AP1000 Piping Design Criteria.pdf

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APl 000 Design Criteria

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TABLE OF CONTENTS Section

Title

Page

1.0

PURPOSE 1 .l Definitions

2.0 3.0 4.0

REGULATIONS AND CODES GENERAL CRITERIA SPECIFIC CRITERIA 4.1 Load Combinations and Stress Limits 4.2 Analysis Criteria 4.3 Seismic Design of Category I Piping 4.4 Other Dynamic Events (Non-Seismic) 4.5 Integral Structural Attachments 4.6 Pipe Break Codes and Standards 4.7 Thermal Cycling and Stratification 4.8 Fracture Toughness Requirements 4.9 Seismic Design of Category II and Seismically Supported Non-Seismic Piping 4.10 Non-Seismic Piping 4.11 Seismically Analyzed Piping 4.12 Emergency Core Cooling Piping

20 22 23 23

REFERENCES

24

Loadings for ASME Class 1,2, 3 and B31 .l Piping Minimum Design Loading Combinations for ASME Class 1,2,3 and B31 .l Piping Additional Load Combinations and Stress Limits for ASME Class 1 Piping Additional Load Combinations and Stress Limits for ASME Class 2 and 3 Piping ASME Ill Service Limits Piping Functional Capability - ASME Class 1, 2 and 3 Stress Limits for ASME/ANSI-B31 .l Piping Additional Stress Limits for Seismic Cate ory II and Sersmtcally Supported Non-Seismic b rprng

26

5.0 Tables 1 2 3 4

Appendices A Stress Intensification Factors for Girth Fillet Welds B Seismic Integrity of CVS System Inside Containment C Seismic Decoupling Evaluation of Wind, Snow and Ice Loads D APP-GW-PI-001,

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Westinghouse

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Class 2

1 .O PURPOSE This Piping Design Criteria document summarizes the mandatory requirements for the Westinghouse API000 plant. This document covers the loadings, methods of analysis and acceptance criteria for ASME III Code piping and instrumentation tubing (seismic category I), seismic Category II ASME/ANSI 831 .I Code piping and instrumentation tubing and ASMU ANSI 831 .I Code piping and instrumentation tubing (non-seismic). Additional requirements are contained in other criteria documents, References 4 through 8, 16, and 17. Appendix A defines the stress intensification factors applicable for girth fillet welds. The criteria is based on the 1989 edition of the ASME Code, Section Ill. Appendix B defines supplemental seismic stress criteria for non-safety related (831 .I, Piping Class D) CVS piping located inside containment and designated as reactor coolant pressure boundary. Appendix C provides a method for seismic analysis decoupling. Appendix D provides criteria for wind, snow and ice loads. Calculated stiffness values based on the pipe support design drawings should not be used in the preliminary piping analysis. The following documents may be prepared based on detailed design information to supplement the requirements of this document. Item

Subsection

Document Description

1

4.22

Design guidelines for ASME Class 2, 3 piping with T tl50”F

2

4.2.3.3

Design guidelines for ASME/ANSI-B31 .I piping with T 2 150°F

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APl 000 Design Criteria 1.1

Definitions

1.1.1

ASME

Westinghouse

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Class 2

ASME is American Society of Mechanical Engineers 1.1.2

NPS

NPS is the nominal pipe size (diameter) of piping components 1.1.3

SSE

SSE is the Safe Shutdown Earthquake. 1.1.4

OBE

OBE is the Operating Basis Earthquake. 1 .I .5

The OBE is not used as a design basis event.

Supporting Systems

Piping systems that provide support to other piping systems are called supporting systems. 1 .I .6

Supported Systems

Piping systems which are supported by other piping systems or by equipment are called supported systems. 1 .I .7

Multiple-Supported

Systems

Piping systems that are supported by two or more supporting systems or building floors. 1 .I .8

1.1.9

Symbols for Response Spectra Combination for Support Input qi

=

combined displacement

response in the normal coordinate for mode i

di

=

maximum value of Dij

Dij

=

displacement spectral value for mode “i” associated with support “j”

Pij

=

participation factor for mode “in associated with support “j”

N

=

number of support points

ISM

ISM is the independent support motion method for seismic response spectra analysis.

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1.1.10 E E is the earthquake smaller than the SSE. E is used for ASME Class 1 piping fatigue evaluation. 2.0

REGULATIONS

AND CODES

The codes and regulations that are applicable to piping design are listed below. Applicable versions of the codes are given in Reference 16. 2.1

Reaulations and Reaulatow Guidance I.

US NRC Standard Review Plan (NUREG 0800) l

S.R.P. 3.7.2 “Seismic System Analysis,” Revision 2, 8/89.

l

S.R.P. 3.7.3 “Seismic Subsystem Analysis,” Revision 2, 8/89.

l

S.R.P. 3.9.1, “Special Topics for Mechanical Components,” Revision 2, 7/81.

l

l

2.

l

R. G. 1.29 - Seismic Design Classification

l

R. G. 1.61 - “Damping Values for Seismic Design of Nuclear Power Plants,” lOi

l

R. G. 1.92 - “Combining Modal Responses and Spatial Components in Seismic Response Analysis,” 2i76 R. G. 1.122 - “Development of Floor Design Response Spectra for Seismic Design of Floor Supported Equipment or Components”

US NRC Bulletins l

79-14 (Revised July 18, 1979, with Supplement of August 15, 1979).

l

88-11, “Pressurizer Surgeline Thermal Stratification,” 12/20/88.

l

4.

S.R.P. 3.9.3, “ASME Code Class 1,2, and 3 Components, Component Supports are Core Support Structures,” Revision 1, 7/81.

US NRC Regulatory Guides

l

3.

S.R.P. 3.9.2 “Dynamic Testing and Analysis of Systems, Components and Equipment,” Revision 2, July 1981.

88-08, “Thermal Stresses in Piping Connected to Reactor Coolant Systems,” 6/22/88, and Supplements I, 2 and 3 dated 6/24/88, 8/4/88, and 4/l l/89.

US Code of Federal Regulations lOCFR50, Appendix G “Fracture Toughness Requirements.”

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Codes 1.

ASME

Codes and Standards

l

ASME

l

ASME/ANSI

l

B&PV

Code, Section Ill - 1989 and 1989 Addenda 831 .I Power Piping - 1989 and 1989 Addenda

ASME/ANSI-OM3, 1987, “Requirements for Preoperational and Initial Start-up Testing - Piping Systems”

l

Code Cases: N-l 22-2, N318-4, N-391 -1 and N-392-2 for integral attachments.

l

Code Case N319-1 for butt welding elbows.

2.

Uniform Building Code, 1988

3.

ASCE Standards l

4.

Welding Research Council Bulletin 300, “Technical Position on Response Spectra Broadening,” December 1984.

EPRI Standards . l

APP-GW-PI

“Independent Support Motion (ISM) Method of Modal Spectra Seismic Analysis,” December 1989; by Task Group on Independent Support Motion as Part of the PVRC Technical Committee on Piping Systems Under the Guidance of the Steering Committee.

Welding Research Council l

6.

Nuclear Structures

PVRC Standards .

5.

ASCE Standard 4-86, “Seismic Analysis of Safety-Related and Commentary,” Q/86.

“ALWR URD,” Volume Ill, Chapter I, Draft Revision 7 “Guidelines for Piping System Reconciliation,” NCIG-05, Revision 1, NP-5639, May 1988

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Westinghouse Proprietary Class 2

GENERAL CRITERIA

3.0

Piping systems design and analysis criteria shall include: l

Design and Analysis Specifications

for ASME Class 1, 2 and 3 (Subsection 2.2.1)

l

Design Criteria Documents for Non-ASME Class (Subsection 2.2.1)

l

Fabrication Specifications

for ASME Class 1, 2 and 3 (Subsection 2.2.1)

The ASME Design and Analysis Specifications shall include at least the following:

and the Non-ASME Design Criteria Documents

.

Scope and applicability

.

Equipment and functions governed

.

Owner and vendor subdivision of responsibilities

.

Documentation

.

Environmental conditions (temperatures,

.

Codes and Standards

.

Piping System Conditions

.

Test Conditions

.

Mechanical Design Parameters

.

System Boundaries

.

Interface Information

.

Characteristics

.

Structural integrity and functionability

.

Loading combinations and stress limits

.

Pipe Break Propagation Requirements

.

Leak-before-break

.

Construction/installation

and Professional Engineer Certification requirements

of Associated

radiation, corrosion, . . .)

Equipment requirements

Requirements

The ASME Fabrication Specifications

Tolerances shall include at least the following:

l

Scope and Applicability

l

Mechanical Design Parameters

l

Codes and Standards

l

Material requirements

l

Documentation

and Certification requirements

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l

Shipping requirements

l

Preservice Inspection Requirements

l

Cleaning Requirements

l

Proprietary

Class 2

The environmental conditions, and piping system conditions shall be consistent with API000 Plant Design Criteria (Reference 4). The plant events which lead to mechanical loadings and the thermal modes of operation will be identified in the ASME Design Specifications or the Design Criteria documents for non-ASME piping systems. The seismic design requirements shall be consistent with API000 Seismic Design Criteria (Reference 6).

4.0

SPECIFIC CRITERIA

4.1

Load Combinations and Stress Limits

The load combinations and allowable stress limits for piping systems are provided in Tables 1 through 7. These tables provide the minimum load combinations. Additional design loads and load combinations may be established for specific systems. Table 1 defines the primary and secondary stress producing loads. Table 2 defines design loading combinations for ASME Class 1, 2, and 3 piping. Tables 3 and 4 define additional load combinations for primary stress producing loads and the ASME Service Level categories for both primary and secondary stress producing loads for ASME Class 1 and ASME Class 2/3 piping, respectively. Table 5 is used in conjunction with Tables 3 and 4 and provides the allowable stress limits for ASME piping for various plant conditions. The ASME Ill Code does not provide stress criteria for certain secondary stress producing loads in piping systems. For systems required to permit fluid flow for emergency and faulted condition thermal loadings, the stress criteria in Table 6 should be met. (Reference 25.) Table 6 also provides stress limits for the seismic anchor motion loads on ASME piping. The load combinations and stress limits for ASME/ANSI 831 .I piping systems is provided in Table 7 for sustained, occasional and thermal loads. ASME/ANSI 831 .I piping that is attached to seismic Category I piping is referred to as seismic Category II piping. ASME/ANSI 831 .I piping that is within the seismic interaction impact zone for Seismic Category I systems, structures and components is referred to as Seismically Supported Piping. ASME/ANSI 831 .I piping that needs to function after the SSE is referred to as Seismically Analyzed Piping. The additional load combination and stress limit for Seismic Category II Piping, Seismically Supported Piping, and Seismically Analyzed Piping is given in Table 6.

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Analvsis Criteria

4.2.1

ASME Section Ill Class 1 Piping

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For ASME Class 1 piping systems, analysis criteria are used which are appropriate for the diameters and temperatures of the various systems. 1.

Class 1 piping greater than 1” NPS shall be analyzed in accordance with Subsection NB of ASME Section Ill. The design criteria for stress limits and loading combinations are shown in Tables 3, 5, and 6.

2.

Class 1 piping equal to or smaller than 1” NPS may be analyzed according to the criteria for Class 2 piping larger than 2” NPS with operating temperatures greater than 150°F.

4.2.2

ASME Section Ill Class 2 and 3 Piping

For ASME Class 2 and 3 piping systems, analysis criteria are used which are appropriate for the diameters and temperatures of the various systems. 1.

Class 2 and 3 piping, with operating temperatures greater than 15O”F, shall be analyzed in accordance with Subsection NC and ND of ASME Section Ill. The design criteria for stress limits and loading combinations are shown in tables 4, 5, and 6.

2.

Class 2 and 3 piping with operating temperatures less than or equal to 150°F may be analyzed using simplified guidelines (Subsection 1 .O, item 1). These guidelines are shown to be equivalent to the detailed analysis in item 1 above. Alternatively, the method of item 1 may be used.

4.2.3

ASMEIANSI

831 .I Piping

For ASME/ANSI 831 .I piping analysis criteria are used which is appropriate for the temperature of the various systems. Non-seismic piping systems that are not sufficiently separated from Category I systems, structures and components by anchors, distance, or barriers such that their failure could result in loss of a required safety function are classified as either seismic Category II or seismically supported non-seismic piping. These piping systems shall be designed to additional requirements for SSE loadings. These requirements are addressed in API000 Design Criteria and Guidelines for Protection from Seismic Interaction (Reference 6). Seismic categories are based R. G. 1.29 (Subsection 2.1.2). Additional requirements for Seismically Analyzed ASME/ ANSI 831 .I Piping are provided in Section 4.11. 1.

ASME/ANSI 831 .I piping with operating temperature greater than 150°F shall be analyzed in accordance with the 831 .I Power Piping Code (Subsection 2.2.1). The criteria for stress limits and loading combinations are shown in Table 7.

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2.

Seismic Category II seismically analyzed, and seismically supported non-seismic ASME/ ANSI 831 .I piping with operating temperature greater than 1 50°F meets the additional requirements of Table 8.

3.

ASME/ANSI 831.1 piping with operating temperatures less than or equal to 150°F may be analyzed using simplified guidelines (Subsection 1 .O, item 2). These guidelines are shown to be equivalent to the analysis in item 1 above. Alternatively, the methods in item 1 above may be used.

4.

Seismic Category II, seismically analyzed, and seismically supported non-seismic ASME/ ANSI 831 .I piping with operating temperature less than or equal to 150°F meets the additional requirements of Table 8.

4.3

Seismic Desian of Cateaorv I Pioina Svstems

Seismic Category I piping systems are analyzed for the SSE according to the rules of the ASME Section Ill Code. The SSE is defined as the maximum vibratory ground motion at the plant site that can be reasonably predicted from geologic and seismic evidence. 4.3.1

Seismic Input

Experienced based design is not used for piping systems. Time History Input The input for the reactor coolant loop piping/support system seismic analysis is in the form of timehistory translational and rotational accelerations. The earthquake accelerations are applied simultaneously at the top of the containment basemat. Alternately, the response spectra method, given below, may be used. Time history input may also be used for auxiliary piping systems. Time history analysis shall consider each soil case described in Reference 8. Response Spectra Input Seismic Analysis using Response Spectra methodology may be used for ASME Class I,2 and 3 and Seismic Category II 831 .I auxiliary piping systems. For the preliminary and intermediate piping analysis stages, the calculated SSE support loads used for support member sizing should be multiplied by 1.2 to account for uncertainties in the piping model. Equivalent Static Input Seismic analysis using the equivalent static input method shall be used for seismically supported non-seismic B31 .I auxiliary systems that are within the seismic interaction impact evaluation zone, that is, systems that are not attached to Seismic Category I piping. The equivalent static input method may also be used for ASME Class I,2 and 3 piping and Seismic Category II 831 .I piping that is attached to Seismic Category I piping.

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APl 000 Design Criteria 4.3.2


Damping Values

The critical damping value to be used for the SSE uniform envelope response spectra seismic analyses of the reactor coolant loop piping and auxiliary piping is defined as follows: Reactor coolant loop piping

4%

Piping systems coupled to the reactor coolant loop or containing flexible equipment and/or structural frames

4%

Piping systems without flexible equipment or structural frames

5%

Flexible equipment and/or structural frames are defined as any components with at least one natural frequency ~33 Hz. For subsystems that are composed of different material types, the composite modal damping approach with the weighted stiffness method may be used to determine the composite modal damping value. Alternatively, the minimum damping value may be used for these systems. Composite modal damping for coupled building and piping systems may be used for piping systems that are coupled to the primary coolant loop system and the interior concrete building. Composite modal damping may be used for piping systems that are coupled to flexible equipment or flexible valves. Piping systems with rigid valves, analyzed by the uniform envelope response spectra method can be evaluated with 5 percent damping. Damping values used for structures and equipment included in the seismic analysis of piping are as follows: Welded steel structures and equipment Friction bolted steel structures and equipment Bearing bolted steel structures and equipment

4% 4% 7%

These same damping values are used for the independent support motion response spectra method. When either the independent support motion response spectra analysis method or the time history integration analysis method is used, the following SSE damping values apply for piping: diameter 5 12” diameter > 12” primary coolant loop

2% 3% 4%

When piping systems and non-simple module steel frames are in a single coupled model, composite damping (as described in Reference 8) is used.

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API 000 Design Criteria 4.3.3


Earthquakes Smaller than SSE

The seismic response for earthquakes smaller than the SSE is considered in the fatigue evaluation of ASME Class 1 piping. There are 5 smaller earthquake events consisting of 63 cycles per event where the response magnitude is equal to one-third of the calculated SSE response. 4.3.4

Dynamic Modeling

The torsional effect of eccentric supports or valve masses and mass spacing shall be considered in the analysis. The spacing of masses shall not be larger than half the span of a simply supported pipe with a natural frequency of 33 Hz. The modeling considerations for supporting and supported systems are presented below. The overlap method described in Appendix C, Section 2-2 may be used to reduce the size of the piping model. 4.3.4.1 Supporting Systems This section deals with the analysis of piping systems which provide support to other piping systems. The supported piping system may be excluded from the analysis of the supporting piping system when the ratio of the supported pipe to supporting pipe moment of inertia is sufficiently small (less than or equal to 0.04). If the ratio of the run piping outside diameter to the branch piping outside diameter (nominal pipe size) exceeds or equals 3.0, the branch piping can be excluded from the analysis of the run piping. The mass and stiffness effects of the branch piping are considered as described below. Stiffness Effect The stiffness effect of the decoupled branch pipe is considered significant when the distance from the run pipe outside diameter to the first rigid or seismic support on the decoupled branch pipe is less than or equal to one half the deadweight span of the branch pipe (given in ASME Ill Code Subsection NF). Mass Effect Considering one direction at a time, the mass effect is significant when the weight of half the span (from the decoupling point) of the branch pipe in one direction is more than 20 percent the weight of the main run pipe span in the same direction. Concentrated weights in the branch pipe are considered. A branch pipe span in x direction is the span between the decoupled branch point and the first seismic or rigid support in the x direction. A main run pipe span in the x direction is the piping bounded by the first seismic or rigid support in the x direction on both sides of the decoupled branch point. Similarly, the same definition applies to the spans in other directions (y and z).

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If the calculated branch pipe weight is less than 20 percent but more than 10 percent of the main run pipe weight, this weight is lumped at the decoupling point of the run pipe for the run pipe analysis. This weight can be neglected if it is less than 10 percent of the main run pipe weight. Required Coupling of Branch Piping If the stiffness and/or mass effects are considered significant, the branch piping is included in the piping analysis for the run pipe analysis. The portion of branch piping considered in the analysis adequately represents the behavior of the run pipe and branch pipe. The branch line model ends in one of the following ways: a) the first six-way anchor; b) four rigid/seismic supports in each of the three perpendicular directions; or c) a rigidly supported zone as described in Subsection 4.9.4. 4.3.4.2

Supported

Systems

This section deals with the analysis of piping systems which are supported by other piping systems or by equipment. A.

Large Diameter Auxiliary Piping This subsection deals with ASME Class 1 piping larger than one inch nominal pipe size and ASME Class 2 and 3 piping with nominal pipe size larger than two inches. The response spectra methodology is used. For piping supported by structural steel framework, see Section 4.3.4.2.C. When the supporting system is a piping system, the supported pipe (branch) can be decoupled from the supporting pipe (run) when the ratio of the run piping nominal pipe size to branch pipe nominal pipe size is greater than or equal to three to one. Decoupling can also be done when the moment of inertia of the branch pipe is less than or equal to 4 percent of the moment of inertia of the run pipe. During the analysis of the branch piping, resulting values of tee anchor reactions are checked against the capabilities of the tee. The seismic inertia effects of equipment and piping that provide support to supported (branch) piping systems are considered when significant. When the frequency of the supporting equipment is less than 33 hertz then either a coupled dynamic model of the piping and equipment is used, or the amplified response spectra at the equipment connection point is used with a decoupled model of the supported piping. When supported piping is supported by larger piping, one of the following methods is used: l

l

A coupled dynamic model of the supported piping and the supporting piping. Amplified response spectra at the connection point to the supporting piping with a decoupled model of the supported piping.

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APl 000 Design Criteria B.

Small-Diameter


Auxiliary Piping

This subsection deals with ASME Code Class 1 piping equal to or less than l-inch nominal pipe size and ASME Class 2 and 3 piping with nominal pipe sizes less than or equal to two inches. This includes instrumentation tubing. These piping systems may be supported by equipment or primary loop piping or other auxiliary piping or both. The response spectra or equivalent static load methodology is used. One of the following methods may be used for these systems: l

l

C.

Same method as described in Subsection 4.3.4.2.A; or, Equivalent static analysis based on appropriate load factors applied to the response spectra acceleration values. (Reference 8, subsection 6.0)

Piping Systems on Modules Many portions of the systems for the API 000 are assembled as modules offsite and shipped to the plant as completed units. This method of construction does not result in any unique requirements for the analysis of these structures, systems, or components. Existing industry standards and regulatory requirements and guidelines are appropriate for the evaluation of structures, systems, and components included in modules. The modules are constructed using a structural steel framework to support the equipment, pipe, and pipe supports in the module. The structural steel framework is designed as part of the building structure. One exception is the pressurizer and safety relief valve module, which is attached to the top of the pressurizer. For this module, the structures and piping arrangements support valves off the pressurizer and not the building structure. The structural steel frame is designed as a component support according to ASME Code, Section Ill, Subsection NF. Piping in modules is routed and analyzed in the same manner as in a plant not employing modules. Piping is analyzed from anchor point to anchor point, which are not necessarily at the boundaries of the module. This is consistent with the manner in which room walls are treated in a nonmodule plant. The supported piping or component may be decoupled from the seismic analysis of the structural frame based on the following criteria. The mass ratio, Rm, and the frequency ratio, Rf, are defined as follows: Rm

=

mass of supported component or piping/mass of supporting structural frame

Rf

=

frequency of the component or piping/frequency

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Decoupling may be done when: l

Rm < 0.01, for any Rf, or

l

Rm 2 0.01 and 5 0.10, if Rf 5 0.8 or if Rf is 2 1.25.

In addition, supported piping may be decoupled if analysis shows that the effect on the structural frame is small, that is, when the change in response is less than IO percent. When piping or components are decoupled from the analysis of the frame, the contributory mass of the piping and components is included as a rigid mass in the model of the structural frame. When piping or components are decoupled from the analysis of the frame using the preceding criteria, the effect of the frame is accounted for in the analysis of the decoupled components or piping. Either an amplified response spectra or a coupled model is used. The amplified response spectra are obtained from the time history SSE analysis of the frame. The coupled model consists of a simplified mass and stiffness model of the frame connected to the seismic model of the components or piping. Alternative criteria may be applied to simple frames that behave as pipe support miscellaneous steel. A frame can be considered simple if the distance from the supported pipe centerline to the building structure does not exceed six feet. Decoupling may be done when the deflection of the frame due to combined faulted condition loading is less than or equal to 118 inch. These deflections are defined with respect to the structure to which the structural frame is attached. The stiffness of the intervening elements between the frame and the supported piping or component is considered as follows: Rigid stiffness values are used for fabricated supports, and vendor stiffness values are used for standard supports such as snubbers and rigid gapped supports. The mass of the structural frame is evaluated as a self-weight excitation loading on the frame and the structures supporting the frame. The same approach is used for pipe support miscellaneous steel, as described in Subsection 4.3.5. When the supported components or piping cannot be decoupled, they are included in the analysis model of the structural frame. The interaction between the piping and the frame is incorporated by including the appropriate stiffness and mass properties of the components, piping, and frame in the coupled model. 4.35

Support Modeling

The stiffness of the pipe support miscellaneous steel is controlled by one of the following methods so that component nozzle loads are not adversely affected by support deformation: Pipe support miscellaneous steel deflections are limited for loading combinations associated with Level D service limits to i/8 inch in each restrained direction. These deflections are defined with respect to the structure to which the miscellaneous steel is attached. These deflection limits provide adequate stiffness for seismic analysis and are small enough to ensure that nozzle loads are not affected by pipe support deformation. In this case, rigid stiffness values are used for struts

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and fabricated supports and vendor stiffness values are used for standard supports such as snubbers, and rigid gapped supports. The mass of the pipe support miscellaneous steel is evaluated as a self weight excitation loading on the steel and the structures supporting the steel. The overall stiffness associated with the displacement limit of l/8 inch shall be equal to or larger than the minimum stiffness defined as: K _ 25(E)

(1)

(L/2)3 where: E

=

elastic modulus of pipe material

I

=

pipe moment of inertia

L

=

standard deadweight span, ASME Ill, Subsection NF

Alternatively, if the above deflection exceeds l/8 inch, the calculated stiffness value of the pipe support and miscellaneous steel is included in the piping analysis. The as-built support design is verified to have a stiffness value within + or - 20% of the as analyzed non-rigid stiffness value. This corresponds to at most a 10% change in system frequency. Rotational supports restrain the pipe cross-section in one or more rotational degrees of freedom. An example is a six-way anchor support that restrains the pipe in three translational and three rotational degrees of freedom. The calculated stiffness values for rotational supports are used in the seismic analysis of the piping systems. Support Mass Considerations The piping system analysis model includes the effect of piping support mass when the contributory mass of the support is greater than 10% of the total mass of the affected piping spans. The contributory mass of the support is the portion of the support mass that is attached to the piping; such as clamps, bolts, trunnions, struts, and snubbers. Supports that are not directly attached to the piping, such as box frames, need not be considered for mass effects. The mass of the applicable support will not affect the response of the system in the supported direction, therefore only the unsupported direction needs to be considered. Based on this reasoning, the mass of full (six-way) anchors can be neglected. The total mass of each affected piping span includes the mass of the piping, fluid contents, insulation, and any concentrated masses (for example, valves or flanges) between the adjacent supports in each unrestrained direction on both sides of the applicable support. For example; the contributory mass of an X direction support must be compared to the mass of the piping spans in the unrestrained Y and Z directions. A contributory support mass that is less than 10% of the masses of the effected spans will have insignificant effect on the response of the piping system and can be neglected.

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API 000 Design Criteria 4.3.6

Multiple-Support

Westinghouse

Class 2

Systems

There are two issues in the seismic analysis of multiple-support motions; and multiple input or envelope response spectra. A.

Proprietary

piping systems, seismic anchor

Seismic Anchor Motions The response due to differential seismic anchor motions is calculated using static analysis (without including dynamic load factor). In this analysis, the static model is identical to the static portion of the dynamic model used to compute the seismic response due to inertial loading. In particular, the structural system supports in the static model are identical to those in the dynamic model. The effect of relative seismic anchor displacements are obtained either by using the worst combination of the peak displacements or by proper representation of the relative phasing characteristics associated with different support inputs. For example, for components supported by the interior concrete building the seismic motions at all elevations above the basemat are taken to be in phase. The results of the modal spectra analysis (multiple input or envelope) are combined with the results from seismic anchor motion by the square-root-sum-of-the-squares methods or the absolute sum method. For components that behave as anchors to the piping system, such as supports and equipment nozzles, the results are combined by absolute sum. For other components, such as pipe, tees, and valves, the results are combined by squareroot-sum-of-the-squares.

B.

Response Spectra Methods The envelope uniform input response spectra can lead to excessive conservatisms unnecessary pipe supports.

and

The use of multiple input response spectra accounts for the phasing and interdependence characteristics of the various support points. The following alternative methods are used for the API000 plant. These are based on the guidelines provided by the PVRC Technical Committee and Piping Systems (Subsection 2.2.4). Envelope Uniform Response Spectra - Method A The seismic response spectra which envelopes all the supports is used in place of the spectra at each support in the envelope uniform response spectra. Also, the contribution from all of the support points are assumed to be in phase and are added algebraically as follows:

qi = di

;

(1)

Pii

j=l

where symbols are defined in Subsection 1 .I 8

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Westinghouse

Proprietary

Class 2

independent Support Motion - Method B When there is more than one supporting structure the independent support motion (ISM) method for seismic response spectra may be used. Each support point is considered to be in a random phase relationship to all the other supports. The displacement response in the modal coordinate (equation (1) above) then becomes: N qi =

C

112

(2)

(PijDij12

j=l

The NRC has approved the combination method in equation (2) above in NUREG-1413 (Subsection 2.3.12). 4.3.7

Combination of Earthquake Motions

The Seismic analysis of Piping Systems considers the combined effects of seismic loads occurring in three mutually perpendicular directions, two in the horizontal direction and one in the vertical direction. The total combined response (displacements, accelerations, stresses, and forces) due to the three components of earthquake motion is obtained by using the following method. l

The peak responses due to the three earthquake components from the response spectrum analyses are combined using the square-root-of-the-sum-of-squares (SRSS) method.

The time-history safe shutdown earthquake analysis of a subsystem can be performed by simultaneously applying the displacements and rotations at the interface point(s) between the subsystem and the system. These displacements and rotations are the results obtained from a model of a larger subsystem or a system that includes a simplified representation of the subsystem. The time-history safe shutdown earthquake analysis of the system is performed by applying three mutually orthogonal and statistically independent, artificial time histories. 4.3.8

Combinations for High Frequency Modes

This section describes alternative methods for accounting for high frequency modes in seismic response spectra analysis. A.

Higher frequency modes can be excluded for the response calculation if the change in response is less than or equal to 10%.

B.

The method described in Appendix A of USNRC Standard Review Plan 3.7.2 (Subsection 3.1 .I) or equivalent may be used for combination of high frequency modes.

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Equivalent methods are available in PIPESTRESS (Reference 15) software. 4.3.9

Proprietary

Class 2

(Reference 14) and GAPPIPE

Combination of Modal Responses

In the response spectrum method for seismic analysis, modal responses are combined by the methods described in USNRC Regulatory Guide 1.92 (Subsection 2.1.2). 4.3.10 Equipment Interfaces This section describes the piping system interface with valves and other equipment. Additional requirements are provided in API000 Mechanical Design Criteria Document (Reference 7) and API000 Auxiliary Equipment Allowable Nozzle Load Limits (Reference 19). 4.3.10.1

Valves 1.

Valve nozzle load limits shall be established to meet operability and structural integrity (pressure boundary) requirements.

2.

For each valve, acceleration limits shall be specified to insure operability and structural integrity requirements.

3.

Valves with substantial extended structures may be supported from the building structure. Valves should be designed to facilitate support attachment as close as possible to the center of gravity of the valve.

4.

Valve opening and closing times should be large enough to minimize the hydraulic loadings on the piping system.

4.3.10.2

Equipment (other than valves) 1.

The local flexibility of the nozzle-to-equipment piping model when significant.

junction should be included in the

2.

The piping and/or equipment design specification shall specify the following: a. Allowable nozzle loads b. Allowable acceleration limits c.

APP-GW-Pl -001,

Any other conditions imposed by the supplier.

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4.3.11 Seismic Response Spectra The seismic floor response spectra are developed in accordance with the API 000 Seismic Design Criteria (Reference 8). A single analysis shall be done using these broadened floor response spectra. 4.3.12 As-Built Reconciliation of Piping Systems The NRC Bulletin 79-14 (Subsection 2.1.3) and ASME Code Section Ill [Section NCA-35541 each requires a reconciliation of the as-built installation of piping systems with the as-analyzed piping systems. The NRC staff has reviewed EPRI Guidelines for Piping System Reconciliation (NCIG-05, Revision 1) (Reference 3) and reported that this guideline offers a technically acceptable method of performing reconciliation of the as-built installation of piping systems with as-analyzed piping systems, provided the commitment to use NCIG-05 is documented in the piping design specifications. For API 000, NCIG-05 shall be specified in piping design specifications and used as the means of as-built piping reconciliation. 4.3.13 Boundary of Decoupled Model (Overlap Region) The entire piping run from anchor to anchor cannot always be included in the dynamic analysis model, due to the limited capacity of piping computer programs. The incorporation of additional anchors to reduce the size of the model is undesirable, since it often results in higher thermal stresses. In these cases, the entire piping system is subdivided into two or more portions. The dynamic model for each portion extends into the other portions. These extensions are called the overlap regions. When the overlap regions are sufficiently long, a reasonable design basis is achieved. Use Appendix C for seismic decoupling. 4.3.14 Rigid Gapped Supports Rigid gapped supports may be used to minimize snubbers and accommodate static and dynamic loadings. The analysis consists of an iterative response spectrum analysis of the piping and support system. The analysis is performed with the computer program GAPPIPE (Reference 15). 4.4

Other Dvnamic Events (non-seismic)

Besides the dynamic loading due to seismic effects, several other dynamic loading conditions of non-seismic origin should be considered in the structural analysis of a piping system. Primary non-seismic dynamic loading conditions are Water Hammer and Operational Pipe Vibration. 4.4.1

Water Hammer

While numerous (approx. 150) occurrences of water hammer in nuclear power plants have been recorded during the last (20) years, only two incidents resulted in a breach of the pressure boundary. Damage due to water hammer events, if any, primarily affects piping/equipment supports.

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The design specification or system criteria document for each system shall define potential water/ steam hammer events so that the system can be evaluated for them and designed to minimize the potential consequences for that type of event. 4.4.2

Operational Steady State Pipe Vibrations

Operational fluid flow may induce cyclic vibratory loadings on the piping system. These effects can be assessed by dynamic tests at plant startup time, reference USNRC SRP, Section 3.9.2. The piping/system designer shall make adequate reference to the necessity for this type of testing in the piping specification and system testing requirements. NUREG-I 061, Vol. 5 Section 7.0 (Reference 3) makes reference to acceptable analysis procedures for this phenomenon. Operational steady state pipe vibrations can be assessed based on local measurements. An acceptable criteria for the maximum amplitude is that it shall not induce stress in the piping greater than one-half of the ASME Section Ill specified endurance limit. Additional information and requirements for vibration testing of piping systems is given in ASMEIANSI-OM3 (Subsection 2.2.1). 4.5

lntearal Structural Attachments

The support members or connections associated with integral structural attachments to piping systems should be designed such that failure from unanticipated loads does not occur in the pipe pressure boundary. The stress evaluation for integral attachments to ASME Class 1, 2 and 3 piping shall be in accordance with ASME Code Cases N-122-2, N-391-2, N-318-5, and N-392-3. For ASME/ANSI 631 .I piping, ASME Code Cases N-318-5 and N-392-3 may be used (Subsection 2.2.1). 4.6

Pioe Break Codes and Standards

Pipe break protection will conform to the criteria in “API 000 Pipe Rupture Protection Design Criteria” (Reference 5). 4.7

Thermal Cvclina and Stratification

The piping stress analysis shall consider the effects of thermal stratification and thermal cycling. Thermal stratification may occur in ASME or non-ASME piping when there are low fluid flow rates and inadequate mixing of hot and cold fluid. NRC Bulletin 88-11 (Subsection 2.1.3) describes stratification in the ASME Class 1 surgeline piping. Thermal cycling may occur in piping connected to the reactor coolant system due to leaking valves. NRC Bulletin 88-08 (Subsection 2.1.3) describes the thermal cycling stresses. See Reference 17. 4.8

Fracture Touahness Reauirements

The fracture toughness requirements of 10CFR50 Appendix G shall be satisfied (Subsection 2.1.4).

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Class 2

Seismic Desian of Cateaotv II and Seismicallv Suooorted Non-Seismic Pioinq

When required to prevent unacceptable seismic interaction with Seismic Category I systems, structures and components, ASME/ANSI 831 .I is designated as either Seismic Category II piping or seismically supported non-seismic piping. A detailed description is provided in Reference 6. The methods for Seismic Category II and Seismically Supported Non-Seismic piping are described below. 4.9.1

Seismic Input

The seismic input is either response spectra or equivalent static input (see Section 4.3.1). 4.9.2

Damping Values

Damping values are the same as Seismic Category I piping (see Section 4.3.2). 4.9.3

Earthquakes Smaller than SSE

Evaluation for earthquakes smaller than SSE is not required. 4.9.4

Modeling and Analysis

The modeling and analysis methods are provided in Reference 6. 4.9.5

Support Modeling

Support modeling is the same as Seismic Category I piping (see Section 4.3.5). 4.9.6

Multiple-Support

Systems

Methods for multiple-support Section 4.3.6). 4.9.7

systems are the same as Seismic Category I piping (see

Combination of Earthquake Motions

Methods for combination of earthquake input motions are the same as Seismic Category I piping (see Section 4.3.7). 4.9.8

Combination of High Frequency Modes

Methods of combination of high frequency modes are the same as Seismic Category I piping (see Section 4.3.8).

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APl 000 Design Criteria 4.9.9


Combination of Modal Responses

Method of modal response combination is the same as Seismic Category I piping (see Section 4.3.9). 4.9.10 Equipment Interfaces This section describes the Seismic Category II piping system interface with non-ASME Ill valves and equipment. 4.9.10.1 Valves SSE acceleration limits shall be specified to assure structural integrity of the extended structures for valves with diaphragm, hydraulic, motor, piston and solenoid operators. 4.9.10.2

Equipment (other than valves) 1.

The equipment and/or equipment design specification shall specify the following: a) Allowable nozzle loads for load combinations with SSE b) SSE acceleration limits c) Other conditions imposed by the supplier

2.

The flexibility of the nozzle-to-equipment model when significant.

junction should be included in the piping

4.9.11 Seismic Response Spectra The response spectra cases are the same as Seismic Category I piping (see Section 4.3.11). 4.9.12 As-built Reconciliation of Piping Systems 1.

For Seismic Category II piping that is attached to Seismic Category I piping, the as-built reconciliation is the same as Seismic Category I piping (see Section 4.3.12).

2.

For Seismic Category II and Seismically Supported Non-Seismic piping that is adjacent to Seismic Category I systems, structures, and components, a plant walkdown should be performed as described in Reference 6.

4.9.13 Boundary of Decoupled Model (Overlap Region) The methods for decoupling in dynamic analysis are the same as Seismic Category I piping (see Section 4.3.13).

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4.9.14 Rigid Gapped Supports The methods for using rigid gapped supports are the same as Seismic Category I piping (see Section 4.3.14). 4.10

Non-Seismic Pioinq

The following criteria applies to ASME/ANSI

631 .l piping.

4.10.1 Static Analysis Model Separate decoupled static analysis models may be used for a large run pipe and a small branch pipe when the following is satisfied. The ratio of the branch pipe moment of inertia to run pipe moment of inertia is less than or equal to 0.06. When the above ratio is not satisfied, a coupled static analysis model of the run and branch pipe shall be used. 4.10.2 Wind, Ice, and Snow Loading The methodology to be used for wind, ice, and snow loading in outdoor piping is presented in Appendix D. 4.11

Seismicallv Analvzed Pioinq

Seismically Analyzed Piping is ASME/ANSI 831.1 piping that needs to function or maintain pressure boundary integrity after the SSE. Examples of systems that contain Seismically Analyzed Piping are the Fire Protection System and the Passive Containment Cooling System. All of the requirements for Seismic Category II piping that are described in Section 4.9 are applicable to Seismically Analyzed Piping. 4.12

Emeraencv Core Coolina Pioinq

The portions of the ASME Ill, Class 3 piping that provide emergency core cooling functions are required to have radiography of a random sample of welds during construction. This includes the following: l

l

l

Injection piping from the accumulators to the reactor coolant system isolation check valves in the direct vessel injection line. Piping from the in-containment refueling water storage tank (IRWST) and recirculation screens to the reactor coolant system isolation check valves in the direct vessel injection line. Piping from the Stage 1, 2, and 3 automatic depressurization IRWST including the spargers.

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system valves to the

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REFERENCES 1.

NUREG-1061-Volume 4 - “Report of USNRC Piping Review Committee - Evaluation of Other Dynamic Loads and Load Combinations,” December 1984.

2.

NUREGICR-5347, “Recommendations for Resolution of Public Comments on USI A-40 Seismic Design Criteria,” Brookhaven National Laboratory, June 1989.

3.

NUREG-1061-Volume 5 - “Summary - Piping Review Committee Conclusions and Recommendations,” 4185.

4.

APlOOO Planf Design Criteria, APP-GW-Gl-001.

5.

APlOOO Pipe Rupture Protection Design Criteria, APP-GW-Nl-001.

6.

APlOOO Design Criteria Guidelines for Protection from Seismic Interaction, APP-GW-Nl-005.

7.

API000

Mechanical Design Criteria APP-G W-M l-00 1.

8.

API000

Seismic Design Criteria APP-GW-Gl-003.

9.

Deleted.

10.

Deleted.

11.

Deleted.

12.

NUREG 1413 - Safety Evaluation Report Related to the Preliminary Design of the Standard Nuclear Steam Supply Reference System RESAR SP/90, Docket No. 50-601, Westinghouse Electric Corp.

13.

Deleted.

14.

“PIPESTRESS

15.

“User’s Manual for GAPPIPE/GAPPOST

16.

API000

17.

EPRI Report TR-103581, ‘Thermal Stratification, Cycling and Striping (TASCS),” Research Project 3153-02, March 1994.

18.

Deleted.

19.

APlOOO Auxiliary Equipment Allowable Nozzle Load Limits, APP-GW-MOR-001.

20.

Design Guide for Wind and Tornado for API000

21.

Piping Handbook, 6th Edition, M. L. Nayyer, McGraw-Hill.

22.

API000

23.

Deleted.

User’s Manual”, DST Computer Services Systems. Computer Program”, RLCA.

Governing Codes and lndustty Standards, APP-GW-G 1X-001.

Civil/Structure

APP-GW-PI-001, Revision 0 02002 Westinghouse Electric Company, LLC 6c.mfrn&m/02

Structures, APP-G W-.51-004.

Design Criteria, APP-G W-Cl-001.

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Note:

Westinghouse

24.

Deleted.

25.

“Functional Capability of Piping Systems,” NUREG-1367, Commission, November 1992.

Proprietary

Class 2

Nuclear Regulatory

References identifed in italics are APlOOO specific documents which have not yet been created. Equivalent AP6000 documents exist and will be revised to reflect APIOOO.

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Proprietary

Class 2

Table 1 (Sheet 1 of 2) Loadings

for ASME Class 1,2, 3, and B31 .l Piping

Load

Description

P

Internal design pressure

PMAX

Peak pressure

DW

Dead weight

DML

Design Mechanical Loads (other than DW). This includes Service Level A loads and RVOS loads that are Service Level B

XL

External Mechanical Loads, such as nozzle reactions associated with piping systems, shall be combined with other loads in the loading combination expressions

SSE

Safe shutdown earthquake (inertia portion)

E

Earthquake smaller than SSE (inertia portion)

FV

Fast valve closure

RVC

Relief/safety valve - closed system (transient)

RVOS

Relief/safety valve - open system (sustained)

RVOT

Relief/safety valve - open system (transient)

DY

Dynamic load associated with various service conditions including FV, RVC, and RVOT as applicable (transient)

DN

Dynamic load associated with Level A (Normal) service conditions including FV, RVC, and RVOT as applicable (transient)

DU

Dynamic load associated with Level B (Upset) service conditions including FV, RVC, and RVOT as applicable (transient)

DE

Dynamic load associated with Level C (Emergency) service conditions including FV, RVC, and RVOT as applicable (transient)

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Proprietary

Class 2

Table 1 (Sheet 2 of 2) for ASME Class 1,2,3,

Loadings

and 831 .l Piping

Load

Description

DF

Transient Dynamic event associated with Level D (Faulted) service conditions during which, or following which, the piping system being evaluated must remain intact including FV, RVC, and RVOT as applicable. This includes postulated pipe rupture events. (transient)

SSES

Seismic anchor motion portion of SSE

ES

Seismic anchor motion of earthquake smaller than SSE

TH

Thermal loads for various service conditions

TNU

Service Level A and B (normal and upset) plant condition thermal loads; including thermal stratification and thermal cycling

TN

Service Level A (normal) plant condition thermal loads

TU

Service Level B [upset) plant condition thermal loads

TE

Service Level C (emergency) plant condition thermal loads

TF

Service Level D (faulted) plant condition thermal loads

SCVNU

Static displacement of steel containment vessel - normal and upset conditions

SCVE

Static displacement of steel containment vessel - emergency condition

SCVF

Static displacement of steel containment vessel - faulted condition

HTDW

Hydrostatic test dead weight

DBPB

Design basis pipe break, includes LOCA and non-LOCA (Transient)

LOCA

Loss-of-coolant

DYS

Dynamic load associated with various service conditions (sustained)

accident

Building structure motions due to automatic depressurization discharge DBPBS

system sparger

Design basis pipe break (sustained)

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API 000 Design Criteria

Westinghouse

Proprietary

Class 2

Table 2 (Sheet 1 of 2) Minimum Design Loading Combinations for ASME Class 1,2, and 3 Piping Condition

Design Loading Combinations(4)(g)

Design

P + DW + DML + XL@)

Level A Service

PMAX(‘) + DW + XL(“) PMAX + DW + DN + XL@)

Level B Service

PMAX + DW + DU + XL@)

Level C Service

PMAX + DW + DE + XL(7)@) PMAX + DW + DY + HYDSP + XL(“)

Level D Service

PMAX + DW + DF + XL@) PMAX + DW + SRSS(2) ((SSE + SSES) + DBPB) + XL(‘“)(6)(‘3) PMAX + DW + RVOS + SRSS (SSE + SSES) + XL(“)(12) PMAX + DW + DYS + DBPBS + SRSS ((SSE + SSES)(“) + DY + HYDSP) + XL(“)

(1)

The values of PMAX in the load combinations may be different for different levels of service conditions as provided in the design transients. For earthquake loadings, PMAX is equal to normal operating pressure at 100% power.

(2)

SRSS equals the square-root-of-the-sum-of-the-squares.

(3)

(Deleted)

(4)

Appropriate loads due to static displacements of the steel containment vessel and building settlement should be added to the loading combinations expressions for ASME Code, Section Ill, Class 2 and 3 systems.

(5)

(Deleted)

(6)

In combining loads, the timing and causal relationships that exist between PMAX, XL, DN, DU, DE, DF and DBPB are considered for determination of the appropriate load combinations.

(7)

The pressurizer safety valve discharge is a Level C service condition.

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Proprietary

Class 2

Table 2 (Sheet 2 of 2) Combinations

Minimum Design Loading for ASME Class 1,2, and 3 Piping

(8)

(Deleted)

(9)

See Table 1 for description of loads.

(10) For components that behave as anchors to the piping system, such as equipment nozzles, SSE and SSES are combined by absolute sum. For other components, such as straight pipe, tees, and valves, SSE and SSES are combined by SRSS method. (11) In combining loads, the timing and causal relationships that exist between PMAX, DY, HYDSP, and XL are considered for determination of the appropriate load combinations. (12) In combining loads, the timing and causal relationships that exist between PMAX, RVOS, and XL are considered for determination of the appropriate load combinations. (13) The combination of DBPB/DBPBS with SSE and other occasional loads is evaluated for the intact portions of the piping systems that are needed to mitigate the consequences of the postulated pipe break.

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-001, Revision

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Proprietary

Class 2

Table 3 Additional Load Combinations and Stress Limits for AMSE Class 1 Piping Loadsm

Condition

Level A/B

Equation (NB3650)

PMAX(‘),

TNU, E, ES, RVC, DN,

IO

11,14

DU, SCVNU(4)(5), RVOS(‘)

Stress Limit 3.0 s,

CUF=i .O

TNU, SCVNU

12

3.0 s,

PMAX + DW + DU

13

3.0 s,

PMAX

13

3.0 s,

Note (3)

Note (3)

+ DW + RVOS(*)

Level C

TE + SCVE

Level D(s)

SSES

h4hh4(6’

TF + SCVF TNU + SSES

1.0s”

Note (3)

Note (3)

C,D, (Ml + M2)/2l@)

6.OS,

(1)

The values of PMAX in the load combinations may be different for different levels of service conditions. For earthquake loading, PMAX is equal to normal operating pressure at 100% power.

(2)

Pressurizer safety valve discharge is classified as a Level C event.

(3)

See Table 6 for functional capability requirements.

(4)

The earthquake loads are assumed to occur at normal 100 percent power operation for the purposes of determining the total moment ranges.

(5)

Square-root-sum-of-the-squares loads.

(6)

F,,

(7)


(8)

Where:

(SRSS) combination is used for ES, E, and other transient

is amplitude of axial force for SSES; AM is nominal pipe metal area.

APP-GW-Pl -001,

Ml is range of moments for TNU, M2 is one half the range of SSES moments, Ml + M2 is larger of Ml plus one half the range of SSES, or full range of SSES C2, Do, I based on ASME Ill.

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Table 4 Additional Load Combinations and Stress Limits for AMSE Class 2,3 Piping Condition

Level A/B

Equation (NCIND3650)

Loadst3) PMAX(‘),

DW + TNU + SCVNUc4)

Building Settlement

11

Stress

Limit

Sh+SA

10a

3.0 s,

Level C

TE + SCVEt4)

Note (6)

Note (6)

Level D

TNU + SSES

i (Ml + M2)/Z(*)

3.0 S,,

FAdA,(5)

l.OSh

SSES TF + SCVFt4)

Note (6)

Note (6)

m:

(1)

The values of PMAX in the load combinations may be different for different levels of service conditions. For earthquake loading, PMAX is equal to normal operating pressure at 100% power.

(2)

Where: Ml is range of moments for TNU, M2 is one half the range of SSES moments, Ml + M2 is larger of Ml plus one half the range of SSES, or full range of SSES.

(3)


(4)

The timing and causal relationships among TNU, TE, TF, SCVNE, and SCVF are considered to determine appropriate load combinations.

(5)

FA, is amplitude of axial force for SSES; A, is nominal pipe metal area.

63)

See Table 6 for functional capability requirements.

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Westinghouse

Table

for Various

State

ASME Section Ill Service Limits Plant Conditions and Nuclear Safety Functions (Reference: ANSI/ANS 51.1)

Service

Pressure Retaining Integrity

Loading

Class 2

5

Nuclear

Plant

Proprietary

Safety

(1) (9)

Function

(2)

Dimensional Stability (3) Active Function

and Support Stability

Normal

Level “A” Service

A

A

A

Upset

Level “B” Service

B

B

B

Emergency

Level “c” Service

C

B (6)

c (7)

Faulted

Level “D” Service (5)

D

B (‘3)

D (7)

Notes:

1)

Does not apply to primary containment

2)

There shall be no loss of nuclear safety function for any Normal, Upset, Emergency, or Faulted Event. For pipe rupture loadings the nuclear safety functions of each piping system are those functions required to bring the plant to a safe shutdown condition.

3)

Dimensional Stability - Maintenance of component configuration within limits that do not preclude the performance of the components intended nuclear safety function.

4)

Active Function is a nuclear safety function which requires a mechanical motion for component operability. Not applicable to piping components.

5)

SSE loads shall be considered as Faulted.

6)

Service Limit C or D shall be permitted provided that an operability assurance program demonstrates functional capability under service loads.

7)

More restrictive service limits should be used only if necessary to insure performance of nuclear safety function.

8)

(Deleted)

9)

This table is also applicable to ASME/ANSI Category I piping.

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Table 6 Piping Functional Capability ASME Class 1,2 and 3(l)

-

Wall Thickness:

Do/t 5 50, where Do, t are per ASME ill

Service Level D Conditions

Equation 9 5 smaller of 2.0 S, and 3.0 S,(2,4~5) Equation 9 5 smaller of 2.0 S,, and 3.0 Sh(3p4s)

External Pressure:

P external 5 Pintemal

TE + SCVE

C2*M*DrJ21 < 6.0 S,(*) (NB-3650) Equation 10a (NC3653.2) 5 3.0 SJ3)

TF + SCVF

C2*M*Do’21 5 6.0 S,(*) (NB-3650) Equation 10a (NC3653.2) 5 3.0 S,t3)

(1)

Applicable to Level C or Level D plant events for which the piping system must maintain an adequate fluid flow path.

(2)

Applicable to ASME Code Class 1 piping.

(3)

Applicable to ASME Code Class 2 and 3 piping.

(4)

Applicable to ASME Code Class 1, 2, and 3 piping when the following limitations are met: 4.1 Dynamic loads are reversing (slug-flow water hammer loads are non-reversing). 4.2 Slug-flow water-hammer loads are combined with other design basis loads (for example: SSE, pipe break loads). 4.3 Steady-state bending stress from deadweight loads does not exceed:

B2;

M 5 0.25 S,

4.4 When elastic response spectrum analysis is used, dynamic moments are calculated using 15% peak broadening and not more than 5% damping.

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5.

For Class 1 piping, when slug-flow water hammer loads are only combined with pressure, weight and other sustained mechanical loads, the Equation 9 stress does not exceed the smaller of 1.8 Sy and 2.25 Sm.

6.

For Class 2 and 3 piping, when slug-flow water hammer loads are only combined with pressure, weight and other sustained mechanical loads, the Equation 9 stress does not exceed the smaller of 1.8 Sy and 2.25 Sh.

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Proprietary

Class 2

Table 7 Stress Limits for ASME/ANSI-B31.1

Piping(‘)

Loads

Load Combination

Stress Limits

Sustained Loads

PMAX + DW + DML

Section 104.8.1, 831.1

Occasional Loads

a) b)

P+DW PMAX + DW + DY

Section 104.8.2, 831 .I

Thermal Loads

a) b)

TNU TF, TE(*)

Section 104.8.3, 831 .I Based on Equation IOa, ASME III, NC 3653.2

(1) Additional requirements apply for Seismic Category II piping (Subsection 4.1 and Table 8). (2) Applicable to level C or level D plant events for which the piping system must maintain an adequate fluid flow path.

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Table 8 Additional Stress Limits for Seismic Category II and Seismically Supported Non-Seismic Piping Load Combination

Stress Equation

PMAX + DW + SSE

ASME III, ND-3653, Equation 9

Smaller of (4.5 Sh and 3.0 Sy)

PMAX + DW + SSE

ASME III, ND-3858

Per 1989 Addenda of ASME Ill

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Stress

Limit

August

2002



APPENDIX STRESS INTENSIFICATION

FACTORS

A FOR GIRTH FILLET WELDS

The criteria below are used in place of those in paragraph NB-3883.4(c)(l) and Footnote 11 to Figures NC/ND-3673.2(b)-1 of the 1989 Addenda to the 1989 Edition of ASME Code, Section Ill. This criteria is based on the criteria included in the 1989 Edition of the ASME Code, Section Ill. For girth fillet welds between the piping and socket welded fittings, valves and flanges, and slip on flanges in ASME Ill Class 1, 2, and 3 piping, the primary stress indices and stress intensification factors are as follows:

Primary Stress Indices B, = 0.75 l3,=

1.5

Stress Intensification i=

2.1’(tr&),

Factor but not less than 1.3

C, = fillet weld leg length based on ASME Ill 1989 Edition, Figures NC/ND-4427-i) sketches (c-l), (c-2), and (c-3). For unequal leg length, use smaller leg length for C,

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APPENDIX SEISMIC INTEGRITY Seismic

Integrity

Proprietary

Class 2

B

OF THE CVS SYSTEM INSIDE CONTAINMENT

of the CVS System

Inside

Containment

To provide for the seismic integrity and pressure boundary integrity of the nonsafety-related (831 .I, Piping Class D) CVS piping located inside containment and designated as reactor coolant pressure boundary, a seismic analysis will be performed with a faulted stress limit equal to the smaller of 4.5 Sh and 3.0 S, and based on the following additional criteria: Additional loading combinations and stress limits for nonsafety-related control system piping systems and components inside containment

Condition Level D

Loading

Equation (ND3650)

Combination(3)

Stress

Limit

9

Smaller of 4.5 Sh or 3.0 s,

FAr,JA,t4)

1.0s))

i (Ml + M2)/Z(*)

3.0 Sh

PMAXf’) + DW + SSE + SSES SSES TNU + SSES

chemical and volume

1.

For earthquake loading, PMAX is equal to normal operating pressure at 100% power.

2.

Where: Ml is range of moments for TNU, M2 is one half the range of SSES moments, Ml + M2 is larger of Ml plus one half the range of SSES, or full range of SSES.

3.


4.

F,,

APP-GW-PI

is amplitude of axial force for SSES; AM is nominal pipe metal area.

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APPENDIX SEISMIC DECOUPLING 1 .O

Proprietary

Class 2

C

OF PIPING SYSTEMS

BACKGROUND

In obtaining proper loads of a piping system, analysts often face the question of whether to include or to eliminate a portion of the piping in the model. Such a question arises in situations where a system has large and small size pipes, scope boundary between two engineering organizations, and too big a mathematical model for computer analysis. Therefore, decoupling methods and criteria are specified for consistency and uniform application among various piping analysts. 2.0

POSITION Seismic decoupling may be necessary when a piping system has an analysis jurisdictional boundary or a system has too big a mathematical model for computer analysis. In order to achieve such decoupling, appropriate boundary conditions, modeling extension, and/or overlapping may be required in the analysis of the system. The following sections present the API000 position for seismic analysis of piping systems. 2.1 MODEL EXTENSION Model extension is applicable to the analysis of small size pipes that are connected to large size pipes (Section 4.3.4.2A - Method 2). The size of this fully coupled model may be reduced, if necessary, due to program limitations by using the overlap method (Section 2.2). The boundary point is the branch connection to the larger size pipe. The model of the smaller pipe is extended to a minimum of four x, y, and z seismic restraints, or the equivalent, beyond the boundary point. At the last x, y, or z restraint, the pipe segment is terminated and a hinged condition is assumed for all x, y, and z directions. The response of the larger size pipe is NOT obtained from this model. See Figure C-l for illustration. The model extension is used to reduce the size of the model that represents the larger size pipe. 2.2 OVERLAP Overlap is applicable to the analysis of small or large size pipes (Section 4.3.4). The overlap method is used to reduce the size of the piping system model. The overlap region begins at a restraint in the x, y or z direction and ends at another restraint in the x, y, or z direction. The overlap region contains at least four restraints in each of the x, y and z directions, including the restraints at each end of the region. The overlap method divides the piping system into two separate systems. Each system includes the overlap region which is terminated by an assumed hinge condition in the x, y, and z directions. See Figure C-2 for illustration. The response of the system in the overlap region is taken as 1 .l times the envelope of the responses of the two systems.

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Figure C-l Model Extension

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Figure C-2 Overlap

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APPENDIX EVALUATION EVALUATION

OF WIND

Proprietary

Class 2

D

OF WIND, SNOW AND ICE LOADS

LOADS

All outdoor piping must be evaluated for the effects of Wind Loadings. Wind load is a uniformly distributed load which acts along the entire length or portion of the exposed piping, and can be applied in any arbitrary horizontal direction. Wind loads are calculated based on the basic wind speed which is presumed to occur less than 2% of the time. Calculation of Wind Pressure Load Per Program PIPESTRESS P = (O.O032)(C,)(V*) Where:

P c, v

= = =

Wind Pressure (Lb/Ftz) Shape Factor Wind Velocity (mph)

This equation is simplified from ANSI A58.1 - 1982, assuming a value of 1 .OOfor the product of 1 .OOfor exposure type B, and importance factor of 1 .ll. From APP-GW-Sl-004 considered: Wind Speed Importance Factor

(Design Guide for Wind and Tornado) - Reference 20, the following will be

= =

110 mph 1 .I1 Seismic Category I Piping 1 .OO Seismic Category II & Non-Seismic Piping

Therefore per PIPESTRESS P = (0.0032)(0.60)(110*)

= 23.23 Lb/Ft*

Analvsis of Wind Loads Wind loads will be evaluated separately for both horizontal directions (i.e., X, Y). Results from the two individual cases will then be maximized to obtain the resultant wind load case. LCAS 71: LCAS 72: CCAS 70:

APP-GW-PI-001,

Wind Load X Wind Load Y Maximum Wind Load

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Evaluation of Wind Loads is performed by Program PIPESTRESS using a WIND Card. The appropriate Wind Pressure and direction cosine are included on this card. The defined wind load will be applied on all member cards following the WIND card until another WIND card for the same load case is encountered. Piping stresses resulting from the wind loads are to be evaluated as an occasional load based on Equation 12Af’) from the 831 .I Code as follows:

Where:

MA Ma k

= = =

Deadweight Maximum Wind Load + Snow / Ice Loadf*) 1.15 for occasional loads acting less than 10% of the time

Notes:

[I] [2]

Assumes that all outdoor piping is 831 .l See section on Snow/Ice Loads for procedure on evaluation of this type of load

EVALUATION OF SNOW/ICE LOADS All outdoor piping must be evaluated for the effects of Snow/Ice Loadings. Snow/Ice loads are uniformly distributed loads which act along the entire length or portion of the exposed piping, and are applied in the downward direction (-Z). Note that this is in addition to the normal deadweight evaluation of the piping, its contents, and any insulation. Snow/Ice loads are occasional loads which are presumed to occur less than 2% of the time. Calculation of Snow/Ice Loads Per Piping Handbook 6th Edition (Mohinder L. Nayyar, McGraw Hill) - Reference 21 Ws = (0.5)(Do)(S) Snow Loads

ws = Do S

= =

Resulting snow load (Lb/Ft) Outside diameter of pipe including insulation (Ft) Snow Loading (Lb/Ft*)

Assuming S = 75 Lb/Ft* Per (APP-GW-Cl-001) Civil/Structural Parameters,” page 50 of 60.

Design Criteria - Reference 22. Table 1 “Site Interface

W, = (37.5)(Do)

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Ice Loads W/L = (1 .36)(t)(D0 + t) W/L Do t

= = =

Resulting ice load (LblFt) Outside diameter of pipe including insulation (in) Assumed thickness of ice (in)

Assuming t = 2 inches Per Piping Handbook 6th Edition (Mohinder L. Nayyar, McGraw Hill). W/L = (1.36)(2)(Do + 2) Calculate both the snow load and the ice load for the applicable size piping and use the maximum value for the evaluation of the snow/ice loads. Analvsis of Snow/Ice Loads Snow and ice loads are evaluated by applying equivalent static forces to the exposed piping in the downward (-2) directions utilizing FORC cards in program PIPESTRESS. LCAS 75: Snow/Ice Load Equivalent static forces should be calculated and applied as follows: Horizontal spans of piping Equivalent force is calculated for each span of piping either between vertical supports, between elbows, or between vertical support and elbow and applied at the center of each span. Vertical spans of piping Equivalent force is calculated for the entire length of vertical piping and applied at the approximate center location of the span.

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Piping stresses resulting from the snow/ice loads are to be evaluated as an occasional load based on Equation 12A form the 831 .l Code as follows:

Where:

MA Ma k

= = =

Deadweight Maximum Wind Load + Snow I Ice Loadt’] 1 .I 5 for occasional loads acting less than 10% of the timef’)

Notes:

[I] [2]

Both snow and ice are not assumed to occur simultaneously. Based on the 2% occurrence criteria, design is based on the maximum of snow or ice load.

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AP1000 Piping Design Criteria.pdf

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