978 I was appointed by Division Managenent to direct and coordinate the efforts of a task force group specifically assen-bled for the investigation and resolution of the soils settlement problen at I
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%e task force consisted of personnel from Bechtel Power the Midland Plant.
Corporation and Constraers Power Ccznpany. Project Engineering, Construction, 1
Quality Assurance and Geotechnical Services were represented in this task Outside consulting services were used for gwtechnical aspects (Drs.
grpup.
Peck and Hendron, et al). Se main purpose of this task group was to inves-tigate the settlement problem, develop renedial action plans for Engineering and Construction, and prepare 10CFR50.55(e) and 10CFR50.54(f) reports for subnittal to the U. S. Nuclear Regulatory Comnission.
The statements in this Affidavit, the attached resume and my testimony on the Diesel Gemrator Building are true and correct to the best of my knowl-edge and belief.
E k '
J E
KarlW/edner Signed and sworn to me I
on this F day of Septtrnber, 1982.
I Aau_
Notary P6blic 1
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KARL WIEDER ITITIQ1:
Chief Civil / Structural Engineer EDUCATIQ1:
BS - Technical University of Graz, Austria MS - Technical University of Graz, Austria PPDFESSIONAL DATA:
Member - Engineering Subcrmnittee on Design Innovations; M mber 1972, Chairman 1973 I
M mber - Special Task Forces: Over/Under Contairrnent; GE - Mark I and III Contairrnents Maber - American Nuclear Society Cbmnittee 2.0 and i
Snhemmittee 2.3 M mber - American Concrete Institute Mmber - Ergineering Society of Detroit Mmber - National Ocrrputer Graphics Association Publications:
ASCE - Journal of the Power Division - Nuclear Power Plant Tornado Design Considerations; Containment Structure for the Trojan Nuclear Plant 1975 International Conference on Prestressed Contain-ment and Reactor Vessels - Design and Construction I
of the Idner Plate for the Arkansas and Midland Contairrnents Registered Professional Engineer in the States of California and Oregon SU!@RRf:
1/2 Year:
BPM - Chief Civil / Structural Engineer
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6 Years:
Engineering Manager 4 Years:
Chief Civil / Structural Engineer 2 Years:
Assistant Chief Civil / Structural Engineer 9 Years:
Supervisory Engineering Assigments 6 Years:
Structural Design Engineering Assigrrnents 4 Years:
Teaching and Engineering Assigrments EXPERIEN 2:
Mr. Wiedner is currently Chief Civil / Structural Engineer in Bechtel Power Managment, an organization overseeing and coordinating engineerirg activities within the four i
Power Divisions of Bechtel Power Corporation.
l Prior to this assigrrnent, Mr. Wiedner was an Engineerirg l
j Manager in the Ann Arbor Power Division. In this position he was overseeing the technical design work and adminis-i tration of two office projects and the Ocmputer Aided Drafting department. Mr. Wiedner was appointed to this I
position in 1976.
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- mm.
EXPERIENCE (Cont'd): Mr. Wiedner was previously the Chief Civil / Structural Engineer in the Ann Arbor Area Office. In this position, he was responsible for project staffing and the technical I
surveillance and guidance of civil / structural design work being performed. Mr. Wiedner assuned this position in 1972. Before transferring to the Ann Arbor Area office in 1972, Mr. Wiedner was the Assistant Chief I
Civil / Structural Engineer in the San Francisco Power Division where he was also responsible for the Mark III contairrnent design task force in addition to his staff I
supervisory responsibilities.
Mr. Wiedner's engineering supervisory positions cover a I
wide range of fossil and nuclear assigrments. These assigrinents included: Civil / Structural Croup Supervisor for the Monticello and Trojan nuclear power plants; Senior Ergineer responsible for the design of a reactor I
building in Tarapur, India, and structural design of other power plant facilities.
Mr. Wiedner joined Bechtel in 1957 as an Engineer assigned to the structural design of the reactor building for the Dresden, Hallam and Big Rock Point nuclear power plants.
Prior to joinirg Bechtel, Mr. Wiedner was an Ergineering Instructor and Engineer involved in the design of such structures as schools, hospitals and industrial plants.
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vi MidlCnd Plcnt Unito l'cnd 2 Public Hearing Testimony DIESEL GENERATOR BUILDING ABSTRACT The diesel generator building is a rectangular, f
reinforced concrete, box-like structure which houses four diesel generators.
The building is founded on approximately 30 feet of plant fill and was constructed between October of 1977 and the spring of 1979.
In August of 1978 the actual building settlement exceeded the estimated 40-year settlement value stated in the
~
Midland Final Safety Analysis Report.
Construction was discontinued until the cause of the excessive settlement was identified and corrective measures were determined.
With the input of consultants, surcharging and dewatering the plant fill were selected as the most effective and feasible corrective measures.
This testimony describes the structural reanalysis of the diesel generator building.
The reanalysis shows there is assurance that the structure will perform its function safely, despite the settlement which has occurred and is predicted to occur over the operating life of the plant.
/
vii Midland P1' ant Units 1 and 2 Public Hearing Testimony E
DIESEL GENERATOR BUILDING TABLE OF CONTENTS Page 1
1.0 BACKGROU _ND 1.1 FUNCTION AND DESCRIPTION 1
1.2 SETTLEMENT BACKGROUND" r*
2 2.0 CORRECTIVE ACTION 3
2.1 REMEDIAL OPERATIONS 3
~
2.1.1 Surcharging 3
2.1.2 Status ( As of December 6, 1979) 5 2.2 STRUCTURAL REANALYSIS 6
2.2.1 Structural Acceptance Criteria 7
g-2.2.1.1 Load Cases 7
2.2.1.2 Load Combinations 9
2.2.1.3 Allowable Material Limits 11 2.2.2 Diesel Generator Building'Apalytical~Model 12 E-2.2.3 Application of Loads to the Building Model 13 2.2.3.1 Dead Loads
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13 2.2.3.2 Settlement Lodds 14 2.2.3.3 Live Loads 19 2.2.3.4 Wind Loads-20 2.2.3.5 Tornado Loads 20 2.2.3.6 Seismic Loads 21
+
2.2.3.7 Thermal Loads 24 2.2.4 Methods of Finite-Element Model Analysis 25 2.2.5 Structural Adequacy Computations 26 3.0 CRACK ANALYSIS 28 4.0 CURRENT STATUS 29
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viii Tchle of Contents (continued) 29 4.1 ANALYSES 30 4.2 CONSTRUCTION 4.3 FURTHER MONITORING 30
5.0 CONCLUSION
S 31 33 FOOTNOTES 38 REFERENCES 1
TABLES 39 l
DGB-1 Loads and Load Combinations for Concrete Struc-tures Other than the Containment Building from the FSAR and Question 15 of Responses to NRC Requests Regarding Plant Fill DGB-2 Loads and Load Combinations for Comparison 41 Analysis Requested in Question 26 of NRC Requests l
Regarding Plant Fill 1
DGB-3 Soil Properties Used in the Seismic Analysis 44 DGB-4 Rebar Stress Values for the Diesel Generator 45 Building Structural Members (According to FSAR and the Responses to NRC Requests Regarding Plant Fill, Question 15)
DGB-5 Rebar Stress Values for the Diesel Generator 47 Building Structural Members (According to ACI 349/1976, as Supplemented by Regulatory Guide 1.142)
FIGURES DGB-1 Site Plan of Midland baits 1 and 2 Power Plant 49 DGB-2 Elevations of the Diesel Generator Building 50 DGB-3 Plan Views and Sections of the Diesel Generator 51 Building DGB-4 Diesel Generator Building Duct Bank Layout 52 DGB-5 Diesel Generator Building Duct Bank Elevation 53 (Surcharge also Shown)
DGB-6 Diesel Generator Building Finite Element Model 54 DGB-7 Summary of Actual and Estimated Settlements 55
ix Table of Contents (continued) l DGB-8A Comparison of Measured Settlement Values with 56 l
Settlement Values Resulting from a Finite Element Analysis of the Diesel Generator Building (Pre-Surcharge Period)
DGB-8B Comparison of Measured Settlement Values with 57 Settlement Values Resulting from a Finite Element Analysis of the Diesel Generator Building (Surcharge Period)
DGB-8C Comparison of Actual Measured Settlements Plus 58 Estimated Secondary Compression Settlement with Settlement Values Resulting from a Finite Element Analysis of the Diesel Generator Building (Post-Surcharge Period) l DGB-9 Diesel Generator Building Dynamic Lumped Mass Model 59 for Seismic Analysis l
DGB-10 Positive Plate Element Forces 60 l
APPENDIXES I
Assessment of the Effects of Cracks in Exterior Walls A-1 I
A Subjected to Tornado Missile Effects B
OPTCON B-1 l
l l
l l
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Midland Plant Units 1 and 2 Public Hearing Testimony DIESEL GENERATOR BUILDING
1.0 BACKGROUND
1.1 FUNCTION AND DESCRIPTION The diesel generator building houses four diesel generators that provide power to attain a safe shutdown of the Midland plant after a design basis accident and to operate the plant during unforeseen power outages.
The diesel generators and the diesel generator building are classified as Seismic Category I items.
As such, the generators must remain functional and the building must maintain its integrity under the action of the loads and load combinations described in the structural acceptance criteria (Subsection 2.2.1) including during and after a postulated safe shutdown earthquake (SSE).
The diesel generator building is located directly south of the turbine building, as shown in Figure DGB-1.
The diesel generator building is a two story, reinforced concrete, box-like structure that is partitioned by reinforced concrete walls into four bays, one for each diesel generator.
The building is 155 feet long, 78 feet, 8 inches wide, and has an overall height of 53 feet, 6 inches.
(See Figures DGB-2 and DGB-3 for plan and section views of the building.)
The diesel generator building was founded on plant fill and constructed between the fall of 1977 and the spring of 1979.
1.2 SETTLEMENT BACKGROUND In August of 1978, jobsite engineers determined from the I
Bechtel Foundation Data Survey Programiti (for footnotes, see Page 33) that the settlement of the diesel generator building exceeded the estimated settlement value (approximately 3 inches) provided in Figure 2.5-48 of the Midland Final Safety Analysis Report (FSAR) (Reference 1).
The diesel generator building settlement and the remedial actions taken are described in the testimony of Gilbert S. Keeley.
Mr. Keeley's testimony describes how this matter was reported to the NRC, and the subsequent l
investigations leading to the conclusion that this unexpected settlement was related to insufficient compaction of plant fill.
These investigations also showed that the diesel generator building was experiencing differential (i.e., uneven) settlement.
It was determined that the four electrical duct banks penetrating the diesel generator building footing from below were restraining the uniform settlement of the building (refer to Figures DGB-4 and DGB-5).
This restraint caused the formation of cracks in the l
concrete superstructure, most noticeably in the east wall and in the interior partition walls, and to a 1csser extent in the north wall.
The maximum crack width encountered at this time was
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28 mills.
These cracks were formed in addition to cracks caused by the normal shrinkage of concrete.
In November 1978, the NRC was notified that, to eliminate duct bank interference with building settlement and to
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provide positive clearance between the building foundation and the duct banks, the duct banks would be separated from the diesel l
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_ generator building by releasing them at the building interface.
When the duct banks were released, the maximum gap (1-1.<2 inches) which existed between certain areas of the building and the soil surfaces partially closed.
In addition, a number of the existing concrete cracks decreased in width after duct bank release.
Subsequent building settlement progressed fairly uniformly.
2.0 CORRECTIVE ACTION Based on the recommendations of soil consultants Dr.
R.B. Peck and Dr. A.J. Hendron, surcharging and subsequent implementation of a permanent dewatering program was selected as the remedial plan.
The criteria for selection and further discussion of surcharging are provided in the testimony of Dr. Peck.
Further discussion of the dewatering program is provided in the testimony of engineering geologist William Paris of Bechtel.
2.1 REMEDIAL OPERATIONS 2.1.1 Surcharging As stated in Interim Report 4 to Management Corrective Action Report 24, surcharging of the diesel generator building began in January 1979.
Approximately 20 feet of sand was gradually placed within the diesel generator building and around its perimeter, extending outward 20 feet from each wall except along the north wall where the diesel generator building is close to the turbine building.
A t that location, sand extended
_ approximately 19 feet and was retained by a 20-foot high temporary retaining wall (refer to Figure DGB-5).
Crack mapping 5:
of the entire structure was initiated prior to the start of surcharging.
This provided a baseline survey for future crack observations and assessment of the building's response to surcharging.
Subsequent crack mapping was done at approximately 1-year intervals, with the most recent crack mapping performed in July 1981.
The observed change in the width of the cracks was on the order of 0.005 to 0.010 inch.
The hold on diesel generator building construction
(
voluntarily implemented on August 23, 1978, was lifted in December 1978 because a completed structure would maximize the effect of surcharging.
The additional weight of the concrete which would be placed was desirable for surcharge purposes, and the completion of the floor slab at elevation 664 and the roof slab would increase the structure's rigidity and ability to distribute loads.
In August 1979 the soil consultants deemed the surcharge operation a success for the reasons stated in Dr. Peck's testimony.
Removal of the surcharge soil (from elevation 654 to elevation 634) commenced on August 15, 1979, and was essentially complete by the end of August 1979.
Settlement measurements continued during hnd after the removal of the surcharge.
l 1 2.1.2 Status (As of December 6, 1979)
On December 6, 1979, the NRC staff issued an Order Modifying Construction Permits.
By that date, the remedial action required to stabilize the diesel generator building (i.e.,
surcharging) was already completed.
Although the structural the reanalysis described in this testimony was not yet complete, response to Question 15 of the NRC Requests Regarding Plant Fill had been submitted (September 1979).
This response included acceptance criteria for Seismic Category I etructures such as the diesel generator building that are partially or entirely founded i
on plant fill.
These acceptance criteria have remained unchanged.
[The response to Question 26 of the NRC Requests Regarding Plant Fill, submitted February 29, 1980, reiterated the response to Question 15 and added a commitment to perform an analysis in accordance with American Concrete Institute (ACI) 349 as supplemented by Regulatory Guide 1.142 for comparison only.]
For additional information on the load combinations of the i
structural acceptance criteria, refer to Subsection 2.2.1.2.
The superstructure of the diesel generator building was completed by March 22, 1979, approximately 8-1/2 months before the NRC's issuance of the Order Modifying Construction Permits.
The majority of the work in progress during December 1979 was not civil / structural in nature.
Remaining work included activities such as installing cable trays, conduit, heating, ventilating, and air conditioning (HVAC) ducts, etc.
The civil / structural work remaining in the building at that time was the construction of secondary structural wallst23 and steel platforms, neither of
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ 4 which contribute significant strength to the building.
None of these activities constituted remedial actions associated with building settlement.
2.2 STRUCTURAL REANALYSIS To account for the effect of the observed and predicted settlement on the diesel generator building, a structural reanalysis was performed.
This reanalysis proceeded by defining the acceptance criteria for the structure (see subsection 2.2.1).
These acceptance criteria differ from the acceptance criteria used in the original design and analysir of the structure and set forth in the FSAR (Revision 0, dated November 1977) only in the addition of four load combinations that include the effect of settlement.
These additional load combinations are described in Subsection 2.2.1.2, Equations 1 through 4.
To investigate the effects of the load combinations on the structure, the structural reana]ysis uses two different mathematical models of the diesel generator building:
a dynamic, lumped mass model and a static, finite-element model.
The I
dynamic, lumped mass model (described in Subsection 2.2.3.6 and 1
illustrated in Figure DGB-9) is used to generate seismic forces in the building, given the input ground motion from the operating basis earthquake (OBE) and SSE specified in the FSAR.
The finite-element model (described in Subsection 2.2.4 and illustrated in Figure DGB-6) is a more complex mathematical model that reduces the diesel generator building to an
- interrelated system of plate, beam, and boundary elements representing the walls, slabs, foundation, and soil.
The finite-element model is used to assess the effect on individual elements of various load combinations applied to the structure as a whole.
(These load combinations include seismic forces generated with j
the dynamic, lumped mass model.)
The finite-element model thereby allows the identificatior of those sections of the diesel generator building that will experience the greatest forces due to the postulated load combinat
..ns.
The allowable stress is then calculated and comparra t-ine actual stress level in these 1
sections based on the force Aved from the finite-element d
model.
This comparison chcus tat even those sections of the 9
i building experiencing '-
t t forces meet the acceptance criteria.
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2.2.1 Structural Acceptance Crgtpria The structural reanalysis of the d' asel generator building was performed to determine ii ;he structure met the structural acceptance criteria.
Settlement effects are included as outlined in the response to NRC Requests Regarding Plant Fill, Question 15, Revision 3, September 1979 (Reference 2).
2.2.1.1 Load Cases The following loads are considered in the reanalysis:
l 1.
Dead loads (D)
_ 2.
Effects of settlement combined with creep, shrinkage, and temperature (T) 3.
Live loads (L) 4.
Wind loads (W) 5.
Tornado loads (W')
6.
OBE loads (E) 7.
SSE loads (E')
8.
Thermal effects (TO)
Temperature effects appear twice in this list (Items 2 and 8).
For load combinations committed to in the response to guestion 15 of the NRC Requests Regarding Plant Fill, temperature effects are contained within the settlement effects term, T.
For l
other load combinations, thermal effects are contained in the thermal term, TO (Refer to Table DGB-1).
All other load cases appearing in Table DGB-1 (e.g.,
l rupture of pipe lines, hydrostatic forces, etc) do not occur in l
l the diesel generator building and are not addressed.
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- _ _ _ _ _ _ _ _ _ _ _ _ _ 2.2.1.2 Load Combinations The load combinations employed for the original analysis and der,ign of the diesel generator building were provided in FSAR Subsection 3.8.6.3 (Revision 0, dated November 1977).
The original design criteria did not contain a settlement effects tern (T).
For the structural reanalysis performed in response to Question 15 of the NRC Requests Regarding Plant Fill (September 1979), four additional load combinations were established and committed to be considered.
These additional combinations consider the effects of differential settlement in combination with long-term operating conditions and with either wind load or OBE.
Table DGB-1 provides the load combinations listed in FSAR Subsection 3.8.6.3 (Revision 0, dated November 1977) and the four additional load combinations.
These load combinations comprise the acceptance criteria for the diesel generator building and are hereinafter referred to as the Midland acceptance criteria.
By requiring combination of differential settlement with wind loads and OBE, the Midland acceptance criteria are more stringent than the requirements of ACI 318.I33 ACI 318 only requires combining the effects of differential settlement with the dead loads and live loads.
The Midland acceptance criteria are less stringent than ACI 349, because ACI 349 as supplemented by Regulatory Guide 1.142 includes load combinations that combine the effects of differential settlement with extreme loads such as tornados and SSEs.
In the response to Question 26 of NRC Requests Regarding Plant Fill, a commitment was made to do a
__ separate structural rearalysis of the diesel generator building in accordance with ACI 349, as supplemented by Regulatory Guide 1.142, for comparative purposes only.HI Table DGB-2 provides the load combinations of ACI 349 as supplemented by Regulatory Guide 1.142.
It is unnecessary to use all Table DGB-1 load combinations in the structural reanalysis.
A number of combinations can be eliminated from the analysis after comparison with more severe loads or load equations.
For example, Equations 6 and 10 from Table DGB-1 are:
1 1
(6)
U = 1.25 (D + L + Ho + E) + 1.0TO l
(10)
U = 1.4 (D + L + E) + 1.0TO + 1.25Ho l
Because there are no significant forces on the structure due to thermal expansion of pipes (HO), these two expressions can be rewritten in simpler forms:
U = 1.25 (D + L + E) + 1.0T (6)
O l
U = 1.4 (D + L + E) + 1.0T (10)
O The second expression is more critical than the first.
Therefore, Equation 10 is used in the analyses and is considered to envelop the lower force components resulting from an analysis using Equation 6.
Using this approach with the entire set of I
i load combinations eliminates the less critical equations and condenses the list to the following 10 load combinations.
Table DGB-1 r
Load Combinations Equation No.
l 1.
1.05D + 1.28L + 1.05T (1) 2.
1.4D + 1.4T (2) 3.
1.0D + 1.0L + 1.0W + 1.0T (3) 4.
1.0D + 1.0L + 1.0E + 1.0T (4) 5.
1.4D + 1.7L (5)
I) 6.
1.25 (D + L + W) + 1.0TO (10) 7.
1.4 (D + L + E) + 1.0TO 8.
0.9D + 1.25E + 1.0T (11)
O (15) 9.
1.0 (D + L + E') + 1.0TO (18) 10.
1.0 (D + L + W') + 1.0TO The same procedure can also be used to reduce the total number of load combinations that must be considered in the comparison ACI 349 analysis.
2.2.1.3 Allowable Material Limits In accordance with regulatory requirements and the recommendations of the American Concrete Institute (ACI 318 and ACI 349), the maximum rebar tensile stress allowed in the diesel generator building rebar equals 0.90 fy (where fy equals yield stress) for computation of section capacities.
Because the diesel generator building rebar has an fy value of 60 ksi, the maximum allowable tensile rebar stress due to flexural and axial loads is 54.0 ksi.
Rebar stress values calculated for critical,
. reinforced concrete sections of the diesel generator building were based on this maximum allowable rebar stress value of 54 ksi and a maximum allowable concrete strain level of 0.003.(53 2.2.2 Diesel Generator Building Analytical Model The structural reanalysis of the diesel generator building uses a finite-element model.
The required load combinations were applied to this model and the resulting forces were investigated for compliance with the structural acceptance criteria.
The diesel generator building was modeled as an assemblage of plate, beam, and boundary elements.
The structure is defined by a set of 853 nodal points and 1,294 elements.
Of these elements, 901 are plate elements representing walls and slabs, 141 are beam elements representing footings, and 252 are boundary elements (translational springs, in both the vertical and horizontal directions) rep resenting varying soil pressures.
Vertical springs were used for dead load, live load, and settlement analysis.
Sets of vertical and horizontal springs were used for other load cases.
Certain items, such as steel platforms and lightly reinforced, interior secondary structural walls, have not been included in the model for the reasons listed in subsequent sections.
Figure DGB-6 illustrates an isometric view of the finite-element model.
l l
I l
.. 2.2.3 Application of Loads to the Building Model The following loads have been applied to the model in the manner noted.
2.2.3.1 Dead Loads The dead load of the structure was simulated by specifying a mass acceleration value equaling that of gravity (32.2 ft/s 2).
Secondary structural walls and platforms were not included in the model because their contribution to the gross weight of the structure is minimal (less than approximately 3 percent) relative to the sum of the other loads considered.
Their exclusion does not significantly affect the magnitude or distribution of stresses.
The louvers on both the north wall and south wall, along with the doors on the north and south walls of the building, were modeled simply as penetrations, with dimensions equivalent to those of the doors and louvers.
This is acceptable because the doors and louvers contribute insignificantly to the building stiffness and total building weight.
The diesel generator pedestals and the ground floor slabs were omitted from the finite-element model because they were not constructed monolithically with the remainder of the structure.
Consequently, they do not add stiffness to the structure.
k
5 2.2.3.2 Settlement Loads The settlement loads for the diesel generator building can be divided into two categories:
those associated with long-term loads (dead loads, live loads, surcharge loads, and differential settlement) and those associated with short-term loads (wind, tornado, and seismic).
For long-term loading, the structural reanalysis addresses four distinct time periods.
A unique set of measured or estimated settlement values then corresponds to each of the following periods:
1.
March 28, 1978, to August 15, 1978 The first scribe mark was placed on the structure on March 28, 1978.
August 15, 1978, represents the closest survey date before halt of construction on the diesel generator building.
2.
August 15, 1978, to January 5, 1979 The duct banks were separated from the structure, and construction activities on the diesel generator i
building resumed during this period.
January 5, 1979, is the last survcy date before the start of surcharge activities.
n 3.
January 5, 1979, to August 3, 1979 surcharge activities occurred within and around the structure during this period.
August 3, 1979, is the last survey date available before the start of surcharge removal.
a 4.
Forty-year settlement This period is composed of the following.
Actual measured settlements from September a.
1979 to December 1981 - These settlements are small when compared with the predicted settlements and are mainly due to dewatering.
b.
Predicted secondary consolidation from December 1981 to December 2025 - These values are based on the conservative assumption that the surcharge remains in place over the life of the plant, thus exceeding the settlement that will actually occur.
i To determine forces resulting from settlement, an analysis was performed separately for each of the above four cases.
Analysis results were first combined with each other to form one settlement term, then combined with other load cases (e.g.,
tornado, seismic, etc) to form the required load L
. t.,
combinations of the Midland position, and of ACI 349 as i.
..'. i supplemented by Regulatory Guide 1.142.
In calculating the forces due to long-term loading, the analysis approach employed either longhand analysis techniques,-
~.'
or finite-element analysis methods.
The analysis technique applied for each unique time period of settlement leads is as follows:
., [.'.
- . * '. l
_'+-
. g Period 1 - March 28, 1978, to August 15, 1978:
?
..u e.
For this settlement period, a longhand analysis was performed
..f to account for stresses in the partially completed structure up to elevation 656'-6".
This calculation indicated that the
..?
maximum displacements would result in a maximum rebar stress
? - -
.s of 11 ksi in the upper part of the structure.
x
a
..e^m Periods 2, 3,
and 4 - August 15, 1978, to January 5, 1979; January 5, 1979, to August 3, 1979; and 40-year Settlements :
A For these three settlement periods individual finite-element i
models were used.
For settlement period 2, the finite-
[- (*[
element model represents the structure as built to elevation
- 4.
......I 662'-0".
For settlement periods 3 and 4, the finite-element
,1 model represents a fully constructed structure.
_y The settlement effects were modeled into the structure with
'.e vertical springs as boundary elements representing varying
.3:, >.s soil conditions.
At 84 locations along the building
- o.. ',c e
___ footings, springs with varying properties were applied to represent the nonhomogeneous nature of soil conditions existing beneath the diesel generator building.
For periods 2, 3,
and 4, springs were typically calculated at each nodal point along the foundation by dividing the structural load represented at the selected point by the measured or predicted settlement at that point.
Figure DGB-7 summarizes the actual and estimated settle-ments employed in the settlement analysis.
Figures DGB-8A, DGB-8B, and DGB-8C give individual isometric presentations of measured and predicted settlements and also show settlement values resulting from the finite-element analysis of the diesel generator building model for periods 2, 3,
and 4.
The comparison shows good correlation between values resulting from the finite-element model and the measured / predicted settlement values.IO Because of the overall stiffness of the structure (shear walls are over 50 feet high and 2-1/2 feet thick) when compared with the stiffness of the underlying soil, the building will undergo mainly rigid body motion.
Differences between calculated and measured / predicted settlements are small and within the accuracy
(
of the survey.
The accuracy of the surveys and of the predictions of future settlements are presented as an error band on Figures DGB-8A, DGB-8B, and DGB-8C.
It can be seen that the differences between the calculated and the measured / predicted I
settlements lie practically all within this error band.
/
l The maximum total rebar stress resulting from all settlement analyses (periods 1, 2,
3, and 4) is approximately
21 ksi, which occurs in the south wall in the vertical direction.
The maximum horizontal rebar stress resulting from all settlement analyses is approximately 18 ksi, which occurs in the south shield wall.
These values represent theoretical stresses that decrease when combined with dead load and live load.
Furthermore, the location of maximum settlement stresses generally does not coincide with the location of maximum seismic or tornado stresses.
Actual calculated moment and forces for settlements have been combined with other load cases and are included in Table I-4 in accordance with the governing load equations.
For short-term loading (i.e.,
seismic, wind, and tornado), the analysis also employed finite-element methods.
Soil springs used for short-term loading were developed based on the assumption that the structural movement was small enough to assume the soil was linearly elastic.
The modulus of elasticity was estimated using soil density and measured shear wave velocity values (796/ft/s).
Springs were developed for the vertical and horizontal modes.
These springs were calculated by determining the amount of force required to produce a unit displacement in the direction indicated by the particular mode.
The footings of the diesel generator building were assumed to be resting on a large mass of elastic soil for the vertical mode and embedded within the mass of soil for the horizontal mode.
The settlement due to seismic shakedown was also identified as a possible occurrence during a seismic event.
The maximum differential settlement due to seismic shakedown, as
l I stated in Question 27 of the NRC Requests Regarding Plant Fill, is approximately 1/4 inch.
The effects of seismic shakedown settlement will act to reduce the effects of differential settlement, and thus, the effect of seismic shakedown was not the governing case in the structural reanalysis of the diesel generator building.
2.2.3.3 Live Loads Live loads were applied to the modeled structure by applying pressure loads on the plate elements which represent the floor slab at elevation 664 and the roof at elevation 680.
During the plant Tife, a maximum live load of 100 psf is predicted to occur on the roof slab, whereas for the floor at elevation 664, a maximum live load of 250 psf is postulated.
One hundred percent of the live load was used in the design of individual structural members, such as floor slab at elevation 664 and roof slab at elevation 680.
For overall building response, however, the live loads considered were limited to 25 percent of the above maximum loads.
This 25-percent value represents the live load expected to be present when the plant is in operation, i.e.,
100 percent of the live load will not act simultaneously on every square foot of the floor space.
i 2.2.3.4 Wind Loads Loads resulting from the design wind (100-year recurrence with a velocity of 85 mph) were applied to the modeled structure as a pressure load on the plate elements that represent the exposed walls.
Wind loads on the roof and south wall hatch covers were determined assuming the hatch covers were in place.
These loads were then distributed to the nodal points which define the perimeter of the respective hatches.
2.2.3.5 Tornado Loads l#I As specified in BC-TOP-3-A (Reference 3), various combinations of velocity wind pressure, atmospheric pressure drop, and local pressures were applied to the modeled structure.
The maximum wind velocity of the tornado was 360 mph.
The original structural analysis performed in accordance with the FSAR (Revision 0, dated November 1977) considered various tornado-generated missiles.
The analysis considered missiles equivalent to a 4-inch by 12-inch by 12-foot wooden plank (108 pounds) traveling end-on at 300 mph at any height; a
4,000-pound automobile with a veJocity of 72 mph no higher than 30 feet above L ie ground with a contact area of 20 square feet; a
1-inch diameter, 3-foot long, 8-pound steel bar traveling at 216 mph at any height in any direction, and a 35-foot long utility pole, 13-1/2 inches in diameter, weighing 1,490 pounds, traveling at 144 mph, and striking the structure not more than
~
i 30 feet above the ground.
For tornado-generated missile loads, the structure was allowed to locally exceed the yield strain.
The results of the original tornado-generated missile load analysis showed the diesel generator building was acceptable.
Results of missile impact tests conducted over the last 7 years indicate that reinforced concrete walls, thinner than the exterior walls of the diesel generator building, have a considerable margin against local damage.
The tests indicate that a wall thickness of 12 inches would sufficiently preclude unacceptable local damage (spalling) from these missiles.
(The thinnest exterior wall of the diesel generator building is 30 inches thick.)
For further information on missile impact and its effect on cracked walls, refer to Appendix A.
2.2.3.6 Seismic Loads The seismic response of a structure depends on the stiffness properties and mass of the structure, the input seismic motion at the structure location, and the soil properties of the foundation medium.
Of these parameters, only soil properties are affected by insufficient compaction of backfill.
The following paragraphs describe how the effects of surcharging and insufficient compaction were accounted for in the revised diesel generator building seismic analyses.
The design spectra and design time-history as defined in FSAR Section 3.7 have been used in the reanalyses.
_ The analytical models used for the original seismic analysis and for the seismic reanalyses described in this testimony are one-dimensional, stick-type, lumped mass models using beam elements to represent the structural stiffness and impedance functions to represent the foundation medium (see Figure DGB-9).
The effect of soil-structural interaction is accounted for by coupling the structural model with the foundation media.
The foundation media are represented by impedance functions which represent the equivalent spring stiffness and radiation damping coefficients as specified in BC-TOP-4-A(s)
(Reference 4).
The structural stiffness of the lumped mass model was not revised in the new dynamic analysis.
The difference in the new model was confined to the treatment of the soil-structural interface.
The revised analysis developed the impedance functions based on the building's foundation dimensions and the modification in the soil properties described below.
In addition, for the horizontal accelerations, the weight of the soil and the concrete base slabs together with the diesel generator pedestals within the building were included in this revised model.
The original (presettlement) diesel generator building seismic analysis was based on the underlying till material with a shear wave velocity value of 1,359 ft/s (see Table DGB-3).
This value was not adjusted for the 30 feet of plant fill between the till and building foundation elevation.
The first seismic
i
} reanalysis accounted for the soil properties of the fill by averaging the measured shear wave velocity of the fill and underlying till over a depth of 75 feet, which is the smallest dimension of the building.
This resulted in the value of 796 ft/s, which was used in the seismic reanalysis.
However, the effect of decreasing shear wave velocity to a lower bound estimate of 500 ft/s was also analyzed.
Both shear wave velocity values of 796 ft/s and 500 ft/s were supplied by soil consultants.
The floor spectra at all elevations of the diesel generator building were generated using a shear wave velocity value of 796 ft/s.
The resulting floor response spectra were combined in an enveloping fashion with the spectra developed in the original analysis which used a shear wave velocity value of 1,359 ft/s.
The floor response spectra were further broadened to account for a lower bound shear wave velocity of 500 ft/s.
- Thus, conservative floor response spectra were generated.
The results of the seismic reanalysis indicated that the seismic forces at all elevations of the diesel generator building were somewhat higher than the forces determined in the original D
analysis.
The highest seismic acceleration was derived from an analysis using a shear wave velocity of 796 ft/s.
This increased seismic load was conservatively simulated by applying the maximum structural acceleration occurring in the dynamic model to each element in the finite-element model in north-south, east-west, and vertical directions.
The combined effect of the three directional responses was assessed using the square-root-of-the-l
__- sum-of-the-squares method recommended in NRC Regulatory Guide 1.92.
The ability of the structure to withstand these increased seismic forces in combination with the other loads is described in Subsection 2.2.5.
2.2.3.7 Thermal Loads Thermal effects were included in the model as a linear variation of temperature across the thickness of an element.
The thermal effect due to linear variation of temperature across the thickness of an element (also called gradient) primarily results in bending moments being applied to the eleme.nt.
In general, the temperature gradient of most concern for the diesel generator building is that anticipated to occur in the winter.
In accordance with the Handbook of Concrete Engineering (Reference 5) and FSAR (Revision 44) meteorological data, the equivalent, steady-state, exterior winter temperature of 14.6F was calculated.
The corresponding maximum interior temperature was 75F, thus resulting in a maximum gradient of 60F.
For
.j
(
additional information on how thermal effects were accounted for
]
in the analysis, see Subsection 2.2.5.
2.2.4 Methods of Finite-Element Model Analysis i
I An elastic, static analysis of the modeled structure was performed using finite-element methods.
This analysis method divides a structure's components into discrete elements of finite size, each having its own structural properties such as thickness, material properties such as modulus of elasticity (E),
and Poisson's ratio of lateral and vertical strains (v).
The elements are connected at common points called nodal points.
A f
system of finite elements and nodal points is termed a finite-l element model (see Figure DGB-6).
Loads are then applied to the i
model as either surface loads on the elements or nodal loads at specific nodal points.
Displacerant of the nodal points resulting from the applied load
.nen calculated, from which element forces and stresses are determined.
The particular finite-element analysis progran used for this analysis is the t
Bechtel Structural Analysis Program (9)
(BSAP).
To determine force components in accordance with accepted anal / sis techniques, the force components resulting from each load c,ondition are calculated independently.
Applicable l
loads are applied to any of three models.
(The three models are similar except for the spring elements used to represent l
different soil pressures and building configurations because of l
the stage of construction.)
Various load factors are then j
applied to tne separate load conditions, which are assembled to create the required load combinations of Table DGB-1.
Using this j
combined response, the structure is examined to ensure that the allowable stress limit is not exceeded.
i f
e-
-,7---
u em-we-, - - + -
w wa-,-
r--
ww
--w-w w
4-
, 2.2.5 Structural Adequacy Computations The computations necessary to verity structural adequacy were performed using a computer analysis program (OPTCON) capable of analyzing reinforced concrete sections.
This reinforced concrete analysis program models a portion of the diesel generator building and analyzes it for forces that resulted from the BSAP finite-element model analysis.
Refer to Appendix B for additional information concerning OPTCON.
To determine the structural adequacy of the diesel generator building, the modeled structure was partitioned into structural categories (i.e., north wall, center wall, roof, etc).
Critical elements from each category were then selected for l
further investigation based on their axial force, moment, and in-plane shear force (see Figure DGB-10).
Once the critical elements were selected, thermal gradients were assigned to each element based on the location of that element within the model.
Using OPTCON, rebar stress values were then calculated in these critical elements to verify that the allowable rebar stress value was not exceeded.
All structural categories of the diesel generator building were investigated and all were found to meet the structural acceptance criteria.
Table DGB-4 shows the results of the analysis.
The left-hand column of Table DGB-4 shows the element with the highest rebar stress value for each structural category.
The second column shows the load combination which produces the highest stress.
The third column presents the rebar
h stress value computed by OPTCON for each critical element within each structural category.
The highest rebar stress value (reflecting the combined effects of flexural, axial, and in-plane shear loads) exists in the south shield wall where the rebar stress value is 42.8 ksi.
The fourth column indicates the concrete compressive stress associated with the maximum rebar tensile stress in each structural category.
The final structural reanalysis of the diesel generator building showed that the critical load comb',aations (Table DGB-1) are those that include either the tornado load case (W'), the OBE load case (E), or the settlement load case (T), specifically:
1.0D + 1.0L + 1.0W' + 1.0T (10) o 1.0D + 1.0T + 1.0L + 1.0E (4) 1.4D + 1.4T (2)
In a majority of the structural categories of the diesel generator building, the tornado load combinations produce the highest stress level.
As stated in Subsection 2.2.1.2, an additional analysis of the diesel generator building was performed for comparison purposes (also see response to Question 26 of Reference 2).
This comparison analysis used the more stringent load combinations of ACI 349 as supplemented by Regulatory Guide 1.142 (see Table DGB-2 for a list of load combinations).
Even when using these more stringent load combinations, the structure meets the acceptance criteria (refer to Table DGB-5).
3.0 CRACK ANALYSIS All concrete structures experience cracking to some extent.
Concern about concrete cracking diminishes after the cause of cracking has been established, and actions have been implemented to 4.smedy the situation.
"oncrete cracking has a number of causes, including the following:
1.
Shrinkage during curing, before the concrete has developed its full strength 2.
Either static or dynamic loads within the elastic capacity of the section 3.
Temperature changes in a structure when no provision was made for movement or controlled cracking 4.
Differential settlement:
Most settlement-induced cracks occur during construction and the early life of the structure.
The cracks in the diesel generator building were caused by shrinkage or a combination of shrinkage and strains induced by foundation displacements.
cracking due to shrinkage is typical of concrete structures and merely indicates that restraint was provided by existing structures while the more recently placed concrete was curing and shrinking.
An independent evaluation and discussion of cracks in the diesel generator building are provided in the testimony of Dr. Sozen.
4.0 CURRENT STATUS 4.1 ANALYSES The structural reanalysis of the diesel generator building required as a result of the settlement problem is completed and highlighted in Section 2.2 of this testimony.
Two additional analyses have also been performed.
The first additional analysis evaluated the building response to ground accelerations in excess of the present FSAR safe shutdown (SSE) values.
Results of this analysis demonstrate that the diesel generator building is capable of withstanding the effects of a seismic event 50% larger than the original SSE and remaining within the code allowable stresses.
The second additional analysis investigated the structure's ability to bridge a postulated soft soil condition.
For analys'is purposes, a local soft soil condition was assumed, which consisted of approximately 30 feet along the south wall and 15 feet along the adjacent interior wall.
A finite-element analysis of the diesel generator building was then performed for the 40-year dead load case, with soil spring constants modified to simulate potential bridging.
Results of this analysis indicated that the diesel generator building can successfully span the assumed soft soil introduced into the analysis without significantly increasing the rebar stress values.
(In general, the rebar stress levels increased by approximately 5 ksi.)
4.2 CONSTRUCTION Structurally, the diesel generator building is complete.
All concrete walls and secondary st<uctural concrete walls have been placed.
Additionally, all miscellaneous structural items (i.e., platforms, etc) have been installed.
The permanent dewatering system referenced earlier has been installed.
This is discussed in the testimony of W.
Paris.
Biweekly settlement readings of the diesel generator building continue.
These readings indicate that very little differential settlement has occurred since removal of the surcharge in August 1978.
Dr. Peck's testimony addresses this subject.
4.3 FURTHER MONITORING Crack mapping of the entire building was initiated before the start of surcharging.
Crack width measurements were taken in January and February 1979, November and December 1979, and July 1981.
Cracks less than 0.010 inch were not mapped.
The measurements taken in July 1981 indicate that some settlement-induced cracks may have increased in width by 0.005 to 0.010 inch and that other settlement-induced cracks may have decreased by 0.005 inch.
The maximum crack width is 0.020 inch, which occurs at a number of locations.
All other cracks are 0.015 inch or less.
However, maximum crack width measurements are very subjective and difficult to measure accurately.
Seasonal variations in temperature and humidity will affect the width of the cracks.
Therefore, regular measurements of differential settlement over the 40-year life of the plant will be relied on to confirm that actual differential settlement is within the limits of the acceptance criteria employed in the structural reanalysis.
5.0 CONCLUSION
S The structural reanalysis performed on the diesel generator building verifies that the integrity of the structure will not be violated, even under the most critical load combinations.
The analysis described ir this testimony shows that the diesel generator building setisfies the Midland acceptance criteria and ACI 349.
The structural reanalysis of the diesel generator building was performed in a conservative fashion.
The following contributed to the conservatism of the analysis:
1.
Assuming surcharge remains in place when predicting 40-year settlement values.
w e
w w
2.
Broadening the floor spectra to account for the lower and upper shear wave velocity values of 500 and 1,359 ft/s, respectively 3.
Applying maximum seismic accelerations to the entire diesel generator building.
The likelihood of settlement-induced cracking of concrete has been minimized by a number of actions, including the following:
1.
Releasing the du;t banks from the structure allowed unrestrained settlement.
2.
Applying a surcharge to the diesel generator building consolidated the plant fill.
3.
Completing the structure provided additional strength and stiffness.
The diesel generator building is a massive, heavily reinforced concrete structure with extensive reserve strength.
Based on the analysis performed, it can be stated that the settlement has had minimal effect on the structural strength, and there is reasonable assurance that the diesel generator building will safely perform its intended function over the operating life of the Midland plant.
FOOTNOTES
3The Bechtel F:undation Settlement Data Survey Program was issued for construction use on May 20, 1977.
The objective of this program was the establishment of surveys to maintain a record of the settlement of major structures, including:
1.
Placing permanent bench marks and control monuments at the jobsite 2.
Establishing elevations for the monuments from which settlement readings will.be made 3.
Taking periodic settlement readings at the settlement markers installed at selected locations on structures in accordance with an established schedule MISecondary structural walls:
Certain walls in the diesel generator building which are subjected to light equipment loads were initially intended to be blockwalls.
Following further investigation, these blockwalls were changed to lightly reinforced concrete walls.
Because these walls are not relied on in the overall building response, they are referred to as secondary structural walls and have not been included in the finite-element model.
13IThe American Concrete Institute (ACI) is an organization of engineers, architects, scientists, constructors, and
l individuals associated in their technical interest with the field of concrete.
The purpose of the ACI is to further engineering and technical education, scientific investigation and research, and development of standards for the design and construction of concrete structures.
The two ACI standards referenced in this testimony are ACI 318, Building Code Requirements for Reinforced Concrete, and ACI 349, Code Requirements for Nuclear Safety Related Concrete Structures.
The ACI 318 code covers the proper design and construction of typical reinforced concrete structures (office structures, commercial buildings, etc).
ACI 318 was approved for use on the Midland project at the time the construction permits were issued.
It is one of many codes and standards incorporated by reference in the FSAR.
The ACI 349 code covers the proper design and construction of concrete structures which form part of a nuclear power plant.
Adherence to ACI 349 is not an NRC requirement, nor is ACI 349 included in the FSAR as one of the licensing bases of the Midland plant.
In February 1980, in response to the NRC Requests Regarding "3
Plant Fill, Question 26, a commitment was made to check the structural adequacy of the diesel generator building in accordance with ACI 349 as supplemented by Regulatory Guide 1.142.
This check was intended for comparison purposes only, and it does not modify the structural acceptance criteria of the diesel generator building as established in the FSAR and the response to Question 15.
ACI 349, as supplemented by Regulatory Guide 1.142, requires the
- inclusion of the settlement effects term (T) in all load combinations.
(58 ccording to nuclear industry practice, rebar yield strain A
and maximum concrete strains are allowed to be locally exceeded when analyzing a structure for tornado-generated missile loads.
re;Bechtel soil engineers generated estimated settlement values using extrapolation; the settlement versus time plot of t1e diesel generator building in the turcharged condition was used for this purpose.
Settlement values resulting from the finite-element model analyses were obtained by applying loads to the model, and then dividing the resultant force at the foundation by the appropriate spring constant.
This report is authored by the Bechtel Power Corporation and contains criteria for the design of nuclear power plant structures for extreme winds and tornado effects.
Extreme wind criteria cover wind velocities up to and including the wind velocities of hurricanes.
The extreme wind velocities specified in this report are identimal to those defined by the wind speed map of ANSI Building Code Requirements A58.2/1972.
The velocities defined correspond to a mean recurrence interval of 100 years.
The design criteria and procedures described in BC-TOP-3-A (Revision 3),
have been reviewed and deemed acceptable by the Regulatory staff.
(Refer to the letter dated October 4, 1974, from R.W. Klecker, Technical Coordinator for Light Water Reactors, Group 1, directorate of Licensing, to J.V. Morowski, Vice-President - Engineering, Bechtel Power Corporation.)
This report is authored by Bechtel Power Corporation and contains the general practice used by Bechtel Power Corporation for the seismic analysis of nuclear power plant structures and components.
This includes the methods of establishing mathematical models for structures and components and the various applicable methods of computing seismic responses such as floor accelerations, shear, moments, and displacements.
The design criteria and procedures described in BC-TOP-4-A (Revision 3 ) have been approved by the NRC staff.
(Refer to the letter dated October 31, 1974, from R.W. Klecker, Technical Coordinator for Light Water Reactors, Group 1, Directorate of Licensing, to J.V. Morowski, Vice-President - Engineering, Bechtel Power Corporation.)
N1BSAP:
The Bechtel Structural Analysis Program (BSAP) is a general purpose, finite-element program for analysis of structural systems subject to static, dynamic, and thermal loads.
The program incorporated an extensive library of beam, shell, and solid elements so that virtually any type of structure can be represented.
Common applications include analysis of nuclear plant structures, pressure vessels, high-rice buildings, transmission towers, and bridges.
BSAP is based on and incorporates features of the SAP program developed at the University of California at Berkeley by Professor E.L. Wilson (Reference 6).
The SAP program was modified to extend capability, enhance usability, and reduce cost of application.
REFERENCES 1.
Consumers Power Company, Midland Plant Units 1 and 2 Final Safety Analysis Report, Docket 50-329, 50-330 2.
Consumers Power Company, Responses to NRC Requests Regarding Plant Fill, Docket 50-329, 50-330 3.
Bechtel Power Corporation, Tornado and Extreme Wind Design Criteria for Nuclear Power Plants, Revision 3, August 1974 (BC-TOP-3-A) 4.
Bechtel Power Corporation, Seismic Analyses of Structures and Equipment for Nuclear Power Plants, Revision 3, Novem-ber 1974 (BC-TOP-4-A) 5.
M. Fintel, Handbook of Concrete Engineering, Van Nostrand Reinhold Company, September 1974 6.
Edward L. Wilson, SAP - A General Structural Analysis Program (Report to Walla Walla District U.S.
Engineers Office, Contract DACW 68-67-C-004),
Structural Engineering Laboratory, University of California, Berkeley, California, September 1970 TABLE DGB-1 LOADS AND LOAD COMBINATIONS FOR CONCRETE STRUCTURES OTHER THAN THE CONTAINMENT BUILDING FROM THE FSAR AND QUESTION 15 OF RESPONSES TO NRC REQUESTS REGARDING PLANT FILL Responses to NRC nequests Regarding Plant Fill, Question 15 a.
Service Load Condition U = 1.05D + 1.28L + 1.05T (1)
U = 1.4D + 1.4T (2) b.
Severe Environmental Condition U = 1.0D + 1.0L + 1.0W + 1.0T (3)
U = 1.0D + 1.0L + 1.0E + 1.0T (4)
FSAR Subsection 3.8.6.3 a.
Normal Load Condition U = 1.4D + 1.7L (5) b.
Severe Environmental Condition (6)
U = 1.25 (D + L + Ho + E) + 1.0To (7)
U = 1.25 (D + L + Ho + W) + 1.0To (8)
U = 0.9D + 1.25 (HO + E) + 1.0To (9)
U = 0.9D + 1.25 (Ho + W) + 1.0To c.
Shear Walls and Moment Resisting Frames (10)
U = 1.4 (D + L + E) + 1.0T + 1.25HO 0
U = 0.9D + 1.25E + 1.0T + 1.25Ho (11) o d.
Structural Elements Carrying Mainly Earthquake Forces, Such as Equipment Supports (12)
U = 1.0D + 1.0L + 1.8E + 1.0To + 1.25Ho e.
Extreme Environmental and Accident Conditions U = 1.05D + 1.05L + 1.25E + 1.0T + 1.0H + 1.0R (13)
A g
U = 0.95D + 1.25E + 1.0Tg + 1.0Hg + 1.OR (14)
Table DGB-1 (continued)
U = 1.0D + 1.0L + 1.0E8 + 1.0To + 1.25Ho + 1.OR (15)
U = 1.0D + 1.0L + 1.0E' + 1.0T
+ 1.0Hg + 1.OR (16)
A (17)
U = 1.0D + 1.0L + 1.0B + 1.0To + 1.2SHo U = 1.0D + 1.0L + 1.0To + 1.25Ho + 1.0W' (18) where B = hydrostatic forces due to the probable maximum flood (PMF)
D = dead loads of structures and equipment and other permanent, load-contributing stress E = operating basis earthquake (OBE)
E' = safe shutdown earthquake (SSE)
Ho = force on structure caused by thermal expansion of pipes under operating conditions g = force on structure caused by thermal expansion of H
pipes under accident conditions L = conventional floor and roof live loads (includes moveable equipment loads or other loads which vary in intensity)
R = local force, pressure on structure, or penetration caused by rupture of pipe T = effects of differential settlement, creep, shrinkage, and temperature o = thermal effects during normal operating conditions T
total thermal effects which may occur during a T3 = design basis accident U = required strength to resist design loads or their related internal moments and forces W = design wind load W' = tornado wind loads, excluding missile effects, if applicable (refer to Subsection 2.2.3.5)
TABLE DGB-2 LOADS AND LOAD COMBINATIONS FOR COMPARISON ANALYSIS REQUESTED IN QUESTION 26 OF NRC REQUESTS REGARDING PLANT FILL ACI 349 as Supplemented by Regulatory Guide 1.142 a.
Normal Load Condition U = 1.4 (D + T) + 1.7L + 1.7Rg U = 0.75 [1.4 (D + T) + 1.7L + 1.7T + 1.7R 3 g
0 b.
Severe Environmental Condition U = 1.4 (D + T) + 1.4F + 1.7L + 1.7H + 1.9Eg + 1.7RO U = 1.4 (D + T) + 1.4F + 1.7L + 1.7H + 1.7W + 1.7RO U = 0.75 [1.4 (D + T) + 1.4F + 1.7L + 1.7H + 1.9E0 + 1.7To
+ 1.7R 3 0
U = 0.75 [1.4 (D + T) + 1.4F + 1.7L + 1.7H + 1.7W + 1.7To
+ 1.7R 3 0
c.
Extreme Environmental Condition U= (D + T) + F + L + H + T
+RO+WT O
U= (D + T) + F + L + H + To+RO + Egg d.
Abnormal Load Condition
+RA + 1.5PA U= (D + T) + F + L + H + T4
+Y
+R
+ 1.25P
+ 1.0(YR 3
U = (D + T) + F + L + H + TA A
3
+Yg) + 1.25EO
+ 1.0(Y
- Y
+RA + 1.0PA U= (D + T) + F + L + H + T3 R
J
+ Y ) + 1.0E 33 g
where Normal loads are those loads encountered during normal plant operation and shutdown, and include:
T
= settlement loads D
= dead loads or their related internal moments and forces
- l f
Table DGB-2 (Continued)
L
= applicable live loads or their related internal moments i
and forces F
= lateral and vertical pressure of liquids or their rela-ted internal moments and forces H
= lateral earth pressure or its related internal moments and forces o = thermal effects and loads during normal operating or T
shutdown conditions, based on the most critical transient or steady-state condition Ro = maximum pipe and equipment reactions if not included in the above loads Severe environmental loads are those loads that could infre-quently be encountered during the plant life and include:
Eo = loads generated by the operating basis earthquake (OBE)
W
= loads generated by the operating basis wind (OBW) speci-fied for the plant Extreme environmental loads are those loads which are credible but highly improbable, and include:
ESS= loads generated by the safe shutdown earthquake (SSE)
WT = loads generated by the design tornado specified for the plant Abnormal loads are those loads generated by a postulated high-energy pipe break accident and include:
P
= maximum differential pressure load generated by a A
postulated break T
= thermal loads under accident conditions generated by a g
postulated break and including To R3 = pipe and equipment reactions under accident conditions generated by a postulated break and including Ro U
= required strength to resist design loads or their related internal moments and forces R = loads on the structure generated by the reaction on Y
the broken high-energy pipe during a postulated break Y
= jet impingement load on a structure generated by a 3
postulated break
43-i Table DGB-2 (Continued) a structure generated by or g = missile impact load or:
Y during a postulated break, such as pipe whipping i
D
..,,---n---n.
,.n.,a..
v-,em, w.,_w.-,
en-,
g-y e.-
TABLE DGB-3 SOIL PROPERTIES USED IN THE SEISMIC ANALYSIS First Second Original RevisedD3 Revised'l i
Analysis Analysis Analysis Modulus of Elasticity (E) 22,000 ksf 6,598 ksf 2,609 ksf Poisson's Ratio 0.42 0.45 0.40 Unit Weight (w) 135 pcf 116 pcf 120 pc/s Shear Wave Velocity (Vg) 1,359 ft/s 796 ft/s 500 ft/s Shear Modulus (G) 7,746 ksf 2,275 ksf 971 ksf I'INote different shear wave velocity values.
TABLE DGB-4 REBAR STRESS VALUES FOR THE DIESEL GENERATOR BUILDING STRUCTURAL MEMBERS (ACCORDING TO THE FSAR AND RESPONSES TO NRC REQUESTS REGARDING PLANT FILL, QUESTION 15)
Compressive Tensile Concrete Rebar Stress Stressian value (ksi)
Value (ksi)
Description of Load"I Allowable Allowable Members / Location Combination
= 54 ksi
= 3.4 ksi Exterior - West 2'-6" thick wall Tornado 25.03 0.425 horizontal rein-forcement Exterior - South 2'-6" thick wall Settlement 30.49 0.000'#
horizontal rein-(Seismic) forcement Elevation - 664'-0" 2'-0" floor slab Tornado 39.15 0.068 E-W reinforcement Elevation - 680'-0" l'-9" floor slab Tornado 36.06 0.834 N-S reinforcement South 2'-0" missile shield Settlement 42.79 0.000!D wall south, horizontal reinforcement Interior 2'-0" interior missile Tornado 28.06 0.000'O shield wall, vertical reinforcement North 2'-0" missile shield Tornado 13.85 0.000 '3 N
wall north, horizontal reinforcement n
TABLE DGB-4 (continued)
Compressive Tensile Concrete Rebar Stress Stress (21 value (ksi)
Value (ksi)
Description of Load
Allowable Allowable I
Members / Location Combination
= 54 ksi
= 3.4 ksi Exterior - North 2'-6" thick wall Tornado 21.90 0.313 horizontal reinforce-ment Exterior - East 2'-6" thick wall Tornado 23.64 0.403 horizontal reinforce-ment Interior' l'-6" thick wall Tornado 16.66 0.000'I horizontal reinforce-ment South 0.000I 2'-0" thick box Tornado 8.02 missile shield / south, horizontal reinforce-ment Exterior Footing 2'-6" thick footing Tornado 35.22 0.881 NOTES:
I The tornado load combination is 1.0(D + L) + 1.0W'
+ 1.0To.
The settlement combination is 1.4(D) + 1.4(T).
The settlement (seismic) combination is 1.0(D + T) + 1.0(L) +
1.0(E).
I#IConcrete stresses shown are associated with maximum rebar tensile stresses shown in this table.
Section is in tension.
TABLE DGB-5 REBAR STRESS VALUES FOR'THE DIESEL GENERATOR BUILDING STROCTURAL MEMBERS (ACCORDING TO ACI 349/1976 AS SUPPLEMENTED BY REGULATORY GUIDE 1.142)
Compressive Tensile Concrete Rebar Stress Stress t2 Value (ksi)
Value (ksi)
Description of Load'"
Allowable Allowable Members / Location Combination
= 54 ksi
= 3.4 ksi Exterior - West 2'-6" thick wall Tornado 28.79 0.486 horizontal rein-forcement Exterior - South 2'-6" thick wall Seismic 33.84 0.000 '
0 horizontal rein-(A) forcement Elevation - 664'-0" 2'-0" floor slab Tornado 39.03 0.032 E-W reinforcement Elevation - 680'-0" l'-9" floor slab Tornado 34.53 0.842 N-S reinforcement South 2'-0" missile shield Seismic 46.55 0.000 '
0 wall south, horizon-(B) tal reinforcement Interior 2'-0" interior mis-Tornado 28.31 0.00001 sile shield wall vertical reinforce-ment North 0
2'-0" missile shield Tornado 12.57 0.000 )
wall north, horizon-tal reinforcement
.y TABLE DGB-5 (continued)
Compressive Tensile Concrete Rebar Stress StressG3 Value (ksi)
Value (ksi)
Description of Load"3 Allowable Allowable 3.4 ksi Members / Location Combination
= 54 ksi
=
Exterior - North 2'-6" thick wall Tornado 23.90 0.305 horizontal rein-fcreement Exterior - East 2'-6" thick wall Tornado 24.96 0.390 horizontal rein-forcement Interior 03 l'-6" thick wall Tornado 20.40 0.000 horizontal rein-forcement Soutn 0
2'-0" thick box Seismic 9.41 0.000 3 missile shield /
(A) south, horizontal reinforcement Exterior Footing 2'-6" thick footing Seismic 37.13 0.927 (A)
NOTES:
"I The tornado load combination is 1.0 (D + L) + 1.0 (W )
T
+ 1.0 (To)
The seismic load combinations are as follows:
A.
1.4 (D + T) + 1.7 (L) + 1.9 (E)
B.
1.0 (D + T) + 1.0 (L) + 1.0 (E') + 1.0 (To)
D' Concrete stresses shown are associated with the maximum rebar tensile stresses shown in this table.
U3 Section is in tension.
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, g. e t BOTTOM OF DUCT ELEVATION 593'-0*h 5:. A u;w':uw:.o.$ x.. ie +. % l i i 1 i l i FIGURE OGG-S DIESEL GENERATOR BUILDING D' JCT BANK ELEVATION l (Surcharge Also Shown) t. I
l ano Li Et D a Ot Ms H n T Ta R Nr g O W. t N /f o ) El d j / / / t L a e e E ct n e Wi"n i i c Et t i T rp r j7 / 7t l I e e e 6 r 6Nvd t e - I n t BF yn e n G c t e e DGn e ,/ / c Nob /5 / EI RD,e ULn v GI o a Q[6 I Ul h FBt a s Rt g On n T ei / - 5 A s r R ep E r s /, ; s#y Np E Gf o LE e S s / s. Ea ~ I e D / ro f / f ( / / // /. / [ //[ i' o >// N, i e )' n e i '6 n NN\\\\ t i r t '2 r e x\\ \\ t 5 e n 1 t e n c e \\x\\\\ \\\\ c \\\\ \\ A\\ gn l i ar cp \\\\ s i t rl ea vn / o l i f at o ca il M=l e )g ps 0 n n yn i t a 1 i r t r t '9 - o e o 4 := t f nec
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I LINE A 1.19 1.02 0.90 0.85 0.76 LINE B 0.77 1.09 1.54 1.9R 2.41 LINE C 1.50 1.51 1.78 1.86 1.91 LINE D 1.33 1.15 1.19 1.18 1.29 TOTAL 4.79 4.77 5.41 5.87 6.37 0 5fil O . 5'N.D.9.1_= >T.'f_o'? t' K9 WF. .7.'J . m JU.'.C. O C .1.4 'fF' y) E =5 d..jdp9 4 E==E om:=/J F. '. ':T.. a 2 y o ,3 3 3 3 1 NORTH d. ?. ?. ? g. y. y lo. { 4 ..g ..g ..g n ? v v v v J K K E E I S. BAY 1 9: BAY 2 ? BAY 3 ?. BAY 4 ? l 6 b 'l A
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k k >k k 1 t un d Ex xa cc l h h 9 cr .4 g y . r...o:Q.:. w.w.1...&f gmw: e..o, Q :ie:s,:s...o. G... v:c: O O O O O LINE A 1.67 1.42 1.28 1.44 1.99 LINE B 1.14 1.12 1.46 1.92 2.21 l LINE C 3.00 2.92 3.16 3.37 3.24 LINE D 1.62 1.67 1,69 1.98 1.89 TOTAL 7.43 7.13 7.59 8.71 9.33 L l LEGEND O DIESEL GENERATOR BUILDING SETTLEENT MARKER SETTLEENT IN INCHES l FOR PRE-SURCHARGE PERIOD (3/78-8/78)............LINE A PRE-SURCHARGE PERIOD ( 8/78-1/79)............LINE B SURCHARGE PERIOD (1/79-8/79) ...............LINE C POST SURCHARGE PERIOD (9/79-12/2025)........LINE D ASSUMING SURCHARGE REMAINS IN PLACE FIGURE DGB-7 SUh44ARY OF ACTUAL AND ESTIMATED SETTLEENTS
REFERENCE SURFACE NORTH / 10.72 l 1.09 0.77 I 1.14 1 1 1. 55 l d* I 1.98 12.401 BAY l BAY 2 BAY 3 BAY 4 1 EASURED SETTLEENTS 4 m I 1.00 1 1.12 't.46 i 3-ROR AND CONSISTS 1,.27 I I 1*86 1 $MfTSOF T I 1. 56 l' I 2.17 1 RV Y CALCULATED ACCURACY SETTLEENTS !.92 2.21 FIGURE DGB-8A COWARISON OF EASURED SETTLEENT VALUES WITH SETTLt.KNT VALUES RESULTING FROM A FINITE ELEENT ANALYSIS OF THE DIESEL GENERATOR BUILDING ) PRE-SURCHARGE PERIOD AUGUST 1978 - JANUARY 1979 ) (VERTICAL SCALE IS MAGNIFIED 300 TIES)
REFERENCE SURFACE NORTH / I t.481 1.51 b: " & OIO MS40c. I 1.721 I 1.831 1 91 1.50 ~
- 3,g
' W M1p.-. r;.p., ',.f, 1.78 1.86 ~' l 1.94l j BAY t BAY 2 BAY 3 BAY 4 i / l l 1 i I ERROR BAND CONSISTS OF 12.95 I I 3.ISf>
- 1. i V8" DUE TO
((i _ _A ce'4+:-:.W-:04cg.;.. &.. I 3.241 3.24 LIMITS OF SURVEY 3*00 ' ACCURACY ' ' '" ^ 9 ~ ' ' " ? M:+-e.: :gpg, 7,.: I3.05 EASURED Q"3. 37'~
- 2. AVERAGE SYSTE-MATIC ERROR OF I
I 0.10 INCH CARRIED ) CALCULATED SETTLEENTS IN THE SURVEY SETTLEENTS FIGURE DGB-8B RNiOS5-2579 COWARISON OF EASURED SETTLEENT VALUES WITH SETTLEENT VALUES TO 9-6-79 RESULTING FROM A FINITE ELEENT ANALYSIS OF THE DIESEL GENERATOR BUILDING SURCHARGE PERIOD JANUARY 1979 - AUGUST 1979 (VERTICAL SCALE IS MAGNIFIED 300 TIMES)
REFERENCE SURi ACE / N p _. 5 1,... . ------- --aF d --- ~ ~ ~ ~~~~ 0 ~ ~ ~ ~ ' f" / I / 1.15 / 1.19 / 1.18 / l1.16 I / rM&4e;0L. J:Z:= OR- 0 c ~ * ' *- 44;c; -5.11 L 1.29 -. i..:. 77 l p, ;.y..y - 7 - i. -
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t, 3, y / j1.33 11.20 l 11.23 1 11.27 I / / l / / / BAY l BAY 2 BAY 3 BAY 4 / / l / / t t / / / / 1 / t O.42 si-----
qF---
eFg, g ----------
0.49 0.43 " E EASURED / PREDICTED ERROR BAND ySETTLEENTS CONSISTS OF: 7 1.67 1.69 / 10.20 INCH DUE i 1.62,(f.1.._...,..g.g,g 3..... .g.,g. .gg.,. U.83 I g ..-,__; :Y: 1.89 PREDICTION TO LIMITS OF
- r. -
c s.- .m..-,,,....#.......,, 'W- ~- i It.66 I I1.71 1 [ l1.7 ACCURACY j N CALCULATED 1.98 l1.89 I SETTLEENTS ACTUAL EASURED SETTLEENT FROM SEPT.14, 1979 TO DEC.31, 1981. --o l THESE INCLUDE EFFECT OF DEWATERING 10 APPROXIMATELY EL. 595', I AND REPRESENT MOVEENT OF THE STRUCTURE DUE TO SETTLEENT OF THE FILL AND NATURAL SOIL BELOW. ACTUAL EASURED SETTLEENTS FROM SEPT.14, 1979 TO DEC.31, 1981 PLUS O==--- ESTIMATED SECONDARY COWRESSION SETTLEENT FROM DEC.31, 1981 TO DEC.31, 2025 ASSUMING SURCHARGE REMAINS IN PLACE. FIGURE DGB-8C COWARISON OF ACTUAL EASURED SETTLEENTS PLUS ESTIMATED SECONDARY COWRESSION SETTLEENT WITH SETTLEENT VALUES RESULTING FROM A FINITE ELEENT ANALYSIS OF THE DIESEL GENERATOR BUILDING POST-SURCHARGE PERIOD SEPTEMBER t979 - DECEMBER 2025 (VERTICAL SCALE IS MAGNIFIED 300 TIES)
.. EL. 6 8 0'-0* M (Lurrped Moss Point) 3 1 (Merrber Nutrber) EL. 66 4'-O' M 2 2 EL. 647'-0* M 3 ROTATIONAL SPRING 3 \\ 4 HORIZONTAL KY\\ [M K* TRANSLATIONAL EL. 630'-0' ,g, '/ SPRING -C "S! Cy ROTATIONAL HORIZONTAL r C 1[KZ DAMPER - 2y DAMPER l //////////f////// VERTICAL DAMPER VERTICAL TRANSLATIONAL SPRING (Ky,C,Kx, etc are inpedance functions) 7 l FIGURE DGB-9 DIESEL GENERATOR BUILDING DYNAMIC LUWED MASS MODEL FOR SEISMIC ANALYSIS
a I I i i S i S yz xz yy yx l S 8 S S yx xx I 1 N ~ s / i N p I N / ,A N s e' 's N / ,) Q S S xx yy S S x/ y xy xy o 'sy S S xz yz S x = axlat force in x-directton x l7 Syy = axial force in y-direction S xy, Syx = In plane shear force i l Mxx =yz = out-of-plane shear force Sx2, S moment about y-ax!a Wyy = moment about x-ax!a yyy I yxx g i I i i, , x,! l 1 / g/ g/ N / i y l 4 \\ f )N, \\.- Q s/s x, x-xx FIGURE DGB-10 POSITIVE PLATE ELEENT FORCES
A-1 APPENDIX A ASSESSMENT OF THE EFFECTS OF CRACKS IN EXTERIOR WALLS SUBJECTED TO TORNADO MISSILE EFFECTS The tornado missiles postulated for the Midland plant are summarized in FSAR Table 3.5-9. A comparison of these missiles with the results of missile impact tests conducted over the last 6 years as shown in Table DGB-Al indicates that the exterior walls have considerable margin against local damage. The tests indicate that a wall thickness of 12 inches would cufficiently preclude unacceptable local damage (spalling) from these missiles. (The thinnest exterior wall containing cracks in the diesel generator building is 30 inches; the thinnest exterior wall in the Midland plant is 24 inches.) The tests indicate that the automobile missilt was incapable of producing local damage (Reference 1). Wall response was checked using the quarter-sine wave forcing function given in Reference 2. A 24-inch wall with nominal reinforcing 2 (0.79 in /ft EWEF), and conservatively assuming simple supports, would remain elastic if struck by the 4,000-pound auto with a velocity of 106 ft/s The maximum interface force indicated by the utility pole tests was 170 kips (Reference 3). The yield resistance (based on a steel stress of 0.9 fy) of the 2-foot thick walls
A-2 casuming simple supports is approximately 445 kips. The impact duration was approximately 70 ms (Reference 3). Assuming a custained step pulse of 170 kips, the calculated impulse duration would be 56 ms which would exceed the natural period of the wall by factors ranging between 2 and 10. In this range, with a resistance-to-force ratio (R/F) of 445 170 or 2.6, the walls would again remain elastic (Reference 4). The structural response from the lighter 8-pound rod and 108-pound plank would be much less than that associated with the 1,500-pound pole and 4,000-pound automobile. The test data from Missile Impact Testing of Reinforced Concrete Panels (Reference 5) provide insight to the ef fect of a precracked concrete condition on the extent of damage to be expected from a subsequent missile strike. Eight of the 11 test slabs were subjected to more than one missile impact. The extent of damage and the effect of precracked slab condition on extent of damage from subsequent missile strikes are summarized in Table DGB-A2. As seen in Table DGB-A2, all eight slabs were subjected to another missile strike while in a precracked condition (from a previous test) as indicated by an X under the C column. Spalling is indicated by an X under the S column. All slabs contained radial cracks. In most cases, these cracks extended beyond the backface fracture plane (see Figure DGB-A1). The formation of a backface fracture plane is indicated by a set of dominant circumfer'ential cracks approximately 3 to 5 feet in diameter. When these characteristic circumferential cracks were not -. -... ~.
A-3 cbserved, the backface fracture plane may not have formed. This is indicated by the letters "NF" in the column entitled " Radial Cracks - Beyond Fracture Plane." An examination of data from these tests indicates no discernible difference in damage can be attributed to the existence of radial cracks caused by a previous missile impact. Only once was any difference in damage observed (test 16F). This was not due to radial cracks but by overlapping of backface fracture planes. The backface fracture plane formed in test 16F overlapped the one previously formed in test 15F. The concrete in the overlapped area was spalled. Spalling (in test 16F) was also observed outside the overlap area. Therefore, the additional damage is considered minor. The radial cracks (roughly perpendicular to the back surface) can be considered analagous to the cracks caused by temperature, shrinkage, and possible p.evious loading history associated with settlement of the plant structures. Therefore, because no discernible difference in damage due to pre-existing radial cracks was observed in the tests, it is concluded that the cracks observed in the plant structures would have no significant effect on local damage due to tornado missile impact. It is also logical to conclude that no backface local damage would occur in the plant walls because the thinnest exterior wall (30 inches thick) with observed cracks in the diesel generator building is more than twice that required to preclude local damage (12 inches as determined from test data) from the missiles postulated for
A-O the plant. A backface fracture plane (a precursor to spalling) would not be expected to form. The effect of these cracks on structural response would also be insignificant because the predicted response from the heaviest missile is within the elastic range of the walls. Again, no difference in structural response was observed between precracked and previously uncracked test slabs. The test walls (less than 24 inches thick) were subjected to much more severe loading, as compared to the plant walls, and sustained some plastic response deformation as indicated by permanent set (difference between pre-and post-shot surface profile measurements). In summation, the observed cracks in exterior plant walls will have an insignificant effect (if any at all) on local damage or structural response due to the tornado missiles postulated for the plant.
A-5 REFERENCES 1. A.E. Stephenson, Tornado Vulnerability Nuclear Production Facility, Sandia Laboratories, April 1975 2. Bechtel Power Corporation, Design of Structures for Missile Impact, BC-TOP-9-A, September 1974 3. A.E. Stephenson, Full Scale Tornado Missile Impact 4 Tests, EPRI, NP-440, Prepared by Sandia Laboratories for EPRI, Research Project RP 399, July 1977 4. J.M.
- Biggs, H.J. Holley Jr.,
R.J. Hansen, J.K. Minami, S.
- Namyet, C.H.
Norris, Structural Design for Dynamic Loads, McGraw-Hill Book Company, 1959 5. F.A. Vassallo, Missile Impact Testing of Reinforced Concrete Panels, Calspan Report HC-5609-D-1, prepared for Bechtel Corporation, January 1975 4 ,e. -e-,-,, ,n,-
A-6 l TABLE DGB-Al COMPARISON OF PLANT MISSILES WITH TEST RESULTS Min. Thickness to Test Slab Defeat Missile w/o Missile from Test Thickness Spalling Indicated Table 3.5-9 Missile (in.) Backface Damage by Tests (in.) 108 lb 200 lb 24 None 4"x12" plank 8" dia. pole G 400 ft/s @ 490 ft/s (Ref. 1) 200 lb 12 Minor cracking 1?, 8" dia. pole @ 440 ft/s (Ref. 1) 8 lb 8 lb 18 None 1" dia. 1" dia. Steel rod Steel rod O 317 ft/s @ 303 ft/s (Ref. 2) 8 lb 12 Backface cracks 12 1" dia. mostly radial Steel rod @ 435 ft/s (Ref. 2) 4,000 lb 3,300 lb 16 None This missile was cutomobile automobile incapable of C 106 ft/s @ 73 ft/s causing backface (Ref. 3 ) local damage 1,490 lb 1,500 lb 18 Minor cracks 13-1/2 in. utility pole dia. @ 205 ft/s O 211 ft/s (Ref. 2) 1,470 lb 12 Cracks mostly 12 utility pole radial + at 204 ft/s (Ref. 2)
TABLE DCB-A2
SUMMARY
OF TEST RESULTS FOR PANELS SUSTAINING MORE THAN ONE MISSILE STRIKE (REF. 1) Radial Cracks Slab Backface Beyond Effect on Panel Thickness Test Velocity Local Damaget 2' Fractere Damage by No. (in.) No. MissileHD (fps) N C S P Plane Next Impact IB 12 3F slug 214 X X yes j 4F slug 122 X X yes nil i 3A 18 SF pipe 210 X NF 6F pipe 319 X yes nil 5B 24 7F pipe 370 X NP 8F pipe 470 X yes nil 6B 24 10F pole 490 X NF llF slug 295 X yes 12F slug 377 X X yes nil [3 2A 12 13F pole 300 X NF 14F pole 440 X NF nil 2B 12 ISP pipe 135 X "a 16F pipe 209 X X yes nil 88 3B-2 18 17F slug 161 X yes nil IBF slug 207 X X yes 3 4A-2 18 19F pipe 307 X yes 20F pipe 455 X X yes nil it3All missiles weighed between 199 and 215 pounds except for tests 19F and 20F, where the pipe missiles weighed 132 pounds. 87' Definition of Symbols: N - No Damage P - Panel perforated C - Radial cracks formed NF - Backface fracture plane not formed l S - Backface spalled '3'Backface fracture planes overlapped. Some additional minor spalling occurred in areas where backface fracture plane of Test 16F overlapped the backface fracture plane formed by Test 15F. This effect is minor because spalling also occurred in Test 16F in areas outside the Test ISP fracture plane. No additional damage could be attributed to the radial cracks formed in Test 15F. 1 l a
) A-8 CROSS SECTION OF WALL MISSILE TYPICAL REBAR FRONT CRATER FACE J ( RN:?!.'?: W 7 t \\ g.?::.*;:6::'i 9 d'[.?.?!i Yf.Q'.y ? 9 79". 4 / CENTER PLUG \\ / \\ g[.-.'[. p O. go f : +,,,,, / \\, d,,ygg 3 ,x f- -i ,) \\ BACK FACE SEPARATION FRACTURE PLANE FIGURE DGB A-1 TYPICAL FRACTURE PLANES IMPACT BELOCITY NEAR THRESHOLD OF SPALLING
C-1 APPENDIX B OPTCON The OPTCON computer code is a versatile and complete design and analysis program for reinforced concrete structures. The program may be used for the investigation of an existing reinforced concrete section where the reinforcing steel area is predetermined. Alternatively, it can be used for obtaining an optimum design by allowing the program to determine the minimum reinforcement required. The computer program operates on the axial force / moment interaction diagram (IAD) of a section, where an IAD is a plot of the maximum allowable resistance of a section for given stress and strain limitations. Combinations of moment (M) and axial load (P) falling within this area are acceptable. Figure DGB-B1 depicts the appropriate IAD for a symmetrically reinforced, symmetrically shaped section subjected to a combination of flexural and axial loads. The OPTCON program handles loads consisting of axial forces and corresponding bending moments due to different types of loads. Special subroutines are provided to incorporate the thermal effects into the design and/or investigation.
C-2 Compression C(-) Sattfles Design Criteria h Interaction Diagrcen j x N x x .Z Compression 1 Fatlure Zone =___-_ s X cP.M f -s 1 1 ~~' - N Balanced / Foifure .] 1 _- ~~ Tension FatIure Zone dei Moment (+)M /,/ ,,,.'/ Tension T(+1 FIGURE DGB B-1 TYPICAL INTERACTION DIAGRAM (for single axis bending and axial loads on a section with symmetrical reinforcement) _ _ _. _.}}