Regulatory Guide 1.124: Difference between revisions

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{{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:Revision I
                                    U.S. NUCLEAR REGULATORY COMMISSION                                                                                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
with the specified seismic event, thus helping to General Design Criterion 2, "Design Bases for                                            mitigate the consequences of system damage. Com Protection Against Natural Phenomena," of Appen                                            ponent supports are deformation sensitive because dix A, "General Design Criteria for Nuclear Power                                            large deformations in them may significantly change Plants," to 10 CFR Part 50, "Licensing of Produc                                            the stress distribution in the support system and its tion and Utilization Facilities," requires that the de                                      supported components.
CLASS 1 LINEAR-TYPE SUPPORTS
 
sign bases for structures, systems, and components important to safety reflect appropriate combinations                                            In order to provide uniform requirements for con of the effects of normal and accident conditions with                                        struction, the component supports, should, as a the effects of natural phenomena such as earthquakes.                                        minimum, have the same ASME Boiler and Pressure The failure of members designed to support safety                                            Vessel Code classification as that of the supported related components could jeopardize the ability of the                                        components. This guide delineates levels of service supported component to perform its safety function.                                         limits and loading combinations, in addition to supplementary criteria, for ASME Class 1 linear-type SThis guide delineates acceptable levels of service                                          component supports as defined by NF-1213 of Sec limits and appropriate combinations' of loadings as                                          tion III. Snubbers are not addressed in this guide.


==A. INTRODUCTION==
sociated with normal operation, postulated accidents, and specified seismic events for the design of Class 1                                           Subsection NF and Appendix XVII of Section III
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.
linear-type component supports as defined in Subsec                                          permit the use of four methods for the design of Class tion NF of Section III of the American Society of                                             I linear-type component supports: linear elastic anal Mechanical Engineers (ASME) Boiler and Pressure                                              ysis, load rating, experimental stress analysis, and Vessel Code. This guide applies to light-water-cooled                                         limit analysis. For each method, the ASME Code de reactors. The Advisory Committee on Reactor                                                  lineates allowable stress or loading limits for various Safeguards has been consulted concerning this guide                                          Code levels of service limits as defined by NF-3113 and has concurred in the regulatory position.                                                of Section III so that these limits can be used in con junction with the resultant loadings or stresses from                              I
                                                                                              the appropriate plant condition


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.
====s. Since the Code does ====


==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.
not specify loading combinations, guidance is re Load-bearing members classified as component                                            quired to provide a consistent basis for the design of supports are essential to the safety of nuclear power                                        component supports.
 
plants since they retain components in place during the loadings associated with normal and upset plant                                              Component supports considered in this guide are conditions under the stress of specified seismic                                            located within Seismic Category I structures and are events, thereby permitting system components to                                              therefore protected against loadings from natural function properly. They also prevent excessive com                                          phenomena or man-made hazards other than the spec ponent movement during the loadings associated with                                          ified seismic events. Thus only the specified seismic emergency and faulted plant conditions combined                                              events need to be considered in combination with the
* Lines indicate substantive change from previous issue.                                    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 isued oGide dscrbe ar acceptable to the NRC staff of implementing  nd akeavalabl tothepubic t~t~dt              Branch.
 
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.
 
5.
 
4.  Environmental Materials      andSiting and Plant                    9. Antitrust Review 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 t imes, and guides will be revised, as appropriate, to accommodate comments                                                                                              place and  ment on an automatic distribution list for single copies of future guides in to reflect new information or experience. This guide was revised as a                                                                                                  specific 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
 
by natural phenomena other than seismic events,                     stresses should be calculated with the values of E and when they exist, should be considered on a case-by                  S, of the component support material at temperature.
 
I case basis.                                                            Allowable service limits for bolted connections are
        1. Design by Linear Elastic Analysis derived from tensile and shear stress limits and their nonlinear interaction; they also change with the size I
          a. Su at Temperature. When the linear elastic                    of the bolt. For this reason, the increases permitted analysis method is used to design Class 1 linear-type               by NF-323 1.1, XVII-21 10(a), and F-1370(a) of Sec component supports, material properties are given by                tion III are not directly applicable to allowable shear Tables 1-2.1, 1-2.2, 1-13.1, and 1-13.3 in Appendix                  stresses and allowable stresses for bolts and bolted I of Section III and Tables 3 and 4 in the latest ac                connections. The increase permitted by NF-3231.1 cepted version 1 of Code Case 1644. These tables list                and F-1370(a) of Section III for shear stresses or I    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 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 port materials.                                                     should be limited to 2S, but not more than Su to en Levels of service limits derived from either mate                sure shakedown. For many allowable stresses above rial property alone may not be sufficient to provide a              the value of 0.6S,. the increase permitted by NF
      consistent safety margin. This is recognized by Sec                3231.1(a) will be above the value of 2S, and will tion III, since XVII-2211(a) of Section III defines                thus violate the normal shakedown range. A
      the allowable stress in tension on a net section as the            shakedown analysis is necessary to justify the smaller value of 0. 6 S, and 0.5Su. To alleviate the               increase of stress above 2S, or Su .
      lack of defined values of Su at temperatures above                      For the linear elastic analysis method, F-1370(a)
      room temperature and to provide a safe design mar                    of Section III permits increase of tension limits for gin, an interim method is given in this guide to obtain values of S, at temperature.
 
the Code level D service limits by a variable factor.
 
that is the smaller value of 1.2Sy/Ft or 0.7Su/Ft. De
                                                                                                                                    !
          While XVII-221 1(a) specifies allowable tensile                pending on whether the section considered is a net stress in terms of both S, and Su, the rest of XVII                  section at pinholes in eyebars, pin-connected plates,
      2000 specifies other allowable service limits in terms              or built-up structural members, Ft may assume the of S, only. This does not maintain a consistent design              smaller value of 0.45S, or 0.375Su (as recommended margin for those service limits related only to mate                by this guide for a net section of pinholes, etc.) or the rial properties. Modifications similar to XVII                      smaller value of 0.6Sy or 0.5Su (for a net section
      2211(a) should be employed for all those service                    without pinholes, etc.). Thus greater values of the limits.                                                            factor may be obtained for sections at pinholes, which does not account for local stress and is not b. Allowable Increase of Service Limits. While                  consistent with NF-323 1. 1 and XVII-21 10(a) of Sec NF-3231.1(a), XVII-2110(a), and F-1370(a) of Sec                    tion III. A procedure to correct this factor is provided tion III all permit the increase of allowable stresses              in this guide.


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 properly.  Load-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.
under various loading conditions, XVII-21 10(b) lim its the increase so that two-thirds of the critical buckl            2. Design by Load Rating ing stress for compression and compression flange members is not exceeded, and the increase allowed                        When load-rating methods are used, Subsection NF
    by NF-323 1. 1(a) is for stress range. Critical buckling            and Appendix F of Section III do not provide a stresses with normal design. margins are derived in                  faulted condition load rating. This guide provides an XVII-2200 ofSection HII. Since buckling prevents                    interim method for the determination of faulted con
    "shakedown" in the load-bearing member, XVII                        dition load rating.


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.
2110(b) must be regarded as controlling. Also, buckl ing is the result of the interaction of the configuration          3. Design by Experimental Stress Analysis of the load-bearing member and its material prop                        While the collapse load for the experimental stress erties (i.e., elastic modulus E and minimum yield                  analysis method is defined by 11-1430 in Appendix II
    strength S,). Because both of these material prop                  of Section III, the various levels of service limits for erties change with temperature, the critical buckling              experimental stress analysis are not delineated. This deficiency is remedied by the method described in
    ' Regulatory Guide 1.85, "Code Case Acceptability-ASME Sec          this guide.


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
tion III Materials," provides guidance for the acceptability of ASME Section III Code Cases and their revisions, including Code      4. Large Deformation Case 1644. Supplementary provisions for the use of specific code cases and their revisions may also be provided and should be con        The design of component supports is an integral sidered when applicable.                                             part of the design of the system and its components.
y and the ultimate tensile strength S
u.  At room temperature, S
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
24-2
y).  Because both of these material properties change with temperature, the critical buckling stresses should use the values of E and S
*I
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
u or S y , at                                                     
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
A complete and consistent design is possible only            lar plant condition, the stresses or loads resulting when system/componeqt/component-support interac              from the loading combinations under that plant condi tion is properly consi'iered. When all three are              tion do not need to satisfy the design limits for the evaluated on an elastic basis, the interaction is usu        plant condition.
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:
* the lesser of 2 or 1.167S
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.
ally valid because individual deformations are small.


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
However, if plastic analysis methods are employed in          7. Definitions the design process, large deformations that would re              Design Condition. The loading condition defined sult in substantially different stress distributions may      by NF-3112 of Section III of the ASME Boiler and occur.                                                       Pressure Vessel Code.
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.


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
When component supports are designed for load                 Emergency Plant Condition. Those operating con ings associated with the faulted plant conditions, Ap        ditions that have a low probability of occurrence.


condition.
pendix F of Section III permits the use of plastic analysis methods in certain acceptable combinations              Faulted Plant Condition. Those operating condi for all three elements. These acceptable combinations        tions associated with postulated events of extremely are selected on the assumption that component sup            low probability.


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.
ports are more deformation sensitive (i.e., their de Levels of Service Limits. Four levels, A, B, C, and formation in general will nave a large effect on the          D, of service limits defined by Section III for the de stress distribution iu the system and its components.)        sign of loadings associated with different plant condi Since large deformations always affect the stress dis tions for components and component supports in nu tribution, care should be exercised even if the plastic      clear power plants.


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.
analysis method is used in thl. Appendix F-approved methodology combination. This is especially impor                Normal Plant Condition. Those operating condi tant for identifying buckling or instability problems        tions in the course of system startup, operation, hot where the change of geometry should be taken into              standby, refueling, and shutdown other than upset, account to avoid erroneous results.                          emergency, or faulted plant conditions.


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.
5. Function of Supported System                                  Operating Basis Earthquake (OBE). As defined in Appendix A to 10 CFR Part 100.


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.
In selecting the level of service limits for different                                                                        I
  loading combinations, the function of the supported              PlantConditions. Operating conditions of the plant system must be taken into account. To ensure that              categorized as normal, upset, emergency, and faulted systems whose normal function is to prevent or miti          plant conditions.


Ultimate tensile strength. Material property based on the engineering stress-strain relationship.
gate consequences of events associated with an emer              Safe Shutdown Earthquake (SSE). As defined in gency or faulted plant condition (e.g., the function of        Appendix A to 10 CFR Part 100.


Upset Plant Conditions. Those deviations from the normal plant condition that have a high probability of occurrence.
ECCS during faulted plant conditions) will operate properly regardless of plant condition, the Code level            Service Limits. Stress limits for the design of com A or B service limits of Subsection NF (which are              ponent supports as defined by Subsection NF of Sec identical) or other justifiable limits provided by the        tion III.


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.
Code should be used.                                             Specified Seismic Events. Operating Basis Earth Since Appendix XVII derived all equations from              quake and Safe Shutdown Earthquake.


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."
AISC rules and many AISC compression equations                    System Mechanical Loadings. The static and have built-in constants based on mechanical prop              dynamic loadings that are developed by the system erties of steel at room temperature, to. use these equa        operating parameters, including deadweight, pres tions indiscriminately for all NF and the latest ac            sure, and other external loadings, but excluding ef cepted version of Code Case 1644 materials at all              fects resulting from constraints of free-end move temperatures would not be prudent. For materials                                                                                  I
                                                                ments and thermal and peak stresses.


Rev. 3 of RG 1.124, Page 7 C. STAFF REGULATORY GUIDANCE The construction of ASME Code
other than steel and working temperatures substan tially different from room temperature, these equa                Ultimate Tensile Strength. Material property based tions should be rederived with the. appropriate mate          on engineering stress-strain relationship.
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.


3 1. The classification of component and piping supports should, as a minimum, be the same as that of the supported components and piping.
rial properties.                                                 Upset Plant Conditions. Those deviations from the
  6. Deformation Limits                                          normal plant condition, that have a high probability of occurrence.


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
Since component supports are deformation
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
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
==C. REGULATORY POSITION==
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
I sensitive load-bearing elements, satisfying the serv ice limits of Section III will not automatically ensure their proper function. Deformation limits, if specified ASME Code' Class 1 linear-type component sup by the Code Design Specification, may be the con                American Society of Mechanical Engineers Boiler and Pressure trolling criterion. On the other hand, if the function          Vessel Code, Section III, Division 1, 1974 Edition, including the of a component support is not required for a particu-          1976 Winter Addenda thereto.
y or 0.33S u, at temperature.


c. The bending stress limit F
I
b resulting from tension and bending in structural members as specified in NF-3320, should be (1) the lesser value of 0.66 S
                                                          1.124-3
y or 0.55 S
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.
ports excluding snubbers, which are not addressed herein, should be constructed to the rules of Subsec or the latest accepted version I of Code Case
                                                                                          1644.


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.
I
      tion NF of Section III as supplemented by the follow ing: s                                                                          c. Method 3. When the values of allowable
          1. The classification of component supports                           stress or stress intensity at temperature for a material should, as .a minimum, be the same as that of the                        are listed in Section III, the ultimate tensile strength supported components.                                                    at temperature for that material may be approximated by the following expressions:
          2. Values of Su at a temperature t should be esti Su = 4S or I    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 Su = 3Sm where support materials whose values of ultimate strength                          Su = ultimate tensile strength at temperature t to Su at temperature have been tabulated by their man                                  be used to determine the service limits ufacturers in catalogs or other publications.                                Su = listed value of allowable stress at temperature t in Section III.


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
Su = Sur S       , but not greater than Sur                    S.= listed value of allowable stress intensity at S~ur temperature t in Section III
u/S y if S u > 1.2S y , or 1.4 if S
    where Su = ultimate tensile strength at temperature t to                        3. The Code levels A and B service limits for com I                                                                              ponent supports designed by linear elastic analysis
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
[                be used to determine the service limits Sur = ultimate tensile strength at room temperature tabulated in Section III, Appendix I, or the 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 latest accepted version 1 of Code Case 1644 S'u = ultimate tensile strength at temperature t tabulated by manufacturers in their catalogs of 5/6 Su is substituted for S,. Examples are shown below in a and
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.     ====
====b.     I====
2  ASME Boiler and Pressure Vessel Code, Section III, Division I, 2007 Edition through the 2008 Addenda.
                  or other publications a. The tensile stress limit Ft for a net section as Sur = ultimate tensile strength at room temperature                    specified in XVII-221 1(a) of Section III should be tabulated by manufacturers in the same pub                    the smaller value of 0.6S, or 0.5Su at temperatbre.


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.
lications.                                                    For net sections at pinholes in eye-bars, pin b. Method 2. This method applies to component                     connected plates, or built-up structural members, Ft support materials whose values of ultimate tensile                        as specified in XVII-221 1(b) should be the smaller strength at temperature have not been tabulated by                        value of 0.45S, or 0.375Su at temperature.


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
their manufacturers in any catalog or publication.
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
b. The shear stress limit Fv for a gross section as Su= Sur      Sy r                                specified in XVII-2212 of Section III should be the smaller value of 0.4S, or 0.33Su at temperature.
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.
,where Many limits and equations for compression Su = ultimate tensile strength at temperature t to strength specified in Sections XVII-2214, XVII
                  be used to determine the service limits
                                                                                2224, XVII-2225, XVII-2240, and XVII-2260 have Sur = ultimate tensile strength at room temperature                    built-in constants based on Young's Modulus of tabulated in Section III, Appendix I, or the                  29,000 Ksi. For materials with Young's Modulus at latest accepted version of Code Case 1644                    working temperatures substantially different from S, = minimum yield strength at temperature t                            29,000 Ksi, these constants should be rederived with tabulated in Section III, Appendix I, or the                  the appropriate Young's Modulus unless the conser latest accepted version 1 of Code Case 1644                    vatism of using these constants as specified can be Syr = minimum yield strength at room temper                            demonstrated.


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.
ature, tabulated in Section III, Appendix I,
                                                                                  4. Component supports designed by linear elastic analysis may increase their level A or B service limits
  ,    If the function of a component support is not required during a plant condition, the design limits of the support for that plant con according to the provisions of NF-323 1. 1(a), XVII
    dition need not be satisfied, provided excessive deflection or fail        2110(a), and F-1370(a) of Section III. The increase ure of the support will not result in the loss of function of any          of level A or B service limits provided by NF
    other safety-related system.                                              3231. 1(a) is for stress range. The increase 'of level A
                                                                          1.124-4


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.
or B service limits provided by F-1370(a) for level D                    Section III divided by 1.7 should not be exceeded for I  service limits, should be the smaller factor of 2 or                      component supports designed by the experimental
    1.167SI/Sy, if S, : 1.2S, or 1.4 if Su -- 1.2Sf,                        stress analysis method.


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.
where S, and Su are component-support material properties at temperature.                                                  6. Component supports subjected to the system mechanical loadings associated with the emergency However, all increases [i.e., those allowed by                        plant condition should be designed within the follow NF-3231.1(a), XVII-2110(a), and F-1370(a)]                                ing design limits except when the normal function of should always be limited by XVII-21 10(b) of Section                      the supported system is to prevent or mitigate the III. The critical buckling strengths defined by                          consequences of events associated with the emer XVII-21 10(b) of Section III should be calculated                        gency plant condition (at which time Regulatory using material properties at temperature. This in                        Position 8 applies): 4"'5 crease of level A or B service limits does not apply to limits for bolted connections. Any increase of limits                          a. The stress limits of XVII-2000 of Section M
    for shear stresses above 1.5 times the Code level A                      and Regulatory Positions 3 and 4, increased accord service limits should be justified.                                      ing to the provisions of XVII-21 10(a) of Section m and Regulatory Position 4 of this guide, should not If the increased service limit for stress range by                    be exceeded for component supports designed by the NF-3231.1(a) is more than 2S, or S., it should be                        linear elastic analysis method.


b. Supports designed by the load-rating method should not exceed the service level C load rating of NF-3382.2 of Section III.
limited to the smaller value of 2S, or S,, unless it can be justified by a shakedown analysis.                                          b. The emergency condition load rating of NF
                                                                              3262.3 of Section III should not be exceeded for
        5. Component supports subjected to the combined                      component supports designed by the load-rating loadings of system mechanical loadings associated                        method.


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
with (1) either (a) the Code design condition or (b)
    the normal or upset plant conditions and (2) the vib                            c. The lower bound collapse load determined by ratory motion of the OBE should be designed within                        XVII-4200 adjusted according to the provision of the following limits: 4,5                                                XVII-4 110(a) of Section III should not be exceeded for component supports designed by the limit analysis a. The stress limits of XVII-2000 of Section III                  method.


====d.      ====
and Regulatory Position 3 of this guide should not be exceeded for component supports designed by the                                 d. The collapse load determined by 11-1400 of linear elastic analysis method. These stress limits                        Section III divided by 1.3 should not be exceeded for may be. increased according to the provisions of                          component supports designed by the experimental NF-3231.1(a) of Section III and Regulatory Position                      stress analysis method.
4  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.
I 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 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.
7. Component supports subjected to the combined loadings of (1) the system mechanical loadings as sociated with the normal plant condition, (2) the vib b. The normal condition load rating or the upset                  ratory motion of the SSE, and (3) the dynamic system condition load rating of NF-3262.3 of Section III                        loadings associated with the faulted plant condition should not be exceeded for component supports de                          should be designed within the following limits except signed by the load-rating method.                                        when the normal function of the supported system is to prevent or mitigate the consequences of events as c. The lower bound collapse load determined by                   sociated with the faulted plant condition (at which XVII-4200 adjusted according to the provision of                          time Regulatory Position 8 applies):
  XVII-4 110(a) of Section III should not be exceeded for component supports designed by the limit analysis                            a. The stress limits of XVII-2000 of Section m method.                                                                   and Regulatory Position 3 of this guide, increased ac cording to the provisions of F-1370(a) of Section III
          d. The collapse load determined by 11-1400 of                    and Regulatory Position 4 of this guide, should not be exceeded for component supports designed by the
      4 S ince component supports are deformation sensitive in the          linear elastic analysis method.


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).  
performance of their service requirements, satisfying these criteria b. The smaller value of T.L. x 2S/S, or T.L. x does not ensure that their functional requirements will be fulfilled.
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.
Any deformation limits specified by the design specification may be controlling and should be satisfied.


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
0.7S/Su should not be exceeded, where T.L., S, and
u/S u*, where TL, S
                                                                            .Su are definedl according to NF.3262.1 of Section.
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).
.I.
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).
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
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==
' Since the design of component supports is an integral part of the        mI, and Su is the minimum ultimate tensile strength design of the system and the design of the component, the de              of the material at service temperature for component signer must make sure that methods used for the analysis of the            supports designed by the load-rating method.
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
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.


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.
system, component, and component support are compatible (see Table F-1322.2-1 in Appendix F of Section I1). Large deforma                    c. The lower bound collapse load determined by tions in the system or components should be considered in the             XVII-4200 adjusted according to the provision of design of component supports.                                              F-1370(b) of Section III should not be exceeded for
                                                                      1.124-5


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 regulations.  Current 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
component supports designed by the limit analysis                       
. 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


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). 
==D. IMPLEMENTATION==
Rev. 3 of RG 1.124, Page 11 REFERENCES
method.
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."
d. The collapse load determined by 11-1400 ad justed according to the provision of F-1370(b) of           The purpose of this section is to provide guidance Section III should not be exceeded for component          to applicants and licensees regarding the NRC staff's supports designed by the experimental stress analysis    plans for using this regulatory guide.


3. U.S. Code of Federal Regulations (CFR), Title 10, Energy, Part 52, "Licenses, Certifications, and Approvals for Nuclear Power Plants."
method.
4. U.S. Nuclear Regulatory Commission (NRC), NUREG-1409, "Backfitting Guidelines," NRC, Washington, DC.


5. NRC, Management Directive 8.4, "Management of Facility-specific Backfitting and Information Collection," NRC, Washington, DC.
8. Component supports in systems whose normal            Except in those cases in which the applicant pro function i' to prevent or mitigate the consequences of    poses an acceptable alternative method for complying events associated with an emergency or faulted plant      with the specified portions of the Commission's regu condition should be designed within the limits de        lations, the methocf described herein will be used in scribed in Regulatory Position 5 or other justifiable    the evaluation of submittals for construction permit
'limits provided by the Code. These limits should be      applications docketed after January 10, 1978. If an defined by the Design Specificatioh and stated in the    applicant wishes to use this regulatory guide in uc PSAR, such that the function of the supported system      veloping submittals for construction permit applica will be maintained when they are subjected to the        tions docketed on or before January 10, 1978, the loading combinations described in Regulatory              pertinent portions of the application will be evaluated'
Positions 6 and 7.                                        on the basis of this guide.


9  Publicly available NRC published documents are available electronically through the NRC Library on the NRC's public Web site at
J*
: 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/.}}
                                                    1.124-6}}


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Latest revision as of 11:40, 28 March 2020

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)
v • d • e


Revision I

U.S. NUCLEAR REGULATORY COMMISSION 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

with the specified seismic event, thus helping to General Design Criterion 2, "Design Bases for mitigate the consequences of system damage. Com Protection Against Natural Phenomena," of Appen ponent supports are deformation sensitive because dix A, "General Design Criteria for Nuclear Power large deformations in them may significantly change Plants," to 10 CFR Part 50, "Licensing of Produc the stress distribution in the support system and its tion and Utilization Facilities," requires that the de supported components.

sign bases for structures, systems, and components important to safety reflect appropriate combinations In order to provide uniform requirements for con of the effects of normal and accident conditions with struction, the component supports, should, as a the effects of natural phenomena such as earthquakes. minimum, have the same ASME Boiler and Pressure The failure of members designed to support safety Vessel Code classification as that of the supported related components could jeopardize the ability of the components. This guide delineates levels of service supported component to perform its safety function. limits and loading combinations, in addition to supplementary criteria, for ASME Class 1 linear-type SThis guide delineates acceptable levels of service component supports as defined by NF-1213 of Sec limits and appropriate combinations' of loadings as tion III. Snubbers are not addressed in this guide.

sociated with normal operation, postulated accidents, and specified seismic events for the design of Class 1 Subsection NF and Appendix XVII of Section III

linear-type component supports as defined in Subsec permit the use of four methods for the design of Class tion NF of Section III of the American Society of I linear-type component supports: linear elastic anal Mechanical Engineers (ASME) Boiler and Pressure ysis, load rating, experimental stress analysis, and Vessel Code. This guide applies to light-water-cooled limit analysis. For each method, the ASME Code de reactors. The Advisory Committee on Reactor lineates allowable stress or loading limits for various Safeguards has been consulted concerning this guide Code levels of service limits as defined by NF-3113 and has concurred in the regulatory position. of Section III so that these limits can be used in con junction with the resultant loadings or stresses from I

the appropriate plant condition

s. Since the Code does

B. DISCUSSION

not specify loading combinations, guidance is re Load-bearing members classified as component quired to provide a consistent basis for the design of supports are essential to the safety of nuclear power component supports.

plants since they retain components in place during the loadings associated with normal and upset plant Component supports considered in this guide are conditions under the stress of specified seismic located within Seismic Category I structures and are events, thereby permitting system components to therefore protected against loadings from natural function properly. They also prevent excessive com phenomena or man-made hazards other than the spec ponent movement during the loadings associated with ified seismic events. Thus only the specified seismic emergency and faulted plant conditions combined events need to be considered in combination with the

  • Lines indicate substantive change from previous issue. 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 isued oGide dscrbe ar acceptable to the NRC staff of implementing nd akeavalabl tothepubic t~t~dt Branch.

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.

5.

4. Environmental Materials andSiting and Plant 9. Antitrust Review 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 t imes, and guides will be revised, as appropriate, to accommodate comments place and ment on an automatic distribution list for single copies of future guides in to reflect new information or experience. This guide was revised as a specific 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

by natural phenomena other than seismic events, stresses should be calculated with the values of E and when they exist, should be considered on a case-by S, of the component support material at temperature.

I case basis. Allowable service limits for bolted connections are

1. Design by Linear Elastic Analysis derived from tensile and shear stress limits and their nonlinear interaction; they also change with the size I

a. Su at Temperature. When the linear elastic of the bolt. For this reason, the increases permitted analysis method is used to design Class 1 linear-type by NF-323 1.1, XVII-21 10(a), and F-1370(a) of Sec component supports, material properties are given by tion III are not directly applicable to allowable shear Tables 1-2.1, 1-2.2, 1-13.1, and 1-13.3 in Appendix stresses and allowable stresses for bolts and bolted I of Section III and Tables 3 and 4 in the latest ac connections. The increase permitted by NF-3231.1 cepted version 1 of Code Case 1644. These tables list and F-1370(a) of Section III for shear stresses or I 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 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 port materials. should be limited to 2S, but not more than Su to en Levels of service limits derived from either mate sure shakedown. For many allowable stresses above rial property alone may not be sufficient to provide a the value of 0.6S,. the increase permitted by NF

consistent safety margin. This is recognized by Sec 3231.1(a) will be above the value of 2S, and will tion III, since XVII-2211(a) of Section III defines thus violate the normal shakedown range. A

the allowable stress in tension on a net section as the shakedown analysis is necessary to justify the smaller value of 0. 6 S, and 0.5Su. To alleviate the increase of stress above 2S, or Su .

lack of defined values of Su at temperatures above For the linear elastic analysis method, F-1370(a)

room temperature and to provide a safe design mar of Section III permits increase of tension limits for gin, an interim method is given in this guide to obtain values of S, at temperature.

the Code level D service limits by a variable factor.

that is the smaller value of 1.2Sy/Ft or 0.7Su/Ft. De

!

While XVII-221 1(a) specifies allowable tensile pending on whether the section considered is a net stress in terms of both S, and Su, the rest of XVII section at pinholes in eyebars, pin-connected plates,

2000 specifies other allowable service limits in terms or built-up structural members, Ft may assume the of S, only. This does not maintain a consistent design smaller value of 0.45S, or 0.375Su (as recommended margin for those service limits related only to mate by this guide for a net section of pinholes, etc.) or the rial properties. Modifications similar to XVII smaller value of 0.6Sy or 0.5Su (for a net section

2211(a) should be employed for all those service without pinholes, etc.). Thus greater values of the limits. factor may be obtained for sections at pinholes, which does not account for local stress and is not b. Allowable Increase of Service Limits. While consistent with NF-323 1. 1 and XVII-21 10(a) of Sec NF-3231.1(a), XVII-2110(a), and F-1370(a) of Sec tion III. A procedure to correct this factor is provided tion III all permit the increase of allowable stresses in this guide.

under various loading conditions, XVII-21 10(b) lim its the increase so that two-thirds of the critical buckl 2. Design by Load Rating ing stress for compression and compression flange members is not exceeded, and the increase allowed When load-rating methods are used, Subsection NF

by NF-323 1. 1(a) is for stress range. Critical buckling and Appendix F of Section III do not provide a stresses with normal design. margins are derived in faulted condition load rating. This guide provides an XVII-2200 ofSection HII. Since buckling prevents interim method for the determination of faulted con

"shakedown" in the load-bearing member, XVII dition load rating.

2110(b) must be regarded as controlling. Also, buckl ing is the result of the interaction of the configuration 3. Design by Experimental Stress Analysis of the load-bearing member and its material prop While the collapse load for the experimental stress erties (i.e., elastic modulus E and minimum yield analysis method is defined by 11-1430 in Appendix II

strength S,). Because both of these material prop of Section III, the various levels of service limits for erties change with temperature, the critical buckling experimental stress analysis are not delineated. This deficiency is remedied by the method described in

' Regulatory Guide 1.85, "Code Case Acceptability-ASME Sec this guide.

tion III Materials," provides guidance for the acceptability of ASME Section III Code Cases and their revisions, including Code 4. Large Deformation Case 1644. Supplementary provisions for the use of specific code cases and their revisions may also be provided and should be con The design of component supports is an integral sidered when applicable. part of the design of the system and its components.

24-2

  • I

A complete and consistent design is possible only lar plant condition, the stresses or loads resulting when system/componeqt/component-support interac from the loading combinations under that plant condi tion is properly consi'iered. When all three are tion do not need to satisfy the design limits for the evaluated on an elastic basis, the interaction is usu plant condition.

ally valid because individual deformations are small.

However, if plastic analysis methods are employed in 7. Definitions the design process, large deformations that would re Design Condition. The loading condition defined sult in substantially different stress distributions may by NF-3112 of Section III of the ASME Boiler and occur. Pressure Vessel Code.

When component supports are designed for load Emergency Plant Condition. Those operating con ings associated with the faulted plant conditions, Ap ditions that have a low probability of occurrence.

pendix F of Section III permits the use of plastic analysis methods in certain acceptable combinations Faulted Plant Condition. Those operating condi for all three elements. These acceptable combinations tions associated with postulated events of extremely are selected on the assumption that component sup low probability.

ports are more deformation sensitive (i.e., their de Levels of Service Limits. Four levels, A, B, C, and formation in general will nave a large effect on the D, of service limits defined by Section III for the de stress distribution iu the system and its components.) sign of loadings associated with different plant condi Since large deformations always affect the stress dis tions for components and component supports in nu tribution, care should be exercised even if the plastic clear power plants.

analysis method is used in thl. Appendix F-approved methodology combination. This is especially impor Normal Plant Condition. Those operating condi tant for identifying buckling or instability problems tions in the course of system startup, operation, hot where the change of geometry should be taken into standby, refueling, and shutdown other than upset, account to avoid erroneous results. emergency, or faulted plant conditions.

5. Function of Supported System Operating Basis Earthquake (OBE). As defined in Appendix A to 10 CFR Part 100.

In selecting the level of service limits for different I

loading combinations, the function of the supported PlantConditions. Operating conditions of the plant system must be taken into account. To ensure that categorized as normal, upset, emergency, and faulted systems whose normal function is to prevent or miti plant conditions.

gate consequences of events associated with an emer Safe Shutdown Earthquake (SSE). As defined in gency or faulted plant condition (e.g., the function of Appendix A to 10 CFR Part 100.

ECCS during faulted plant conditions) will operate properly regardless of plant condition, the Code level Service Limits. Stress limits for the design of com A or B service limits of Subsection NF (which are ponent supports as defined by Subsection NF of Sec identical) or other justifiable limits provided by the tion III.

Code should be used. Specified Seismic Events. Operating Basis Earth Since Appendix XVII derived all equations from quake and Safe Shutdown Earthquake.

AISC rules and many AISC compression equations System Mechanical Loadings. The static and have built-in constants based on mechanical prop dynamic loadings that are developed by the system erties of steel at room temperature, to. use these equa operating parameters, including deadweight, pres tions indiscriminately for all NF and the latest ac sure, and other external loadings, but excluding ef cepted version of Code Case 1644 materials at all fects resulting from constraints of free-end move temperatures would not be prudent. For materials I

ments and thermal and peak stresses.

other than steel and working temperatures substan tially different from room temperature, these equa Ultimate Tensile Strength. Material property based tions should be rederived with the. appropriate mate on engineering stress-strain relationship.

rial properties. Upset Plant Conditions. Those deviations from the

6. Deformation Limits normal plant condition, that have a high probability of occurrence.

Since component supports are deformation

C. REGULATORY POSITION

I sensitive load-bearing elements, satisfying the serv ice limits of Section III will not automatically ensure their proper function. Deformation limits, if specified ASME Code' Class 1 linear-type component sup by the Code Design Specification, may be the con American Society of Mechanical Engineers Boiler and Pressure trolling criterion. On the other hand, if the function Vessel Code,Section III, Division 1, 1974 Edition, including the of a component support is not required for a particu- 1976 Winter Addenda thereto.

I

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ports excluding snubbers, which are not addressed herein, should be constructed to the rules of Subsec or the latest accepted version I of Code Case

1644.

I

tion NF of Section III as supplemented by the follow ing: s c. Method 3. When the values of allowable

1. The classification of component supports stress or stress intensity at temperature for a material should, as .a minimum, be the same as that of the are listed in Section III, the ultimate tensile strength supported components. at temperature for that material may be approximated by the following expressions:

2. Values of Su at a temperature t should be esti Su = 4S or I 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 Su = 3Sm where support materials whose values of ultimate strength Su = ultimate tensile strength at temperature t to Su at temperature have been tabulated by their man be used to determine the service limits ufacturers in catalogs or other publications. Su = listed value of allowable stress at temperature t in Section III.

Su = Sur S , but not greater than Sur S.= listed value of allowable stress intensity at S~ur temperature t in Section III

where Su = ultimate tensile strength at temperature t to 3. The Code levels A and B service limits for com I ponent supports designed by linear elastic analysis

[ be used to determine the service limits Sur = ultimate tensile strength at room temperature tabulated in Section III, Appendix I, or the 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 latest accepted version 1 of Code Case 1644 S'u = ultimate tensile strength at temperature t tabulated by manufacturers in their catalogs of 5/6 Su is substituted for S,. Examples are shown below in a and

b. I

or other publications a. The tensile stress limit Ft for a net section as Sur = ultimate tensile strength at room temperature specified in XVII-221 1(a) of Section III should be tabulated by manufacturers in the same pub the smaller value of 0.6S, or 0.5Su at temperatbre.

lications. For net sections at pinholes in eye-bars, pin b. Method 2. This method applies to component connected plates, or built-up structural members, Ft support materials whose values of ultimate tensile as specified in XVII-221 1(b) should be the smaller strength at temperature have not been tabulated by value of 0.45S, or 0.375Su at temperature.

their manufacturers in any catalog or publication.

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

,where Many limits and equations for compression Su = ultimate tensile strength at temperature t to strength specified in Sections XVII-2214, XVII

be used to determine the service limits

2224, XVII-2225, XVII-2240, and XVII-2260 have Sur = ultimate tensile strength at room temperature built-in constants based on Young's Modulus of tabulated in Section III, Appendix I, or the 29,000 Ksi. For materials with Young's Modulus at latest accepted version of Code Case 1644 working temperatures substantially different from S, = minimum yield strength at temperature t 29,000 Ksi, these constants should be rederived with tabulated in Section III, Appendix I, or the the appropriate Young's Modulus unless the conser latest accepted version 1 of Code Case 1644 vatism of using these constants as specified can be Syr = minimum yield strength at room temper demonstrated.

ature, tabulated in Section III, Appendix I,

4. Component supports designed by linear elastic analysis may increase their level A or B service limits

, If the function of a component support is not required during a plant condition, the design limits of the support for that plant con according to the provisions of NF-323 1. 1(a), XVII

dition need not be satisfied, provided excessive deflection or fail 2110(a), and F-1370(a) of Section III. The increase ure of the support will not result in the loss of function of any of level A or B service limits provided by NF

other safety-related system. 3231. 1(a) is for stress range. The increase 'of level A

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or B service limits provided by F-1370(a) for level D Section III divided by 1.7 should not be exceeded for I service limits, should be the smaller factor of 2 or component supports designed by the experimental

1.167SI/Sy, if S, : 1.2S, or 1.4 if Su -- 1.2Sf, stress analysis method.

where S, and Su are component-support material properties at temperature. 6. Component supports subjected to the system mechanical loadings associated with the emergency However, all increases [i.e., those allowed by plant condition should be designed within the follow NF-3231.1(a), XVII-2110(a), and F-1370(a)] ing design limits except when the normal function of should always be limited by XVII-21 10(b) of Section the supported system is to prevent or mitigate the III. The critical buckling strengths defined by consequences of events associated with the emer XVII-21 10(b) of Section III should be calculated gency plant condition (at which time Regulatory using material properties at temperature. This in Position 8 applies): 4"'5 crease of level A or B service limits does not apply to limits for bolted connections. Any increase of limits a. The stress limits of XVII-2000 of Section M

for shear stresses above 1.5 times the Code level A and Regulatory Positions 3 and 4, increased accord service limits should be justified. ing to the provisions of XVII-21 10(a) of Section m and Regulatory Position 4 of this guide, should not If the increased service limit for stress range by be exceeded for component supports designed by the NF-3231.1(a) is more than 2S, or S., it should be linear elastic analysis method.

limited to the smaller value of 2S, or S,, unless it can be justified by a shakedown analysis. b. The emergency condition load rating of NF

3262.3 of Section III should not be exceeded for

5. Component supports subjected to the combined component supports designed by the load-rating loadings of system mechanical loadings associated method.

with (1) either (a) the Code design condition or (b)

the normal or upset plant conditions and (2) the vib c. The lower bound collapse load determined by ratory motion of the OBE should be designed within XVII-4200 adjusted according to the provision of the following limits: 4,5 XVII-4 110(a) of Section III should not be exceeded for component supports designed by the limit analysis a. The stress limits of XVII-2000 of Section III method.

and Regulatory Position 3 of this guide should not be exceeded for component supports designed by the d. The collapse load determined by 11-1400 of linear elastic analysis method. These stress limits Section III divided by 1.3 should not be exceeded for may be. increased according to the provisions of component supports designed by the experimental NF-3231.1(a) of Section III and Regulatory Position stress analysis method.

I 4 of this guide when effects resulting from constraints of free-end displacements are added to the loading combination.

7. Component supports subjected to the combined loadings of (1) the system mechanical loadings as sociated with the normal plant condition, (2) the vib b. The normal condition load rating or the upset ratory motion of the SSE, and (3) the dynamic system condition load rating of NF-3262.3 of Section III loadings associated with the faulted plant condition should not be exceeded for component supports de should be designed within the following limits except signed by the load-rating method. when the normal function of the supported system is to prevent or mitigate the consequences of events as c. The lower bound collapse load determined by sociated with the faulted plant condition (at which XVII-4200 adjusted according to the provision of time Regulatory Position 8 applies):

XVII-4 110(a) of Section III should not be exceeded for component supports designed by the limit analysis a. The stress limits of XVII-2000 of Section m method. and Regulatory Position 3 of this guide, increased ac cording to the provisions of F-1370(a) of Section III

d. The collapse load determined by 11-1400 of and Regulatory Position 4 of this guide, should not be exceeded for component supports designed by the

4 S ince component supports are deformation sensitive in the linear elastic analysis method.

performance of their service requirements, satisfying these criteria b. The smaller value of T.L. x 2S/S, or T.L. x 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.

0.7S/Su should not be exceeded, where T.L., S, and

.Su are definedl according to NF.3262.1 of Section.

.I.

' Since the design of component supports is an integral part of the mI, and Su is the minimum ultimate tensile strength design of the system and the design of the component, the de of the material at service temperature for component signer must make sure that methods used for the analysis of the supports designed by the load-rating method.

system, component, and component support are compatible (see Table F-1322.2-1 in Appendix F of Section I1). Large deforma c. The lower bound collapse load determined by tions in the system or components should be considered in the XVII-4200 adjusted according to the provision of design of component supports. F-1370(b) of Section III should not be exceeded for

1.124-5

component supports designed by the limit analysis

D. IMPLEMENTATION

method.

d. The collapse load determined by 11-1400 ad justed according to the provision of F-1370(b) of The purpose of this section is to provide guidance Section III should not be exceeded for component to applicants and licensees regarding the NRC staff's supports designed by the experimental stress analysis plans for using this regulatory guide.

method.

8. Component supports in systems whose normal Except in those cases in which the applicant pro function i' to prevent or mitigate the consequences of poses an acceptable alternative method for complying events associated with an emergency or faulted plant with the specified portions of the Commission's regu condition should be designed within the limits de lations, the methocf described herein will be used in scribed in Regulatory Position 5 or other justifiable the evaluation of submittals for construction permit

'limits provided by the Code. These limits should be applications docketed after January 10, 1978. If an defined by the Design Specificatioh and stated in the applicant wishes to use this regulatory guide in uc PSAR, such that the function of the supported system veloping submittals for construction permit applica will be maintained when they are subjected to the tions docketed on or before January 10, 1978, the loading combinations described in Regulatory pertinent portions of the application will be evaluated'

Positions 6 and 7. on the basis of this guide.

J*

1.124-6


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