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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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 dx.V*ofS cioI

This guide delineates acceptable design limits and Subsction NF and Appendix XVII of Section III

ppropriate combinations of loadings associated waith ..-' mpernitthe use of four methods for the design of Class I

ormal operation, postulated accidents, and specified liniear-type component supports: linear elastic analysis.

.0 pismic

• omponn events anentsupportas for supportss defined in'

,ction IlI of the American Society of M.echanic.,

the design of Class

..

SOlno n;ubsection cio N-pe NFP of load rating, experimental stress analysis, and limit

"-..-analysis. For each method, , . the,.. ASME Code delineates 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 Loa-baring members em rsclasslif. 'd ;as "component sup-. support df design limits; they are not necessarily related to

! orts are essential to th safety of nuclear power ants sine theysrentain como nents"i paceaurig ther ants since they retain companents In place during the

)adings associated with normal, upset, and emergency ant counuiions unuer. me suess of specifieu seismic ents, thereby permitting system components to func- n properly. They also prevent excessive component ovement during combined the loadings associated with a seismic faulted fined plant conditions. Since the Code does not specify loading combinations, guidance is required to provide a consistent basis for the design of compoitent supports.

The component supports considered in this guide are located within containment and are therefore assumed pnt condition with the specified to be protected against loadings froin natural phenoin- ent, thus helping to mitigate the consequences of ena or man-made hazards other than the specified stem damage. Component supports are deformation seismic events. Thus only the specified seismic events nsitivc because large deformations in thenm may signifi- need to be considered in combination with the loadings atly change the stress distribution in the support associated with plant conditions to develop appropriate fstem and its supported components. loading combinations.

USNRC REGULATORY GUIDES Comments sho-id be sent to the Secretary of the Commlssion. U.S. Nuclear Regulatory Commission, Washington, D.C. 20566. Attention: Docketing and Pguleory Guide* are Issued to describe and make oawilahl to the public Servi.e Soction.

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a eValtuating the naed tot an aur;Vrov.vion. divisiort deuied to -no U S. Nuclear Reguiatosry Commistlon. Washington. D.C.

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1. Design by Linear Elastic Analysis shakedown. For many allowable stresses above the value Stre of 0.6S%.. the increase permitted by NF-323 1.1 (a) will be Simd a. S, at Temperature. When the linear elastic anal- above t'he value of 2Sx and will thus violate the normal but ysis method is used to design Class I linear-type shakedown range. A shakedown analysis is necessary to ani component supports, material properties are given by justify the increase of stress above 2Sy or SU . met Tables 1-13.1 and 1-13.3 in Appendix I of Section III and for Tables 3 and 4 in Code Case 1644-4. These tables list For the linear elastic analysis method, F-1370(a) of the values for the minimum yield strength Sy at various Section II permits increase of tension design limits for avoi temperatures but only room temperature values for the the faulted operating condition category by a variable ultimate tensile strength Su. At room temperature, Sy factor which is the smaller value of i.2Sy/Ft or S. I

varies from 50% to 87% of Su for component su-port 0.7S1,/Ft. Depending on whether the section considered materials. is a net section at pinholes in eyebars, pin-connected Ii plates, or built-up structural members, F1 may assume natib Design limits derived from either material property the smaller value of 0.45Sy or 0 .3 7 5 Su (as recom- take alone may not be sufficient to provide a consistent mended by this guide for a net section at pinholes, etc.) norn design margin. This is recognized by Section HI, since or the smaller value of 0.6Sy or O.5Su (for a net section ditic XVU-221 l(a) of Section I1l defines the allowable stress without pinholes, etc.). Thus greater values of the factor ECC

in tension on a net section as the smaller value of 0.6Sy may be obtained for sections at pinholes, which does not prop and O.5Su. To alleviate the lack of defined values of S, account for local stress and is not consistent with for at temperatures above room temperature and to provide NF-3231.1 and XVII-2110(a) 6f Section I11. A pro- cond a safe design margin, an interim method is given in this cedure to correct this factor is provided in this guide. ideni guide to obtain values of Su at temperature.

2. Design by Load Rating Si While XVII-221 1(a) specifies allowable tensile stress AISC

in terms of both Sy and Su, the rest of XVII-2000 When load-rating methods are used, Subsection NF built- specifies other allowable design limits in terms of Sy and Appendix F of Section Ill do not provide a faulted steel only. This does not maintain a consistent design margin condition load rating. This guide provides an interim indisc for those design limits related only to material proper- method for the determination of faulted condition load als a ties. Modifications similar to XVII-2211(a) should be rating. matei employed for all those design limit

s. substc

3. Design by Experimental Stress Analysis equat b. Increase of Design Limits. While NF-3231.1(a), mater XVII-21 10(a), and F-1370(a) of Section III all permit While the collapse load for the experimental stress the increase of allowable stresses under various loading analysis method is defined by 11-1430 in Appendix ii of 6. De conditions, XVII-21 10(b) limits the increase so that Section II, the design limits for experimental stress two-thirds of the critical buckling stress for compression analysis for various operating condition categories are Sin and compression flange members is not excee:. d, and not delineated. This deficiency is remedied by the load-b the increase allowed by NF-3231.1(a) is for stres- range. method described in this guide. Sectio Critical buckling stresses with normal design margins are functi derived in XVII-2200 of Section Ill. Since buckling 4. Large Deformation Design prevents "shakedown" in a load-bearing member, XVII- Onth

2110(b) must be regarded as controlling. Also, buckling The design of component supports is an integral part suppol is the result of the interaction of the configuration of of the design of the system and its components. A the str the load-bearing member and its material properties (i.e., complete and consistent design is possible only when tions i elastic modulus E and minimum yield strength Sy). system/component/component-support interaction is the de- Because both of these material properties change with properly considered. When all three are evaluated on an temperature, the critical buckling stresses should be elastic basis, the interaction is usually valid because 7. Del calculated with the values of E and Sy of the component individual deformations are small. However, if plastic support material at temperature. Allowable design limits analysis methods are employed in the design process, Des, for bolted connections are derived from tensile and shear large deformations that would result in substantially NF-311 stress limits and their nonlinear interaction; they also different stress distributions may occu

r. Vessel I

change with the size of the bolt. For this reason, the increases permitted by NF-3231.1, XVII-2110(a), and For the evaluation of the faulted operating condition Eme F-1370(a) of Section Ill are not directly applicable to tions th category, Appendix F of Section IlI permits the use of allowable shear stresses and allowable stresses for bolts plastic analysis methods in certain acceptable combina- Faul and bolted connections. tions for all three elements. These acceptable combina- associat tions are selected on the assumption that component probabi The range of primary plus secondary stresses should supports are more deformation sensitive (i.e., their be limited to 2Sy but not more than Su to ensure deformation in general will have a large effect on the "" Norn in the c

1.124-2

stress distribution in the system and its components). refueling, and shutdown tither than upset, emergency, or SK Since large deformations always affect the stress ditri- faulted plant conditions.

ononai( ( bution, care should be exercised even if tht, plastic Lary to ' analysis method is used in the )Appendix F-approved Operating Appendix A toBasis

10 CFR Part 100. (OBE). As defined in Earthquake methodology combination. This is especially important for identifying buckling or instab ility problems where Operating Condition Categorie

s. Categories of design

'I0(a) of the change of geometry should be taken into account to limits for component supports as defined by NF-3113 of nits for avoid erroneous results, Section [i1 of the ASME Code.

n ariable

5. Function of Supported System Plant Conditions. Operating conditions of the plant

/Ft or categorized as normal, upset, emergency, and faulted ridered In selecting design limits for different loading combi- plant conditions.

nnected assume. .nations, the function of the supported system must be Safe Shutdown Earthquake (SSE). As defined in recom- taken into account. To ensure that systems whose Appendix A to 10 CFR Part 100.

les, etc.) hormal safety-related function occurs during plant con- ditions other than normal or upset (e.g., the function of Specified Seismic Events. Operating Basis Earth-

section ECCS during faulted plant conditions) will operate quake and Safe Shutdown Earthquake.

le factor

oes not properly regardless of plant condition, the design limits System MechanicalLoadings. The static and dynamic nt with for the design, normal, and upset plant operating loadings that are developed by the system operating A pro- condition categories of Subsection NF (which are parameters, including deadweight, pressure, and other jide. identical) should be used. non-self-limiting loadings, but excluding effects resulting from constraints of free-end movements and thermal and Since Appendix XVII deriyed all equations from peak stresses.

AISC rules and many AISC.compressior equations have built-in constants based on mechanical properties of Ultimate Tensile Strength. Material property based

tion NF

steel at room temperature, to use these equations on engineering stress-strain relationship.

a faulted i interim indiscriminately for all NF and Code Case 1644 materi- Upset Plant Conditions. Those deviations from the tion load als at all temperatures would not be prudent. For normal plant condition that have a high probability of materials other than steel and working temperatures occurrence.

substantially different from room temperature, these

( equations should be rederived with the appropriate material propertie

C. REGULATORY POSITION

.tal stress ASME Codel Class I linear-type component supports idix II of 6. Deformation Limits excluding snubbers, which are not addressed herein, tal stress should be constructed to the rules of Subsection NF of iodes are Since component supports are deformation-sensitive Section [If as supplemented by the following: 2 by tka load-bearing elements, satisfying the design limits of Section III will not automatically ensure their proper 1. The classification of component supports should, function. Deformation limits, if specified by the Code as a minimum, be the same as that of the supported Design Specification, may be the controlling criterion. components.

On the other hand, if the function of a component support is not required for a particular plant condition, 2. Values of Su at a temperature t should be

ýgpal part the stresses or loads resulting from the loading combina- nents. A estimated by either Method I or Method 2 on an interim ly when tions under that plant condition do not need to satisfy basis until Section III includes such values.

action is the design limits for that plant condition.

ted on an a. Method 1. This method applies to component I because 7. Definitions support materials whose values of ultimate strength Su if plastic at temperature have been tabulated by their manufac- Iprocess, Design Condition. The loading condition defined by turers in catalogs or other publications.

stantially NF-3112 of Section III of the ASME Boiler and Pressure Vessel Code.

Emergency Plant Condition. Those operating condi- condition tions that have a low probability of occurrence. lAmerican Society of Mechanical Engineers Boiler and the use of Pressure Vessel Code, Section Ill. Division 1, 1974 Edition, combina-. Faulted Plant Condition. Those operating conditions including the 1974 Winte; Addenda thereto.

combina. associated with postulated events of extremely low 21i the function of a component support Is not required urnj~ent probability. during a plant condition, the design limits of the support for that S*ie Ier plant condition need not be satisfied, provided excessive Normal Plant.condition. Those operating conditions deflection o: failure of the support will not result in the loss of MLton the function of any other safety-related system.

in the course of system startup, operation, hot standby,

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a. The tensile stress limit Ft for a net section as Su Sur . but not greater than Sur 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 where built-up structural members, F, as specified in XVII-

2211(b) should be the smaller value of 0.45Sy or Su = ultimate tensile strength at temperature t to be 0.375SU at temperature.

used to determine the design limits Sur= ultimate tensile strength at room temperature b. The shear stress limit F. for a gross section as specified in XVII.2212 of Section 111 should be the tabulated in Section IN, Appendix i, or Code smaller value of OASy ir 0.33S, at temperature.

Case 1644-4 Sý =ultimate tensile strength at temperature t tab- c. The bearing stress limit F, on the projected area ulated by manufacturers in their catalogs or of bolts in bearing-type connections as specified in XVf.U-

other publications 2461.2 of Section I1l should be the smaller value of

1.35Sy or 0.9Su at temperature, where Sy and S, are

• SLr .ultimate tensile strength at room temperature material properties of the connected part.

tabulated by manufacturers in the same publi- cations.

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 b. Method 2. This method applies to component on Young's Modulus of 29,000 Ks: Ftr materials with support materials whose values of ultimate tensile Young's Mlodulus at working temperatures substantially strength at temperature have not been tabulated by their different from 29,000 Ksi, these constants sihould be re- manufacturers in any catalog or publication. derived with tie appropriate Young's Modulus unless conservatism .of using these constants as specified can be SU =Sur S demonstrated.

Syr where 4. Component supports designed by linear elastic Su = ultimate tensile strength at temperature t to be 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

7)

used to determine the design limits provided by NF-3231.l(a) is for stress range. The Sur = ultimate tensile strength at room temperature increase of design limits provided by F-1370(a) for the tabulated in Section 111, Appendix I, or Code faulted operating condition category should be the Case 1644-4 smaller factor of 2 or 1.16 7Su/Sy, if Su > 1.2S., or 1.A

if Su < 1.2S y , where Sy and Su are component-support Sy = minimum yield strength at temperature t tab- material properties at temperature.

ulated in Section III, Appendix I, or Code Case

1644-4 However, all increases [i.e., those allowed by Syr minimum yield strength at room temperature, NF-3231.1(a), XVII.2110(a), and F-1370(a)] should tabulated in Section III, Appendix 1, or Code always be limited by XVII-21 10(b) of Section III. The Case 1644-4. critical buckling strengths defined by XVII-21 10(b) of Section III should be calculated using material properties

3. The design limits for component supports de- at temperature. This increase of design limits does not signed by linear elastic analysis for the design condition apply to design limits for bolted connections and shear

3 and the normal or upset operating condition categories, stresses. Any increase of design limits for bolted con- when these limits are related to Sy alone, should meet nections and shear stresses should be justified.

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 If the increased design limit for stress range by are shown .below in a and b. The bearing stress limit NF-3231.1(a) is more than 2 Sy or Su, it should be specified by XVII-2461.2 should be modified by c limited to the smaller value of 2Sy or Su unless it can be (below). justified by a shakedown analysis.

3 Code operating condition categories only specify design S. Component supports subjected to the most ad- limits. They are not necessarily related to corresponding plant conditions. verse combination of the vibratory motion of the OBE 1~~

1.124-4

- A

and system mechanical loadings 4 associated with either b. The emergency condition load rating of the Code design condition or the normal or upset plant NF-3262.3 of Section [it should not be exceeded for conditions should be designed within the following component supports designed by the load-rating limits: 5. 6 method.

a. The stress limits of XVII-2000 of Section ifl anf Regulatory Position 3 of this guide should not be c. The lower bound collapse load determined by exceeded for component supports designed by. the linear XVII-4200 adjusted according to the provision of elastic analysis method. These stress limits may be XV 1-4110(a) of Section Ill should not be exceeded for increased according to the provisions of NF-323 L.1(a) of component supports designed by the limit analysis Section I11 and Regulatory Position 4 of this guide when method.

effects resulting from constraints of free-end mechanical and seismic displacements are added to the loading d. The collapse load detcrmined by 11-1400 of combination. Section III divided by 1.3 should not be exceeded for component supports designed by the experimental stress b. The normal condition load rating or the upset analysis method.

condition load rating of NF-3262.3 of Section Ill should not be exceeded for component supports designed by the load-rating method. 7. Component supports subjected to the most ad- verse combination of the vibratory motion of &S-Eand c. The lower bound collapse load determined by system mechanical loadings 4 associated simultaneously XVII-4200 adjusted according to the provision of with the faulted plant condition and the normal plant XVII-41 10(a) of Section III should not be exceeded for condition should be designed within the following design component supports designed by the limit analysis limits except when their normal function is required method. during the faulted plant condition (at which time Regulatory Position g applies): 3 . 5.,6 d. The collapse load determined by 11-1400 of Section III divided by 1.7 should not be exceeded for a. The stress limits of XVII-2000of Section III

component supports designed by the experimental stress and Regulatory Position 3 of this guide, increased analysis method. according to the provisions of F-1370(a) of Section III

and Regulatory Position 4 of this guide, should not be

6. Component supports subjected to the most ad- exceeded for component supports designed by the linear verse combination of system mechanical loadings4 asso- elastic analysis method.

ciated with the emergency plant condition should be designed within the following design limits except when b. The smaller value of T.L. X 2S/S, or their normal function is required during the emergency T.L. X 0.TSu/Su should not be exceeded, where T.L., S,

plant condition (at which time Regulatory Position 8 and S, are defined according to NF-3262.1 of Section applies):S. 6 l1l, and Su is the minimum ultimate tensile strength of the material at service temperature for component a. The stress limits of XVII-2000 of Section IlI supports designed by the load-rating method.

and Regulatory Positions 3 and 4, increased according to the provisions of XVII-2110(a) of Section Ill and c. The lower bound collapse load determined by Regulatory Position 4 of this guide, should not be XVII-4200 adjusted according to the provision of exceeded for component supports designed by the linear F-1370(b) of Section III should not be exceeded for elastic analysis method. component supports designed by the limit analysis method.

• 4 System mechanical loadings include all non-self-Limiting d. The collapse load determined by 11-1400 ad- loadings and do not include loadings resulting from constraints justed according to the provision of F-1370(b) of of frec-end displacements and thermal or peak stresses. Section III should not be exceeded for component S$ince component supports are deforma'ion sensitive in the supports designed by the experimental stress analysis performance of their service requirements, satisfying these criteria does not ensure that their functional requirements will method.

6e futrlibd. Any deformation limits specified by the design specification may be controlling and should be satisfied. 8. Component supports whose normal function is

6 Since the design of component supports is an integral part required during an emergency or faulted plant condition of the design of the system and the design of the component, the and that are subjected to loading combinations described designer must make sure that methods used for the analysis of the system, component, and component support are compatible in Regulatory Positions 6 and 7 should be designed (see Table F-1322.2-1 in Appendix F of Section ill). Large within the design limits described in Regulatory Position deformations in the system or compohnnts should be considered 5 or other justifiable design limits.

in the design of component supports.

1.124-5

D. IMPLEMENTATION

specified porlions of the Commission's regulations, the method described herein will be used in the evaluation N.

of submittals for construction permit applications dock- The purpose of this section is t,, provide guidance to applicants and liceiisces regarding tile NRC staff's plans for using this regulatory guide.

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 Except in those cases in which the applicant proposes July 1. 1977, the pertinent portions of the application an acceptable alternative method for complying with the will be evaluated on the basis of this guide.

I ~

1.124-6