Regulatory Guide 1.130

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

ML13350A267
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Issue date:	07/31/1977
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RG-1.130
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U.S. NUCLEAR REGULATORY COMMISSION

July 1977 REGULATORY GUIDE

OFFICE OF STANDARDS DEVELOPMENT

REGULATORY GUIDE 1.130

DESIGN LIMITS AND

LOADING COMBINATIONS

FOR CLASS I PLATE-AND-SHELL-TYPE

COMPONENT SUPPORTS

A. INTRODUCTION

conditions under the stress of specified seismic events, thereby permitting system components to General Design Criterion 2, "Design Bases for function properly. They also prevent excessive corn- Protection Against Natural Phenomena," of Appen- ponent movement during the loadings associated dix A, "General Design Criteria for Nuclear Power with emergency and faulted plant conditions corn- Plants," to 10 CFR Part 50, "Licensing of Produc- bined with a specified seismic eventvor other natural tion and Utilization Facilities," requires that the phenomena, thereby helping ,t0:t mitigate system design bases for structures, systems, and components damage. Component supports: are 'deformation- important to safety reflect appropriate combinations sensitive because large deformations in component of the effects of normal and accident conditions with supports may significantly"change the stress distribu- the effects of natural phenomena such as earth- tion in the support, system and its 'components.

quakes. The failure of members designed to support safety-related components could jeopardize the NF- 1122 and NA-21346 f Section 111 of the ASME

ability of the supported component to perform its Boiler and :?resure Vesel Code imply that the clas- safety function.

sification' §6-f ;omp6nent supports should, as a limt a

miniium ebe the~same as that of the supported com- This guide delineates acceptable design limits and pon

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Th'is should be considered as a requirement.

appropriate combinations of loadings associated with r

e di i*:i*`Z_1hisi!gdidle delineates design limits and loading corn- normal operation, postulated accidents, and specified "ib.i'ition s, in addition to supplementary criteria, for seismic events for the design of Class I pla-I'iiid.

'lass I plate-and-shell-type component supports as shell-type component supports as defined in desec d~fined by NF-1212 of Section II1. Snubbers installed tion NF of Section III of the America,:.'Socic*. of.02 for protection against seismic or dynamic loadings of Mechanical Engineers (ASME) Boilq,,;'and Prri other origins are not addressed in this guide.

Vessel Code.' This guide applies to lighti-water"ooled reactors.

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Load-bearing menil uassified as component supports are t '

c sUety of nuclear power plants becau they air. ompon**n ts in place dur- ing a

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~IcchanicaI Engineers Boiler and Pressure Vessel Co Section ItI, Division 1. 1974 Edition, including the

1974 Wintc ddenda thereto. Copies or the Code may be ob- tained from the American Society of Mechanical Engineers, United Engineering Center. 345 East 47th Street, New York. N.Y.

10017.

three methods for the design of Class I plate-and- shell-type component supports: (1) linear elastic analysis, (2) load rating, and (3) experimental stress analysis. For each method, the ASME Code delineates allowable stress or loading limits for various Code service level 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. Since the Code does not specify loading combinations, guidance is needed to provide a consistent basis for the design of component supports.

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Most of the component supports considered in this guide are located within containment.. They are therefore assumed to be protected against loadings from natural'phenomena or man-made hazards other than the specified seismic events for ordinary nuclear

power plants and the wave motion for floating nuclear power plants. Thus only the appropriate loadings from natural phenomena and the specified seismic events or wave motions need to be considered in combination with the loadings associated with plant conditions to develop appropriate loading com- binations.

I. Design by Linear Elastic Analysis When the linear-elastic-analysis method is used to design Class I plate-and-shell-type component sup- ports, material properties are given by Table I- 11.1 of Appendix I to Section III and Table I of Code Case

1644.5. These tables list values for the design stress intensity Sm at various temperatures. Yet faulted condition category design limits are determined by Sm, Sy. and Su. The load-rating method also requires the use of Su.

The minimum yield strength Sy at various temperatures could be found in Table 1-13.1 of Ap- pendix I to Section III and Table 3 of Code Case

1644.5 for the design of Class I plate-and-shell-type component supports, but values for the ultimate ten- sile strength S. above room temperature are not listed in Section Ill. An interim method should therefore be used to obtain values of Su .at temperature in order to provide a safe design margin.

While NF-3224 and F-1323.1(a) of Section Ill per- mit the increase of allowable stresses under various loading conditions, F-1370(c) limits the increase to two-thirds of the critical buckling strength of the component support at temperature. Since buckling prevents "shake-down" in a load-bearing member, it must be regarded as controlling for the level A service limits and F-1370(c) must be regarded as controlling for the level D service limits. Also, buckling is the result of the interaction of the configuration at 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 com- ponent support material at temperature.

Allowable design limits for bolted connections are derived on a different basis that varies with the size of the bolt. For this reason, the increases permitted by NF-3224 and F-1323.1(a) of Section III are not directly applicable to bolts and bolted connections.

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 deficiency should be provided for by the interim method described in this guide.

3. Design by Experimental Stress Analysis While the collapse load for the experimental-stress- analysis method is defined by 11.1430 in Appendix 1I

to Section IIt, the design limits for the experimental- stress-analysis method for variovs operating condi- tion categories are not delineated. This deficiency can be remedied by the interim method described in this guide.

4. Large Deformations The design of component supports is an integral part of the design of a 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 used in the design process, large deformations that would result in sub- stantially different stress distributions may occur.

For the evaluation of the level D service limits, Ap- pendix F to Section Ill permits the use of plastic analysis methods in certain acceptable combinations for all three elements. These acceptable combinations are selected on the assumption that component sup- ports are more deformation-sensitive (i.e., their deformation in general will have a large effect on the stress distribution in the system and its components).

Since large deformations always affect stress dis- tribution, care should be exercised even if the plastic analysis method is used in the Appendix-F-approved methodology combination. This is especially impor- tant for identifying buckling or instability problems, where the change of geometry should be taken into account to avoid erroneous results.

5. Function of the Supported System In selecting design limits for different loading com- binations, the function of the system and its supports must be taken into account. If a support's service is required by the normal function of the supported system during any plant operating condition, the design limits for the normal-operating-condition category or some other justifiable design limits should be used to evaluate the effect of all loading combinations during that specific plant operating condition. This will ensure the proper functioning of safety-related systems, such as the injection of the

1.130-2

0

Emergency Core Cooling System (ECCS) under the action of a Loss-of-Coolant Accident (LOCA) and a Safe Shutdown Earthquake (SSE) during the faulted plant condition.

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 con- trolling criterion. On the other hand, if the function of a component support is not required for a par- ticular plant condition, the stresses or loads resulting from the loading combinations under the particular plant condition do not need to satisfy the design limits for the plant condition.

7. Definitions Critical Buckling Strength. The strength at which lateral displacements start to develop simultaneously with in-plane or axial deformations.

Emergency Plant Condition. Those operating con- ditions that have a low probability of occurrence.

Faulted Plant Condition. Those operating condi- tions associated with postulated events of extremely low probability.

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

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

Operating Condition Categories. Categories of design limits for component supports as defined by NF-3113 of Section III 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 dead weight, pres- sure, and other non-self-limiting loadings, but ex- cluding 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 Condition, Those deviations from the normal plant condition that have a high probability of occurrence.

C. REGULATORY POSITION

All ASME Code Class I plate-and-shell-type com- ponent supports except snubbers, which are not ad- dressed in this guide, should be constructed to the rules of Subsection NF of Section 111, as sup- plemented by the following:2

1. The classification of component supports should, as a minimum, be the same as that of the sup- ported components.

2. Values of Su at temperature, when they are not listed in Section III, should be estimated by either Method 1, Method 2, or Method 3, as described below on an interim basis until Section I1I includes such values. Values of Sv at temperature listed by Tables 1-1.1, 1-1.2, andl-11.1 of Appendix I and Table 3 of the latest approved version of Code Case

1644 of Section III may be used for the interim calculation.

a. Method I. This method applies to component support materials whose values of ultimate strength Su at temperature have been tabulated by their manufacturers in catalogs or other publications.

Su =S.ur Ž

, but not greater than Sur ur 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, Ap- pendix I, or Code Case 1644 S= ultimate tensile strength at temperature t tabulated by manufacturers in their catalogs or other publications S

= ultimate tensile strength at room temperature tabulated by manufacturers in the same publications.

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.

S

Sy u

-Sur S

_____

____yr

- If the function of a component support is not required during a plant condition. the design limits of the support for that plant con- dition need not be satisfied. provided excessive deflections or failure of the support will not result in the loss of function of any other safety-related system.

1.130-3

.whete 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 HIl, Ap- pendix 1, or Code Case 1644 Sy = minimum yield strength at temperature t tabulated in Section II1, Appendix 1, or Code Case 1644

=yr minimum yield strength at room temperature, tabulated in Section 111, Ap- pendix 1, or Code Case 164z c. Method 3. Since the listed values of Sm at temperature in Section III will always be less than one-third of the corresponding values of ultimate

strength Su at temperature, Su at temperature may be

replaced by the value of 3 Sm at the same temperature.

3, Design limits for component supports designed

by linear elastic analysis should always be limited by the critical buckling strength. The critical buckling strength should be calculated using temperature material properties. A design margin of 2 for flat plates and 3 for shells should be maintained for l loadings combined according to Regulatory Posi- tions 4 and 5 of this guide. Design limits related to critical buckling strength should not be increased un- less the Code specifically allows such an increase.

4. Component supports subjected to the most adverse combination of the vibratory motion of the OBE. or the appropriate wave motion and system mechanical loadings ' associated with either the Code design condition or the normal or upset plant condi- tions should be designed with the following limits:4'5 a. The stress limits of (I) NF-3221.1 and NF-

3221.2 for design condition loadings, (2) NF-3222 for normal and upset operating condition loadings, and

(3) Regulatory Position 3 of this guide should not be exceeded for component supports designed by the linear-elastic-analysis method.

SSys.tem mechanical loadings include all non-scif-limiting loadings and do not include effects resulting from constraints of free-end displacements and thermal or peak stresses.

Since component supports are deformation-sensitive in the performance or their service requirements, satisfying these limits does not ensure the fulfilling of their functional requirements. Any deformation limits specified by the design specification may be controlling and should be satisfied.

' Since the design of component supports is an integral part of the design of the system and the design of the component, the 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 of Appendix F to Section I11). Large deformations in the system or components should be considered in the design of com- ponent supports.

b. The normal condition load rating or the upset condition load rating of NF-3262.2 of Section III

should not be exceeded for component supports designed by the load-rating method.

c. 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.

5. The limits in Regulatory Position 4 or some other justifiable design limits should not be exceeded by those component supports whose service is re- quired by the normal function of the supported system during emergency or faulted plant conditions.

6. Component supports subjected to the most adverse combination of system mechanical loadings'

associated with the emergency plant condition should be designed within the following design limits: 1-1 a. The stress limits of NF-3224 of Section III

and Regulatory Position 3 should not be exceeded for component supports designed by the linear-elastic- analysis method.

b. The emergency condition load rating of NF-

3262.2 of Section III should not beexceeded for com- ponent supports designed by the load-rating method.

c. The collapse load determined by 11-1400 of Section III and 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 adverse combination of the vibratory motion of SSE

or the appropriate wave motion and system mechanical loadings3 associated simultaneously with the faulted plant condition and the upset plant condi- tion should be designed within the following design limits:4-"

.a. The stress limits of F-1323.1(a) and F-1370(c)

of Section Ilf should not be exceeded for component supports designed by the linear-elastic-analysis method.

b. The value of T.L. x 0.7O -should not be ex- Su ceeded, where T.L. and Su are defined according to NF-3262.1 of Section HI and SL is the ultimate ten- sile strength of thematerial at service temperature for component supports designed by the load-rating method.

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

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D. IMPLEMENTATION

The purpose of this section is to provide guidance to applicants and licensees regarding the NRC staff's plans for using this regulatory guide.

Except in those cases in which the applicant proposes an acceptable alternative method for com- plying with the specified portions of the Commis- sion's regulations, the method described herein will be used in the evaluation of submittals for construc- tion permit applications docketed after April i, 1978.

If an applicant wishes to use this regulatory guide in developing submittals for construction permit ap- plications docketed on or before April 1, 1978, the pertinent portions of the application will be evaluated on the basis of this guide.

1.130-5