Regulatory Guide 1.124

Service Limits & Loading Combinations for Class 1 Linear-Type Component Supports

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Issue date:	01/31/1978
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RG-1.124 Rev 1
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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

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.

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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.

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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.

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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

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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.

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