ML20196C571
| ML20196C571 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 07/31/1988 |
| From: | OMAHA PUBLIC POWER DISTRICT |
| To: | |
| Shared Package | |
| ML20196C542 | List: |
| References | |
| NUDOCS 8812080037 | |
| Download: ML20196C571 (40) | |
Text
1 ALTERNATE SEISMIC CRITERIA & METHODOLOGIES FOR FORT CALHOUN STATION VOLUME 1 CRITERIA & METH000LOGIES s
Prepared for U.S. Nuclear Regulatory Comission i
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Prepared by l
Omaha Public Power District July, 1988 4
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TABLE OF CONTENTS EASA VOLUME 1: CRITFRIA & METHODOLOGIES 1.0 IMTR000CTION 1
l 2.0 SCOPE 3
3.0 ALTERNATE SEISMIC CRITERIA 5
t 3.1 Piping and Pipe Supports 10 3.2 Electrical Raceways 25 3.3 HVAC 30 3.4 Concrete Expansion Anchors 35 j
4.0 ALTERNATE ANALYSIS METHODOLOGIES 40 4.1 Load Generation 40 4.2 Piping and Pipe Supports 41 4.3 Electrical Raceways 50 4.4 HVAC 53 i
5.0 REFERENCES
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1.0 INTRODUCTION
This document provides a set of alternate seismic criteria and methodologies for Fort Calhoun Station, Unit 1.
These alternate criteria and methodologies do not replace the current Fort Calhoun, Unit 1. USAR criteria and evaluation methodologies. These are retained as the principal design basis for the existing structures, systems and components. The alternate criteria and methodologies provide an alternative basis for future new designs, modifications and reanalyses of piping and pipe supports, electric raceways, HVAC and ancbr bolts.
In conjunction with the alternate criteria, revised seismic response spectra have been developed for the Reactor Building, Auxiliary Building and Intake Structure using current site-specific seismic hazard evaluation and soil-structure interaction methodologies.
Fort Calhoun, Unit 1, was designed in the late 60's and early 70's, using the design techniques of that period. Since that time, there have been considerable advancements in seismic design criteria and analysis Cethodologies, particularly in the last five years.
In general, these advanced criteria and methodologies show that previous approaches overpredict the seismic response and underpredict the seismic capacity of structures, systems and components.
This has resulted in the design of complex and rigid systems which actually reduce maintainability and reliability during normal plant operations.
Recent seismic testing and experience data collection programs sponsored by the NRC, utility groups and EPRI further demonstrate that the piping, receway and HVAC systems installed in power and industrial facilities are very unlikely to fall during an earthquake, even if they have been designed only to carry dead loads.
To reduce overconservatisms in seismic analysis and dJsign, the most effective approach is to develop a consistent set of alternate criteria and methodologies which evaluate both seismic demand and capacity aspects.
Seismic demand can be reduced by using acceptable state-of-the-art seismic load generation and analysis techniques.
Seismic capacity estimates can be increased by using results of extensive industry-sponsored research and test programs.
The alternate seismic criteria and methodologies are not part of any specific OPPO new design or modification effort.
It is not intended to apply them wholesale in reevaluation of piping, electric raceway and HVAC systems to remove supports.
The intent of the submittal is to license a set of alternate criteria and niethodologies which can be used (in addition to those accepted in the USAR) for future new designs, modifications and reanalyses.
By requesting timely approval from the NRC, both the NRC and OPPD will benefit from a review and approval period in which issues can be discussed separately from any particular new design or modification effort.
This document contains two volumes. Volume 1 discusses the alternate seismic criteria and methodologies and Volume 2 discusses the justifications of these criteria and methodologies.
In Volume 1. Section 2 defines the scope of this document; Section 3 discusses in detail the alternate seismic criteria for piping (large bore, small bore and instrument tubing), pipe supports (standard component type supports and linear type supports), electrical raceways (conduits, cable trays, raceway supports and raceway-to-support connections),
HVAC (ducts, supports and miscellaneous hardware), and anchor bolts used for piping, raceway and HVAC systems; Section 4 discusses in detail the alternate seismic methodologies for load generation and analysis techniques for the systems involved.
In Volume 2. justifications are provided for all criteria and methodology items which are exceptions to the applicable codes, standards, and/or current USAR approaches.
2.0 SCOPE This report provides a consistent set of siternate seismic criteria and methodologies to the USAR [8] Appendix F seismic criteria for Fort Calhoun Station, Unit 1.
The alternate criteria and methodologies do not replace the current USAR criteria or evaluation methodologies.
The presently accepted USAR criteria and methodologies are to remain the principal design basis for all existing structures, systems and components.
The alternate criteria and methodologies can be employed to perform new designs, modifications or reanalyses of the following Seismic Category I structures, systems and components: piping and pipe supports (including instrument tubing), electrical raceways, HVAC and associated anchor bolts.
For Fort Calhoun Station, Unit 1. Seismic Category I structures, systems and components are divided into two subcategories: Critical Quality Elements i
(CQE) and Limited CQE, as shown in Table 2.0-1.
The alternate seismic criteria and methodologies are based on applicable codes, standards, recent developments and improvements ir, seismic criteria and methodologies, and seismic test and experience da'ca programs.
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TABLE 2.0-1 STRUCTURES, SYSTEMS AND COMPONENTS CLASSIFICATION FOR FORT CALHOUN SEISMIC CATEGDRY [a] [b]
SEISMIC CATEGORY I NON-SEISMIC CATEGORY I (Nuclear Safety Related)
(Non-Nuclear Safety Related)
A.
Critical Quality Elements (CQE) [c]
Those structures, systems and components whose settsfactory performance is not required to 8.
Limited Critical Quality Elements prevent or mitigate the (Limited CQE) [d]
consequences of postulated accidents that could cause undue risk to the health and safety of the public Notes:
(a) General correspondence to the defir.ition of "Seismic Design Classification," NRC Regulatory Guide 1.29 Revision 3. September 1978.
(b) Per the Fort Calhoun USAR Appendix F [8), the Seismic Category I is designated as "Class 1", and Non-Seismic Categery I is designated as "Class 2".
These designations should not be confused with ASME B & PV Code classifications.
[c] CQE: Critical Quality Elements are defined as those structures, systems and components whose satisfactory performance is required to prevent or mitigate the consequences of postulated accidents that could cause undue risk to the health and safety of the public.
(d)
Limited COE:
Limited Critical Quality Elements are defined as those structures, systems and components whose satisfactory performance is required to prevent or mitigate the consequences of failures of those structures, systems and components identified as CQE.
3.0 ALTERNATE SEISMIC CRITERIA The following (.iternate criteria are applied to structures, systems, and components for Seismic Category I design.
Codes / Standards Reauirements Applicable governing codes and industry standards for the applicable structures, systems and components are shown in Table 3.0-1.
ASME B & PV Code classifications for piping system alternate seismic criteria are shown in Table 3.0-2.
Ooeratina Conditions and Service Limits Operating conditions and service limits are defined in accordance with ASME B & PV Code NCA-2000 rules. Specific Design and Service Loadings and their combinations applicable to each plant operating condition are to be defined by the applicable Design Specification in accordance with ASME B & PV Code NCA-2140.
General loading definitions for each operating condition are shown in Table 3.0-3.
Ctfinitions of seismic loading follow for each applicable operating ccndition.
(1) Desian and Normal Condition (Service Level A): Any condition in the course cf system startup, operation in the design power range, and system shutdown in the absence of Upset, Emergency, or Faulted conditions. This includes those pressures, temperatures, and mechanical loads selected as the basii for the design of the component.
(2) Umset Condition (Service Level B): Any deviation from normal conditions anticipated to occur often enough that the component design should include a capability to withstand the conditions without impatring operation.
The Upset condition includes those transients caused by:
a fault in a system component requiring isolation from the system, the effect of specified earthquake for which the system must remain operational or must regain its operational status, transient due to a loss of load or power, and any system upset not resulting in a forced outage.
This operating condition includes those pressure, temperature, and mechanical loads provided in the Design Specification.
The seismic event loading associated with this condition is:
Desian Earthauake (OBE):
The Desi s Earthquake is that earthquake which, considering the regional and local geology and seismology and specific characteristics of the local subsurface material, could reasonably be expected to affect the plant site during the operating life of the plant.
The Design Earthquake for Fort Calhoun applicable to these alternate criteria is described in Section 4.1.
In this report, the designation QHI will be used for the Design Earthquake.
(3) Emeraency Condition (Service Level C): Any deviation from Normal conditions which requires shutdown for correction of the conditions or repair of damage in the system.
This condition has a low probability cf occurrence (the total number of postulated occurrences for Emergency condition shall not cause more than 25 significant stress cycles), but is included to provide assurance that no loss of structural integrity will result as an accompanying effect of any damage developed in the system.
This operating condition includts those pressure, temperature, and mechanical loads provided in the Design Specification.
(4)
Faulted Condition (Service Level D):
Those combinations of conlitions associated with extremely low-probability events whose consequeves are such that the integrity and operability of the system may be impabed to the extent that consideration for public health and safety may be involved.
This operating condition includes those pressure, temperature, and mechanical loads provided in the Design Specification.
The seismic event loading associated with this condition is:
Maximum HyootheticLLIAlth2 Eke (SSE1:
The Maximum Hypothetical Earthquake is that earthquake dich is based upon an evaluation of the maximum earthquake potential considering the regional and local geology, seismology, and specific cheacteristics of local subsurface material.
It is that earthquake which produces the maximum vibratory ground motion for which those structures, systems, and components classified as Safety Category I are designed to remain functional.
The Maximum Hypothetical Earthquake for Fort Calhoun applicable to these alternate criteria is described in Section 4.1.
In this report, the designation SSE will be used for the Maximum Hypothetical Earthquake.
Service Limits are those limits on the operating conditions which must be satisfied to meet the requirements of governing codes and standards.
Service licits must be satisfied for all loadings identified in the Design Specifications to which the structures, systems and components may be subjected in the performance of their specified service function.
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TABLE 3.0-1 GOVERNING CODES AND INDUSTRY STANDARDS STRUCTURES, SYSTEMS AND COMPONENTS CODE / STANDARD (a) (b)
Pinina. & Pine suonorts ASME B&PV Section III, 1980 Edition (Including Instrument Tubing) through Sumer 1981 Addenda (1)
Electrical Raceways (c)
Conduit and Cable Tray Spans Manufacturer's Catalog Supports (1)
AISI Cold-Formed Steel Design Manual, 1986 Edition (2)
(11) ASME B&PV Section III, 1980 Edition through Sumer 1981 Addenda (1)
(iii) IEEE Standard 344-1987 [9]
liVAC [c]
Ducts (Cold-Formed)
AISI Cold-Formed Steel Design Manual, 1986 Edition (2)
Ducts (Pipe Cross-Sections)
ASME B&PV Section III, 1980 Edition through Sumer 1981 Addenda (1)
Supports (Hot-Rolled)
ASME B&PV Section III, 1980 Edition through Sumer 1981 Addenda (1)
Anchor Bolts (c)
EPRI Report NP-5228 (10]
Notes:
(a)
ASME B & PV Codes Cases used in this document are the latest l
approved Code Case revision, and are not limited to the revision established by the governing ASME B & PV Code edition. Code Cases used are discussed in the applicable sections of this report.
(b)
NRC Regulatory Guides used for the alternate criteria are discussed in the applicable sections of this report.
(c)
Results from seismic testing and experience data are also applied for the qualifications of electric raceways, HVAC and anchor bolts.
See applicable sections of this report.
TABLE 3.0-2 CODE CLASSIFICATIONS FOR ALTERNATE SEISMIC CRITERIA FOR PIPING SYSTEMS CRITERIA CLASSIFICATION ASME B & PV Code [a] Section III Section III Section III Section III Subsection Subsection Subsection Subsection NF NB (Class 1) NC (Class 2)
ND (Class 3)
(Class 1,2,3)
ANSI /ANS
- 51.1-1983 (b)
(d)
SC-l&-2 [e]
SC-3 SC-1, -2 & -3 NRC RG 1.26 (c)
(d)
A&B C
A, B & C Notes:
(a)
ASME B&PV Section III, 1980 Edition through Summer 1981 Addenda.
[b]
General correspondence to safety class of "Nuclear Safety Criteria for the Design of Stationary Pressurized Hater Reactor," ANSI /ANS-51.1-1983.
(c)
General correspondence to quality group of "Quality Group Classification and Standards for Hater, Steam, and Radioactive-Haste Containing Components of Nuclear Power Plants," NRC Regulatory Guide 1.26 Revision 3. February 1976.
[d]
The following piping systems may, as an option, be designed based on ASME B & PV Code Class 1 criteria:
a) Seismic Category I components of the reactor coolant pressure boundary (up to the second isolation / check valve from the RCL) whose failure during normal operations would prevent orderly shutdown and cooldown assuming normal makeup systems or b) Seismic Category I system components in which thermal operating modes are defined.
(e)
Instrument Tubing, and HVAC Duct (with pipe cross-sections) may be analyzed per ASME B & PV Code Subsection NC rules.
TABLE 3.0-3 DESIGN AND SERVICE LOADING FOR PLANT OPERATING CONDITIONS PLANT OPERATING DESIGN AND SERVICE LOADING [a]
I CONDITIONS l
Design Design Pressure, Design Temperature, Deadweight.
Normal Normal Condition Pressure, Normal Temperature, (Service Level A)
Deadweight, Anchor Motions (Loading and Movements from Nozzles Supports, etc.),
Transient Events associated with the Normal Condition.
I Upset Upset Condition Pressure, Upset Temperature, (Service Level B)
Deadweight, Anchor Motions (Loading and Movements from Nozzles Supports, etc.), Design I
Earthquake (OBE), Transient and Other Dynamic Events associated with the Upset Condition.
Emergency Emergency Condition Pressure, Emergency (Service Level C)
Temperature, Deadweight, Anchor Motions (Loading and Movements from Nozzles, Supports etc.) Dynamic Events associated with the l
Emergency Condition.
Faulted Faulted Condition Pressure, Faulted l
(Service Level D)
Temperature, Deadweight, Anchor Motions i
(Loading and Movements from Nozzles, Supports, l
etc.), Maximum Hypothetical Earthquake (SSE),
i Dynamic Events associated with a Loss of l
Coolant Accident (LOCA), Other Dynamic Events associated with the Faulted Condition.
Note:
(a)
Specific loadings and their combinations for particular structures, systems and components are defined by the appl icable j
Design Specification.
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3.1 Piping and Pipe Supports The general criteria for piping and pipe supports shall be based on the requirements set forth in ASME B & PV Code,Section III, Subsections NC/ND and NF [1], as Code Class 2/3.
Stress allowables shall be based on the ASME B &
PV Code, except as stated in the following subsections. On a case-by-case basis, piping and pipe supports may be qualified based on the requirements set forth in ASME B & PV Code,Section III, Subsections NB and NF, as Code Class 1 cr qualified by a specific stress-strain correlation criterion.
Criteria for piping are separated into Subsections 3.1.1 and 3.1.2 for large bore and small bore piping, respectively. Criteria for large bore piping are intended for analysis principally by computer techniques; Small bore piping criteria are intended for analysis by hand calculations.
Small bore piping criteria may be used as criteria for Seismic Category I instrument tubing. As an alternative, small bore piping and instrument tubing may be designcd in accordance with the large bore piping criteria. Criteria for pipe supports are presented in Subsection 3.1.3.
3.1.1 Large Bore Piping Large bore piping is defined to be piping larger than 2 inch nominal diameter.
Large bore piping qualification shall consider the effects of design and service loadings for plant operating conditions.
Definitions of specific loadings are provided in the component Design Specification.
Seismic loading shall be in compliance with methodology provided in Section 4.1.
Acceptable methods of analysis include linear response spectrum, linear time-history, and specific non-linear analysis as defined and provided in Section 4.2.
3.1.1.1 Elastic Stress Criteria - ASME 8 & PV Code Class 2/3 The ASME B & PV Code Class 2/3 acceptance criteria and Service Level stress licits for each of the plant operating conditions are provided in Table 3.1-1.
Alternatively, for the Upset condition the seismic OBE stresses may be addressed through a fatigue evaluation. Acceptability may be demonstrated according to the simplified fatigue evaluation defined by NUREG 1061, Volume 2
[3].
3.1.1.2 Elastic Stress Criteria - ASME 8 & PV Code Class 1 The ASME B & PV Code Class I acceptance criteria and Service Level stress licits for each of the plant operating conditions are provided in Table 3.1-2.
Piping systems which meet the requirements of Table 3.0-2 Note (d) may be qualified by the ASME B & PV Code Class 1 approach.
Alternatively, for the Upset condition, the seismic OBE stresses may be evaluated based on the approach given in ASME B & PV Code Case N-451.
3.1.1.3 Inelastic Strain Criteria In cases where the elastically calculated primary stress (Code Equation 9) from the Faulted conditon exceeds the ASME B & PV Section III Subsection NC/ND 11;1ts (provided in Table 3.1-1), carbon steel and stainless steel piping components may alternatively be qualified by inelastic strain criteria, using a stress-strain correlation. This qualification requires that the piping strain associated with an elastica 11y-calculated primary stress be determined and limited, as defined below:
A.
Stress-Strain Correlation The following stress / strain conversion shall be applied:
For carbon steel:
et"K s for stainless steel:
it " K s
E where it Pipe strain (inch / inch).
Elastica 11y-calculated primary stress (psi), for ae the Faulted condition, per Table 3.1-1.
This is based on stress intensification factor approach.
E Young's modulus (psi), from Appendix I of the ASME B & PV Code.
Strain correlation factor Ks The strain correlation factor Ks is defined to be equal to factor Ke from ASME B & PV Code NS-3228.3, as follows:
K l
Ks*
e" where n Code-defined material parameter The material parameter, n, and the applicable pipe temperature limit.
T
, are defined in ASME 8 & PV Code Table NB-3228.3(b)-1 and are tNulatedas' I
i T,,, (.7) f Material n
Stainless Steel 0.3 800 Carbon Steel 0.2 700 8.
Strain Limits Strains shall be limited to 1% for carbon steel piping and 2% for stainless steel piping.
If strains for stainless steel piping exceed 1%,
three additional checks shall be satisfied.
These are:
(1) Compressive Wrinkling Check:
(t I
Nominal wall thickness of pipe (inches) where t
Mean radius of pipe (inches)
R
=
(2) L.v Cycle Fatigue Check:
g U,
Number of equivalent peak-to-peak SSE cycles where n Number of allowable :ycles under SSE loads N
Allowable usage factor for SSE Ua where N is calculated as follows:
N
'91.875' 5 0.751H/Z where M Resultant moment due to SSE (kip-in.).
Seismic anchor movement moments and inertia moments shall be combined by Square-Root-of the-Sumof-Square (SRSS) method 1
Stress Intensification Factor.
The product 0.751 must be greater than or equal to 1.0 Section modulus of pipe (in.3)
Z (3) Load Capacity and Displacement Check:
X - 1 + 170( et - 0.01 )
where X Inelastic response factor for multiplying reaction loads (i.e., nozzle and support loads), valve accelerations and displacements obtained from the elastica 11y calculated stress
( a ) analysis, described in Subsection e
3.1.1.3A The factor X shall be applied only to the piping span qualified by the strain criteria, through the first support or nozzle in each of the three orthogonal directions on each side of any strain location.
C.
Apolication Limits Both carbon steel and stainless steel piping may be qualified by the strain criteria, provided that the following constraints are met: __
l (1)
In calculating the elastic primary stress, o,, at least 50% of a, is due to earthquake loading.
(2)
In calculating moments due to earthquakes, the response spectrum method is used, with damping not exceeding that specified in Code Case N-411.
(3) Pipe component diameter / wall thickness ratio ( Do/t ) does not exceed 50.
(4) Heldments as well as piping base materials are ductile (no quenched and tempered ferritic steels or cold worked austenitic stainless steels).
Material has a maximum ratio of minimum yield strength to minimum tensile strength of 0.8, in accordance with ASME B & PV Code NS-3228.3(f).
j (5) Joints are butt welded or girth fillet welded (no threadsd or seal-welded).
Bolted-flanged joints are qualified per the requirements of ASME B & PV Code NC/ND-3650.
(6)
The cumulative usage factor ( Ua ) due to the SSE does not exceed 1/3.
3.1.1.4 Additional Criteria The following subsections describe additional criteria to be used in conjunction with the elastic and inelastic piping criteria given above.
A.
Seismic to Non-Seismic Pice Decouclina Criteria If a pipe system contains a seismic to non-seismic boundary (Seismic i
Category I/Non-Seismic Category I boundary), the seismic analysis shall include a portion of the non-seismic piping up to the next pipe anchor or i
to the second pipe support in each of three orthogonal directions, whichever is closer.
Each of these supports are to be qualified by meeting the pipe support criteria provided in Subsection 3.1.3.
8.
Support Stiffness Generic or calculated support stiffness values shall be used to model pipe supports for computer analysis. Generic support stiffness values are provided in Table 3.1-3.
They reflect the lower bound support stiffnesses used for typical r.jpe support designs. Calculated support stiffness values should be used in tre analysis if they are lower than generic support stiffness values by an order of magnitude or more.
Fcr cases whare piping is connected to flexible equipment or structures, the influence of this flexibility shall be considered.
Flexible equipment or structures are defined to be those whose fundamental natural frequency is below the the floor cut-off frequency or 33 Hz, whichever is less.
Stiffnesses of flexible equipment or structures should be used in the analysis l
when the calculated stiffness values are lower than generic stiffness values by an order of magnitude or more. As an alterriative, pipe-equipment or i
pipe-structure coupled analysis may also be performed to account for stiffness interaction between the piping system and flexible equipment or structures.
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t Co Branch Line Decoucling A pipe branch line may be decoupled from a main line provided that:
(1) The moment of inertia ratto (main / branch) is greater than or equal to 25 and the nominal pipe diameter ratio (main / branch) is greater than or equal to 3.
(2) The decoupled branch line does not include a termination which imposes a significant reaction load on the main line (e.g., anchor or nozzle within a pipe span of the main / branch intersection point).
(3) The decoupled branch line does not include a second branch line decouplec 1
from the first branch line, within close proximity of the main /first:
branch intersection point.
(4) An equivalent mass equal to 1/2 first branch pipe span length (i.e., to
'r the first branch line support) is lumped at the intersection point.
These equivalent masses are to be considered in the main pipe line analysis.
If the equivalent branch pipe mass is less than the equivalent mass of main pipe with length equal to 2 nominal pipe diameters, then it need not be considered.
If these decoupling criteria are satisfied, the main line may be evaluated althout considering the branch line.
The branch line may then be evaluated considering the run line to be an anchor with imposed movements.
In other cases, the branch line shall be included with the model of the main line, up I
to an anchor point or up to and including the second support in each of three orthogonal directions.
i As an alternative, a coupled run line and branch line analysis is acceptable, f
D.
Snubber Activation By Dynamic Events Snubber /Rinid S egort Interaction i
Snubbers located close to rigid supports / anchors may not experience large encugh pipe movement to be activated by a dynamic event. When a snubber is l
located in close proximity to a rigid support / anchor, the analysis shall assume that the snubber fails to activate. Snubbers are considered inactive i
if their locations, with respect to a rigid support in the same direction.
4 fall within the following distances:
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(1) 3 times the pipe diameter, for pipe sizes equal to or greater than 8" in nominal diameter, and j
(2) S times the pipe diameter, for pipe sizes less than 8" but greater than 2" in nominal diameter.
l If the predicted seismic movement in the direction of restraint is greater I
than 1/16 inch at an inactive snubber location, the snubber may then be reanalyzed with the snubber activated.
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01h.er Locations A determination should be made of whether the predicted dynamic movement at a proposed snubber location is sufficient for snubber activation.
If the predicted movement is less than 1/16 inch, no snubber activation is expected.
E.
In-Line Eauiement Influence The influence of flexible in-line equipment on piping components shall be considered in the piping system analysis.
In-line equipment is defined to be equipment which is mounted on the piping component (such as valves, etc.).
Flexible in-line equipment is defined to be equipment whose fundamental natural frequency is below the floor cut-off frequency or 33 Hz, whichever is less.
Typical flexible in-line equipment items are valves with heavy operators.
F.
Ploe Integral Attachment criteria Intensification of pipe component stresses due to pipe integral attachments shall be taken into account when checking for compliance with the strecs licits. Criteria for qualification shall consider the configuration and orientation of the attachment.
Local stresses due to the integral attachment shall be calculated and combined with the piping stresses at the attachment location.
Local stresses may be calculated and combined with the piping stresses based on the criteria established in the following ASME B & PV Code Cases:
ASHE B & PV Code ASME B & PV Code Integral Attachment Class 1 Class 2/3 Rectangular Cross-Section (Lug)
N-122 N-318 Hollow Circular Cross-Section (Trunnion)
N-391 N-392 These Code Cases provide criteria with limited appitcability to specific integral attachment geometries.
For geometries which fall outside these Code Case limits, local stresses shall be calculated based on experimental or other acceptable analytical criteria.
Specifically, criteria provided by the HRC Bulletins (5) (6) (7) are acceptable.
G.
Eist_Auatut criteria Structures, systems and components important to plant safe shutdown shall be uaigned to accommodate the effects of postulated pipe rupture. These structures, systems and components shall be appropriately protected against the dynamic effects of missiles, pipe whipping, and discharging fluids.
Protection of the structures, systems and components important to plant safe shutdown may be provided by any of the following methods:
(1) Separation of high and moderate energy systems from essential s lety-related systems and components.
(2)
Enclosing either the high and moderate energy systems or the essential safety-related systems and components in protective structures.
(3) Where neither separation nor protective enclosures are practical, taking special protective measures to ensure the operability of safety-related features.
The first two methods can be performed by review of the piping layout and plant arrangement drawings to show that the effects of postulated piping breaks at any location are isolated or physically remote from essential systems and components.
The third method consists of postulating pipe break and/or crack locations, then performing an analysis to evaluate the dynamic effects associated with high or moderate energy fluid system piping.
The criteria provided by the following two documents shall be used in pipe rupture-related work:
(1)
Branch Technical Position ASB 3-1, "Protection Against Postulated Piping failures in Fluid Systems Outside Containment," as attached to NRC Standard Review Plan, Section 3.6.1 (13).
Per the Fort Calhoun USAR Appendix H (8),
Fort Calhoun shall comply with Appendix B of ASB 3-1.
(2) NRC Generic Letter 87-11. "Relaxation in Arbitrary Intermediate Pipe Rupture Requirement" (14).
On a case-by-case basis, leak-before-break (LBB) criteria may br applied in lieu of installation of pipe rupture hardware.
If LBB criterir, are used, the licitations stated in NUREG 1061, Volume 3 (11), shall be observed. Other options, such as any future revisions of SRP, may also be *.pplied in lieu of installation of pipe rupture hardware.
3.1.2 Small Bore Piping And Tubing Small bore piping is defined to be piping of 2 inch nominal diameter or smaller.
Tubing is defined to be instrument tubing of 3/4 inch outside diameter or smaller.
Small bore piping and tubing qualification shall consider the effects of design and service loadings for plant operating conditions. Definitions of specific loadings are provided in the component Design Specification.
Seismic loading shall be in compliance with methodology provided in Section 4.1.
The criteria for small bore piping and tubing are separated according to their intended use in two basic evaluation approaches:
chart methods (i.e., hand or nomograph) and rigorous analysis methods.
Both approaches are based on the requirements set forth in ASHE B & PV Code Section III Subsection NC/ND, as Code Class 2/3.
These are described in the following two subsections.
3.1.2.1 Chart / Nomograph Criteria This subsection gives criteria for the generation of charts or nomographs used to perform verification / design of small bore piping and tubing configurations.
Nomographs shall be developed from span length limits which are calculated in accordance with ASME B & PV Code NC/ND-3600 stress limits.
The span length l
licit calculations shall include consideration of the effects of concentrated l
masses (e.g., valves, etc.), design /servit ' d oressure and temperature, acceleration limits, and support / equipment re ction limits.
In addition, the following restrictions shall be considered in developing nomographs:
I t
(1)
Flexible Valve Operators:
Nomographs shall not be used to design piping in the vicinity of flexible valve operators. As an alternative, the flexible valve may be supported such that its effects can be decoupled from the nomograph-designed spans.
Flexible operators are defined to be those whose fundamental natural frequency is below the floor cut-off frequency or 33 Hz, whichever is i
less.
(2) Support Stiffnesses:
The span length limit calculations shall consider the influence of support stiffnesses.
(3) High Temperature Systems: When the temperature of any system exceeds 150'F, adequate thermal flexibility shall be provided.
(4) Anchor Motions: When anchor motions due to thermal expansion or seismic response are expected, adequate flexibility shall be provided.
Nomographs generated based on these criteria will be inherently conservative, due to their need for simplification.
L 3.1.2.2 Rigorous Analysis Criteria As an alternative to the chart / nomograph approach, small bore piping and l
tubing may be qualified based on application of the large bore piping criteria presented in Subsection 3.1.1.
The large bs's criteria may be applied to evaluations based on either hand i
calculations or romputer techniques.
The hand calculations shouid use the equivalent static coefficient method described in Subsection 4.2.2.
Computer techniques shall be the same as those used for large bore piping. All evaluations shall be in accordance with ASME B & PV Code NC/ND-3600 stress litits.
t 3.1.3 Pipe Supports Pipe supports are categorized into standard component supports and linear type supports.
They shall be designed for all service levels.
The loading of each i
service level is defined in Table 3.0-3.
The alternate seismic criteria developed for both types of supports are presented in Tables 3.1-4 and 3.1-5 i
and are discussed in the following subsections.
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3.1.3.1 Standard Component Type Supports The design criteria of standard component supports (or standard catalog items) are provided in Table 3.1-4.
They are based on manufacturer recomended allowable loads for each service level or available test results.
A Oualification by Manufacturer Recommended Allowable Leadi Manufacturers generally provide allowable loads for each service level for their catalog items.
However, allowables are soaetimes provided for Service Level A (Normal condition) only.
In this case the allowable increase factors shown in Table 3.1-4 shall be applied to the manufacturer recomended allowable loads for Service Level A to obtain allowable loads for other service levels. A minimum factor of safety of 1.5 shall be maintained for Service Level D allowable loads.
If test ultimate loads are provided in manufacturer's catalogs, guidelines as discussed in Item 8 below may also be used to determine the allowable load for et,a service level.
8.
Qualification by itatic Load Ratteg In cases where tests using the static load rating approach are performed to determine the capacity of catalog items, the safety factors specified in Table 3.1-4 shall be applied to the test ultimate load to determine the allowable load for each service level. The test ultimate load is the average ultimate load of three tests, provided no individual test result deviates more than i 10% from the average. Alternatively, a) if less than three tests are performed, the test ultimate load is taken as the lowest test result reduced by 10%; b) if one or more result out of three tests deviates more than i 10%
from the average, the test ultimate load is taken as the lowest of the three test results; c) if more than three tests are performed, the test ultimate load is taken as the average of the three lowest results.
C.
Qualification by Analysis In addition, allowable loads of standard catalog items may also be determined analytically using appropriate stress allowables from Subsection 3.1.3.2.
3.1.3.2 Linear Type Supports The design criteria for linear type supports of Class 1, 2 and 3 systems are based on maximum stress theory in accordance with the rules of ASME 8 & PV Code NF-3230 and Appendix XVII-2000. Table 3.1-5 provides detailed 11;1tations of each service level for this support type.
The linear type support criteria are developed for structural steel, welds, structural bolts and base plates.
A.
Structural Steel The capacity of structural steel components shall be obtained by applying the design requirements for structural steel members described in ASME B & PV Code l
Appendix XVII-2200.
In applying the ASME B & PV Code rules, a departure from l L
the Code will be ta.an on a case-by-case basis for the qualificati',.. vi structural steel.
The Code values for material yield strength will be increased by 20 percent to account for strain rate effects and the difference between average and Code-specified minimum yield strength.
The increase of yield strength shall not be applied to allowable stresses for Service Level A (Normal) condition or compressive allowable stresses for all service conditions.
In addition, a maximum ductility of 3 may be used to account for the plastic deformation capacity of structural steel cc,Lonents to maintain t
their design function if the ASME B & PV Code Service Level D limits are exceeded.
The methodology for ductility calculation is discussed in Subsection 4.2.4.
B.
Heldt The allowable stresses used for welds as described in ASME B & PV Code, Appendix XVII-2450, shall not include the increases for material overstrength or strain rate effects. Weld allowables shall not exceed the applicable allowable stress value for the base metal being joined or the electrode being used.
C.
ita ttural Bolts Structural bolts shall be evaluated in accordance with ASME B & PV Code, l
Appendix XVII-2460.
The tension load on bolt shall be the sum of the external i
load and any bolt tension resulting from prying action produced by deformation of the connected part.
Bolts in bearing type connections subjected to combined shear and tension shall satisfy the tension / shear interaction requirement specifisi in ASME B & PV Code, Appendix XVII-2461.3.
D.
Rase Plates The bending stress about the weaker axis shall meet the requirements of the ASME B & PV Code, Appendix XVII-2214.3. The additional tensile load on a bolt resulting from prying action produced by the flexibility of the connected base plate shall be evaluated (see Section 3.4 of this report).
3.1.3.3 Concrete Expansion Anchors The design criteria for concrete expansion anchors are described in Section 3.4.
V h
r TABLE 3.1-1 CODE EQUATION STRESS LIMITS FOR B&PV CODE CLASS 2/3 COMPONENTS [a]
PLANT OPERATING B&PV CODE STRESS CONDITION [b]
EQUATION LIMITS [c]
Design Eq. 8 of NC/ND-3652.1 1.0Sh Normal / Upset Eq. 10 of NC/ND-3652.3 SA (Service Level A/B)
Eq. 10s of NC/ND-3652.3 3.0$c
'q. 11 of NC/ND-3652.3 SA+Sh Upset Eq. 9 of NC/ND-3652.2 (d) 1.2Sh (Service Level B)
Emergency Eq. 9 of NC/ND-3652.2 1.8Sh (Service Level C)
Faulted Eq. 9 of NC/ND-3652.2 (e) 2.4Sh (Service Level D)
Notes:
(a)
The piping shall conform to the requirements of ASME B & PV Code NC-3600 and ND-3600.
(b)
Plant operating conditions are per Section 2.0 of this report.
(c) Definition of S. Sc. SA and stress limits for the ASME 8 & PV Code h
equations indicated are per ASME B & PV Code NCIND-3650 and NC/ND-3611.2 or Appendix F.
[d] On a case-by-case basis, simplified fatigue evaluation per NUREG 1061, Volume 2 may be applied for Upset condition qualification.
(e) On a case-by-case basis, stress-strain correlation per Subsection 3.1.1.3 of this document may be epplied for Faulted condition qualification.
i TABLE 3.1-2 CODE EQUATION STRESS LINITS FOR B&PV 000E CLASS 1 COMPONENTS [a]
PLANT OPERATING 8&PV CODE STRESS CONDITION [b1 EOUATION [c]
LIMITS tel Design Primar! Stress Intensity (per 1.5Sm Eq. 9 of NB-3652)
Normal / Upset Primary Plus Secondary Stress 3Sm (Service Level A/B)
Intensity Range (per Eq. 10 of NB-3653.1)
Peak Stress Intensity Ra ye (per Eq. 11 of NB-3653.2 )
Simpit fied Elastic-Plastic 01scon-3Sm tinuity Stress Intensity Range (per Eq. 12 and 13 of NB-3653.6(a)
& (b) and "thermal stress rachet" check per NB-3653.7. Performed if Eq. 10 limit is not satisfied.)
Cumulative Fatigue Damage (per 1.0 NB-3653.3, NS-3653.4 Nd-3653.5, Eq. 14 of NB-3653.6(c))
Upset Primary Stress Intensity 1.85m but (Service Level B)
(Eq. 9 of NB-3652) (d) not greater than 1.5Sy Emergency Primary Stress Intensity 2.25Sm but (Strvice Level C)
(Eq. 9 of NB-3652) not greater than i.BSy Faulted Primary Stress Intensity 3.05 but (Service Level D)
(Eq. 9 of HB-3652) not, greater thaa 2.4Sy Notes:
(a) The piping shall conform to the requirements of ASME B & PV Code NB-3600.
(b) Plant operating ccaditions are per Section 2.0 of this report.
(c) Definition of Se and Sy, and stress limits for the ASME B & PV Code equations indicated art per ASME B & PV Code NB-3650 or Appendix F.
(d) On a cast-by-case basis, ASME B & PV Code Case N-451 may be applied for Upset condition primary stress qualification. _
TABLE 3.1-3 GENERIC PIPE SUPPORT STIFFNESSES NONINAL PIPE TRANSLATIONAL STIFFNESS DIAMETER (Inch)
(1bs./ Inch) 2 1/2 6.25 x 103 3
9.01 x 103 4
1.60 x 104 6
3.60 x 104 8
6.41 x 104 10 1.00 x 105 12 1,44 x 105 14 1.96 x 105 16 2.56 x 105 18 3.25 x 105 20 4.00 x 105 24 5.75 x 105 28 7.81 x 105 30 9.01 x 10b Ot$1GN CRITERIA FOR $ FAN 0ARD COMPONENT (04 CATALOG) $UPPORTS CRITERIA COMPONENT
$TRES$
APPLICABLE NORML & UP$ti EMERGENCY FAULTED TYP[$
CONDITION CODE (LEVEL A & 0) fLEVEL C)
(LEVEL 0) fai All All A$nt and knufacturer knufacturer knufacturer Deviations recessended recommended recommended capacity for capacity for capacity for Level A Level C Level O or er 1.33shnuf ac turer 2.0sManuf acturer rer.'. amended recommended capacity for capacity for Level A Level A l
or er er Test Ultimate /3.0 Test Ultimate /2.25 Test Ultimate /1.5 or er er Analysis (b)
Analysis (b)
Analysis (b) l Note (a) A minime facter of safety of 1.5 shall be maintellied for Service Level e allowable leads.
(b) For qualification by analysis, use appropriate stress allowables from $vbsection 3.1.3.2 of this report. l
Tast[ 3.1-5 GE5BEul CatfERIA NE LIIEAR TTFE SurpWETS [a]
CRITERIA Clustuust 5seE55 AFFLICast5 IWeekt WPSEg Esatar.sarY ung,yEB TYPE CWWETISI COBE (LEVEL A)
(LEWL 3) [b]
(tDEL C) [b]
(LEWEL 3) [b] [c]
5tructural fension AM nopendin XVII-1.2 s Appendim XVII-1.2 s 1.33 m Appendia 1.2 s Appendin F.
Steel and 2211 2211 XVII-2211 F-1370 er deviations e ag3.0 Shear A$fE Appendis XVII-1.2 s Appendim XVII-1.2 a 1.33 s Appendia 1.2 m Ap W im F.
and 2212 2212 XVII-22n2 F-7?T deviations Cemqpres-ASME Appendia WII-Appendim XVII-1.33 m Appendia Appendin F.
slon 2213 2213 XVII-2213 F-1370 Sending ASME and Appendis XVII-1.2 a Appendiu XVII-1.2 s 3.33 m Appendia 1.2 m Appendin F.
deviations 2214 2214 XVII-2214 F-1370 or w ( 3.0 Combined ASME Appendia XVII-Appendim XVII-Appendim XVII.
Appendis XVII-Stresses 2215 2215 2215 2215 Weld All ASME Appendis XVII-Appendim XVII-1.33 m Appendia Appendia F.
2450 2450 XVII-2450 F-1370 i
Structural All ASME Appendis XVII-Appendis XVII-1.33 a Appendia Aspendia F.
Bolt 2460 2460 XVII-2460 F-1370 Base Plate Sending ASME Appendte XVII-Aspendte XVII-1.33 m Appendis Appendia F.
2214.3 2214.3 XVII-2214.3 F-1370 htes:
[a] Other desip reesirements for strweteral steel mem6ers such as s1-far-ss ratios, stability, and wlJth to thicliness raties shall be in confomance with ASME S & PV Code Appendis XVII-2220 and Appendia F. F-1370.
[b] On a case-by-case basis. 20 percent increase in yield strece*h may be applied to the A5ME B & PV Code Service Levels B. C and D allemables. The Level D allo== ables based on mini.am tensile strength shall met be lacreased.
[c]
w -
Dwctility Factor 1
_,-.- ~ -..
-, - - - - - - - -. - - -. ~ -, - - - - - - - - - - - - - - -
3.2 Electrical Raceways i
A large body of experience data concerning the seismic performance of electrical raceways in power and industrial facilities (151 shows that the spans or conduits and cable trays are very unlikely to fail during an earthquake, even when they have been designed only to carry dead loads.
The few instances of raceway failure under seismic loads which have been observed t
in this experience database are traceable to overloaded, unstable or l
improperly installed supports. Therefore, the primary focus of the evaluation criteria presented in this section is on the raceway supports. Conduits and cable trays themselves are acceptable if they meet relatively simple a110wable span and inspection requirements which are based on manufacturer i
recommendations.
3.2.1 Conduit Evaluations Conduits shall be evaluated by comparing the conduit span to an allowable l
span.
The allowable span for each size of conduit is the free span which l
produces a maximum bending stress, under gravity loads with 100% fill, of 0.6 l
times the yield strength of the conduit steel.
The maximum bending stress i
shall be determined considering the reduced conduit cross-section in the I
threaded region.
t 3.2.2 Cable Tray Evaluations i
Cable Trays are acceptable if they meet the following requirements:
l (A) Cable tray spans are less than the maximum recommended by the manufacturer for normal service. Manufacturers' catalogs (e.g., (161) list cable tray allowable spans which are typically developed for static vertical loads. On a case-by-case basis, manufacturers' recommended t
i spans may be proportionately increased for lightly loaded cable trays,
(
(B) Cable fill is not greater than 2 inches above the top of the cable tray h
siderails, m ere cable fill extends above side rails, and on all l
i vertical cable trays, cables must be securely tied to the cable tray with plastic ties.
(C) Cable tray splices are properly installed (e.g.
no missing bolts) according to manufacturer's recoamendations.
l 3.2.3 Support Eva194tions Electrical raceway support criteria are provided in this section for the following components:
Hot-Rolled Steel I
Cold-For Steel Catalog. Ne t
Rod Hangs 1 i
The criteria are shown in Table 3.2-1 and discussed in detail in the following
(
subsections.
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3.2.3.1 Hot-Rolled Steel Member, component and weld stresses shhl1 be evaluated in accore nce with the
- SME 8 & PV Code,Section III Subsection NF [1], consistent wita 'he criteria N r linear type ?upports given in Subsection 3.1.3.2.
3.2.3.2 Cold-Formed Steel Member stresses shall be evaluated in accordance with the A!SI Mar,aal (2).
Allowable stresses for each Applicable load condition are incressed by the following factors:
i Lead Condition M,lowable Sti M f f n tig Normal 1.0 Upset 1.0 Imergency 1.33 l
l Faulted 1.6 t
1 Alternatively, members may be qualified by compar14cn with allowable loads i
determined by the cyclic load rating procedure given Ir. Subsection 3.2.3.30.
l l
Cold-formed steel connections shall be qualified gs follows:
A.
Hilded Cold-Formed Steel Connections Welded connections may be qualified by the c rite load rating procedure given in Subsection 3.2.3.30 or by comparison to a lowable loads determined from the l
AISI Manual, with the appropriate allowable stress increases gi wn above.
If l
the AISI Manual is used, allowable loads on thin sheet (thickness les. than l
l 0.18") welded connections are based on the capacity of the adjoining sheet steel.
Therefore, the presence of weld undertuts critically reduces the l
connection capacity.
The evaluation of existing welds must include an inspection for weld undercutting, and a proportionel reduction of the weld capacity for any weld undercut greater than 10'f. of the thickness of the thinner connected sheet.
B.
Cl.ig Angle Connections Clip angle connections shall be evaluated by the cycite load rating procedure j
given in Subsection 3.2.3.3D.
3.2.3.3 Catalog Itses Catalog items (e.g., clamps) shall be evaluated by comparison to allowahle loads determined from one of the followimp a) manufacturer's cattlog, b) analysis, c) static Icad rating or d) cyt,ll'. load rating.
A.
Dutljfintion by Manuf acturtr's Allowable loads Manufacturers' catalogs typically provide allowable working loads for catalog l
itess. These allowable loads will be taken to be applicable to normal and upset pla?.t conditions. Allowable load increase factors, os shown below, may be 49 piled to mandicturers' specified allowable loads provided a minimum I
factor of safety of 1.5 is maintained.,
4 Load Condition Allowable Stress Increase Normal 1.0 Upset 1.0 Emergency 1.33 Faulted 2.0 B.
QgAlification by Analysis Allowable loads are determined analytically using appropriate stress allowables from Subsection 3.1.3.2 or 3.2.3.2.
C.
Oualification by Static Load Ratino The allowable load is calculated based on the test ultimate load with a factor of safety dependent on the load condition, according to the procedure given in Subsection 3.1.3.18.
D.
Oualification by Cvelic Load Ratina Components will be qualified if the cumulative fatigue usage under all plant operating conditions is less than 1.0.
The cumulative fatigue usage is computed by considering the fatigue damage caused by five OBE events and one SSE event. Therefore, components are acceptable if:
"151 5n
+
0BE < l.0 N
N SSE OBE Where n SSE Number of equivalent peak-to-peak load er displacement cycles for SSE NSSE Number of allowable load or displacement cycles for SSE i
0BE Number of equivalent peak-to-peak load or n
=
displacement cycles for OBE OBE Number of allowable load or displacement N
cycles for OBE The values NSSE and NOB established as follows:E are determined from a safe-life fatigue curve The mean number of cycles to failure, Nr and cyclic load or displacement, R, are assumed to conform to a linear relationship between log (N ) and log (R). The safe-life at any load or f
displacement level is Nr divided by 1.5 or Nr subtracted by two standard deviations, whichever is smaller.
3.2.3.4 Rod Hangers Rod hangers shall be qualified by the cyclic load rating procedure than in Subsection 3.2.3.30.
4
3.2.4 Raceway-to-Support Connections Raceway qualifications must confirm by inspection that positive raceway-to-support connections are provided at all supports utilizing standard components.
In addition, the inspection shall verify that: a) Conduit clamps or cable tray clips have no missing bolts; b) Cable tray clips provide restraint in both directions of the plane perpendicular to the longitudinal axis of the cable tray.
3.2.5 Concrete Expan:lon Anchors Support anchorage evaluations shall follow the criteria presented in Section 3.4.
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TABLE 3.2-1 STRESS LIMITS FOR RACEHAY SUPPORTS CRITERIA [a]
COMPONENT NORMAL UPSET EMERGENCY FAULTED [b]
Hot-Rolled (See Subsection 3.1.3.2)
Steel Cold-Formed 1.0 x AISI 1.0 x AISI 1.33 x AISI 1.6 x AISI Steel or Cyclic Load Rated Allowable l
Catalog 1.0Lc 1.0Lc 1.33Lc 2.0Lc Items or Analysis [c] Analysis [c] Analysis [c]
Analysis [c]
or Tu/3.0 u/3.0 Tu/2.25 Tu/1.5 T
or Cyclic Load Rated Allowable Rod Cyclic Load Rated Allowable Hangers Notes:
[a] Lc Hanufacturer's Catalog Allowable for Normal Load
=
Conditions Test Ultimate Load Tu
[b] A minimum factor of safety of 1.5 shall be maintained.
[c] For qualification by analysis, use appropriate stress allowables from Subsection 3.1.3.2 or 3.2.3.2.
/
3.3 HVAC The seismic criteria given in this section are applicable to all Seismic Category I HVAC ducts and supports at Fort Calhoun Station, Unit 1.
Ducts and supports designed in accordance with these criteria, when exposed to loading in the applicable Design Specification, shall not experience stresses or loads in excess of the allowable limits indicated in the following subsections and summarized in Table 3.3-1.
The criteria detailed below provide for a comprehensive qualification of HVAC systems.
The criteria address the following attributes:
A.
Ducts Cold-Formed Sheet Steel Ducts Pipe Section Ducts B.
Supports Structural Members Penetrations Helds Anchorages C.
Miscellaneous Structural Steel Bolts Hardware Duct Straps Screws (connecting duct to support)
Duct Stiffeners Duct Joints (i.e., companion angles, flanges, pocket-locks, etc)
Screws and Bolts 3.3.1 Duct Qualification The criteria for the qualification of HVAC ducts are dependent on the duct 4
material.
Cold-formed steel duct sections shall be evaluated by analysis, in accordance with AISI Hanual (2), by comparison with test data, or through use of experience data.
Pipe section type ducts shall be evaluated in accordance eith ASHE B & PV Code NC-3600 (1).
3.3.1.1 Qualification by Analysis The loads on the ducts shall be determined using the methodologies given in Section 4.4.
A.
Basic Allowable Stress Duct stresses shall be evaluated in accordance with either the AISI Hanual for cold-formed steel duct material or in accordance with ASHE B & PV Code NC-3600.
for hot-rolled duct material. Appropriate allowable stresses for each applicable loading condition, as given in Subsection 3.2.3.2 for cold-formed steel ducts and Subsection 3.1.1.1 for pipe section ducts, shall be used.
B.
Spr ial Considerations Bccause cold-formed ducts are thin-walled, evaluations shall address the following, in accordance with the AISI Hanual:
(1) Effective section properties for rectangular ducts (2) Curling of duct walls toward the neutral axis (3) Local wall buckling of round ducts 3.3.1.2 Qualification by Test Hhere test results are available, a review shall be performed to determine thether the configuration and the loading considered in the test are appilcable to the design being considered.
The review shall include as a miaimum the following attributes:
(1) Duct size, gage, and material (2) Duct joint fabrication details (3) Duct-to-support connection details (4) Typical natural frequency of.3 stem (5) Loading (static and seismic)
(6) Duct spans (7) Duct stiffener details (8) Overall construction For test results where the component was tested to failure, the factors of safety for static load rating shall be applied for eacn applicable loading condition according to the procedure given in Subsection 3.1.3.18.
3.3.1.3 Qualification by Experience Data Experience data showing that a duct systems survived an actual earthquake may be used to show the acceptability of similar duct systems at Fort Calhoun.
The review for similarity shall include the same attributes described for qualification by test (Subsection 3.3.1.2).
The review must also show that the intensity of the earthquake motion experienced by the system or component envelops the intensity of the SSE event for Fort Calhoun defined in Section 4.1. _
3.3.2 HVAC Supports The qualification of the HVAC supports rcquires the evaluation of the structural members, penetrations, welds, and anchorages.
Each of these items shall be evaluated by analysis, test, or experience data.
The evaluation of concrete expansion anchors shall be in accordance with Section 3.4.
4 3.3.2.1 Qualification by Analysis Any of the support components may be evaluated using conventional stress analysis.
The duct supports are constructed of hot-rolled structural steel members and shall be evaluated in accordance with Subsection 3.1.3.2.
The telds shall be evaluated in accordance with Subsection 3.1.3.2.
Certain ducts pass through leak-tight penetrations in the building structures.
Loads on the penetration from the duct shall be calculated and compared with the original design allowables for the penetrations.
3.3.2.2 Qualification by Test Support components may be qualified by test where test results are available.
The allowable load may be calculated based on the test ultimate load of the component.
The factor of safety for static load rating given in Subsection 3.1.3.1B shall be applied to the test ultimate load.
3.3.2.3 Qualification by Experience Data Where experiance data are available that show a support component survived an i
actual seismic event, those data may be used to show the acceptability of the support component at Fort Calhoun, as described in Subsection 3.3.1.3.
3.3.3 Miscellaneous Hardware The balance of miscellaneous hardware for the duct / support system shall be evaluated by comparison to allowable loads determined from the manufacturer's catalog, analysis, test, or experience data.
The following criteria shall be applied to the following hardware:
(1) Structural Steel Bolts (2) Duct Straps (3)
Screws (connecting duct to support)
(4) Duct Stiffeners s
(5) Duct Joints (i.e., companion angles, flanges, pocket-locks, etc)
(6) Screws and Bolts.
3.3.3.1 Qualification by Manufacturer's Allowables Where the manufacturer of the hardware has specified a rated load, the load or service condition for the rated load should be determined.
If such determination is not possible, the Normal condition may be assumed.
Load Condition Allowable Load Increase Factor Normal 1.0 Upset 1.0 Emergency 1.33 Faulted 2.0 3.3.3.2 Qualification by Analysis The allowable load may be determined analytically by considering the physical and material properties of the hardware and using the allowable load increases for the applicable loading conditions given in Subsection 3.2.3.2 for cold-formed steel and Subsection 3.1.3.2 for hot-rolled steel.
3.3.3.3 Allowable Determined by Test The allowable load may be calculated based on the test ultimate load of the component.
The factors of safety for static load rating given in Subsection 3.1.3.1B shall be applied to the test ultimate load.
3.3.3.4 Qualification by Experience Data Hhere experience data are available that show a duct / support system or l
component survived an actual seismic event, those data may be ured to show the acceptability of duct / support systems or components at Fort Calhcun, as described in Subsection 3.3.1.3.
1
/ _ _ _ _ _ _ _ _ _.
TABLE 3.3-1 STRESS LIMITS FOR HVAC DUCTS f
CRITERIA [a]
COMPONENT NORMAL UPSET EMERGENCY FAULTED [b]
Quai Cold-Formed 1.0 x AISI 1.0 x AISI 1.33 x AISI 1.6 x AISI Steel Ducts Tu/3.0 Tu/3.0 Tu/2.25 Tu/1.5 or Exp. Data Exp. Data Exp. Data Exp. Data Pipe Section (See Subsection 3.1.1.1)
Steel Ducts SMAcorts (See Subsection 3.1.3.2) or Tu/3.0 Tu/3.0 Tu/2.25 Tu/1.5 or Exp. Data Exp. Data Exp. Data Exp. Data Hiscellaneous 1.0Lc 1.0Lc 1.33Lc 2.0Lc Hardware or Analysis (c) Analysis (c) Analysis (c)
Analysis (c) or Tu/3.0 Tu/3.0 Tu/2.25 Tu/1.5 or Exp. Data Exp. Data Exp. Data Exp. Data Notes: (a)
Lc Manufacturer's Catalog Allowable for Normal Load Conditions Test Ultimate Load Tu (b) A minimum factor of safety of 1.5 shall be maintained.
(c) For qualification by analysis, use appropriate stress allowables from Subsection 3.1.3.2 or 3.2.3.2. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
3.4 Concrete Expansion Anchors This section provides the criteria for the evaluation of concrete expansion anchors.
3.4.1 Load Combinations Concrete expansion anchors shall be evaluated for loads applicable to the Faulted condition.
3.4.2 Factor of Safety Allowable loads in tension and shear acting on concrete expansion anchors shall be obtained from the manufacturer's reported ultimate cepacities with a factor of safety of 4 on non-shell type anchors and a factor of safety of 5 on shell type anchors.
On a case-by-case basis, the factor of safety for non-shell anchors may be reduced to 2.5 and the factor of safety for shell anchors may be reduced to 4, provided the following restrictions are satisfied:
(1) Anchor bolt tightness is checked by applying a torque, using a standard hand wrench, and verifying that the anchor does not rotate. A s'nall amount of initial rotation is acceptable provided the nut or bolt tightens and resists the torque.
(2) n inspection confirms that washers are present between the anchor or nut and the base plate.
(3) An inspection confirms that the concrete is sound and uncracked other than hair-line shrinkage cracks.
(4) An inspection confirms that there is no gap greater than 1/4 inch between the equipment base and the concrete surface which would induce flexure in the anchor bolt.
(5) The anchor strength has not been degraded due to corrosion or mechanical abrasion.
3.4.3 Tension / Shear Interaction Anchors subjected to combined tonsion and shear shall be evaluated using the following interaction formulas, provided that the anchor is not installed in a concrete topping:
l
If V is less than or equal to 0.4Vall, h2
[y h2 T
1.0 (Tallj (Vall)
If V is greater than 0.4V a11, W
+
V 1.0 T ;j V
~
3 all where T
Calculated anchor bolt tension Allowable anchor bolt tension T,jj V
Calculated anchor bolt sh2ar V
Allowable anchor bolt shear all 3.4.4 Edge Distance Requirements Expansion anchors located adjacent to a free edge may be considered to achieve full shear capacity provided that the distance from the center line of the anchor to the free edge is a least ten anchor bolt diameters.
If the anchor is located between five and ten diameters from the edge, the allowable shear capacity shall be taken to be:
2n4(ED)2 4y V,jj n
where 4,
0.85 f
Concrete compressive strength (psi) e ED Edge distance (inches)
V" Manufacturer's catalog capacity with appropriate factor of safety.
No reduction in tensile capacity is required provided the edge distance is at least five bolt diameters.
Expansion anchors located close to chamfered concrete edges are subject to a reduction of allowable shear and tension loads equal to:
CH 1,0
~
EDHIN where CH Distance from bolt center to near edge of chamfer (inches)
EDHIN = Hanufacturer's minimum edge distance (inches)
Special requirements for anchors installed in concrete toppings are provided l
in Subsection 3.4.7.
l l
3.4.5 Spacing Requirement The allowable tensile capacity of anchors spaced closer than ten bolt diameters shall be reduced by a factor equal to:
S 10db Spacing (inches) where S
Nominal bolt diameter (inches) d b
This reduction factor shall not be less than 0.5 or greater than 1.0.
Alternatively, appropriate reductions of tensile capacity for c'osely spaced anchors may be developed analytically based on theoretical formulations of anchor capacity (e.g., using ACI 349-80 (12), Appendix B).
3.4.6 Embedment Depth Requirements The embedment depth of installed expansion anchors shall be at least equal to the minimum specified in the manufacturer's catalog minus 1/4 inch to account for the initial tightening (this reduction is applicable only to non-shell anchors).
The thickness of grout shall not be considered when establishing embedment depths.
Concrete topping may be considered as specified in Subsection 3.4.7.
3.4.7 Criteria for Anchors Installed in Concrete Topping Expansion anchors installed in concreto topping are subject to the following additional criteria:
(A) Allowable loads in tension and shear acting on concrete expansion anchors shall be obtained from the manufacturer's reported ultimated capacities with a factor of safety of 4 on non-shell type anchors and a factor of safety of 5 on shell anchors. On a case by case basis, the factor of safety for non-shell anchort may be reduced to 2.5 and factor of safety of shell anchors may be reduced to 4 provided the inspections rquirements specified in Section 3.4.2 are satisfied.
However, in no case shall the net tension acting on a bolt group installed in concrete topping exceed the allowables specified in Table 3.4-1.
(B)
In areas where the 28-day cylinder strength of the topping is less than i
80 percent of the design strength, the allowable shear and tension l
capacity of the anchors shall be reduced by
[f actual)1/2 c
fhdesign f L___ ___
(C) Anchors subjected to combined tension and shear shall be evaluated using the linear interaction equation:
v
+
< l.0 T
V,jj all (D) The allowable shear strength for anchors located less than 10 bolt diameters or three times the topping thickness from a free edge is:
V 4
A,77 fV all n
l l
where p
0.85 i
1/2 l
2 2
2 sin ~I(t/ED), ED2 t A
t(ED -t)
+ ED gff 2
nED /2,
ED < t Topping thickness (inches) t Edge distance (inches)
ED V" - Manufacturer's catalog capacity with appropriate factor of safety (E) The allowable tensile strength for anchors located less than 15 inches from a free edge is linearly reduced to 50 percent at the manufacture 's minimum edge distance.
3.4.8 Prying Factors All calculated tensile loads on expansion anchors shall be increased to account for base plate prying.
Prying factors may be derived for specific base plate configurations and load directions by a rigorous analysis which considers the effects of base plate flexibility and anchor bolt stiffness.
Otherwise, if no base plate analysis is performed, a factor of 1.5 shall be applied to the net tension acting on the anchor bolt.
I L_
TABLE 3.4-1 ALL0HABLE NET TENSION ACTING ON A BOLT GROUP INSTALLED IN CONCRETE TOPPING [a]
i l
EMBEDMENT DEPTH TOPPING THICKNESS [b]
ALLOKABLE NET TENSION (inches)
(inches)
(pounds) l l
2" 1/2" 2"
2500 1-3/4" - 2" 1-3/4" 1976 1-1/2" 3/4" 1-1/2" 1452 l
1-1/4" 1/2" 1
'I4" 1008 1" 1/4" 1"
645 i
Notes:
(a) No restrictions apply if the total embedment depth at least 1/2" greater than the design thickness of the topping.
(b) The allowable tension is based on embedment depth.
However, if l
actual topping thickness is known, the allowable based on actual topping thickness may be used regardless of embedment depth.
]
k e
a
a -
L k
k 4.0 ALTERNATE ANALYSIS METHODOLOGIES
[
This section provides methodologies applicable for use with the alternate criteria provided in Section 3.
This includes acceptable methods for generation of seismic loading, and for techniques used in the analysis of piping, pipe st.pports, electrical raceways and HVAC.
4.1 Load Generation 4.1.1 Seismic Hazard for Fort Calhoun The seismic hazard of the Fort Calhoun site was evaluated using the state-of-the-art methodology embodied in the EQHAZARD computer program.
The EQHAZARD methodology and associated data base have been developed by EPRI to m
evaluate seismic hazard of sites located in the eastern U.S.
The EPRI methodology is documented in detail in (20).
Free-field ground acceleration response spectra developed using EQHAZARD were compared to the design basis ground acceleration response spectra.
The design basis ground spectra were shown to be conseiyative in comparison to the EQHAZARD spectra and are therefore judged to be an adequate basis on which to develop input motion for a
Subsection 4.1.2.
Co mistent with USAR commitments, the vertical direction ground response spectra are 2/3 of the horizontal direction.
{
4.1.2 Input Motion I
Three statistically independent artificial time histories were developed, one g
for each of the three mutually orthogonal earthquake directions.
These time histories envelop the design ground motion in accordance with the procedures in the NRC Standard Review Plan, Section 3.7.1 (22).
The criteria for statistical independence are met since the correlation coefficient between any two time histories is less than 10.16 (21).
4.1.3 Soil-Structure Interaction The design basis Fort Calhoun Unit I soil-structure interaction (SSI) analyses were based on the lumped parameter method, using frequency-independent soil springs.
These analyses were performed in 1970.
Since then, more refined SSI techniques have been developed.
Refined SSI analyses were performed using the SASSI/CLASSI methodologies to generate updated floor response spectra for the Reactor Building, Auxiliary Building and Intake Structure.
The SASSI program was used to develop complex and frequency-dependent impedance functions for the soil / pile foundation system. The real term of the complex impedance function represents the stiffness of the foundation / soil system. The imaginary part represents the damping or energy dissipation of the foundation / soil system.
The CLASSI was used to ;alculate the structural respor.ses in terms of response spectra at g
each major elevation in the structures.
Input to CLASSI are the SASSI-generated impedance functions, the dynamic properties of the structures and E
the free-field artificial time histories.
For the SSI analysis, the ground E
motion time histories are applied at the level of the foundation in the free-field. The floor response spectra are broadened by 151. to account for uncer-tainties in modeling parameters in accordance with NRC Regulatory Guide 1.122.
r L
{,
r b
4.2 Piping and Pipe Supports Three linear elastic analysis techniques a:e acceptWie for analysis of seismic loading on piping systems.
They are the response spectra, equivalent static coefficient, and linear time history analysis methods.
Their use and applicable constraints are provided in Subsections 4.2.1, 4.2.2 and 4.2.3.
In addition, nonlinear analysis techniques are provided in Subsection 4.2.4.
l 4.2.1 Response Spectra Method l
l The response spectra method is an acceptable technique for performing seismic analysis, using the elastic and inelastic criteria provided in Subsection l
3.1.1.
Response spectra analysis shall be performed by either the single level (enveloped) or multiple level response spectra techniques.
Single Level Resoonse Analysis The single level (enveloped) response spectra analysis method determines the seismic response from the envelope of all spectra applicable to the piping system attachment points. The following constraints apply:
(1) Modal Combination per NRC Regulatory Guide 1.92 or the Complete Quadratic Combination (CQC) method.
(2) Critical Damping per NRC Regulatory Guide 1.61 or ASHE B & PV Code Case N-411.
(3) Hissing mass correction to be applied.
(4) Spectra Peak Broadening per NRC Regulatory Guide 1.122 or peak shifting per ASME B & PV Code Case N-397.
Multiole level Resoonse Analysis When response spectra magnitudes vary signhicantly at the piping system support points, the application of independent support motion (ISH or multiple level) response spectra analysis may be of benefit.
The method shall only be applied between separate buildings, floor levels, and/or individual structures. The following constraints apply:
(1) Modal Combination per NRC Regulatory Guide 1.92, CQC method or random vibration method when used in conjunction with support level combination.
(2) Critical Damping per NRC Regulatory Guide 1.61 or ASHE B & PV Code Case
~
N-411.
(3) Hissing mass correction to be applied.
(4) Spectra Peak Broadening per NRC Regulatory Guide 1.122.
(5) Support level combination by absolute summation or by the random vibration method.
/.
4.2.1.1 Seismic Response Combination The total seismic respons: Aall ba '.... 'ned with thI following techniques:
MnAAl Combinations Dynamically calculated modes shall be combined using any of the coiabination rules provided in Regulatory Guide 1.92 or by CQC method.
The CQC method is an accurate procedure for combining modal responses.
The 1
9echnique uses random vibration theory to provide a realistic response for closely spaced modes.
The method reduces to the SRSS method for well spaced natural frequencies.
The CQC method [17] requires that all modal response terms be combined as:
R P )R))U2
( E2 R
gg where R
Combined Response P)
Correlation coefficient between modes i and j g
(based on Random Vibration Principles)
R, R)
Modal responses for modes i and j g
(including directional sign for each mode)
The cross-modal correlation coefficient (P<j) is a function of the duration and frequency content of the loading, moda' frequencies, and damping ratios of the piping system.
Its formulation can be found in Reference [17).
The method will provide more accurate responses of closely spaced coupled modes than do the Regulatory Guide 1.92 methods. Higlier modes in the rigid range of the input spectra shall be included using the missing mass correction.
Suoport Level Combination For independent support motion, combination of support levels shall be made by absolute sum or through a stationary random vibration method. When combination is performed by the random vibration method, it also includes combination of closely spaced modes (as opposed to modal combination per Regulatory Guide 1.92).
The random vibration method (191 orovides for combination rules which can be used for determination of bot' the iynamic (inertia) response and the pseudostatic (SAH) response.
1 _ _ _.....
~
The combination rule for the dynamic response is written as:
d (I I I I Rh Rh Pg)
R d
Maximum dynamic response where:
R R h
- Maximum dynamic response of mode i due to the excitation applied at support level k d
Maximum dynamic response of mode j due to the R
$j excitation applied at support level 1 ik$1 - Correlation coefficient for modes i and j and P
support levels k and 1 (as described in Reference (19])
The combination rule for the pseudostatic response is written as:
RP (I I R[RyPkl ) 1 k I where:
RP Maximum total pseudostatic response l
R[-Maximumpseudostaticresponseduetomotion applied at support k R{=Haximumpseudostaticresponseduetomotion applied at support 1 kl - Correlation coefficient for support levels k and 1 P
(as described in Reference (19])
Missing Mass Correction l
A missing mass correction for high frequency modes in the rigid range shall be l
made.
The "rigid mass" mode shall then be combined with the low frequency modes by the SRSS method (4).
The rigid range is defined to be frequencies above tne floor cut-off frequency or 33 Hz, whichever is lower.
1 Directional Resoonse Combination l
The seismic spectra of three translational directions shall be applied simultaneously, with their response combined by the SRSS method, as per I
Sill 5mic Anchor Hotion The SAH effects on piping systems shall be evaluated if resultant SAH displacement at any anchor or support location exceeds 1/16 inch (on a case-by-case basis, higher SAH displacements m&y be ignored if justifications are provided).
The SAM stresses and reactions when combined with sustained stresses and reactions shall be absolutely summed.
The SAM stresses and reactions shall be combined with seismic inertial stresses and reactions by the SRSS method (4).
-43 I
4.2.1.2 Modal Damping The modal damping values for piping systems prcvided by Regulatory Guide 1,61 or a less conservative damping values provided Oy ASHE O '. PV Code Case N-411 shall be used. Analysis of any specific piping system shall consistently use one or the other of these two sets of damping values.
The damping values given by ASME B & PV Code Case N-411 may not be used on piping systems which use energy absorbing supports (covered by ASHE B & PV Code Case N-420), or in which stress corrosion cracking has been identified.
4.2.1.3 Dynamic Event Combinations Seismic loading shall be combined with LOCA or water hammer / steam hammer loading (e.g. rapid valve closure or opening) by the SRSS method (4, 18).
4.2.1.4 Spectra Peak Broadening or Shifting Response spectra used for sei n analysis shall have the spectral peaks broadened per Regulatory Gu'.de 1.1M.
As an alternative, spectral peak shifting of the unbroadened raw floor response spectra may be used per ASHE B
& PV Code Case N-397, for single level response spectrum analysis (3).
4.2.2 Equivalent Static Coefficleat Method The equivalent static coefficient method is an acceptable method for I
determination of the seismic response of small bore piping and tubing.
It is applicable to evaluations using the elastic stress criteria and inelastic I
strain criteria provided in Subsection 3.1.1.
This method is based on multiplying the system mass by the applicable spectral acceleration and by a static coefficient, thus estinting the equivalent dynamic response of the system.
The static coefficient is used to take into account the effects of both multi-frequency excitation and multi-mode response, for non-rigid system excitation.
At a maximum, the static coefficient can be conservatively assumed to be 1.5 (as used in Regulatory Guide 1.100).
Less conservative values for the static coefficients may be
/
used with justification.
The method is limited by the following constraints:
w (1) Single level (enveloped) response spectra shall be used.
(2) Damping values per Regtlatory Guide 1.61 or ASHE B & PV Code Case N-411.
L' (3) Spectra Peak Broadening per Regulatory Guide 1.122.
(4) Determination of the total seismic response and its combination with other dynamic events is to be in accordance with Subsections 4.2.1.1 and 4.2.1.3.
The one exception is that the response of each translational
'a direction is to be calculated separately, then combined by the SRSS method.
. l <
The analysis of small bore piping and tubing is separated into two groups:
rigid systems and non-rigid systems.
The rigid group is defined to be those systems whose fundamental natural frequen y 's equal to or above the floor cut-off frequency or 33 Hz, whichever is less.
Likewise, the non-rigid group are those systems whose natural frequency is below the floor cut-off frequency or 33 Hz, whichever is less.
The seismic response of the piping / tubing system can be calculated in accordance with the critical parameters defined in Table 4.2-1.
The general equation for the seismic response is:
KMSa U
Seismic system response where U Equivalent static coefficient K
1 Total span and support mass i
H l
Sa Response spectrum acceleration l
4.2.3 Linear Time History Analysis Method In lieu of the response spectrum analysis techr.iques, time histories of l
support motion may be used as excitation to the piping system.
If the motions j-at the different support locations are distinct, independent support motion
~
(multiple level) time histories shall be used to perform the analysis.
The method is acceptable for use with the elastic stress criteria provided in Subsection 3.1.1.
It shall be applied with the techniques as described in the following subsections.
Included are the following constraints to those techniques:
(1) Damping values per Regulatory Guide 1.61.
(2)
Both acceleration and displacement motion are to be considered at support points.
(3) Support levels are to be combined by absolute summation for independent support motion time history analysis.
4.2.3.1 Seismic Response & Event Combinations Seismic response and its combination with other dynamic events is restricted by the following:
Directional Response Combinati_on The three translational directions of seismic time-history motion may be applied, per Regulatory Guide 1.92, either:
(1) separately, with their responses combined by the SRSS method, or (2) simultaneously, with their responses combined algebraically at each time step.
Seismic Anchor Hotion The SAM effects on piping systems shall be evaluated if resultant SAH displacement at any anchor or support location exceeds 1/16 inch (on a case-by-case basis, higher SAM displacements may be ignored if justifications are provided).
The SAM stresses and reactions when combined with the sustained stresses and reactions shall be absolutely summed.
The SAM stresses and reactions shall be combined with the seismic inertial stresses and reactions by either of the following two methods:
(1) separately, with their maximum responses combined by the SRSS method, or (2) simultaneously, with their responses combined algebraically at each time step.
AvnAmic Event Combination Maximum time history seismic response shall be combined with LOCA or water hammer / steam hammer loading (e.g. rapid value closure or opening) by the SRSS Hethod [4, 18].
l 4.2.3.2 Damping l
l Damping values for piping systems as provided by Regulatory Guide 1.61 shall be used for linear time history analysis.
4.2.4 Nonlinear Analysis Method 4.2.4.1 Quasi - Nonlinear Support Analysis In cases where the elastically calculated tensile and bending stresses of structural steel components exceed the Level D limits specified by Table 3.1-5, a quasi-nonlinear analysis may be performed to ev31uate tbs inelastic behavior of structural steel components.
Specific criteria quasi-nonlinear analysis are based on a ductility approach.
.proach is described below.
A.
Generation of Ductility Demand Resoonse Soectra Ductility is defined as the maximum displacement calculated from a nonlinear analysis divided by the yield displacement.
The nonlinear response shall be estimated using ductility demand response spectra.
These demand response I
spectra may be generated for the applicable range of frequency ratios and l
force to resistance ratios by performing nonlinear dynamic analysis of simple and generic systems subjected to dynamic harmonic loading.
l
. E
B.
Determine the Frequency Ratio (f /f )
g s fo is the lowest frequency of the piping in the vicinity of the support
~
uhder investigation, and fs is the frequency of the support on which the l
piping is supported.
C.
DeterminetheForcetoResistanceRatio(F/RQ F is the inertia portion of the total load on the support and Rm is the support capacity.
The ratio of F to Rm is calculated using the following equation:
H N
E_
E_
+
x
+
Y
=
R, P
H,p H
y yp t2here Seismic load and coments acting on the support P, H, H
=
x Y
of interest Plastic moment capacities of the steel structure H,p, Hyp Yield load of the steel structure P).
D.
Obtain the Ductility Demand (u) i l
The ductility demand (u) shall be obtained from the ductility demand response l
spectra calculated previously, interpolated linearly if necessary.
If the l
obtained ductility demand is less than or equal to 3, the support member is acceptable.
4.2.4.2 Nonlinear Piping Analysis A.
Stress-Strain Correlation The allowable strain criteria discussed in Subsection 3.1.1.3 are acceptable for use with the response spectra and equivalent static coefficient methods discussed in Subsections 4.2.1 and 4.2.2.
.~
l P
- l
l
(
B.
Nonlinear Time History Analysis Method The nonlinear time history analysis shall account for nonlinearities in the piping system due to material nonlinearities of piping, pipe supports or support structures.
Input time history motions shall be taken from e
appropriate locations of the structural analysis models.
The dampthg used in the nonlinear analysis shall be Rayleigh type damping.
The hysteretic behavior due to material yielding shall also be factored into the evaluation.
l l
l l
l l
l l
l l
l l
E l
l l
1
TABLE 4.2-1 DETERMINATION OF PARAMETERS FOR THE EQUIVALENT STATIC COEFFICIENT METHOD SYSTEM FUNDAMENTAL RESPONSE SPECTRUM EQUIVALENT STATIC NATURAL FREQUENCY [a]
ACCELERATICN [b]
EFFICIENT (f)
(S )
(K)
I I
S rigid a
rigid IA Ipeak < I < I a
rigid f
S 1'
IIIpeak apeak Unknown S
1.5 ag Notes:
[a]
f Fundamental natural frequency of system I rigid Cut-off frequency of response spectrum or 33 Hz, whichever is less fpeak Frequency of response spectrum peak
[b]
S Spectral acceleration at systet:# fundamental a f natural frequency S
Spectral acceleration above cut-off frequency a
l rigid S
Peak spectral acceleration a
peak l
Y __
4.3 Electrical Raceways This section provides details of the method for analysis of electrical raceways and describes the load combination procedures to be used in the evaluation of electrical raceway supports. The seismic evaluation of raceways for support qualification may be performed using either equivalent static or response spectra methods.
4.3.1 Equivalent Static Method N
Seismic loads on electrical raceways shall be evaluated by the equivalent static analysis method whereby a single "equivalent" static coefficient is selected and used to compute support loads by static analysis in accordance eith the procedure outlined below.
A.
Mass Distribution The mass to be considered for all frequency and loading determinations shall include all permanent dead loads. This includes the mass of the cable tray or conduit, supports, and any other permanently attached components.
The tributary length of the cable tray or conduit will be based on the system l
configuration, with consideration of the influence of support stiffness.
~
1 l
B.
Encuency Calculations In general, the fundamental frequency of the raceway system must te calculated in order to obtain its acceleration response.
However, if the design margi.1 of the support is expected to be large or the system or support configuration is complex, the fundamental frequency need not be calculated.
In that case, the peak acceleration of the floor response spectrum shall be used as the acceleration response of the system.
If the fundamental frequency of the raceway / support system is calculated, then l
the acceleration corresponding to the fundamental frequency shall be used as the accele.Clon response of the system, if the system frequency is greater than the frequency corresponding to the peak of the response spectrum.
Otherwise, the peak acceleration shall be used as the acceleration response of the system.
In order to simplify this calculation, the frequencies of the cable tray or conduit and supports may be determined separately with the system frequency estimated using the following method:
2 jj7}2 1/f
. jjf 2
.<h e re,
f Frequency of raceway system f;
Frequency of support including the contributory mass of the the cable tray or isnduit f2 Frequency of cable tray or conduit spanning between supports, assuming the supports are rigid l
l 50
C.
Damoina The acceleration response of the raceway system shall be determined from the acceleration responte spectrum for the appropriate building floor eievation and direction of loading, at the following damping levels:
Ee-ent of Critical Damoina OBE SSE Conduits 4%
7%
Cable Trays 10%
15%
0.
Seismic Desian loads Seismic loads on supports are generally calculated by multiplying the total i
tributary mass of the raceway times the acceleration response and an equivalent static coefficient (defined below). This is done separately for each of the three orthogonal directions.
l l
For multiple-tiered supports, advantage may be taken for trays or conduits that will not oscillate in phase. Cable trays or conduits whose frequencies are spaced apart by more than 10% may be assumed to vibrate out of phase and thus the SRSS method may be used to combine the support loads.
Cable trays or l
conduits whose frequencies are spaced within 10% are considered to be moving in phase, therefore absolute summation must be used to combine the support loads.
This procedure is only valid for frcquencies below the floor cut-off frequency or 33 Hz, whichever is less.
For frequencies above the cut-off freqLency or 33 Hz, absolute summation shall be used.
An equivalent static coefficient (K) of 1.0 shall be used if the fundamental system frequency is greater than or equal to 33 Hz or the rigid cut-off frequency of the appropriate floor response spectrum, whichever is less.
If the fundamental frequency is less than 33 Hz or the right cut-off frequency thichever is less, or if the fundamental frequency is not calculated, then K shall be taken to be 1.5, unless a lower value is justified by a rigorous analysis of the contribution of higher modes.
The seismic load in each direction of loading, V, shall be calculated from:
KHSa U
Seismic system response where U
=
Equivalent static coefficient as given above K
Effective mass as defined above H
Sa - Response spectrum acceleration Yable 4.2-1 summarizes the values of K and Sa which shall be used for various calculated frequencies..
E.
Load Combination The seismic loads acting on a support shall be calculated separately for each of three orthogonal directions using the above procedure.
The total seismic response of any particular support component in any direction may then be calculated by using the SRSS method to combine the directional responses due to each of the three seismic load inputs.
The response due to gravity shall be added to the total seismic re:ponse by absolute summation.
4.3.2 Response Spectra Method The response spectra method shall be used by modeling the raceway and supports together as one system model.
The mass and damping values to be considered are those indicated in Section 4.3.1.
Detciled representations of supports may be included in the system model.
Alternatively, the supports may be separately evaluated for equivalent stiffness modeled in the analysis.
The response spectra analysis shall be performed using the enveloped response spectra method that is discussed in detail for piping in Section 4.2.1.
4.4 HVAC i
In general, simple beam or frame equations can be used to determine load and stress levels in the ducts, connections, and supports for other than seismic type loading.
For seismic loading, one of the methods described below shall be used. The seismic evaluation of the HVAC ducts and supports may be performed using either equivalent static or response spectra sethods.
r 4.4.1 Equivalent Static Method Equivalent static scismic loads shall be calculated in accordance with the procedure outlined below.
The loads shall then be combined with the other design loads as defined in the appropriate design specification.
A.
Mass Distribution The mass to be considered for all frequency and loading determinations shall l
include all permanent dead loads.
This includes the self weight of ducts, i
compar. ion angles duct stiffeners, support steel, insulation, and any other l
permanently attached components.
B.
Freauency Calculations When no frequency calculations are performed, the system shall be evaluated using the peak acceleration from the appropriate response spectrum.
Where frequency calculations are performed, then the frequency in each of the three orthogonal directions shall be determined.
The response of both the ducts and supports shall be considered in this evaluation.
F equency calculations shall be in accordance with the methods given for electrical raceways in Subsection 4.3.1.
C.
Damoing Damping values of 4% and 7% for OBE and SSE, respectively, shall be used for cold-formed ducts for determining the seismic design loads.
For pipe section ducts, the piping damping values indicated in Section 4.2 shall be used.
Higher damping values may be used if justification is y ovided.
D.
Seismic Desian loadi The seismic desigo load shall be calculated based on the frequency calculation indicated above with acceleration and equivalent static coefficient (K) solected in accordance with table 4.2-1.
The seismic design load. U, for each direction of loading shall be calculated with the equation given for electrical raceways in Subsection 4.3.1.
E.
Load _ Combination i
The seismic loads acting on a duct support shall be calculated separately for each of three orthogonal directions using the above procedure.
The total seismic response of any particular support component in any direction may then be calculated by using the SRSS method to combine the directional response due to each of the three seismic load inputs.
w-The response due to gravity shall be added to the total seismic response by absolute summuation.
4.4.2 Response Spectra Method
(.
The response spectra method shall be used by modeling the ducts and supports together as one system model.
The mass and damping values to be considered are those indicated in Subsection 4.4.1.
f1 Detailed representations of supports may be included in the system model.
Alternatively, the.upports may be separately evaluated far equivalent stiffness nodeled in the analysis.
,g*
l T5e response spectra analysis shall 6.e performed using the envelope responst igectra method that is discussed in detail for pipir.; in Subsection 4.2.i.
l i
i ci
' %g c
'I 2) e -
e e
og n
W 4
=
t
- J
4 a
5,0 REFERENCES (1) American Society of Mechanical Engineers, Boiler & Pressure Vessel l
Code (ASME B & PV Code)Section III, 1980 Edition with Addenda l
through Summer 1981.
[2] American Iron and Steel Institute (AISI), "Cold-Formed Steel Design Manual," 1986 Edition.
(3) NUREG-1061 Volume 2, Report of the U.S. NRC Piping Review Committee:
"Evaluation of Seismic Designs - A Review of Seismic Design Requirements for Nuclear Power Plant Piping," April 1985.
(4) NUREG-1061 Volume 4, Report of the U.S. NRC Piping Review Committee:
"Evaluation of Other Dynamic Loads and Load Combinations " December 1984.
[5] Helding Research Council (HRC) Bulletin No. 107, "Local Stresses in Spherical and Cylindrical Shells due to External Loading," March 1979 Revision.
[6] Welding Research Council (HRC) Bulletin No. 256, "Review of Data Relevant to the Design of Tubular Joints for Use in Fixed Offshore Platforms," January 1980.
[7] Helding Research Council (HRC) Bulletin No. 297 "Local Stresses in Cylindrical Shells Due to External Loading on Nozzles - Supplement to HRC Bulletin No.107," August 1984.
[8] Docket No. 50285, Fort Calhoun Updated Safety Analysis Report (USAR), Revision 7/87.
[9]
Institute of Electrical and Electronics Engineers (IEEE), Standard 344-1987, "!EEE Recommended Practices for Seismic Qualification of Class IE Equipment for Nuclear Power Generating Stations."
(10] EPRI Report No. NP-5228, "Seismic Verification of Nuclear Plant Equipment Anchorage " UR$/Blume, May 1987.
[11] NUREG-1061, Volume 3, Report of the U.S. NRC Piping Review Committee:
"Evaluation of Potential for Pipe Breaks," November 1984.
[12] ACI Standard 349-80, "Code Requirements for Nuclear Safety Related Structures".
[13) NUREG-0800, U.S. NRC Standard Review Plan 3.6.1, "Plant Design for Protection Against Postulated Piping Failures in Fluid Systems Outside Containment," Revision 1-July 1981.
l 55-m
=
(14] U.S. NRC Generic Letter 87-11. "Relaxation in Arbitrary Intermediate Pipe Rupture Requirements," dated June 19, 1987.
[15] EQE Incorporated, "The Performance of Cable Tray and Conduit Systems in Actual and Simulated Seismic Motion," Draft B, November 1986.
1 (16] P-H Industries Publication No. 569A, Cable Trav Systems, (17] Hilson, E.L., Der Kiureghian, A., Bayo, E.P., "A Replacement for the SRSS Method in Seismic Analysis," Earthquake Engineering and Strcctural Dynamics, Volume 9, 1981.
[18] NUREG-484, "Methodology for Combining Dynamic Responses,"
Revision 1, dated April, 1980.
[19) A. Asfura, "A New Combination Rule for Seismic Analysis of Piping Systems," Proceedings of the 1985 Pressure Vessels and Piping Conference, Vol. 98-3 June 1985, New Orleans, Louisiana.
[20] Electric Power Research Institute, "Seismic Hazard Methodology for the Central and Eastern United States," Volumes 1-10, Publication No. EPRI NP-4726, July 1986.
[21] Chen C., "Definition of Stistically Independent Time Histories,"
Journal of the Structural Division, ASCE February 1975.
[22) NUREG-0800, U.S. NRC Standard Review Plan 3.7.1, "Seismic Design J
Parameters," Revision 1 - July 1981.
I L
,