Regulatory Guide 1.124: Difference between revisions

From kanterella
Jump to navigation Jump to search
(Created page by program invented by StriderTol)
(Created page by program invented by StriderTol)
Line 1: Line 1:
{{Adams
{{Adams
| number = ML13141A666
| number = ML003739380
| issue date = 07/08/2013
| issue date = 01/31/1978
| title = Service Limits and Loading Combinations for Class 1 Linear-Type Supports
| title = Service Limits & Loading Combinations for Class 1 Linear-Type Component Supports
| author name =  
| author name =  
| author affiliation = NRC/RES
| author affiliation = NRC/RES
Line 9: Line 9:
| docket =  
| docket =  
| license number =  
| license number =  
| contact person = Rodriguez-Luccioni H L
| contact person =  
| document report number = RG 1.124, Rev. 3
| document report number = RG-1.124 Rev 1
| package number = ML13141A655
| document type = Regulatory Guide
| document type = Regulatory Guide
| page count = 11
| page count = 6
}}
}}
{{#Wiki_filter:Written suggestions regarding this guide or development of new guides may be submitted through the NRC's public Web site under the Regulatory Guides document collection of the NRC Library at http://www.nrc.gov/reading-rm/doc-collections/reg-guides/contactus.html.  Electronic copies of this regulatory guide, previous versions of this guide, and other recently issued guides are available through the NRC's public Web site under the Regulatory Guides document collection of the NRC Library at http://www.nrc.gov/reading-rm/doc-collections/.  The regulatory guide is also available through the NRC's Agencywide Documents Access and Management System (ADAMS) at http://www.nrc.gov/reading-rm/adams.html, under ADAMS Accession No. ML13141A666.
{{#Wiki_filter:U.S. NUCLEAR REGULATORY
COMMISSION
Revision I January 1978 REGULATORY
GUIDE OFFICE OF STANDARDS
DEVELOPMENT
REGULATORY
GUIDE 1.124 SERVICE LIMITS AND LOADING COMBINATIONS
FOR CLASS 1 LINEAR-TYPE
COMPONENT
SUPPORTS


U.S. NUCLEAR REGULATORY COMMISSIONJuly 2013Revision 3 REGULATORY GUIDE  OFFICE OF NUCLEAR REGULATORY RESEARCH
==A. INTRODUCTION==
  REGULATORY GUIDE 1.124 SERVICE LIMITS AND LOADING COMBINATIONS FOR
General Design Criterion
CLASS 1 LINEAR-TYPE SUPPORTS
2, "Design Bases for Protection Against Natural Phenomena," of Appen dix A, "General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50, "Licensing of Produc tion and Utilization Facilities," requires that the de sign bases for structures, systems, and components important to safety reflect appropriate combinations of the effects of normal and accident conditions with the effects of natural phenomena such as earthquakes.


==A. INTRODUCTION==
The failure of members designed to support safety related components could jeopardize the ability of the supported component to perform its safety function.
Purpose This regulatory guide delineates levels of service limits and appropriate combinations of loadings associated with normal operation, postulated accidents, and specified seismic events for the design of Class 1 linear-type component and piping supports, as defined in Subsection NF of the American Society of Mechanical Engineers (ASME) Boiler and Pressu re Vessel Code (BPVC), Section III, "Rules for Construction of Nuclear Power Plant Components" (Ref. 1), that the staff of the U.S. Nuclear Regulatory Commission (NRC) considers acceptable. This guide applies to light-water-cooled reactors.
 
SThis guide delineates acceptable levels of service limits and appropriate combinations'
of loadings as sociated with normal operation, postulated accidents, and specified seismic events for the design of Class 1 linear-type component supports as defined in Subsec tion NF of Section III of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. This guide applies to light-water-cooled reactors.


Applicable Rules and Regulations General Design Criterion 2, "Design Bases for Protection against Natural Phenomena," of Appendix A, "General Design Criteria for Nuclear Power Plants," to Title 10 of the Code of Federal Regulations (10 CFR) Part 50, "Domestic Licensing of Production and Utilization Facilities" (Ref. 2), requires that the design bases for structures, systems, and components important to safety reflect appropriate combinations of the effects of normal and accident conditions with the effects of natural phenomena such as earthquakes.  The failure of members designed to support safety-related components and piping could jeopardize the ability of the supported component or piping to perform its safety function.  This is also applicable under 10 CFR Part 52, "Licenses, Certifications, and Approvals for Nuclear Power Plants" (Reg. 3) Purpose of Regulatory Guides The NRC issues regulatory guides to describe methods to the public that the staff considers acceptable for use in implementing specific parts of the agency's regulations, to explain techniques that the staff uses in evaluating specific problems or postulated accidents, and to provide guidance to applicants.  Regulatory guides are not substitutes for regulations and compliance with them is not Rev. 3 of RG 1.124, Page 2 required.  Methods and solutions that differ from those set forth in regulatory guides will be deemed acceptable if they provide a basis fo r the findings required for the issuance or continuance of a permit or license by the Commission. Paperwork Reduction Act This regulatory guide contains information collections that are covered by the requirements of 10 CFR Part 50 and 10 CFR Part 52 that the Office of Management and Budget (OMB) approved under OMB control number 3150-0011 and 3150-0151, respectively.  The NRC may neither conduct nor sponsor, and a person is not required to respond to, an information collection request or requirement unless the requesting document displays a currently valid OMB control number.
The Advisory Committee on Reactor Safeguards has been consulted concerning this guide and has concurred in the regulatory position.


==B. DISCUSSION==
==B. DISCUSSION==
Reason for Revision Revision 3 of RG 1.124 updates the NRC's approval of the ASME Boiler and Pressure Vessel Code (ASME B&PV Code), Section III, Division 1, 2007 Edition through the 2008 Addenda, as one acceptable means for delineating levels of service limits and appropriate combinations of loadings associated with normal operation, postulated accidents, and specified seismic events for the design of Class 1 linear-type component and piping supports.  Revision 2 of RG 1.124 approved the 2001 Edition through the 2003 Addenda of the ASME B&PV Code.  None of the changes from the 2001 Edition through the 2003 Addenda, to the 2007 Edition through the 2008 Addenda, were in the areas covered by RG 1.124.  In addition, Revision 3 of RG 1.124 includes editorial changes to improve clarity and provide a new standardized format for regulatory guides.
Load-bearing members classified as component supports are essential to the safety of nuclear power plants since they retain components in place during the loadings associated with normal and upset plant conditions under the stress of specified seismic events, thereby permitting system components to function properly.
 
They also prevent excessive com ponent movement during the loadings associated with emergency and faulted plant conditions combined
* Lines indicate substantive change from previous issue.with the specified seismic event, thus helping to mitigate the consequences of system damage. Com ponent supports are deformation sensitive because large deformations in them may significantly change the stress distribution in the support system and its supported components.
 
In order to provide uniform requirements for con struction, the component supports, should, as a minimum, have the same ASME Boiler and Pressure Vessel Code classification as that of the supported components.
 
This guide delineates levels of service limits and loading combinations, in addition to supplementary criteria, for ASME Class 1 linear-type component supports as defined by NF-1213 of Sec tion III. Snubbers are not addressed in this guideSubsection NF and Appendix XVII of Section III permit the use of four methods for the design of Class I linear-type component supports:
linear elastic anal ysis, load rating, experimental stress analysis, and limit analysis.
 
For each method, the ASME Code de lineates allowable stress or loading limits for various Code levels of service limits as defined by NF-3113 of Section III so that these limits can be used in con junction with the resultant loadings or stresses from the appropriate plant conditions.
 
Since the Code does not specify loading combinations, guidance is re quired to provide a consistent basis for the design of component supports.
 
Component supports considered in this guide are located within Seismic Category I structures and are therefore protected against loadings from natural phenomena or man-made hazards other than the spec ified seismic events. Thus only the specified seismic events need to be considered in combination with the loadings associated with plant conditions to develop appropriate loading combinations.
 
Loadings caused USNRC REGULATORY
GUIDES Comments should be sent to the Secretdry of the Commission, US. Nuclear Regu Regulatory Guides are issued to describe and make available to the public methods latory Commission.


Background Load-bearing members classified as component and piping supports are essential to the safety of nuclear power plants because they hold components and piping in place during the loadings associated with normal and upset plant conditions under the stress of specified seismic events, thereby permitting system components and piping to function properlyLoad-bearing members also prevent excessive movement of components and piping during the loadings associated with emergency and faulted plant conditions combined with the specified seismic event, thus helping to mitigate the consequences of system damage.  Component and piping supports ar e deformation-sensitive because large deformations can significantly change the stress distribution in the support system and its supported components and piping. To provide uniform requirements for construction, component and piping supports should, as a minimum, have the same ASME Code classification as that of the supported components and piping.  This guide delineates levels of service limits and loading combinations, in addition to supplementary criteria, for ASME Class 1 linear-type component and piping supports, as defined by NF-1213 of Section III.  This guide does not address snubbers. Subsection NF of Section III permits the use of four methods for the design of Class 1 linear-type component and piping supports:  (1) linear elastic analysis, (2) load rating, (3) experimental stress analysis, and (4) limit analysis.  For each method, the ASME Code delineates allowable stress or loading limits for various code levels of service limits as defined by NF-3113 of Section III, so that these limits can be used in conjunction with the resultant loadings or stresses from the appropriate plant conditions.  Because the ASME Code does not specify loading combinations, guidance is required to provide a consistent basis for the design of supports.
WashingtonC
D.C. 20555, Attention:
Docketing and Servic Reguatoy Gide ar isued o dscrbe nd akeavalabl tothepubic t~t~dt Branchacceptable to the NRC staff of implementing specific parts of the Commission's regulations, to delineate techniques used by the staff in evaluating specific problems The guides are issued in the following ten broad divisions or postulated accidents, or to provide guidance to applicants.


Rev. 3 of RG 1.124, Page 3 Component and piping supports considered in this guide are located within seismic Category I structures and, therefore, are assumed to be protected against loadings from natural phenomena or manmade hazards other than the specified seismic events.  Thus, only the specified seismic events need to be considered in combination with the loadings associated with plant conditions to develop appropriate loading combinations.  Loadings caused by any natural phenomena other than seismic events should be should be considered on a case-by-case basis.
Regulatory Guides are not substitutes for regulations, and compliance with them is not required.


1. Design by Linear Elastic Analysis a. S y and S u at Temperature Tables U and Y-1 in Subpart 1 of Part D of Section II and Tables 3, 4, and 5 in the latest accepted versions 1 of ASME Code Cases N-71, "Additional Materials for Subsection NF, Class 1,2,3, and MC Component supports Fabricated by Welding, Section III, Division 1," and N-249, "Additional Materials for Subsection NF, Class 1,2,3, and MC Component Supports Fabricated without Welding, Section III, Division 1," give the relevant material properties when the linear elastic analysis method is used to design Class 1 linear-type component and piping supports.  These tables list values for the minimum yield strength S
1. Power Reactors 6. Products Methods and solutions different from those set out in the guides will be accept- 2. Research and Test Reactors 7. Transportation able If they provide a basis for the findings requisite to the issuance or continuance
y and the ultimate tensile strength S
3. Fuels and Materials Facilities
u. At room temperature, S
8. Occupational Health of a permit or license by the Commission.
y varies from 62 percent to 93 percent of S
u for support materials. Levels of service limits that are derived from either material property alone might be insufficient to provide a consistent safety margin.  Section III recognizes this issue in NF-3322.1(a), which defines the allowable stress in tension on a net section as the lesser of two values, 0.6S
y or 0.5S u. Although NF-3322.1(a) specifies allowable tensile stress in terms of both S
y and S u , the rest of NF-3320 notes other allowable service limits in terms of S
y only.  This does not maintain a consistent design margin for those service limits related only to material properties.  Modifications similar to NF-3322.1(a) should be employed for all those service limits.


b. Allowable Increase of Service Limits Although NF-3321.1(a) and F-1334 of Section III of the ASME Code permit the increase of allowable stresses under various loading conditions, NF-3321.1(b) limits th e increase to less than or equal to two-thirds of the critical buckling stress for compression and compression flange members.  NF-3322.1(c) of Section III derives critical buckling stresses with normal design margins.  Because buckling prevents "shakedown" in the load-bearing member, NF-3322.1(c) must be controlling.  Also, buckling is the result of the interaction of the geometry of the load-bearing member and its material properties (i.e., elastic modulus E and minimum yield strength S
4. Environmental andSiting
y).  Because both of these material properties change with temperature, the critical buckling stresses should use the values of E and S
9. Antitrust Review 5. Materials and Plant Protection
y of the support material at temperature. Tensile and shear stress limits and their nonlinear interaction are used to derive allowable service limits for bolted connections, which also change with the size of the bolt.  For this reason, the increases permitted by NF-3321.1(a) and F-1334 of Section III do not directly apply to allowable tensile stresses and allowable shear stresses for bo lts and bolted connections.  As speci fied in F-1335 of Section III, the allowable increase in tensile stress for bolts should not exceed the lesser value of 0.70 S
10. General Comments and suggestions for improvements in these guides are encouraged at all Requests for tingle copies of issued guides (which may be reproduced)  
u or S y , at                                                     
or for place t imes, and guides will be revised, as appropriate, to accommodate comments and ment on an automatic distribution list for single copies of future guides in specific to reflect new information or experience.
1  Regulatory Guide 1.84, "Design, Fabrication, and Materials Code Case Acceptability, ASME Section III," provides guidance for the acceptability of ASME Section III Code Cases and their revisions, including Code Cases N-71 and N-249.  Code Cases identified as "Conditionally Acceptable Section III Code Cases" are acceptable, provided that they are used with the identified limitations or modifications.


Rev. 3 of RG 1.124, Page 4 temperature, and the allowable increase in shear stress for bolts should not exceed the lesser value of
This guide was revised as a result of divisions should be made in writing to the US. Nuclear Regulatory Commission, substantive comments received from the public and additional staff review. Washington, D.C. 20555, Attention:  
0.42 S u or 0.6 S y, at temperature. For the linear elastic analysis method, F-1334 permits an increase of tension limits for the level D service limits by a variable factor that is:  
Director, Division of Document Control.I I
* the lesser of 2 or 1.167S
I I by natural phenomena other than seismic events, when they exist, should be considered on a case-by case basis. 1. Design by Linear Elastic Analysis a. Su at Temperature.
u/S y if S u is greater than 1.2S
y, or
* 1.4 if S u if less than 1.2S
y.  Depending on whether the section considered is a net section at pinholes in eyebars, pin-connected plates, or built-up structural members, F
t may assume the lesser value of 0.45S
y or 0.375S
u (as recommended by this guide for a net section of pinholes, for example) or the lesser value of 0.6S
y or 0.5S u (for a net section without pinholes, for example).
2. Design by Load Rating NF-3380 of Section III specifies the qualification of linear-type component and piping supports to service level A, B, and C limits, using load-rating criteria. F-1334.8 specifies the qualification of linear-type supports to service level D limits using load rating criteria.  This guide provides additional guidance for the determination of the service level D load rating.


3. Design by Experimental Stress Analysis Although II-1430 in Appendix II to Section III defines the test collapse load for the experimental stress analysis method, the various levels of service limits for experimental stress analysis are not delineated.  The method described in this guide remedies this deficiency.
When the linear elastic analysis method is used to design Class 1 linear-type component supports, material properties are given by Tables 1-2.1, 1-2.2, 1-13.1, and 1-13.3 in Appendix I of Section III and Tables 3 and 4 in the latest ac cepted version 1 of Code Case 1644. These tables list values for the minimum yield strength S, at various temperatures but only room temperature values for the ultimate tensile strength S.. At room temperature, S, varies from 50% to 87% of Su for component sup port materials.


4. Large Deformation The design of component and piping supports is an integral part of the design of the system and its components and piping.  A complete and consistent design is possible only when the interaction between the system, components and piping, and suppor t is properly considered. When all three are evaluated on an elastic basis, the interaction is usually valid because individual deformations are small.  However, if the design process uses plastic analysis methods, large deformations may occur that would result in substantially different stress distributions. When component and piping suppor ts are designed for loadings asso ciated with the faulted plant conditions, Appendix F to Section III of the ASME Code permits the use of plastic analysis methods in certain acceptable combinations for all three elements.  The selection of these acceptable combinations assumes that supports are more deformation-sensitive (i.e., their deformation, in general, will have a large effect on the stress distribution in the system and its components and piping).  Because large deformations always affect the stress distribution, care should be exercised even when using the plastic analysis method in the methodology combination approved in Appendix F.  This is especially important for identifying buckling or instability problems when the change of geometry should be considered to avoid erroneous results. 5. Function of Supported System In selecting the level of service limits for different loading combinations, the decision must take into account the function of the supported system. To ensure that systems will operate properly regardless of plant condition if their normal function is to prevent or mitigate the consequences of events Rev. 3 of RG 1.124, Page 5 associated with an emergency or faulted plant condition (e.g., the function of the emergency core cooling system (ECCS) during faulted plant conditions, it is appropriate to use the level A or B service limits specified in Subsection NF of the ASME Code Section III (or other justifiable limits provided by the code). Because NF-3320 derived all equations from American Institute of Steel Construction (AISC) rules and many AISC compression equations have bu ilt-in constants based on mechanical properties of steel at room temperature, it would be imprudent to use these equations indiscriminately for all NF
Levels of service limits derived from either mate rial property alone may not be sufficient to provide a consistent safety margin. This is recognized by Sec tion III, since XVII-2211(a)  
sections and the latest accepted version of ASME Code Cases N-71 and N-249 involving materials at all temperatures.  For materials other than steel and working temperatures substantially different from room temperature, these equations should be rederived with the appropriate material properties.
of Section III defines the allowable stress in tension on a net section as the smaller value of 0.6 S, and 0.5Su. To alleviate the lack of defined values of Su at temperatures above room temperature and to provide a safe design mar gin, an interim method is given in this guide to obtain values of S, at temperature.


6. Deformation Limits Because component and piping supports are deformation-sensitive load-bearing elements, satisfying the service limits of Section III will not automatically ensure their proper function.  If specified by the code design specification, deformation limits might be the controlling criterion. However, if a particular plant condition does not require the function of a support, the stresses or loads resulting from the loading combinations under that plant condition do not need to satisfy the design limits for the plant
While XVII-221 1(a) specifies allowable tensile stress in terms of both S, and Su, the rest of XVII 2000 specifies other allowable service limits in terms of S, only. This does not maintain a consistent design margin for those service limits related only to mate rial properties.


condition.
Modifications similar to XVII 2211(a) should be employed for all those service limits.  b. Allowable Increase of Service Limits. While NF-3231.1(a), XVII-2110(a), and F-1370(a)
of Sec tion III all permit the increase of allowable stresses under various loading conditions, XVII-21 10(b) lim its the increase so that two-thirds of the critical buckl ing stress for compression and compression flange members is not exceeded, and the increase allowed by NF-323 1. 1(a) is for stress range. Critical buckling stresses with normal design. margins are derived in XVII-2200
ofSection HII. Since buckling prevents "shakedown" in the load-bearing member, XVII 2110(b) must be regarded as controlling.


7. Definitions Critical buckling strength. The strength at which lateral displacements start to develop simultaneously with in-plane or axial deformation.   Design condition.  The loading condition defined by NF-3112 of Section III of the ASME Boiler and Pressure Vessel Code.
Also, buckl ing is the result of the interaction of the configuration of the load-bearing member and its material prop erties (i.e., elastic modulus E and minimum yield strength S,). Because both of these material prop erties change with temperature, the critical buckling ' Regulatory Guide 1.85, "Code Case Acceptability-ASME
Sec tion III Materials," provides guidance for the acceptability of ASME Section III Code Cases and their revisions, including Code Case 1644. Supplementary provisions for the use of specific code cases and their revisions may also be provided and should be con sidered when applicable.


Emergency plant conditions.  Those operating conditions that have a low probability of occurrence.  Faulted plant conditions.  Those operating conditions associated with postulated events of extremely low probability.  Levels of service limits.  Four levels of service limits-A, B, C, and D-defined by Section III of the ASME Boiler and Pressure Vessel Code for the design of loadings associated with different plant conditions for components and piping and component and piping supports in nuclear power plants.  Operating-basis earthquake.  Seismic event defined in Appendix A to 10 CFR Part 100, "Reactor Site Criteria."  Normal plant conditions.  Those operating conditions that occur in the course of system startup, operation, hot standby, refueling, and shutdown, with the exception of upset, emergency, or faulted plant conditions.  Plant conditions.  Operating conditions of the plant categorized as normal, upset, emergency, and faulted plant conditions.  Safe-shutdown earthquake.  Seismic event defined in Appendix A to 10 CFR Part 100.
*I stresses should be calculated with the values of E and S, of the component support material at temperature.


Rev. 3 of RG 1.124, Page 6 Service limits.  Stress limits for the design of com ponent and piping supports, defined by Subsection NF of Section III of the ASME Boiler and Pressure Vessel Code.
Allowable service limits for bolted connections are derived from tensile and shear stress limits and their nonlinear interaction;
they also change with the size of the bolt. For this reason, the increases permitted by NF-323 1.1, XVII-21 10(a), and F-1370(a)
of Sec tion III are not directly applicable to allowable shear stresses and allowable stresses for bolts and bolted connections.


Specified seismic events.  Operating-basis earthquake and safe-shutdown earthquake, defined above.  System mechanical loadings.  The static and dynamic loadings developed by the system operating parameters-including deadweight, pressure, and other external loadings-and effects resulting from constraints of free-end movements, but excluding effects resulting from thermal and peak stresses generated within the component or piping support.
The increase permitted by NF-3231.1 and F-1370(a)
of Section III for shear stresses or shear stress range should not be more than 1.5 times the level A service limits because of the potential for non-ductile behavior.


Ultimate tensile strength.  Material property based on the engineering stress-strain relationship.
The range of primary plus secondary stresses should be limited to 2S, but not more than Su to en sure shakedown.


Upset Plant ConditionsThose deviations from the normal plant condition that have a high probability of occurrence.
For many allowable stresses above the value of 0.6S,. the increase permitted by NF 3231.1(a)
will be above the value of 2S, and will thus violate the normal shakedown range. A shakedown analysis is necessary to justify the increase of stress above 2S, or Su For the linear elastic analysis method, F-1370(a)
of Section III permits increase of tension limits for the Code level D service limits by a variable factor.  that is the smaller value of 1.2Sy/Ft or 0.7Su/Ft.


Harmonization with International Standards ASME is the leading international developer of codes and standards associated with the art, science, and practice of mechanical engineering. Since the first issuance in 1914 of the Boiler & Pressure Vessel Code, ASME has maintained a commitment to enhance public safety and technological advancement. Pertinent to this regulatory guide, Subsection NF of the ASME Boiler and Pressure Vessel Code, Section III, "Rules for Construction of Nuclear Power Plant Components," contains requirements for the material, design, fabrication, and examination of supports which are intended to conform to the requirements for Classes 1,2,3 and MC construction.  This regulatory guide incorporates similar design and preoperational testing guidelines and it is consistent with the basics safety principles provided in Subsection NF of Section III of the BPVC.
De pending on whether the section considered is a net section at pinholes in eyebars, pin-connected plates, or built-up structural members, Ft may assume the smaller value of 0.45S, or 0.375Su (as recommended by this guide for a net section of pinholes, etc.) or the smaller value of 0.6Sy or 0.5Su (for a net section without pinholes, etc.). Thus greater values of the factor may be obtained for sections at pinholes, which does not account for local stress and is not consistent with NF-323 1. 1 and XVII-21 10(a) of Sec tion III. A procedure to correct this factor is provided in this guide.  2. Design by Load Rating When load-rating methods are used, Subsection NF and Appendix F of Section III do not provide a faulted condition load rating. This guide provides an interim method for the determination of faulted con dition load rating.  3. Design by Experimental Stress Analysis While the collapse load for the experimental stress analysis method is defined by 11-1430 in Appendix II of Section III, the various levels of service limits for experimental stress analysis are not delineated.


Documents Discussed in Staff Regulatory Guidance This regulatory guide endorses the use of one or more codes or standards developed by external organizations, and other third party guidance documents.  These codes, standards and third party guidance documents may contain references to other codes, standards or third party guidance documents ("secondary references").  If a secondary reference has itself been incorporated by reference into NRC regulations as a requirement, then licensees and applicants must comply with that standard as set forth in the regulation.  If the secondary reference has been endorsed in a regulatory guide as an acceptable approach for meeting an NRC requirement, then the standard constitutes a method acceptable to the NRC staff for meeting that regulatory requirement as described in the specific regulatory guide.  If the secondary reference has neither been incorporated by reference into NRC regulations nor endorsed in a regulatory guide, then the secondary reference is neither a legally binding requirement nor a "generic" NRC approval as an acceptable approach for meeting an NRC requirement.  However, licensees and applicants may consider and use the information in the secondary reference, if appropriately justified and consistent with current regulatory practice, consistent with applicable NRC requirements such as 10 CFR 50.59, "Changes, Tests, and Experiments."
This deficiency is remedied by the method described in this guide.  4. Large Deformation The design of component supports is an integral part of the design of the system and its components.


Rev. 3 of RG 1.124, Page 7 C. STAFF REGULATORY GUIDANCE The construction of ASME Code
24-2 I!
2 Class 1 linear-type component and piping supports excluding snubbers, which this guide does not address, should fo llow the rules of Subsection NF of Section III, as supplemented by the stipulations below.
A complete and consistent design is possible only when system/componeqt/component-support interac tion is properly consi'iered.


3 1. The classification of component and piping supports should, as a minimum, be the same as that of the supported components and piping.
When all three are evaluated on an elastic basis, the interaction is usu ally valid because individual deformations are small. However, if plastic analysis methods are employed in the design process, large deformations that would re sult in substantially different stress distributions may occur.  When component supports are designed for load ings associated with the faulted plant conditions, Ap pendix F of Section III permits the use of plastic analysis methods in certain acceptable combinations for all three elements.


2. The ASME Code level A and B service limits for component and piping supports designed by linear elastic analysis, which are related to S
These acceptable combinations are selected on the assumption that component sup ports are more deformation sensitive (i.e., their de formation in general will nave a large effect on the stress distribution iu the system and its components.)
y, should meet the appropriate stress limits of Subsection NF of Section III but should not exceed the limit specified when the value of 5/6 S
Since large deformations always affect the stress dis tribution, care should be exercised even if the plastic analysis method is used in thl. Appendix F-approved methodology combination.
u is substituted for S
y. Examples are shown below in Regulatory Positions 2a, 2b, and 2c:
a. The tensile stress limit F
t for a net section, as specified in NF-3322.1(a)(1) of Section III, should be the lesser of two values, 0.6S
y or 0.5S u, at temperature.  For net sections at pinholes in eyebars, pin-connected plates, or built-up structural members, F
t as specified in NF-3322.1(a)(2) should be the lesser of two values, 0.45S
y or 0.375S
u , at temperature.


b. The shear stress limit F
This is especially impor tant for identifying buckling or instability problems where the change of geometry should be taken into account to avoid erroneous results.
v for a gross section as specified in NF-3322.1(b)(1) of Section III, should be the lesser of two values, 0.4S
y or 0.33S u, at temperature.


c. The bending stress limit F
5. Function of Supported System In selecting the level of service limits for different loading combinations, the function of the supported system must be taken into account. To ensure that systems whose normal function is to prevent or miti gate consequences of events associated with an emer gency or faulted plant condition (e.g., the function of ECCS during faulted plant conditions)  
b resulting from tension and bending in structural members as specified in NF-3320, should be (1) the lesser value of 0.66 S
will operate properly regardless of plant condition, the Code level A or B service limits of Subsection NF (which are identical)
y or 0.55 S
or other justifiable limits provided by the Code should be used. Since Appendix XVII derived all equations from AISC rules and many AISC compression equations have built-in constants based on mechanical prop erties of steel at room temperature, to. use these equa tions indiscriminately for all NF and the latest ac cepted version of Code Case 1644 materials at all temperatures would not be prudent. For materials other than steel and working temperatures substan tially different from room temperature, these equa tions should be rederived with the. appropriate mate rial properties.
u, at temperature, for compact sections, (2) the lesser value of 0.75S
y or 0.63 S
u, at temperature, for doubly symmetrical members with bending about the minor axis, and (3) the lesser value of 0.6


S y or 0.5 S u, at temperature, for box-type flexural members and miscellaneous members. Many of the limits and equations for compression strength specified in NF-3320 have built-in constants based on Young's Modulus of 29,000 Ksi.  For materials with Young's Modulus at working temperatures substantially different from 29,000 Ksi, these constants should be re-derived with the appropriate Young's Modulus unless the conservatism of using these constants as specified is demonstrated.
6. Deformation Limits Since component supports are deformation sensitive load-bearing elements, satisfying the serv ice limits of Section III will not automatically ensure their proper function.


3. Component and piping supports designed by linear elastic analysis may increase their level A or B service limits according to the provisions of NF-3321.1(a) of Section III of the ASME Code.
Deformation limits, if specified by the Code Design Specification, may be the con trolling criterion.


F-1334 permits an increase of level A or B service limits for level D service limits by the lesser factor of 2 or 1.167S
On the other hand, if the function of a component support is not required for a particu-lar plant condition, the stresses or loads resulting from the loading combinations under that plant condi tion do not need to satisfy the design limits for the plant condition.
u/S y if S u > 1.2S y , or 1.4 if S
u  1.2S y , where S y and S u are support material properties at temperature. However, all increases (i.e., those allowed by NF-3321.1(a) and F-1334) should always be subject to the limits in NF-3321.1(b).  Material properties at temperature should be used to calculate the critical buckling strengths defined by NF-3321.1(b).  As specified in F-1335, the allowable increase in tensile stress for bolts should not exceed the lesser value of 0.70 S u or S
y , at temperature, and the allowable increase in shear stress for bolts should not exceed the lesser value of 0.42 S u or 0.6 S
y, at temperatur


====e.     ====
7. Definitions Design Condition.
2  ASME Boiler and Pressure Vessel Code, Section III, Division I, 2007 Edition through the 2008 Addenda.


3  If the function of a component or piping support is not required during a plant condition, satisfaction of the design limits of the support for that plant condition is not needed, provided excessive deflection or failure of the support will not result in the loss of function of any other safety-related system.
The loading condition defined by NF-3112 of Section III of the ASME Boiler and Pressure Vessel Code.  Emergency Plant Condition.


Rev. 3 of RG 1.124, Page 8 If the increased service limit for stress range by NF-3321.1(a) is more than 2S
Those operating con ditions that have a low probability of occurrence.
y or S u , its limit should be the lesser of two values, 2S
y or S u, unless a shakedown analysis justifies it.


4. The limits in Regulatory Positions 4a through 4d should apply to the design of component and piping supports subjected to the combined loadings of system mechanical loadings
Faulted Plant Condition.
4 associated with (1) either the ASME Code design condition or the normal or upset plant conditions and (2) the vibratory motion of the operating-basis earthquake.5,6 a. Supports designed by the linear elastic analysis method should not exceed the stress limits of NF-3320 of Section III and Regulatory Position 2 of this guide.


b. Supports designed by using the load-rating method should not exceed the service level A or service level B load rating of NF-3382 of Section III.
Those operating condi tions associated with postulated events of extremely low probability.


c. The lower bound test collapse load determined by NF-3340 and adjusted according to the provision of NF-3341.1(a) of Section III should not be less than that required to support a factored load equal to 1.7 times those of the service level A and B limits for supports designed by the limit analysis method.
Levels of Service Limits. Four levels, A, B, C, and D, of service limits defined by Section III for the de sign of loadings associated with different plant condi tions for components and component supports in nu clear power plants.  Normal Plant Condition.


d. Supports designed by using the experimental stress analysis method should not exceed the test collapse load determined by II-1400 of Section III divided by 1.7.
Those operating condi tions in the course of system startup, operation, hot standby, refueling, and shutdown other than upset, emergency, or faulted plant conditions.


5. The limits in Regulatory Positions 5a through 5d should apply to the design of component and piping supports subjected to the system mechanical loadings associated with the emergency plant condition, except when the normal function of the supported system is to prevent or mitigate the consequences of events associated with the emergency plant condition (Regulatory Position 7 then applies).5,6 a. Supports designed by using the linear elastic analysis method should not exceed the stress limits of NF-3320 and Regulatory Positions 2 and 3, increased according to the provisions of NF-3321.1(a) of Section III and Regulatory Position 3.
Operating Basis Earthquake (OBE). As defined in Appendix A to 10 CFR Part 100. Plant Conditions.


b. Supports designed by the load-rating method should not exceed the service level C load rating of NF-3382.2 of Section III.
Operating conditions of the plant categorized as normal, upset, emergency, and faulted plant conditions.


c. The lower bound test collapse load determined by NF-3340 adjusted according to the provision of NF-3341.1(a) of Section III should not be less than that required to support a factored load equal to 1.3 times that of the service level C limit for supports designed by the limit analysis metho
Safe Shutdown Earthquake (SSE). As defined in Appendix A to 10 CFR Part 100.  Service Limits. Stress limits for the design of com ponent supports as defined by Subsection NF of Sec tion III. Specified Seismic Events. Operating Basis Earth quake and Safe Shutdown Earthquake.


====d.      ====
System Mechanical Loadings.
System mechanical loadings include all non-self-limiting loadings and the effects resulting from constraints of free-end displacements, but not the effects resulting from thermal or peak stresses generated within the component or piping support. 5  Because component and piping supports are deformation-sensitive in the performance of their service requirements, satisfying these criteria does not ensure that their functional requirements will be fulfilled.  Any deformation limits specified by the design specification may be controlling and should be satisfied.


6  Because the design of component and piping supports is an integral part of the design of the system and the component and piping, the designer should make sure that methods used for the analysis of the system, component and piping, and support are compatible.  The designer of supports should consider large deformations in the system or components and piping.
The static and dynamic loadings that are developed by the system operating parameters, including deadweight, pres sure, and other external loadings, but excluding ef fects resulting from constraints of free-end move ments and thermal and peak stresses.


Rev. 3 of RG 1.124, Page 9 d. Supports designed by using the experimental stress analysis method should not exceed the test collapse load determined by II-1400 of Section III divided by 1.3.
Ultimate Tensile Strength.


6. The limits in Regulatory Positions 6a through 6d should apply to the design of component and piping supports subjected to the combined loadings of (1) the system mechanical loadings associated with the normal plant condition, (2) the vibratory motion of the safe-shutdown earthquake, and (3) the dynamic system loadings associated with the faulted plant condition, except when the normal function of the supported system is to prevent or mitigate the consequences of events associated with the faulted plant condition (Regulatory Position 7 then applies).  
Material property based on engineering stress-strain relationship.
a. Supports designed by using the linear elastic analysis method should not exceed the stress limits of NF-3320 of Section III and Regulatory Position 2 of this guide, increased


according to the provisions of F-1334 of Section III and Regulatory Position 3.
Upset Plant Conditions.


b. Supports designed by using the load-rating method should not exceed the lesser value of TL x 2F all/S u* or TL x 0.7 S
Those deviations from the normal plant condition, that have a high probability of occurrence.
u/S u*, where TL, S
u, and S u* are defined in F-1332.7 of Section III and F
all is the allowable stress value defined in NF-3382.1.


c. Supports designed by the limit analysis method should not exceed the lower bound test collapse load determined by NF-3340, adjusted according to the provision of F-1334.6(a).  
C. REGULATORY
d. Supports designed by using the experimental stress analysis method should not exceed the test collapse load determined by II-1400, adjusted according to the provision of F-1334.6(c).
POSITION ASME Code' Class 1 linear-type component sup American Society of Mechanical Engineers Boiler and Pressure Vessel Code, Section III, Division 1, 1974 Edition, including the 1976 Winter Addenda thereto.1.124-3 I I I I
7. The limits in Regulatory Position 4 or other justifiable limits provided by the ASME Code should apply to the design of component and piping supports in systems whose normal function is to prevent or mitigate the consequences of events associated with an emergency or faulted plant condition. The design specification should define these limits, which are typically stated in the preliminary and final safety analysis reports (PSA
ports excluding snubbers, which are not addressed herein, should be constructed to the rules of Subsec tion NF of Section III as supplemented by the follow ing: s 1. The classification of component supports should, as .a minimum, be the same as that of the supported components.
R, FSAR), so that the function of the supported system will be maintained when it is subjected to the loading combinations described in Regulatory Positions 5 and 6.


==D. IMPLEMENTATION==
2. Values of Su at a temperature t should be esti mated by one of the three following methods on an interim basis until Section III includes such values: a. Method 1. This method applies to component support materials whose values of ultimate strength Su at temperature have been tabulated by their man ufacturers in catalogs or other publications.
The purpose of this section is to provide information on how applicants and licensees
 
7 may use this guide and information regarding the NRC's plans for using this regulatory guide. In addition, it describes how the NRC staff complies with 10 CFR 50.109, "Backfitting" and any applicable finality provisions in 10 CFR Part 52, "Licenses, Certifications, and Approvals for Nuclear Power Plants." Use by Applicants and Licensees Applicants and licensees may voluntarily
Su = Sur S , but not greater than Sur S~ur where Su = ultimate tensile strength at temperature t to be used to determine the service limits Sur = ultimate tensile strength at room temperature tabulated in Section III, Appendix I, or the latest accepted version 1 of Code Case 1644 S'u = ultimate tensile strength at temperature t tabulated by manufacturers in their catalogs or other publications Sur = ultimate tensile strength at room temperature tabulated by manufacturers in the same pub lications.
8use the guidance in this document to demonstrate compliance with the underlying NRC regulations. Methods or solutions that differ from those described                                                     
 
7  In this section, "licensees" refers to licensees of nuclear power plants under 10 CFR Parts 50 and 52; and the term "applicants," refers to applicants for licenses and permits for (or relating to) nuclear power plants under 10 CFR Parts 50 and 52, and applicants for standard design approvals and standard design certifications under 10 CFR Part 52.
b. Method 2. This method applies to component support materials whose values of ultimate tensile strength at temperature have not been tabulated by their manufacturers in any catalog or publication.
 
Sy Su= Sur r ,where Su = ultimate tensile strength at temperature t to be used to determine the service limits Sur = ultimate tensile strength at room temperature tabulated in Section III, Appendix I, or the latest accepted version of Code Case 1644 S, = minimum yield strength at temperature t tabulated in Section III, Appendix I, or the latest accepted version 1 of Code Case 1644 Syr = minimum yield strength at room temper ature, tabulated in Section III, Appendix I, , If the function of a component support is not required during a plant condition, the design limits of the support for that plant con dition need not be satisfied, provided excessive deflection or fail ure of the support will not result in the loss of function of any other safety-related system.I 1.124-4 I or the latest accepted version I of Code Case 1644.  c. Method 3. When the values of allowable stress or stress intensity at temperature for a material are listed in Section III, the ultimate tensile strength at temperature for that material may be approximated by the following expressions:
Su = 4S or Su = 3Sm where Su = ultimate tensile strength at temperature t to be used to determine the service limits Su = listed value of allowable stress at temperature t in Section III.  S.= listed value of allowable stress intensity at temperature t in Section III 3. The Code levels A and B service limits for com ponent supports designed by linear elastic analysis which are related to S, should meet the appropriate stress limits of Appendix XVII of Section III but should not exceed the limit specified when the value of 5/6 Su is substituted for S,. Examples are shown below in a and b.  a. The tensile stress limit Ft for a net section as specified in XVII-221 1(a) of Section III should be the smaller value of 0.6S, or 0.5Su at temperatbre.
 
For net sections at pinholes in eye-bars, pin connected plates, or built-up structural members, Ft as specified in XVII-221 1(b) should be the smaller value of 0.45S, or 0.375Su at temperature.
 
b. The shear stress limit Fv for a gross section as specified in XVII-2212 of Section III should be the smaller value of 0.4S, or 0.33Su at temperature.
 
Many limits and equations for compression strength specified in Sections XVII-2214, XVII 2224, XVII-2225, XVII-2240, and XVII-2260
have built-in constants based on Young's Modulus of 29,000 Ksi. For materials with Young's Modulus at working temperatures substantially different from 29,000 Ksi, these constants should be rederived with the appropriate Young's Modulus unless the conser vatism of using these constants as specified can be demonstrated.
 
4. Component supports designed by linear elastic analysis may increase their level A or B service limits according to the provisions of NF-323 1. 1(a), XVII 2110(a), and F-1370(a)
of Section III. The increase of level A or B service limits provided by NF 3231. 1(a) is for stress range. The increase 'of level A I [I
I or B service limits provided by F-1370(a)
for level D service limits, should be the smaller factor of 2 or 1.167SI/Sy, if S, : 1.2S, or 1.4 if Su -- 1.2Sf, where S, and Su are component-support material properties at temperature.
 
However, all increases
[i.e., those allowed by NF-3231.1(a), XVII-2110(a), and F-1370(a)]
should always be limited by XVII-21 10(b) of Section III. The critical buckling strengths defined by XVII-21 10(b) of Section III should be calculated using material properties at temperature.
 
This in crease of level A or B service limits does not apply to limits for bolted connections.
 
Any increase of limits for shear stresses above 1.5 times the Code level A service limits should be justified.
 
If the increased service limit for stress range by NF-3231.1(a)
is more than 2S, or S., it should be limited to the smaller value of 2S, or S,, unless it can be justified by a shakedown analysis.


8  In this section, "voluntary" and "voluntarily" mean that the licensee is seeking the action of its own accord, without the force of a legally binding requirement or an NRC representation of further licensing or enforcement action.
5. Component supports subjected to the combined loadings of system mechanical loadings associated with (1) either (a) the Code design condition or (b) the normal or upset plant conditions and (2) the vib ratory motion of the OBE should be designed within the following limits: 4,5 a. The stress limits of XVII-2000
of Section III and Regulatory Position 3 of this guide should not be exceeded for component supports designed by the linear elastic analysis method. These stress limits may be. increased according to the provisions of NF-3231.1(a)
of Section III and Regulatory Position 4 of this guide when effects resulting from constraints of free-end displacements are added to the loading combination.


Rev. 3 of RG 1.124, Page 10 in this regulatory guide may be deemed acceptable if they provide sufficient basis and information for the NRC staff to verify that the proposed alternative demonstrates compliance with the appropriate NRC regulationsCurrent licensees may continue to use guidance the NRC found acceptable for complying with the identified regulations as long as their current licensing basis remains unchanged
b. The normal condition load rating or the upset condition load rating of NF-3262.3 of Section III should not be exceeded for component supports de signed by the load-rating methodc. The lower bound collapse load determined by XVII-4200
. Licensees may use the information in this regulatory guide for actions which do not require NRC review and approval such as changes to a facility design under 10 CFR 50.59, "Changes, Tests, and Experiments." Licensees may use the information in this regulatory guide or applicable parts to resolve regulatory or inspection issues. Use by NRC Staff  The NRC staff does not intend or approve any imposition or backfitting of the guidance in this regulatory guide.  The NRC staff does not expect any existing licensee to use or commit to using the guidance in this regulatory guide, unless the licensee makes a change to its licensing basis.  The NRC staff does not expect or plan to request licensees to voluntarily adopt this regulatory guide to resolve a generic regulatory issue.  The NRC staff does not expect or plan to initiate NRC regulatory action that would require the use of this regulatory guide.  Examples of such unplanned NRC regulatory actions include issuance of an order requiring the use of the regulatory guide, requests for information under 10 CFR 50.54(f) as to whether a licensee intends to commit to use of this regulatory guide, generic communication, or promulgation of a rule requiring the use of this regulatory guide without further
adjusted according to the provision of XVII-4 110(a) of Section III should not be exceeded for component supports designed by the limit analysis methodd. The collapse load determined by 11-1400 of 4 S ince component supports are deformation sensitive in the performance of their service requirements, satisfying these criteria does not ensure that their functional requirements will be fulfilled.


backfit consideration. During regulatory discussions on plant specific operational issues, the staff may discuss with licensees various actions consistent with staff positions in this regulatory guide, as one acceptable means of meeting the underlying NRC regulatory requirement.  Such discussions would not ordinarily be considered backfitting even if prior versions of this regulatory guide are part of the licensing basis of the facility.  However, unless this regulatory guide is part of the licensing basis for a facility, the staff may not represent to the licensee that the licensee's failure to comply with the positions in this regulatory guide constitutes a violation. If an existing licensee voluntarily seeks a license amendment or change and (1) the NRC staff's consideration of the request involves a regulatory issue directly relevant to this new or revised regulatory guide and (2) the specific subject matter of this regulatory guide is an essential consideration in the staff's determination of the acceptability of the licensee's request, then the staff may request that the licensee either follow the guidance in this regulatory guide or provide an eq uivalent alternative process that demonstrates compliance with the underlying NRC regulatory requirements. This is not considered backfitting as defined in 10 CFR 50.109(a)(1) or a violation of any of the issue finality provisions in 10 CFR Part 52. Additionally, an existing applicant may be required to comply to new rules, orders, or guidance if 10 CFR 50.109(a)(3) applies. If a licensee believes that the NRC is either using this regulatory guide or requesting or requiring the licensee to implement the methods or processes in this regulatory guide in a manner inconsistent with the discussion in this Implementation section, then the licensee may file a backfit appeal with the NRC in accordance with the guidance in NUREG-1409, "Backfitting Guidelines," (Ref. 4) and the NRC Management Directive 8.4, "Management of Facility-Specific Backfitting and Information Collection" (Ref. 5). 
Any deformation limits specified by the design specification may be controlling and should be satisfied.
Rev. 3 of RG 1.124, Page 11 REFERENCES
9  1. American Society of Mechanical Engineers (ASME), Section III, "Rules for Construction of Nuclear Power Plant Components," ASME Boiler and Pressure Vessel Code, American Society of Mechanical Engineers, New York, NY.


10  2. U.S. Code of Federal Regulations (CFR), Title 10, Energy, Part 50, "Domestic Licensing of Production and Utilization Facilities."
' Since the design of component supports is an integral part of the design of the system and the design of the component, the de signer must make sure that methods used for the analysis of the system, component, and component support are compatible (see Table F-1322.2-1 in Appendix F of Section I1). Large deforma tions in the system or components should be considered in the design of component supports.1.124-5 Section III divided by 1.7 should not be exceeded for component supports designed by the experimental stress analysis method.  6. Component supports subjected to the system mechanical loadings associated with the emergency plant condition should be designed within the follow ing design limits except when the normal function of the supported system is to prevent or mitigate the consequences of events associated with the emer gency plant condition (at which time Regulatory Position 8 applies): 4"'5 a. The stress limits of XVII-2000
of Section M and Regulatory Positions
3 and 4, increased accord ing to the provisions of XVII-21 10(a) of Section m and Regulatory Position 4 of this guide, should not be exceeded for component supports designed by the linear elastic analysis method. b. The emergency condition load rating of NF 3262.3 of Section III should not be exceeded for component supports designed by the load-rating method.  c. The lower bound collapse load determined by XVII-4200
adjusted according to the provision of XVII-4 110(a) of Section III should not be exceeded for component supports designed by the limit analysis method.  d. The collapse load determined by 11-1400 of Section III divided by 1.3 should not be exceeded for component supports designed by the experimental stress analysis method. 7. Component supports subjected to the combined loadings of (1) the system mechanical loadings as sociated with the normal plant condition, (2) the vib ratory motion of the SSE, and (3) the dynamic system loadings associated with the faulted plant condition should be designed within the following limits except when the normal function of the supported system is to prevent or mitigate the consequences of events as sociated with the faulted plant condition (at which time Regulatory Position 8 applies):
a. The stress limits of XVII-2000
of Section m and Regulatory Position 3 of this guide, increased ac cording to the provisions of F-1370(a)
of Section III and Regulatory Position 4 of this guide, should not be exceeded for component supports designed by the linear elastic analysis method.  b. The smaller value of T.L. x 2S/S, or T.L. x 0.7S/Su should not be exceeded, where T.L., S, and .Su are definedl according to NF.3262.1 of Section.


3. U.S. Code of Federal Regulations (CFR), Title 10, Energy, Part 52, "Licenses, Certifications, and Approvals for Nuclear Power Plants."
mI, and Su is the minimum ultimate tensile strength of the material at service temperature for component supports designed by the load-rating method. c. The lower bound collapse load determined by XVII-4200
4. U.S. Nuclear Regulatory Commission (NRC), NUREG-1409, "Backfitting Guidelines," NRC, Washington, DC.
adjusted according to the provision of F-1370(b)  
of Section III should not be exceeded for I.I.


5. NRC, Management Directive 8.4, "Management of Facility-specific Backfitting and Information Collection," NRC, Washington, DC.
component supports designed by the limit analysis method.  d. The collapse load determined by 11-1400 ad justed according to the provision of F-1370(b)
of Section III should not be exceeded for component supports designed by the experimental stress analysis method. 8. Component supports in systems whose normal function i' to prevent or mitigate the consequences of events associated with an emergency or faulted plant condition should be designed within the limits de scribed in Regulatory Position 5 or other justifiable
'limits provided by the Code. These limits should be defined by the Design Specificatioh and stated in the PSAR, such that the function of the supported system will be maintained when they are subjected to the loading combinations described in Regulatory Positions
6 and 7.


9  Publicly available NRC published documents are available electronically through the NRC Library on the NRC's public Web site at
==D. IMPLEMENTATION==
: http://www.nrc.gov/reading-rm/doc-collections/The documents can also be viewed on-line or printed for a fee in the NRC's Public Document Room (PDR) at 11555 Rockville Pike, Rockville, MD; the mailing address is USNRC PDR, Washington, DC 20555; telephone 301-415-4737 or (800) 397-4209; fax (301) 415-3548; and e-mail pdr.resource@nrc.gov.  10 Copies of American Society of Mechanical Engineers (ASME) standards may be purchased from ASME, Two Park Avenue, New  York, New York 10016-5990; Telephone (800) 843-2763.  Purchase information is available through the ASME Web site store at  http://www.asme.org/Codes/Publications/.}}
The purpose of this section is to provide guidance to applicants and licensees regarding the NRC staff's plans for using this regulatory guideExcept in those cases in which the applicant pro poses an acceptable alternative method for complying with the specified portions of the Commission's regu lations, the methocf described herein will be used in the evaluation of submittals for construction permit applications docketed after January 10, 1978. If an applicant wishes to use this regulatory guide in uc veloping submittals for construction permit applica tions docketed on or before January 10, 1978, the pertinent portions of the application will be evaluated'
on the basis of this guide.1.124-6}}


{{RG-Nav}}
{{RG-Nav}}

Revision as of 04:04, 21 September 2018

Service Limits & Loading Combinations for Class 1 Linear-Type Component Supports
ML003739380
Person / Time
Issue date: 01/31/1978
From:
Office of Nuclear Regulatory Research
To:
References
RG-1.124 Rev 1
Download: ML003739380 (6)


U.S. NUCLEAR REGULATORY

COMMISSION

Revision I January 1978 REGULATORY

GUIDE OFFICE OF STANDARDS

DEVELOPMENT

REGULATORY

GUIDE 1.124 SERVICE LIMITS AND LOADING COMBINATIONS

FOR CLASS 1 LINEAR-TYPE

COMPONENT

SUPPORTS

A. INTRODUCTION

General Design Criterion 2, "Design Bases for Protection Against Natural Phenomena," of Appen dix A, "General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50, "Licensing of Produc tion and Utilization Facilities," requires that the de sign bases for structures, systems, and components important to safety reflect appropriate combinations of the effects of normal and accident conditions with the effects of natural phenomena such as earthquakes.

The failure of members designed to support safety related components could jeopardize the ability of the supported component to perform its safety function.

SThis guide delineates acceptable levels of service limits and appropriate combinations'

of loadings as sociated with normal operation, postulated accidents, and specified seismic events for the design of Class 1 linear-type component supports as defined in Subsec tion NF of Section III of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. This guide applies to light-water-cooled reactors.

The Advisory Committee on Reactor Safeguards has been consulted concerning this guide and has concurred in the regulatory position.

B. DISCUSSION

Load-bearing members classified as component supports are essential to the safety of nuclear power plants since they retain components in place during the loadings associated with normal and upset plant conditions under the stress of specified seismic events, thereby permitting system components to function properly.

They also prevent excessive com ponent movement during the loadings associated with emergency and faulted plant conditions combined

  • Lines indicate substantive change from previous issue.with the specified seismic event, thus helping to mitigate the consequences of system damage. Com ponent supports are deformation sensitive because large deformations in them may significantly change the stress distribution in the support system and its supported components.

In order to provide uniform requirements for con struction, the component supports, should, as a minimum, have the same ASME Boiler and Pressure Vessel Code classification as that of the supported components.

This guide delineates levels of service limits and loading combinations, in addition to supplementary criteria, for ASME Class 1 linear-type component supports as defined by NF-1213 of Sec tion III. Snubbers are not addressed in this guide. Subsection NF and Appendix XVII of Section III permit the use of four methods for the design of Class I linear-type component supports:

linear elastic anal ysis, load rating, experimental stress analysis, and limit analysis.

For each method, the ASME Code de lineates allowable stress or loading limits for various Code levels of service limits as defined by NF-3113 of Section III so that these limits can be used in con junction with the resultant loadings or stresses from the appropriate plant conditions.

Since the Code does not specify loading combinations, guidance is re quired to provide a consistent basis for the design of component supports.

Component supports considered in this guide are located within Seismic Category I structures and are therefore protected against loadings from natural phenomena or man-made hazards other than the spec ified seismic events. Thus only the specified seismic events need to be considered in combination with the loadings associated with plant conditions to develop appropriate loading combinations.

Loadings caused USNRC REGULATORY

GUIDES Comments should be sent to the Secretdry of the Commission, US. Nuclear Regu Regulatory Guides are issued to describe and make available to the public methods latory Commission.

WashingtonC

D.C. 20555, Attention:

Docketing and Servic Reguatoy Gide ar isued o dscrbe nd akeavalabl tothepubic t~t~dt Branch. acceptable to the NRC staff of implementing specific parts of the Commission's regulations, to delineate techniques used by the staff in evaluating specific problems The guides are issued in the following ten broad divisions or postulated accidents, or to provide guidance to applicants.

Regulatory Guides are not substitutes for regulations, and compliance with them is not required.

1. Power Reactors 6. Products Methods and solutions different from those set out in the guides will be accept- 2. Research and Test Reactors 7. Transportation able If they provide a basis for the findings requisite to the issuance or continuance

3. Fuels and Materials Facilities

8. Occupational Health of a permit or license by the Commission.

4. Environmental andSiting

9. Antitrust Review 5. Materials and Plant Protection

10. General Comments and suggestions for improvements in these guides are encouraged at all Requests for tingle copies of issued guides (which may be reproduced)

or for place t imes, and guides will be revised, as appropriate, to accommodate comments and ment on an automatic distribution list for single copies of future guides in specific to reflect new information or experience.

This guide was revised as a result of divisions should be made in writing to the US. Nuclear Regulatory Commission, substantive comments received from the public and additional staff review. Washington, D.C. 20555, Attention:

Director, Division of Document Control.I I

I I by natural phenomena other than seismic events, when they exist, should be considered on a case-by case basis. 1. Design by Linear Elastic Analysis a. Su at Temperature.

When the linear elastic analysis method is used to design Class 1 linear-type component supports, material properties are given by Tables 1-2.1, 1-2.2, 1-13.1, and 1-13.3 in Appendix I of Section III and Tables 3 and 4 in the latest ac cepted version 1 of Code Case 1644. These tables list values for the minimum yield strength S, at various temperatures but only room temperature values for the ultimate tensile strength S.. At room temperature, S, varies from 50% to 87% of Su for component sup port materials.

Levels of service limits derived from either mate rial property alone may not be sufficient to provide a consistent safety margin. This is recognized by Sec tion III, since XVII-2211(a)

of Section III defines the allowable stress in tension on a net section as the smaller value of 0.6 S, and 0.5Su. To alleviate the lack of defined values of Su at temperatures above room temperature and to provide a safe design mar gin, an interim method is given in this guide to obtain values of S, at temperature.

While XVII-221 1(a) specifies allowable tensile stress in terms of both S, and Su, the rest of XVII 2000 specifies other allowable service limits in terms of S, only. This does not maintain a consistent design margin for those service limits related only to mate rial properties.

Modifications similar to XVII 2211(a) should be employed for all those service limits. b. Allowable Increase of Service Limits. While NF-3231.1(a), XVII-2110(a), and F-1370(a)

of Sec tion III all permit the increase of allowable stresses under various loading conditions, XVII-21 10(b) lim its the increase so that two-thirds of the critical buckl ing stress for compression and compression flange members is not exceeded, and the increase allowed by NF-323 1. 1(a) is for stress range. Critical buckling stresses with normal design. margins are derived in XVII-2200

ofSection HII. Since buckling prevents "shakedown" in the load-bearing member, XVII 2110(b) must be regarded as controlling.

Also, buckl ing is the result of the interaction of the configuration of the load-bearing member and its material prop erties (i.e., elastic modulus E and minimum yield strength S,). Because both of these material prop erties change with temperature, the critical buckling ' Regulatory Guide 1.85, "Code Case Acceptability-ASME

Sec tion III Materials," provides guidance for the acceptability of ASME Section III Code Cases and their revisions, including Code Case 1644. Supplementary provisions for the use of specific code cases and their revisions may also be provided and should be con sidered when applicable.

  • I stresses should be calculated with the values of E and S, of the component support material at temperature.

Allowable service limits for bolted connections are derived from tensile and shear stress limits and their nonlinear interaction;

they also change with the size of the bolt. For this reason, the increases permitted by NF-323 1.1, XVII-21 10(a), and F-1370(a)

of Sec tion III are not directly applicable to allowable shear stresses and allowable stresses for bolts and bolted connections.

The increase permitted by NF-3231.1 and F-1370(a)

of Section III for shear stresses or shear stress range should not be more than 1.5 times the level A service limits because of the potential for non-ductile behavior.

The range of primary plus secondary stresses should be limited to 2S, but not more than Su to en sure shakedown.

For many allowable stresses above the value of 0.6S,. the increase permitted by NF 3231.1(a)

will be above the value of 2S, and will thus violate the normal shakedown range. A shakedown analysis is necessary to justify the increase of stress above 2S, or Su . For the linear elastic analysis method, F-1370(a)

of Section III permits increase of tension limits for the Code level D service limits by a variable factor. that is the smaller value of 1.2Sy/Ft or 0.7Su/Ft.

De pending on whether the section considered is a net section at pinholes in eyebars, pin-connected plates, or built-up structural members, Ft may assume the smaller value of 0.45S, or 0.375Su (as recommended by this guide for a net section of pinholes, etc.) or the smaller value of 0.6Sy or 0.5Su (for a net section without pinholes, etc.). Thus greater values of the factor may be obtained for sections at pinholes, which does not account for local stress and is not consistent with NF-323 1. 1 and XVII-21 10(a) of Sec tion III. A procedure to correct this factor is provided in this guide. 2. Design by Load Rating When load-rating methods are used, Subsection NF and Appendix F of Section III do not provide a faulted condition load rating. This guide provides an interim method for the determination of faulted con dition load rating. 3. Design by Experimental Stress Analysis While the collapse load for the experimental stress analysis method is defined by 11-1430 in Appendix II of Section III, the various levels of service limits for experimental stress analysis are not delineated.

This deficiency is remedied by the method described in this guide. 4. Large Deformation The design of component supports is an integral part of the design of the system and its components.

24-2 I!

A complete and consistent design is possible only when system/componeqt/component-support interac tion is properly consi'iered.

When all three are evaluated on an elastic basis, the interaction is usu ally valid because individual deformations are small. However, if plastic analysis methods are employed in the design process, large deformations that would re sult in substantially different stress distributions may occur. When component supports are designed for load ings associated with the faulted plant conditions, Ap pendix F of Section III permits the use of plastic analysis methods in certain acceptable combinations for all three elements.

These acceptable combinations are selected on the assumption that component sup ports are more deformation sensitive (i.e., their de formation in general will nave a large effect on the stress distribution iu the system and its components.)

Since large deformations always affect the stress dis tribution, care should be exercised even if the plastic analysis method is used in thl. Appendix F-approved methodology combination.

This is especially impor tant for identifying buckling or instability problems where the change of geometry should be taken into account to avoid erroneous results.

5. Function of Supported System In selecting the level of service limits for different loading combinations, the function of the supported system must be taken into account. To ensure that systems whose normal function is to prevent or miti gate consequences of events associated with an emer gency or faulted plant condition (e.g., the function of ECCS during faulted plant conditions)

will operate properly regardless of plant condition, the Code level A or B service limits of Subsection NF (which are identical)

or other justifiable limits provided by the Code should be used. Since Appendix XVII derived all equations from AISC rules and many AISC compression equations have built-in constants based on mechanical prop erties of steel at room temperature, to. use these equa tions indiscriminately for all NF and the latest ac cepted version of Code Case 1644 materials at all temperatures would not be prudent. For materials other than steel and working temperatures substan tially different from room temperature, these equa tions should be rederived with the. appropriate mate rial properties.

6. Deformation Limits Since component supports are deformation sensitive load-bearing elements, satisfying the serv ice limits of Section III will not automatically ensure their proper function.

Deformation limits, if specified by the Code Design Specification, may be the con trolling criterion.

On the other hand, if the function of a component support is not required for a particu-lar plant condition, the stresses or loads resulting from the loading combinations under that plant condi tion do not need to satisfy the design limits for the plant condition.

7. Definitions Design Condition.

The loading condition defined by NF-3112 of Section III of the ASME Boiler and Pressure Vessel Code. Emergency Plant Condition.

Those operating con ditions that have a low probability of occurrence.

Faulted Plant Condition.

Those operating condi tions associated with postulated events of extremely low probability.

Levels of Service Limits. Four levels, A, B, C, and D, of service limits defined by Section III for the de sign of loadings associated with different plant condi tions for components and component supports in nu clear power plants. Normal Plant Condition.

Those operating condi tions in the course of system startup, operation, hot standby, refueling, and shutdown other than upset, emergency, or faulted plant conditions.

Operating Basis Earthquake (OBE). As defined in Appendix A to 10 CFR Part 100. Plant Conditions.

Operating conditions of the plant categorized as normal, upset, emergency, and faulted plant conditions.

Safe Shutdown Earthquake (SSE). As defined in Appendix A to 10 CFR Part 100. Service Limits. Stress limits for the design of com ponent supports as defined by Subsection NF of Sec tion III. Specified Seismic Events. Operating Basis Earth quake and Safe Shutdown Earthquake.

System Mechanical Loadings.

The static and dynamic loadings that are developed by the system operating parameters, including deadweight, pres sure, and other external loadings, but excluding ef fects resulting from constraints of free-end move ments and thermal and peak stresses.

Ultimate Tensile Strength.

Material property based on engineering stress-strain relationship.

Upset Plant Conditions.

Those deviations from the normal plant condition, that have a high probability of occurrence.

C. REGULATORY

POSITION ASME Code' Class 1 linear-type component sup American Society of Mechanical Engineers Boiler and Pressure Vessel Code,Section III, Division 1, 1974 Edition, including the 1976 Winter Addenda thereto.1.124-3 I I I I

ports excluding snubbers, which are not addressed herein, should be constructed to the rules of Subsec tion NF of Section III as supplemented by the follow ing: s 1. The classification of component supports should, as .a minimum, be the same as that of the supported components.

2. Values of Su at a temperature t should be esti mated by one of the three following methods on an interim basis until Section III includes such values: a. Method 1. This method applies to component support materials whose values of ultimate strength Su at temperature have been tabulated by their man ufacturers in catalogs or other publications.

Su = Sur S , but not greater than Sur S~ur where Su = ultimate tensile strength at temperature t to be used to determine the service limits Sur = ultimate tensile strength at room temperature tabulated in Section III, Appendix I, or the latest accepted version 1 of Code Case 1644 S'u = ultimate tensile strength at temperature t tabulated by manufacturers in their catalogs or other publications Sur = ultimate tensile strength at room temperature tabulated by manufacturers in the same pub lications.

b. Method 2. This method applies to component support materials whose values of ultimate tensile strength at temperature have not been tabulated by their manufacturers in any catalog or publication.

Sy Su= Sur r ,where Su = ultimate tensile strength at temperature t to be used to determine the service limits Sur = ultimate tensile strength at room temperature tabulated in Section III, Appendix I, or the latest accepted version of Code Case 1644 S, = minimum yield strength at temperature t tabulated in Section III, Appendix I, or the latest accepted version 1 of Code Case 1644 Syr = minimum yield strength at room temper ature, tabulated in Section III, Appendix I, , If the function of a component support is not required during a plant condition, the design limits of the support for that plant con dition need not be satisfied, provided excessive deflection or fail ure of the support will not result in the loss of function of any other safety-related system.I 1.124-4 I or the latest accepted version I of Code Case 1644. c. Method 3. When the values of allowable stress or stress intensity at temperature for a material are listed in Section III, the ultimate tensile strength at temperature for that material may be approximated by the following expressions:

Su = 4S or Su = 3Sm where Su = ultimate tensile strength at temperature t to be used to determine the service limits Su = listed value of allowable stress at temperature t in Section III. S.= listed value of allowable stress intensity at temperature t in Section III 3. The Code levels A and B service limits for com ponent supports designed by linear elastic analysis which are related to S, should meet the appropriate stress limits of Appendix XVII of Section III but should not exceed the limit specified when the value of 5/6 Su is substituted for S,. Examples are shown below in a and b. a. The tensile stress limit Ft for a net section as specified in XVII-221 1(a) of Section III should be the smaller value of 0.6S, or 0.5Su at temperatbre.

For net sections at pinholes in eye-bars, pin connected plates, or built-up structural members, Ft as specified in XVII-221 1(b) should be the smaller value of 0.45S, or 0.375Su at temperature.

b. The shear stress limit Fv for a gross section as specified in XVII-2212 of Section III should be the smaller value of 0.4S, or 0.33Su at temperature.

Many limits and equations for compression strength specified in Sections XVII-2214, XVII 2224, XVII-2225, XVII-2240, and XVII-2260

have built-in constants based on Young's Modulus of 29,000 Ksi. For materials with Young's Modulus at working temperatures substantially different from 29,000 Ksi, these constants should be rederived with the appropriate Young's Modulus unless the conser vatism of using these constants as specified can be demonstrated.

4. Component supports designed by linear elastic analysis may increase their level A or B service limits according to the provisions of NF-323 1. 1(a), XVII 2110(a), and F-1370(a)

of Section III. The increase of level A or B service limits provided by NF 3231. 1(a) is for stress range. The increase 'of level A I [I

I or B service limits provided by F-1370(a)

for level D service limits, should be the smaller factor of 2 or 1.167SI/Sy, if S, : 1.2S, or 1.4 if Su -- 1.2Sf, where S, and Su are component-support material properties at temperature.

However, all increases

[i.e., those allowed by NF-3231.1(a), XVII-2110(a), and F-1370(a)]

should always be limited by XVII-21 10(b) of Section III. The critical buckling strengths defined by XVII-21 10(b) of Section III should be calculated using material properties at temperature.

This in crease of level A or B service limits does not apply to limits for bolted connections.

Any increase of limits for shear stresses above 1.5 times the Code level A service limits should be justified.

If the increased service limit for stress range by NF-3231.1(a)

is more than 2S, or S., it should be limited to the smaller value of 2S, or S,, unless it can be justified by a shakedown analysis.

5. Component supports subjected to the combined loadings of system mechanical loadings associated with (1) either (a) the Code design condition or (b) the normal or upset plant conditions and (2) the vib ratory motion of the OBE should be designed within the following limits: 4,5 a. The stress limits of XVII-2000

of Section III and Regulatory Position 3 of this guide should not be exceeded for component supports designed by the linear elastic analysis method. These stress limits may be. increased according to the provisions of NF-3231.1(a)

of Section III and Regulatory Position 4 of this guide when effects resulting from constraints of free-end displacements are added to the loading combination.

b. The normal condition load rating or the upset condition load rating of NF-3262.3 of Section III should not be exceeded for component supports de signed by the load-rating method. c. The lower bound collapse load determined by XVII-4200

adjusted according to the provision of XVII-4 110(a) of Section III should not be exceeded for component supports designed by the limit analysis method. d. The collapse load determined by 11-1400 of 4 S ince component supports are deformation sensitive in the performance of their service requirements, satisfying these criteria does not ensure that their functional requirements will be fulfilled.

Any deformation limits specified by the design specification may be controlling and should be satisfied.

' Since the design of component supports is an integral part of the design of the system and the design of the component, the de signer must make sure that methods used for the analysis of the system, component, and component support are compatible (see Table F-1322.2-1 in Appendix F of Section I1). Large deforma tions in the system or components should be considered in the design of component supports.1.124-5 Section III divided by 1.7 should not be exceeded for component supports designed by the experimental stress analysis method. 6. Component supports subjected to the system mechanical loadings associated with the emergency plant condition should be designed within the follow ing design limits except when the normal function of the supported system is to prevent or mitigate the consequences of events associated with the emer gency plant condition (at which time Regulatory Position 8 applies): 4"'5 a. The stress limits of XVII-2000

of Section M and Regulatory Positions

3 and 4, increased accord ing to the provisions of XVII-21 10(a) of Section m and Regulatory Position 4 of this guide, should not be exceeded for component supports designed by the linear elastic analysis method. b. The emergency condition load rating of NF 3262.3 of Section III should not be exceeded for component supports designed by the load-rating method. c. The lower bound collapse load determined by XVII-4200

adjusted according to the provision of XVII-4 110(a) of Section III should not be exceeded for component supports designed by the limit analysis method. d. The collapse load determined by 11-1400 of Section III divided by 1.3 should not be exceeded for component supports designed by the experimental stress analysis method. 7. Component supports subjected to the combined loadings of (1) the system mechanical loadings as sociated with the normal plant condition, (2) the vib ratory motion of the SSE, and (3) the dynamic system loadings associated with the faulted plant condition should be designed within the following limits except when the normal function of the supported system is to prevent or mitigate the consequences of events as sociated with the faulted plant condition (at which time Regulatory Position 8 applies):

a. The stress limits of XVII-2000

of Section m and Regulatory Position 3 of this guide, increased ac cording to the provisions of F-1370(a)

of Section III and Regulatory Position 4 of this guide, should not be exceeded for component supports designed by the linear elastic analysis method. b. The smaller value of T.L. x 2S/S, or T.L. x 0.7S/Su should not be exceeded, where T.L., S, and .Su are definedl according to NF.3262.1 of Section.

mI, and Su is the minimum ultimate tensile strength of the material at service temperature for component supports designed by the load-rating method. c. The lower bound collapse load determined by XVII-4200

adjusted according to the provision of F-1370(b)

of Section III should not be exceeded for I.I.

component supports designed by the limit analysis method. d. The collapse load determined by 11-1400 ad justed according to the provision of F-1370(b)

of Section III should not be exceeded for component supports designed by the experimental stress analysis method. 8. Component supports in systems whose normal function i' to prevent or mitigate the consequences of events associated with an emergency or faulted plant condition should be designed within the limits de scribed in Regulatory Position 5 or other justifiable

'limits provided by the Code. These limits should be defined by the Design Specificatioh and stated in the PSAR, such that the function of the supported system will be maintained when they are subjected to the loading combinations described in Regulatory Positions

6 and 7.

D. IMPLEMENTATION

The purpose of this section is to provide guidance to applicants and licensees regarding the NRC staff's plans for using this regulatory guide. Except in those cases in which the applicant pro poses an acceptable alternative method for complying with the specified portions of the Commission's regu lations, the methocf described herein will be used in the evaluation of submittals for construction permit applications docketed after January 10, 1978. If an applicant wishes to use this regulatory guide in uc veloping submittals for construction permit applica tions docketed on or before January 10, 1978, the pertinent portions of the application will be evaluated'

on the basis of this guide.1.124-6