Regulatory Guide 1.124

Design Limits and Loading Combinations for Class 1 Linear-Type Component Supports

ML13350A273
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Issue date:	11/30/1976
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RG-1.124
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.a..: ..... .-,- .... * .,. .:, U.S. NUCLEAR REGULATORY

COMMISSION

November 1976 REGULATORY

GU`DE OFFICE OF STANDARDS

DEVELOPMENT

REGULATORY

GUIDE 1.124 DESIGN LIMITS AND LOADING COMBINATIONS

FOR CLASS 1 LINEAR-TYPE

COMPONENT

SUPPORTS[*

A. INTRODUCTION

General Design Criterion 2, "Design Bases for Protec- NF-1122 and NA-2134 of Section Ill of the ASME ion Against Natural Phenomena," of Appendix A, Boiler and Pressure Vessel Code imply that the classifica-

'General Design Criteria for Nuclear Power Plants," to tion of component supports slhould, as a minimum, be 0 CFR Part 50, "Licensing of Production and Utiliza- the same as that of the supported componets.

This ion Facilities," requires, in part, that the design bases should be considered as a requirement.

This guide or structures, systems, and components important to delineates design limits and loading combinations, in afety reflect appropriate combinations of the effects of addition to supplerientary criteria, for ASME Class I ormal and accident conditions with the effects of linear-type componmi.t supports as defined by NF.1213 atural phenomena such as earthquakes.

The failure of of Section Ill. Snubbers uistalled for protection against aembers designed to support safety-related components seismic or dynamic loadings of other origins are not ould jeopardize the ability of the supported component addressed in this guide.o perform its safety function.*Pu sit ..-, on. .NF ad Ap e cioI This guide delineates acceptable design limits and Subsction NF and Appendix XVII of Section III ppropriate combinations of loadings associated waith ..-' mpernit the use of four methods for the design of Class I ormal operation, postulated accidents, and specified liniear-type component supports:

linear elastic analysis.pismic events for the design of Class load rating, experimental stress analysis, and limit anentsupportas defined in' ..cio N-pe -analysis.

For each method, the ASME Code delineatessupportss SOlno n;ubsection NFP of "-.. , .,.. .,ction IlI of the American Society of M.echanic., allowable stress or loading limits for various Code ngincers (ASME) Boiler and Pressure Vessel Code. This, operating condition categories as defined by NF.3113 of....... aSection III so that these limits can be used in con-ide applies to light-water-cooled reactors. " " junction with the resultant loadings or stresses from the appropriate plant conditions.

However, the Codc's

B. DISCUSSION

..`.

operating condition categories are simply component Load-be members 'd " support design limits; they are not necessarily related to Loa-baring em rsclasslif.

as component sup-. df orts are essential to th safety of nuclear power fined plant conditions.

Since the Code does not ants sine theysrentain como nents" i paceaurig ther specify loading combinations, guidance is required to ants since they retain companents In place during the provide a consistent basis for the design of compoitent)adings associated with normal, upset, and emergency supports..0!ant counuiions unuer. me suess of specifieu seismic ents, thereby permitting system components to func-n properly.

They also prevent excessive component ovement during the loadings associated with a faulted pnt condition combined with the specified seismic ent, thus helping to mitigate the consequences of stem damage. Component supports are deformation nsitivc because large deformations in thenm may signifi-atly change the stress distribution in the support fstem and its supported components.

The component supports considered in this guide are located within containment and are therefore assumed to be protected against loadings froin natural phenoin-ena or man-made 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.

• 0 USNRC REGULATORY

GUIDES Pguleory Guide* are Issued to describe and make oawilahl to the public a rthod acceptaeble ta the NRC stall of Iemplamsnting traincc pPAs of the tlmmslaion'i requlmitlons.

to delneate tachpiques used by the stilt in vlmu.n9 Sptecific probiem's a' co-'atuted accidents, ot to provide quldanel to eppli-Ito. iegutetor Guids are not substitutes tor reguletions.

and con-,liance h h then I ncot required, Methods and ssitmtas difsroot tnom triosi %tr cut In guides will be ccuptaible it they provide a beasi Io, the lCndhg ruuUiaite tO isuafnceilOof inIotuence of a l or liercense theth

1",ent2 and suggestions fur improwqnients In theseu fl-de, are incouraoed-s 0,4 5', efl guides will be ivied., s to *ccuotnnousat coat.*'tnd it %tflct new information or eApartence.

H'eot, or comrmtent on" ' -i-d within ebout two ninnih$s After its isoasnee.

will Dc par.a eValtuating the naed tot an aur;V rov.vion.1. Power Reactors 2. Rauaatch and Teot Reectot, 3. Fuels and 6.1stetoe Factiltjia

4. Environmental and S;tlni 5. MuArletIl end Plant Proltctiun S. Products 7. Tianipott iion 1. Occupational Health 9. Antitrust Review to. en.eral Comments sho-id be sent to the Secretary of the Commlssion.

U.S. Nuclear Regulatory Commission, Washington, D.C. 20566. Attention:

Docketing and Servi.e Soction.The guides ere Issued In the following ten braid disialone:

Corolea of pubilihed gvilet mme be obtained by written request irdlcatitg l1.4 divisiort deuied to -no U S. Nuclear Reguiatosry Commistlon.

Washington.

D.C.ME&. Attention;

D;rector.

Office of Standards Develorment.

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1. Design by Linear Elastic Analysis a. S, at Temperature.

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

Design limits derived from either material property alone may not be sufficient to provide a consistent design margin. This is recognized by Section HI, since XVU-221 l(a) of Section I1l defines the allowable stress in tension on a net section as the smaller value of 0.6Sy and O.5Su. To alleviate the lack of defined values of S, at temperatures above room temperature and to provide a safe design margin, an interim method is given in this guide to obtain values of Su at temperature.

While XVII-221 1(a) specifies allowable tensile stress in terms of both Sy and Su, the rest of XVII-2000 specifies other allowable design limits in terms of Sy only. This does not maintain a consistent design margin for those design limits related only to material proper-ties. Modifications similar to XVII-2211(a)

should be employed for all those design limits.b. Increase of Design Limits. While NF-3231.1(a), XVII-21 10(a), and F-1370(a)

of Section III all permit the increase of allowable stresses under various loading conditions, XVII-21 10(b) limits the increase so that two-thirds of the critical buckling stress for compression and compression flange members is not excee:. d, and the increase allowed by NF-3231.1(a)

is for stres- range.Critical buckling stresses with normal design margins are derived in XVII-2200

of Section Ill. Since buckling prevents "shakedown" in a load-bearing member, XVII-2110(b) must be regarded as controlling.

Also, buckling is the result of the interaction of the configuration of the load-bearing member and its material properties (i.e., elastic modulus E and minimum yield strength Sy).Because both of these material properties change with temperature, the critical buckling stresses should be calculated with the values of E and Sy of the component support material at temperature.

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

they also change with the size of the bolt. For this reason, the increases permitted by NF-3231.1, XVII-2110(a), and F-1370(a)

of Section Ill are not directly applicable to allowable shear stresses and allowable stresses for bolts and bolted connections.

The range of primary plus secondary stresses should be limited to 2Sy but not more than Su to ensure shakedown.

For many allowable stresses above the value of 0.6S%.. the increase permitted by NF-323 1.1 (a) will be above t'he value of 2Sx and will thus violate the normal shakedown range. A shakedown analysis is necessary to justify the increase of stress above 2Sy or SU .For the linear elastic analysis method, F-1370(a)

of Section II permits increase of tension design limits for the faulted operating condition category by a variable factor which is the smaller value of i.2Sy/Ft or 0.7S 1 ,/Ft. Depending on whether the section considered is a net section at pinholes in eyebars, pin-connected plates, or built-up structural members, F1 may assume the smaller value of 0.45Sy or 0.3 7 5 Su (as recom-mended by this guide for a net section at pinholes, etc.)or the smaller value of 0.6Sy or O.5Su (for a net section without pinholes, etc.). Thus greater values of the factor may be obtained for sections at pinholes, which does not account for local stress and is not consistent with NF-3231.1 and XVII-2110(a)

6f Section I11. A pro-cedure to correct this factor is provided in this guide.2. Design by Load Rating When load-rating methods are used, Subsection NF and Appendix F of Section Ill do not provide a faulted condition load rating. This guide provides an interim method for the determination of faulted condition load rating.3. Design by Experimental Stress Analysis While the collapse load for the experimental stress analysis method is defined by 11-1430 in Appendix ii of Section II, the design limits for experimental stress analysis for various operating condition categories are not delineated.

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

A complete and consistent design is possible only when system/component/component-support interaction is properly considered.

When all three are evaluated on an elastic basis, the interaction is usually valid because individual deformations are small. However, if plastic analysis methods are employed in the design process, large deformations that would result in substantially different stress distributions may occur.For the evaluation of the faulted operating condition category, Appendix F of Section IlI permits the use of plastic analysis methods in certain acceptable combina-tions for all three elements.

These acceptable combina-tions are selected on the assumption that component supports are more deformation sensitive (i.e., their deformation in general will have a large effect on the Stre Simd but ani met for the avoi S. I Ii natib take norn ditic ECC prop for cond ideni Si AISC built-steel indisc als a matei substc equat mater 6. De Sin load-b Sectio functi Design Onth suppol the str tions i the de-7. Del Des, NF-311 Vessel I Eme tions th Faul associat probabi"" Norn in the c 1.124-2 stress distribution in the system SK Since large deformations always a ononai( ( bution, care should be exercised Lary to ' analysis method is used in the )methodology combination.

This is for identifying buckling or instab 0(a) of the change of geometry should be nits for avoid erroneous results, ariable/Ft or 5. Function of Supported System ridered and its components).

ffect the stress ditri-even if tht, plastic Appendix F-approved especially important ility problems where taken into account to'I:n n nected assume.recom-les, etc.): section le factor:oes not nt with A pro-jide.:tion NF a faulted i interim tion load.tal stress idix II of tal stress iodes are by tka (In selecting design limits for different loading combi-.nations, the function of the supported system must be taken into account. To ensure that systems whose hormal safety-related function occurs during plant con-ditions other than normal or upset (e.g., the function of ECCS during faulted plant conditions)

will operate properly regardless of plant condition, the design limits for the design, normal, and upset plant operating condition categories of Subsection NF (which are identical)

should be used.Since Appendix XVII deriyed all equations from AISC rules and many AISC.compressior equations have built-in constants based on mechanical properties of steel at room temperature, to use these equations indiscriminately for all NF and Code Case 1644 materi-als at all temperatures would not be prudent. 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 Since component supports are deformation-sensitive load-bearing elements, satisfying the design limits of Section III will not automatically ensure their proper function.

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

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

7. Definitions Design Condition.

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

Those operating condi-tions that have a low probability of occurrence.

refueling, and shutdown tither than upset, emergency, or faulted plant conditions.

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

Categories of design limits for component supports as defined by NF-3113 of Section [i1 of the ASME Code.Plant Conditions.

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

Safe Shutdown Earthquake (SSE). As defined in Appendix A to 10 CFR Part 100.Specified Seismic Events. Operating Basis Earth-quake and Safe Shutdown Earthquake.

System Mechanical Loadings.

The static and dynamic loadings that are developed by the system operating parameters, including deadweight, pressure, and other non-self-limiting loadings, but excluding effects resulting from constraints of free-end movements and thermal and peak stresses.Ultimate Tensile Strength.

Material property based on engineering stress-strain relationship.

Upset Plant Conditions.

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

C. REGULATORY

POSITION ASME Codel Class I linear-type component supports excluding snubbers, which are not addressed herein, should be constructed to the rules of Subsection NF of Section [If as supplemented by the following:

2 1. The classification of component supports should, as a minimum, be the same as that of the supported components.

2. Values of Su at a temperature t should be estimated by either Method I or Method 2 on an interim basis until Section III includes such values.a. Method 1. This method applies to component support materials whose values of ultimate strength Su at temperature have been tabulated by their manufac-turers in catalogs or other publications.

lAmerican Society of Mechanical Engineers Boiler and Pressure Vessel Code, Section Ill. Division 1, 1974 Edition, including the 1974 Winte; Addenda thereto.21i the function of a component support Is not required during a plant condition, the design limits of the support for that plant condition need not be satisfied, provided excessive deflection o: failure of the support will not result in the loss of function of any other safety-related system.ýgpal part nents. A ly when action is ted on an I because if plastic Iprocess, stantially condition the use of combina-.combina.urnj~ent S*ie Ier MLt on the Faulted Plant Condition.

Those operating conditions associated with postulated events of extremely low probability.

Normal Plant .condition.

Those operating conditions in the course of system startup, operation, hot standby, 1.124-3 Su Sur .but not greater than Sur where Su = ultimate tensile strength at temperature t to be used to determine the design limits Sur= ultimate tensile strength at room temperature tabulated in Section IN, Appendix i, or Code Case 1644-4 Sý =ultimate tensile strength at temperature t tab-ulated by manufacturers in their catalogs or other publications

• SLr .ultimate tensile strength at room temperature tabulated by manufacturers in the same publi-cations.b. Method 2. This method applies to component support materials whose values of ultimate tensile strength at temperature have not been tabulated by their manufacturers in any catalog or publication.

SU =Sur S Syr where Su = ultimate tensile strength at temperature t to be used to determine the design limits Sur = ultimate tensile strength at room temperature tabulated in Section 111, Appendix I, or Code Case 1644-4 Sy = minimum yield strength at temperature t tab-ulated in Section III, Appendix I, or Code Case 1644-4 Syr minimum yield strength at room temperature, tabulated in Section III, Appendix 1, or Code Case 1644-4.3. The design limits for component supports de-signed by linear elastic analysis for the design condition and the normal or upset operating condition categories, 3 when these limits are related to Sy alone, should meet the appropriate stress limits of Appendix XVII of Section Ill but should not exceed the limit specified when the value of 5/6 Su is substituted for Sy. Examples are shown .below in a and b. The bearing stress limit specified by XVII-2461.2 should be modified by c (below).3 Code operating condition categories only specify design limits. They are not necessarily related to corresponding plant conditions.

a. The tensile stress limit Ft for a net section as specified in XVII-2211(a)

of Section Ill should be the smaller value of 0.6S, or O.5S at temperature.

For net sections at pinholes in eye-bars, pin-connected plates, or built-up structural members, F, as specified in XVII-2211(b) should be the smaller value of 0.45Sy or 0.375SU at temperature.

b. The shear stress limit F. for a gross section as specified in XVII.2212 of Section 111 should be the smaller value of OASy ir 0.33S, at temperature.

c. The bearing stress limit F, on the projected area of bolts in bearing-type connections as specified in XVf.U-2461.2 of Section I1l should be the smaller value of 1.35Sy or 0.9Su at temperature, where Sy and S, are material properties of the connected part.Many Lmits and equations for compression strength specified in Sections XVII-2214, X'" 2224, XVII-2225, XVII-2240, and XVII-2260

have bi.-.: -in constants based on Young's Modulus of 29,000 Ks: Ftr materials with Young's Mlodulus at working temperatures substantially different from 29,000 Ksi, these constants sihould be re-derived with tie appropriate Young's Modulus unless conservatism .of using these constants as specified can be demonstrated.

4. Component supports designed by linear elastic analysis may increas, titeir design limits according to the provisions of NF-3231.1(a), XVII-2110(a), and F-1370(a)

of Section IlI. The increase of design limits provided by NF-3231.l(a)

is for stress range. The increase of design limits provided by F-1370(a)

for the faulted operating condition category should be the smaller factor of 2 or 1.1 6 7Su/Sy, if Su > 1.2S., or 1.A if Su < 1.2 S y , where Sy and Su are component-support material properties at temperature.

7)However, all increases

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

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

This increase of design limits does not apply to design limits for bolted connections and shear stresses.

Any increase of design limits for bolted con-nections and shear stresses should be justified.

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

is more than 2 Sy or Su, it should be limited to the smaller value of 2Sy or Su unless it can be justified by a shakedown analysis.S. Component supports subjected to the most ad-verse combination of the vibratory motion of the OBE 1~~1.124-4-A

and system mechanical loadings 4 associated with either the Code design condition or the normal or upset plant conditions should be designed within the following limits: 5.6 a. The stress limits of XVII-2000

of Section ifl anf Regulatory Position 3 of this guide should not be exceeded for component supports designed by. the linear elastic analysis method. These stress limits may be increased according to the provisions of NF-323 L.1(a) of Section I11 and Regulatory Position 4 of this guide when effects resulting from constraints of free-end mechanical and seismic displacements are added to the loading combination.

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

adjusted according to the provision of XVII-41 10(a) of Section III should not be exceeded for component supports designed by the limit analysis method.d. The collapse load determined by 11-1400 of Section III divided by 1.7 should not be exceeded for component supports designed by the experimental stress analysis method.6. Component supports subjected to the most ad-verse combination of system mechanical loadings 4 asso-ciated with the emergency plant condition should be designed within the following design limits except when their normal function is required during the emergency plant condition (at which time Regulatory Position 8 applies):S.

6 a. The stress limits of XVII-2000

of Section IlI and Regulatory Positions

3 and 4, increased according to the provisions of XVII-2110(a)

of Section Ill and Regulatory Position 4 of this guide, should not be exceeded for component supports designed by the linear elastic analysis method.* 4 System mechanical loadings include all non-self-Limiting loadings and do not include loadings resulting from constraints of frec-end displacements and thermal or peak stresses.S$ince component supports are deforma'ion sensitive in the performance of their service requirements, satisfying these criteria does not ensure that their functional requirements will 6e futrlibd.

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

6 Since the design of component supports is an integral part of the design of the system and the design of the component, the designer must make sure that methods used for the analysis of the system, component, and component support are compatible (see Table F-1322.2-1 in Appendix F of Section ill). Large deformations in the system or compohnnts should be considered in the design of component supports.b. The emergency condition load rating of NF-3262.3 of Section [it should not be exceeded for component supports designed by the load-rating method.c. The lower bound collapse load determined by XVII-4200

adjusted according to the provision of XV 1-4110(a)

of Section Ill should not be exceeded for component supports designed by the limit analysis method.d. The collapse load detcrmined by 11-1400 of Section III divided by 1.3 should not be exceeded for component supports designed by the experimental stress analysis method.7. Component supports subjected to the most ad-verse combination of the vibratory motion of &S-E and system mechanical loadings 4 associated simultaneously with the faulted plant condition and the normal plant condition should be designed within the following design limits except when their normal function is required during the faulted plant condition (at which time Regulatory Position g applies): 3.5., 6 a. The stress limits of XVII-2000of Section III and Regulatory Position 3 of this guide, increased according to the provisions of F-1370(a)

of Section III and Regulatory Position 4 of this guide, should not be exceeded for component supports designed by the linear elastic analysis method.b. The smaller value of T.L. X 2S/S, or T.L. X 0.TSu/Su should not be exceeded, where T.L., S, and S, are defined according to NF-3262.1 of Section l1l, and Su is the minimum ultimate tensile strength of the material at service temperature for component supports designed by the load-rating method.c. The lower bound collapse load determined by XVII-4200

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

of Section III should not be exceeded for component supports designed by the limit analysis method.d. The collapse load determined by 11-1400 ad-justed according to the provision of F-1370(b)

of Section III should not be exceeded for component supports designed by the experimental stress analysis method.8. Component supports whose normal function is required during an emergency or faulted plant condition and that are subjected to loading combinations described in Regulatory Positions

6 and 7 should be designed within the design limits described in Regulatory Position 5 or other justifiable design limits.1.124-5

D. IMPLEMENTATION

The purpose of this section is t,, provide guidance to applicants and liceiisces regarding tile NRC staff's plans for using this regulatory guide.Except in those cases in which the applicant proposes an acceptable alternative method for complying with the specified porlions of the Commission's regulations, the method described herein will be used in the evaluation of submittals for construction permit applications dock-eted after JAly 1, 1977. If an applicant wishes to use this regulatory guide in developing submittals for construction permit applications docketed on or before July 1. 1977, the pertinent portions of the application will be evaluated on the basis of this guide.N.)I~1.124-6