Regulatory Guide 1.57: Difference between revisions

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{{Adams
{{Adams
| number = ML12325A043
| number = ML003740195
| issue date = 05/08/2013
| issue date = 06/30/1973
| title = Design Limits and Loading Combinations for Metal Primary Reactor Containment System Components
| title = Design Limits and Loading Combinations for Metal Primary Reactor Containment Systems Components
| author name =  
| author name =  
| author affiliation = NRC/RES
| author affiliation = NRC/RES
Line 9: Line 9:
| docket =  
| docket =  
| license number =  
| license number =  
| contact person = O'Donnell E M
| contact person =  
| document report number = RG 1.57, Rev. 2
| document report number = RG-1.57
| package number = ML1235A046
| document type = Regulatory Guide
| document type = Regulatory Guide
| page count = 16
| page count = 6
| revision = 0
}}
}}
{{#Wiki_filter:Written suggestions regarding this guide or development of new guides may be submitted through the NRC's public Web site under the Regulatory Guides document collection of the NRC Library at http://www.nrc.gov/reading-rm/doc-collections/reg-guides/contactus.htm Electronic copies of this regulatory guide and previous version of this guide and other recently issued guides are available through the NRC's public Web site under the Regulatory Guides document collection of the NRC Library at http://www.nrc.gov/reading-rm/doc-collections/. The regulatory guide is also available through the NRC's Agencywide Documents Access and Management System (ADAMS) at http://www.nrc.gov/reading-rm/adams.html, under Accession No. ML12325A04 U.S. NUCLEAR REGULATORY COMMISSION REGULATORY GUIDE OFFICE OF NUCLEAR REGULATORY RESEARCH May 2013Revision 2 REGULATORY GUIDE 1.57 DESIGN LIMITS AND LOADING COMBINATIONS FOR METAL PRIMARY REACTOR CONTAINMENT SYSTEM COMPONENTS INTRODUCTION
{{#Wiki_filter:-*-  
U.S. ATOMIC ENERGY COMMISSION  
REGULATORY GUI
¶
DIRECTORATE OF REGULATORY STANDARDS
REGULATORY GUIDE 1.57 DESIGN LIMITS AND LOADING COMBINATIONS  
FOR METAL PRIMARY REACTOR CONTAINMENT SYSTEM COMPONENTS


==Purpose==
==A. INTRODUCTION==
This regulatory guide describes an approach that the staff of the U.S. Nuclear Regulatory Commission (NRC) considers acceptable for use in designing metal primary reactor containment system components and it provides methods for demonstrating containment structural integrit Applicable Rules and Regulations
General Design Criterion 2, "Design Bases for Protection Against Natural Phenomena," of Appendix A  
* Appendix A, to Title 10, Part 50, of the Code of Federal Regulations (10 CFR Part 50), "Domestic Licensing of Production and Utilization Facilities" (Ref. 1) provides general design criteria (GDC)
to 10 CFR Part 50, "General Design Criteria for Nuclear Power Plants," requires, in part, that the design bases for structures, systems, and components important to safety reflect appropriate combinations of the effects of normal and accident conditions with the effects of natural phenomena such as earthquakes. This guide delineates acceptable design limits and appropriate combinations of loadings associated with normal operation, postulated accidents, and specified seismic events for the design of components of metal primary reactor containment systems. This guide applies to light-water-cooled reactors. The Advisory Committee on Reactor Safeguards has been consulted concerning this guide and has concurred in the regulatory position.
for nuclear power plant The following GDCs are of importance to the design of metal primary reactor containment system component o GDC 1, "Quality standards and records," requires, in part, that structures, systems, and components (SSCs) important to safety be designed, fabricated, erected, and tested to quality standards commensurate with the importance of the safety functions to be performe o GDC 2, "Design bases for protection against natural phenomena," requires that structures important to safety be designed to withstand the effects of expected natural phenomena when combined with the effects of normal accident conditions without loss of capability to perform their safety functio In addition, to ensure that the containment of a nuclear power plant is designed to withstand natural phenomena, it is necessary to specify the most severe natural phenomena event that may occur as a function of the frequency of occurrenc o GDC 4, "Environmental and dynamic effects, design bases," requires that nuclear power plant SSCs important to safety be designed to accommodate the effects of and be Rev. 2 of RG 1.57, Page 2 compatible with environmental conditions associated with normal operation, maintenance, testing, and postulated accidents, including loss-of-coolant accidents (LOCAs). o GDC 16, "Containment design," requires that the reactor containment and its associated systems be provided to establish an essentially leak tight barrier against uncontrolled release of radioactivity to the environment and to ensure that design conditions important to safety are not exceeded for as long as required for postulated accident condition o GDC 50, "Containment Design Basis," requires that the reactor containment structure (including access openings, penetrations, and containment heat removal systems) be designed so that the structure and its internal compartments will have the capability to accommodate, without exceeding the design leakage rate and with sufficient margin, the calculated pressure and temperature conditions caused by a LOCA.


* 10 CFR Part 50 provides for the domestic licensing of production and utilization facilitie o 10 CFR 50.34(f), 10 CFR 50.34(f)(3)(v)(A) and (B) require specific steel containments to meet specific provisions of the Boiler and Pressure Vessel (B&PV) Code promulgated by the American Society of Mechanical Engineers (ASME), when subjected to loads resulting from fuel damage, metal-water reactions, hydrogen burning, and inerting system actuation o 10 CFR 50.44 provides the requirements for combustible gas control for currently-licensed reactors and for future water-cooled reactor applicants and licensee o 10 CFR 50.55a incorporates by reference (with conditions) codes and standards applicable to metal primary reactor containment system component o 10 CFR 50, Appendix J contains requirements for primary reactor containment leakage testing for water-cooled power Reactors. Leak tightness of the containment structure must be tested at regular intervals during the life of the plan o 10 CFR Part 50, Appendix S, "Earthquake Engineering Criteria for Nuclear Power Plants," contains the requirements for the operating-basis earthquake (OBE) and safe-shutdown earthquake (SSE). The OBE serves the function as an inspection-level earthquake below which the effect on the health and safety of the public would be insignificant and above which the licensee would be required to shut down the plant and inspect for damag
==B. DISCUSSION==
* 10 CFR Part 52 (Ref. 2) governs the issuance of early site permits, standard design certifications, combined licenses, standard design approvals, and manufacturing licenses for nuclear power facilities licensed under Section 103 of the Atomic Energy Act of 1954, as amended (68 Stat. 919), and Title II of the Energy Reorganization Act of 1974 (88 Stat. 1242). o 10 CFR 52.47 provides requirements on the content of technical information for standard design certifications submitted under Part 5 o 10 CFR 52.77 and 52.79 provide requirements on the technical content of combined operating license application Rev. 2 of RG 1.57, Page 3 Meeting these regulatory requirements provides assurance that steel containments used for nuclear power plants will be designed to be capable of performing their containment function as long as required to prevent or mitigate the spread of radioactive material, and that they can withstand the effects of natural phenomena and other external events and maintain the plant in a safe conditio Related Guidance
The design conditions and functional requirements of components which provide a pressure boundary for the primary reactor containment function should be reflected in the application of appropriate design limits (e.g., stress or strain limits) for the most adverse combination of loadings to which these components might be subjected. For components constructed in accordance with Subsection NE (Code Class MC) of Section III *of the American Society of Mechanical Engineers (ASME)  
* NUREG-0800, "Standard Review Plan [SRP] for the Review of Safety Analysis Reports for Nuclear Power Plants," Section 3.8.2, "Steel Containment," (Ref. 3) provides information on how the staff will review the portions of a license application or a license amendment relating to steel containmen
Boiler and Pressure Vessel Code, provision of a design specification is required which stipulates the design requirements for the components (e.g.,  
* NUREG/CR-6906, "Containment Integrity Research at Sandia National Laboratories - An Overview," (Ref. 4) provides guidance for containment model test
the mechanical and operational loadings). 
* Regulatory Guide 1.29, "Seismic Design Classification," (Ref. 5) describes a method that the NRC staff considers acceptable for use in identifying and classifying those features of light-water- reactor (LWR) nuclear power plants that must be designed to withstand the effects of the safe shutdown earthquake (SSE).
However, neither Section III nor any other published code or national standard provides adequate guidance for selecting combinations of loadings for design or for identifying Seismic Category I
* Regulatory Guide 1.7, "Control of Combustible Gas Concentrations in Containment" (Ref. 6), describes methods acceptable to the NRC staff for implementing 10 CFR 50.4
components (i.e.,  
* Regulatory Guide 1.84, "Design, Fabrication, and Materials Code Case Acceptability, ASME Section III," (Ref. 7), identifies the Code Cases that have been determined by the NRC to be acceptable alternatives to parts of ASME Section II
components that should be designed to remain functional under the effects of the Safe Shutdown Earthquake [SSE]). This conclusion is supported by B-1223.4(a) of Appendix B to Section III, "Owner's Design Specification"  
* Regulatory Guide 1.193, "ASME Code Cases Not Approved for Use," (Ref. 8), provides tables listing unapproved Code Cases for ASME Sections III and X
which states, in part, "The system's function, the environmental conditions under which these functions are performed, and the loading combinations must be evaluated from the system standpoint. This Section [Il] does not provide guidance in the identification of these system functions, conditions, and loading combinations." It is apparent from a review of recent applications for construction permits in which ASME Code design specifications are reflected that adequate guidance for selecting loading combinations is not presently available. For essentially identical components that perform a containment function, the loading combinations and associated design limits are not consistent among different applications for construction permits.
* American Society of Mechanical Engineers, Boiler & Pressure Vessel Code, Section III, Division 1, Subsection NE, Class MC Components, "Rules for Construction of Nuclear Facility Components," (Ref. 9) provides rules for Class MC components in the construction of nuclear facilitie
* American Society of Mechanical Engineers, Boiler & Pressure Vessel Code, Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components," (Ref. 10) provides rules for inspection of nuclear power plant components during the period they are in us Information Collection Requirements This regulatory guide contains information collection requirements covered by 10 CFR Part 50 and 10 CFR Part 52 that the Office of Management and Budget (OMB) approved under OMB control number 3150-0011 and 3150-0151, respectivel The NRC may neither conduct nor sponsor, and a person is not required to respond to, an information collection request or requirement unless the requesting document displays a currently valid OMB control numbe Rev. 2 of RG 1.57, Page 4 DISCUSSION Reason for Revision RG 1.57 was revised to correct an editorial error in a title found on page 10 of RG 1.57, Revision. 1 which referred to the "Ultimate Capacity of Concrete Containment" when it should have been "Ultimate Capacity of Steel Containments." In addition, the text in this section referred to SRP Section 3.8.2 "Steel Containment" for guidance without further elaboratio That was corrected by importing the guidance found in Section 3.8.2 into Revision This did not change the staff regulatory guidanc In addition, editorial changes were made to improve clarity, and ADAMS Accession Numbers were added in the reference section to facilitate public access the document Background The American Society of Mechanical Engineers (ASME) publishes the "Rules for Construction of Nuclear Facility Components," as Section III, "Nuclear Components," of the ASME Boiler &Pressure Vessel (B&PV) Cod Sections III and XI of the B&PV Code are incorporated by reference, with conditions, into 10 CFR 50.55 Section III, Division 1, Subsection NE, sets forth the rules for Class MC components, which include metal containments and appurtenances, as well as metal portions of concrete containments that are not backed by concret ASME B&PV Code Section III, Division 1, is hereinafter referred to as "the Code." The existing Section III of the Code is based on the current class of light-water reactors and, as such, may not adequately address design and construction features of the next generation of advanced reactor However, the provisions of this guide may be used for the current light-water reactors, as well as future advanced reactors, such as the Advanced Pressurized-Water Reactor (AP1000) and the Economic Simplified Boiling-Water Reactor (ESBWR).


The NRC is committed to the use of consensus codes and standards for the design, construction, and licensing of commercial nuclear power reactors facilitie Thus, the recent significant advancement in the technology (both in the nuclear industry and the Code) has prompted a need to revise the regulatory guidance for metal containment Toward that end, this regulatory guide provides guidance on the use of codes and standards for the design of advanced reactors to ensure that SSCs will perform their intended safety function While this regulatory guide is only directly applicable to light-water reactor metal containments, the principles may be applied to non-light water reactor containments, subject to review by the NRC. 10 CFR 50.44(b)(2)(i) requires that all currently licensed boiling-water reactors with Mark I or Mark II type containments must have an inert atmospher CFR 50.44(b)(2)(ii) requires that all currently licensed boiling-water reactors with Mark III type containments and all pressurized-water reactors with ice condenser containments must have the capability for controlling combustible gas generated from a metal-water reaction involving 75 percent of the fuel cladding surrounding the active fuel region so that there is no loss of containment structural integrit CFR 50.44(b)(5)(v)(B) requires that for all currently licensed boiling-water reactors with Mark III type containments and all pressurized-water reactors with ice condenser containments, demonstrate that systems and components necessary to establish and maintain safe shutdown and to maintain containment integrity will be capable of performing their functions during and after exposure to the environmental conditions created by the burning of hydrogen, including local detonations, unless such detonations can be shown to be unlikely to occu CFR 50.44(c)(3) requires that future water-cooled reactors containments that do not rely upon an inert atmosphere to control combustible gases must have the capability for controlling combustible gas generated from a metal-water reaction involving 100 percent of the fuel cladding surrounding the active fuel region so that there is no loss of containment structural integrit CFR 50.44(c)(5) requires that for future water-cooled reactors containments, an applicant must perform an analysis that demonstrates Rev. 2 of RG 1.57, Page 5 containment structural integrit This demonstration must use an analytical technique that is accepted by the NRC and include sufficient supporting justification to show that the technique describes the containment response to the structural loads involve The analysis must address an accident that releases hydrogen generated from 100 percent fuel clad-coolant reaction accompanied by hydrogen burnin To address the requirements of 10 CFR 50.34(f) and 10 CFR 50.44(b) and (c), Staff Regulatory Guidance Position I. B. 3. (c) "Level C Service Limits," on page 10 provides load combinations for pressure loads that result from a fuel-clad metal-water reaction, an uncontrolled hydrogen burn, and from a post-accident condition inerted by carbon dioxid The design conditions and functional requirements of components that provide a pressure boundary for the primary reactor containment function should be reflected in the application of appropriate design limits (e.g., stress or strain limits) for the most adverse combination of loadings to which these components might be subjecte For components constructed in accordance with Subsection NE of the Code (Code Class MC), the NRC requires provision of a design specification, which stipulates the design requirements (e.g., the mechanical and operational loadings) for the component In Appendix B to the Code, entitled "Owner's Design Specifications," Paragraph B-2125, "Load Combinations," states, "In order to provide a complete definition of service loads, the combination of specific events must be considere Since these combinations are a function of specific systems which make up a part of a specific type of nuclear facility, this section does not directly address service loads other than to provide different stress limits for various loadings." To further provide a consistent basis for the design of metal containment system components, this guide delineates acceptable design limits for appropriate combinations of loading The intent is to address only the most adverse combinations of loadings resulting from those events or conditions identified herein (e.g., those combinations of loadings that result in the limiting or controlling design condition). These loadings are associated either with conditions for which the containment function is required in combination with specified seismic events producing possible mechanisms for failure that could affect the function and/or integrity of structures, systems, and components important to safet Included in the latter are the loadings associated with the vibratory motion of the safe-shutdown earthquake (SSE), design external pressure (if applicable), and other loadings that induce compressive stresse The effects of natural phenomena other than earthquakes, such as tornadoes, hurricanes, and floods, are not considered in this guide, because a Category I concrete shield building typically protects the steel containment from the effects of tornadoes, hurricanes, and floods occurring outside the shield buildin In addition to the loading combinations addressed in this guide, primary reactor containment components enclosed within Seismic Category I structures should be designed to withstand the effects of pertinent natural phenomena not otherwise protected against. The approach set forth in this guide is directly related to Section III of the Cod Design limits as specified in Section III are adopted to provide assurance of maintaining the pressure-retaining integrity of the primary reactor containmen The primary reactor containment system of metal construction includes all components that perform a containment function, such as (1) the containment vessel(s), (2) penetration assemblies and access openings, and (3) piping systems attached to the containment vessel nozzles or penetration assemblies out to and including all pumps and valves required to isolate the containmen Rev. 2 of RG 1.57, Page 6 The only components that are classified as ASME Code Class MC (i.e., components constructed in accordance with the rules of Subsection NE of the Code) are metal containment vessels, including parts and appurtenances thereo Such parts and appurtenances may include mechanical, electrical, and piping penetration assemblies,2 bellows-type expansion joints, and access opening Piping, pumps, and valves that are defined as components of primary metal containment systems are constructed in accordance with the rules for either Code Class 1 or Code Class 2 components, as required by Article NE-112 Any piping penetration assemblies or appurtenances that are not a part of the containment vessel should be constructed in accordance with the rules for Code Class 1 or Code Class 2 components, as required by the intended service functio In addition to the above discussion, 10 CFR 50.55a also imposes the examination requirements established in Section XI, Subsection IWE, of the ASME B&PV Code (Ref. 10), as they relate to metal containments and liners of concrete containment Secondary Reference Documents Used in Staff Regulatory Guidance This regulatory guide endorses, in part, the ASME Boiler & Pressure Vessel Code (Ref. 9 & 10). The Code contains references to other codes, standards and third party guidance documents ("secondary references"). If a secondary reference has itself been incorporated by reference into NRC regulations as a requirement, then licensees and applicants must comply with that standard as set forth in the regulatio If the secondary reference has been endorsed in a regulatory guide as an acceptable approach for meeting an NRC requirement, then the standard constitutes a method acceptable to the NRC staff for meeting that regulatory requirement as described in the specific regulatory guid If the secondary reference has neither been incorporated by reference into NRC regulations nor endorsed in a regulatory guide, then the secondary reference is neither a legally-binding requirement nor a "generic" NRC approval as an acceptable approach for meeting an NRC requiremen However, licensees and applicants may consider and use the information in the secondary reference, if appropriately justified and consistent with current regulatory practice, consistent with applicable NRC requirements such as 10 CFR 50.5 Refer to NCA-9200 of the Code for definitions of "parts" and "appurtenances." 2 Penetration assemblies are parts or appurtenances that are required to permit piping, mechanical devices, and electrical connections to pass through the containment vessel shell or head and maintain leak tight integrity, while compensating for such things as temperature and pressure fluctuations and earthquake movement Rev. 2 of RG 1.57, Page 7 STAFF REGULATORY GUIDANCE I. Code Class MC vessels, electrical and mechanical penetration assemblies, and other penetration assemblies (excluding bellows-type expansion joints) that are parts or appurtenances of the vesse Code Class MC components of primary metal containment systems that are completely enclosed within Seismic Category I structures3 should be designed to withstand the following loads and loading combinations within the specified design limits. A. Loads D Dead loads. L Live loads, including all loads resulting from platform flexibility and deformation and from crane loading, if applicable. Pt Test pressure. Tt Test temperature. To Thermal effects and loads during startup, normal operating, or shutdown conditions, based on the most critical transient or steady-state condition. Ro Pipe reactions during startup, normal operating, or shutdown conditions based on the most critical transient or steady-state condition. Po External pressure loads resulting from pressure variation either inside or outside containment. E Loads generated by the operating-basis earthquake including sloshing effects, if applicable. E' Loads generated by the SSE, including sloshing effects. Pa Pressure load generated by the postulated pipe break accident (including pressure generated by postulated small-break or intermediate-break pipe ruptures), pool swell, and subsequent hydrodynamic loads.4 Ta Thermal loads under thermal conditions generated by the postulated pipe break accident, pool swell, and subsequent hydrodynamic reaction loads.5 Ra Pipe reactions under thermal conditions generated by the postulated pipe break accident, pool swell, and subsequent hydrodynamic reaction loads.5 Ps All pressure loads that are caused by the actuation of safety relief valve (SRV) discharge, including pool swell and subsequent hydrodynamic loads. Ts All thermal loads that are generated by the actuation of SRV discharge, including pool swell and subsequent hydrodynamic thermal load Components of primary reactor containment systems are Seismic Category I for seismic design purposes in accordance with Regulatory Guide 1.2 Seismic Category I SSCs are designed to remain functional if the SSE occur For load combinations 1.2.3.1(4), 1.2.3.3(3), and 1.2.3.4(2), a small or intermediate pipe break is postulate For all other load combinations involving a loss of coolant accident (LOCA), the design-basis LOCA is postulate Rev. 2 of RG 1.57, Page 8 Rs All pipe reaction loads that are generated by the actuation of SRV discharge, including pool swell and subsequent hydrodynamic reaction loads. Yr Equivalent static load on the structure generated by the reaction on the broken pipe during the design-basis accident. Yj Jet impingement equivalent static load on the structure generated by the broken pipe during the design-basis accident. Ym Missile impact equivalent static load on the structure generated by or during the design-basis accident, such as pipe whipping. FL Load generated by the post-LOCA flooding of the containment, if any. Pg1 Pressure resulting from an accident that releases hydrogen generated from 100% fuel clad metal-water reaction. Pg2 Pressure resulting from uncontrolled hydrogen burning. Pg3 Pressure resulting from post-accident inerting, assuming carbon dioxide is the inerting agen See Regulatory Guide 1.7 "Control of Combustible Gas Concentrations in Containment," for additional guidance about the pressure load Pg3 due to combustible gas concentration. B. Loading Combinations and Design Limits The specified loads and load combinations are acceptable if found to be in accordance with the following guidanc The following load combinations include all loading combinations for which the containment might be designed for or subjected to during the expected life of the plant: 1. Testing Condition This includes the testing condition of the containment to verify its leak integrit In this case, the loading combination includes: D + L + Tt + Pt 2. Design Conditions These include all design loadings for which the containment vessel or portions thereof might be designed for during the expected life of the plan Such loads include design pressure, design temperature, and the design mechanical loads generated by the design-basis acciden In this case, the loading combination includes: D + L + Pa + Ta + Ra
However, components that perform a primary reactor containment function are identified as Category I for seismic design purposes by Regulatory Guide 1.29 (Safety Guide 29), "Seismic Design Classification."  
To further provide a consistent basis for the design of metal containment system components, this guide delineates acceptable design limits for appropriate combinations of loadings. The intent of this guide is to address only the most adverse combinations of loadings resulting from those events or conditions identified herein (e.g., those combinations of loadings that result in the limiting or controlling design condition). These loadings are associated either with conditions for which the containment function is required in combination with specified seismic events (i.e., one-half the SSE and SSE) or with other conditions (appropriately combined with specified seismic events) producing possible mechanisms for failure that could affect the function and/or structural integrity of structures, systems, and components important to safety. Included in the latter USAEC REGULATORY GUIDES
Copies of published guides may be obtained by request indicating the divisions desired to the US. Atomic Energy Commission. Washington, D.C. 20545, Regulatory Guides are issued to describe and make available to the public Attention: Director of Regulatory Standards. Comments n--d suggestions for methods acceptable to the AEC Regulatory staff of implementing specific parts of improvements in these guides are encouraged and should be sent to the Secretary the Commission's regulations, to delineate techniques used by the staff in of the Commission, US. Atomic Energy Commission, Washington, D.C. 20645, evaluating specific problems or postulated accidents, or to provide guidance to Attention: Chief, Public Proceedings Staff.


Rev. 2 of RG 1.57, Page 9 3. Service Conditions The load combinations in these cases correspond to and include Level A service limits, Level B service limits, Level C service limits, Level D service limits and the post-flooding conditio The loads may be combined by their actual time history of occurrence, taking into consideration their dynamic effect upon the structure. (a) Level A Service Limits These service limits are applicable to the service loadings to which the containment is subjected, including the plant or system design-basis accident conditions for which the containment function is required, excepting only those categorized as Level B, C, or D, or Testing Loading The loading combinations corresponding to these limits include the following: (i) Normal operating plant condition D + L + To + Ro + Po (ii) Operating plant condition in conjunction with multiple SRV actuations D + L + Ts + Rs + Ps (ii) Loss-of-coolant accident D + L + Ta + Ra + Pa (iv) Multiple SRV actuations in combination with a small- or intermediate-break accident D + L + Ta + Ra + Pa + Ts + Rs + Ps (v) Normal operating plant conditions in combination with inadvertent full actuation of a post-accident inerting hydrogen control system [reference 10 CFR 50.34(f)(3)(v)(B)(1)] D + L + To + Ro + Po + Pg3 (vi) Pressure test load to ensure that the containment will safely withstand the pressure calculated to result from carbon-dioxide inerting [reference 10 CFR 50.34(f)(3)(v)(B)(2)] D + 1.10 x Pg3 (b) Level B Service Limits These service limits include the loads subject to Level A service limits, plus the additional loads resulting from natural phenomena during which the plant must remain operationa The loading combinations corresponding to these limits include the following:
applicants. Regulatory Guides are not substitutes for regulations and compliance with them is not required. Methods and solutions different from those set out in The guides are issued in the following ten broad divisions:  
Rev. 2 of RG 1.57, Page 10 (i) Design-basis LOCA in combination with the operating-basis earthquake (if E one-third E', only its contribution to cyclic loading needs to be considered) D + L + Ta + Ra + Pa + E (ii) Operating plant condition in combination with the operating-basis earthquake (if E one-third E', only its contribution to cyclic loading needs to be considered) D + L + To + Ro + Po + E (iii) Operating plant condition in combination with the operating-basis earthquake and multiple SRV actuations (if E one-third E', only its contribution to cyclic loading needs to be considered) D + L + Ts + Rs + Ps + E (iv) Loss-of-coolant accident in combination with a single active component failure causing one SRV discharge D + L + Ta + Pa + Ra + Ts + Rs + Ps (c) Level C Service Limits These service limits include the loads subject to Level A service limits, plus the additional loads resulting from natural phenomena for which safe shutdown of the plant is require The loading combinations corresponding to these limits include the following: (i) Loss-of-coolant accident in combination with the SSE D + L + Ta + Ra + Pa + E' (ii) Operating plant condition in combination with the SSE D + L + To + Ro + Po + E' (iii) Multiple SRV actuations in combination with a small- or intermediate-break accident and SSE D + L + Ta + Ra + Pa + Ts + Rs + Ps + E' (iv) Dead load plus pressure resulting from an accident that releases hydrogen generated from 100% fuel clad metal-water reaction accompanied by hydrogen burning [reference 10 CFR 50.34(f)(3)(v)(A)(1); 10 CFR 50.44] D + Pg1 + Pg2 [NOTE: In this load combination, Pg1 + Pg2 should not be less than 310 kPa (45 psig) and evaluation of instability is not required.]
the guides will be acceptable if they provide a basis for the findings requisite to the issuance or continuance of a permit or license by the Commission.
Rev. 2 of RG 1.57, Page 11 (v) Dead load plus pressure resulting from an accident that releases hydrogen generated from 100% fuel clad metal-water reaction accompanied by the added pressure from post-accident inerting, assuming carbon dioxide as the inerting agent [reference 10 CFR 50.34(f)(3)(v)(A)(1); 10 CFR 50.44] D + Pg1 + Pg3 [NOTE: In this load combination, Pg1 + Pg3 should not be less than 310 kPa (45 psig) and evaluation of instability is not required.] (d) Level D Service Limits These service limits include other applicable service limits and loadings of dynamic nature for which the containment function is require The load combinations corresponding to these limits include the following: (i) Loss-of-coolant accident in combination with the SSE and local dynamic loadings D + L + Ta + Ra + Pa + Yr + Yj + Ym + E' (ii) Multiple SRV actuations in combination with a small- or intermediate-break accident, SSE, and local dynamic loadings D + L + Ta + Ra + Pa + Yr + Yj + Yj + Ps + Ts + Rs + E' (iii) Post-LOCA flooding of the containment in combination with the operating-basis earthquake D + L + FL + E C. Design Limits Total stresses for the combination of loads delineated in Regulatory Position 1.2 (above) are acceptable if found to be within the limits defined by Articles NE-3221.1, NE-3221.2, NE-3221.3 and NE-3221.4 of the Code. D. Treatment of Buckling Effects Earthquake, thermal, and pressure loads require consideration of buckling of the shel Buckling of shells with more complex geometries and loading conditions than those covered by Article NE-3133 of the Code should be considered in accordance with the criteria described in ASME Code Case N-284-2 An acceptable approach to this problem is to perform a nonlinear analysi Code Case N-284-2, "Metal Containment Shell Buckling Design Methods, Class MC Section III, Division 1," has been endorsed by RG 1.8 Revision 2 of N-284 corrected errata, misprints, recommendations, and errors identified by the NRC staff in N-284-1 as the use of N-284-1 is unacceptable to the NRC, as discussed in Regulatory Guide 1.19 Rev. 2 of RG 1.57, Page 12 II. Bellows-Type Expansion Joints that are Parts or Appurtenances of ASME Code Class MC Vessels Bellows-type expansion joints that are parts or appurtenances of Code Class MC components that are completely enclosed within Seismic Category I structures should be designed to withstand the loads and loading combinations within the design limits specified in Regulatory Position 1 (above), as applicable, supplemented by the design limits specified in Article NE-3366.2(b) of the Code. II Ultimate Capacity of Steel Containments Determination of the Ultimate Capacity of the Containment for New Reactors A nonlinear finite element analysis should be performed to determine the ultimate capacity of the containmen For new reactors a determination of the internal pressure capacity for containment structures, as a measure of the safety margin above the design-basis accident pressure is neede . Cylindrical Steel Containments An acceptable method for cylindrical steel containments is to estimate the capacity based on attaining a maximum global membrane strain away from discontinuities (i.e., the hoop membrane strain in a cylinder) of 1.5 percen To conduct the necessary analysis, both nonlinear material behavior and nonlinear geometric behavior must be considered. The stress-strain curve for the steel containment material should be based on the code-specified minimum yield strength and a stress-strain relationship above yield that is representative of that specific grade of steel. The stress-strain curve must be developed for the design basis accident temperatur . Non-cylindrical Containments Analyses of non-cylindrical containments and analyses of cylindrical containments that use alternate failure criteria will be subject to detailed staff review, on a case-by- case basi Application of the Analysis to Existing Containment Structures In applying the analysis to existing containment structures, it is permissible to use as-built material properties for the steel containment material. Sufficient material certification data must be available to establish with reasonable confidence a lower bound, a median, and an upper bound value for the important material parameters. These values must be adjusted for the design-basis accident temperature. For deterministic assessments, the lower bound values should be used. For probabilistic risk assessment, calculations of failure probability vs. pressure should consider the statistical distribution of the material propertie Containment Penetrations The methods described above apply to the containment structure. A complete evaluation of the internal pressure capacity must also address major containment Rev. 2 of RG 1.57, Page 13 penetrations, such as the removable drywell head and vent lines for BWR designs, equipment hatches, personnel airlocks, and major piping penetrations. Other potential containment leak paths through mechanical and electrical penetrations should also be addresse Special Considerations for Steel Ellipsoidal and Torispherical Heads Under internal pressure, a potential failure mode of steel ellipsoidal and torispherical heads is buckling, resulting from a hoop compression zone in the knuckle region. This potential mode of failure needs to be evaluated, to determine if it is the limiting condition for the pressure capacity of the containment. The analysis should consider nonlinear material and geometric behavior and address the effect of initial geometric imperfections either explicitly (direct modeling) or implicitly (through the use of appropriate imperfection sensitivity knockdown factors). If appropriately demonstrated, residual post buckling strength can be considered in determining the pressure capacit The details of the analysis and the results should be submitted in a report form with the following identifiable information: Original design pressure, P, as defined in ASME Code, Section III, Division 1, Subsection NE, Sub article NE-3112.1; Calculated static pressure capacity; Equivalent static pressure response calculated from dynamic pressure; Associated failure mode; Criteria governing the original design and the criteria used to establish failure; Analysis details and general results; and Appropriate engineering drawings adequate to allow verification of modeling and evaluation of analyses employed for the containment structur Rev. 2 of RG 1.57, Page 14 IMPLEMENTATION The purpose of this section is to provide information on how applicants and licensees6 may use this guide and information regarding the NRC's plans for using this regulatory guid In addition, it describes how the NRC staff complies with 10 CFR 50.109, "Backfitting" and any applicable finality provisions in 10 CFR Part 52, "Licenses, Certifications, and Approvals for Nuclear Power Plants." Use by Applicants and Licensees Applicants and licensees may voluntarily 7use the guidance in this document to demonstrate compliance with the underlying NRC regulation Methods or solutions that differ from those described in this regulatory guide may be deemed acceptable if they provide sufficient basis and information for the NRC staff to verify that the proposed alternative demonstrates compliance with the appropriate NRC regulation Current licensees may continue to use guidance the NRC found acceptable for complying with the identified regulations as long as their current licensing basis remains unchanged. Licensees may use the information in this regulatory guide for actions which do not require NRC review and approval such as changes to a facility design under 10 CFR 50.59, "Changes, Tests, and Experiments." Licensees may use the information in this regulatory guide or applicable parts to resolve regulatory or inspection issue Use by NRC Staff The NRC staff does not intend or approve any imposition or backfitting of the guidance in this regulatory guid The NRC staff does not expect any existing licensee to use or commit to using the guidance in this regulatory guide, unless the licensee makes a change to its licensing basi The NRC staff does not expect or plan to request licensees to voluntarily adopt this regulatory guide to resolve a generic regulatory issu The NRC staff does not expect or plan to initiate NRC regulatory action which would require the use of this regulatory guid Examples of such unplanned NRC regulatory actions include issuance of an order requiring the use of the regulatory guide, requests for information under 10 CFR 50.54(f) as to whether a licensee intends to commit to use of this regulatory guide, generic communication, or promulgation of a rule requiring the use of this regulatory guide without further backfit consideration. During regulatory discussions on plant specific operational issues, the staff may discuss with licensees various actions consistent with staff positions in this regulatory guide, as one acceptable means of meeting the underlying NRC regulatory requiremen Such discussions would not ordinarily be considered backfitting even if prior versions of this regulatory guide are part of the licensing basis of the facilit However, unless this regulatory guide is part of the licensing basis for a facility, the staff may not represent to the licensee that the licensee's failure to comply with the positions in this regulatory guide constitutes a violatio If an existing licensee voluntarily seeks a license amendment or change and (1) the NRC staff's consideration of the request involves a regulatory issue directly relevant to this new or revised regulatory guide and (2) the specific subject matter of this regulatory guide is an essential consideration in the staff's    6 In this section, "licensees" refers to licensees of nuclear power plants under 10 CFR Parts 50 and 52; and the term "applicants," refers to applicants for licenses and permits for (or relating to) nuclear power plants under 10 CFR Parts 50 and 52, and applicants for standard design approvals and standard design certifications under 10 CFR Part 5 In this section, "voluntary" and "voluntarily" means that the licensee is seeking the action of its own accord, without the force of a legally binding requirement or an NRC representation of further licensing or enforcement actio Rev. 2 of RG 1.57, Page 15 determination of the acceptability of the licensee's request, then the staff may request that the licensee either follow the guidance in this regulatory guide or provide an equivalent alternative process that demonstrates compliance with the underlying NRC regulatory requirements. This is not considered backfitting as defined in 10 CFR 50.109(a)(1) or a violation of any of the issue finality provisions in 10 CFR Part 5 Additionally, an existing applicant may be required to comply to new rules, orders, or guidance if 10 CFR 50.109(a)(3) applie If a licensee believes that the NRC is either using this regulatory guide or requesting or requiring the licensee to implement the methods or processes in this regulatory guide in a manner inconsistent with the discussion in this Implementation section, then the licensee may file a backfit appeal with the NRC in accordance with the guidance in NUREG-1409, "Backfitting Guidelines," (Ref. 11) and the NRC Management Directive 8.4, "Management of Facility-Specific Backfitting and Information Collection" (Ref. 12). REFERENCES8 1. U.S. Code of Federal Regulations, "Domestic Licensing of Production and Utilization Facilities," Appendix A, "General Design Criteria for Nuclear Power Plants," Part 50, Title 10, "Energy." 2. U.S. Code of Federal Regulations, "Licenses, Certifications, and Approvals for Nuclear Power Plants," Part 52, Title 10, "Energy."


3. U.S. Nuclear Regulatory Commission, "Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants," NUREG-0800, Washington, D . U.S. Nuclear Regulatory Commission, "Containment Integrity Research at Sandia National Laboratories - An Overview," NUREG/CR-6906, Washington, DC, ADAMS Accession Number ML06244007 . U.S. Nuclear Regulatory Commission, "Seismic Design Classification," Regulatory Guide 1.29, Washington, D . U.S. Nuclear Regulatory Commission, "Control of Combustible Gas Concentrations in Containment," Regulatory Guide 1.7, Washington, D . U.S. Nuclear Regulatory Commission, "Design, Fabrication, and Materials Code Case Acceptability, ASME Section III," Regulatory Guide 1.84, Washington, D . U.S. Nuclear Regulatory Commission, "ASME Code Cases Not Approved for Use," Regulatory Guide 1.193, Washington, D Publicly available documents from the U.S. Nuclear Regulatory Commission (NRC) are available electronically through the NRC Library on the NRC's public Web site at http://www.nrc.gov/reading-rm/doc-collections/. The documents can also be viewed on-line for free or printed for a fee in the NRC's Public Document Room (PDR) at 11555 Rockville Pike, Rockville, MD; the mailing address is USNRC PDR, Washington, DC 20555; telephone (301) 415-4737 or (800) 397-4209; fax (301) 415 3548; and e-mail pdr.resource@nrc.go Rev. 2 of RG 1.57, Page 16 9. American Society of Mechanical Engineers, Boiler & Pressure Vessel Code, Section III, Division 1, Subsection NE, Class MC Components, "Rules for Construction of Nuclear Facility Components," New York, New Yor . American Society of Mechanical Engineers, Boiler & Pressure Vessel Code, Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components," New York, New York. 1 U.S. Nuclear Regulatory Commission, "Backfitting and Information Collection, NUREG-1409, July 1990, Washington, DC, ADAMS Accession No. ML032230247. 12. U.S. Nuclear Regulatory Commission, "Management of Facility-specific Backfitting and Information Collection," NRC Management Directive 8.4, October 2004, Washington, DC, ADAMS Accession No. ML05011015 Copies of American Society of Mechanical Engineers (ASME) standards may be purchased from ASME, Three Park Avenue, New York, New York 10016-5990; Telephone (800) 843-276 Purchase information is available through the ASME Web site store at http://www.asme.org/Codes/Publications/}}
===1. Power Reactors ===
 
===6. Products ===
2. Research and Test Reactors
 
===7. Transportation ===
3. Fuels and Materials Facilities
8. Occupational Health Published guides will be revised periodically, as appropriate, to accommodate
4. Environmental and Siting
9. Antitrust Review comments and to reflect new information or experience.
 
5. Materials and Plant Protection
10. General JUNE 1973 DE
 
are the loadings associated with the vibratory motion of the SSE, design external pressure (if applicable), and other loadings that induce compressive stresses. The effects of natural phenomena other than earthquakes, such as tornadoes, hurricanes, and floods, are not considered in this guide. The scope of this guide is limited to primary reactor containment components that are completely enclosed within Seismic Category I
structures (e.g.,
concrete shield buildings).
These structures are often designed to withstand applicable design basis natural phenomena in addition to earthquakes and therefore offer protection against those phenomena for structures, systems, and components located therein. In addition to the loading combinations addressed in this guide, primary reactor containment components enclosed within Seismic Category I
structures should be designed to withstand the effects of pertinent natural phenomena not otherwise protected against.
 
The approach set forth in this guide is directly related to Section III of the ASME Code. Design limits as specified in Section III are adopted to provide assurance of maintaining the pressure-retaining integrity of the primary reactor containment. Since primary reactor containment is an engineered safety feature whose function is required in the event of loss-of-coolant accidents within the reactor coolant pressure boundary, the ability to withstand the loadings associated with those accidents is, in effect, a normal design condition for the containment. The design limits provided by Subsection NE of Section III of the Code, in recognition of the containment function, are analogous to the normal operating condition category design limits that are applied to ASME Code Class I components. To accommodate extreme loadings such as the impact forces from jet impingement and associated reactions and still maintain pressure-retaining integrity, Section III
selectively provides special design limits.
 
The primary reactor containment system of metal construction includes all components which perform a containment function such as (1) the containment vessel or vessels,  
(2)
penetration assemblies and access openings, and (3)
piping systems attached to the containment vessel nozzles or to penetration assemblies out to and including all pumps and the valves required to isolate the containment. Many of these components, particularly piping, pumps, and valves, perform a dual function, that is, a service function (e.g., steam and feedwater piping) in addition to a containment function.
 
Subsection NE of Section III of the ASME Code requires that these components be constructed in accordance with the rules for either Code Class I or Code Class 2 piping, pumps, or valves as determined by their intended service function. In addition; Subsection NE states that components performing this dual function shall meet the more stringent requirements for their intended service function or containment function considered independently or in combination. As a result of investigating piping systems that penetrate containment and perform a containment function, it is concluded that the service function requirements for piping, pumps, and valves of these systems are controlling for design purposes. Therefore, as stated in note 3 to the regulatory position set forth in this guide, Regulatory Guide 1.48, "Design Limits and Loading Combinations for Seismic Category I Fluid System Components,"  
should apply to the design of Code Class 1 or 2 piping, pumps, and valves that are defined as containment system components, including any piping penetration assemblies or portions thereof that are not a part of the containment vessel. The only components that are classified as ASME Code Class MC (i.e., components constructed in accordance with the rules of Subsection NE of Section III of the Code) are metal containment vessels, including parts and appurtenances thereof. Such parts and appurtenances may include mechanical, electrical, and piping penetration assemblies, and bellows-type expansion joints.
 
1. ASME Code Class MC Vessels and Penetration Assemblies that are Parts or Appurtenances of the Vessel (Excluding Bellows-Type Expansion Joints). 
a.
 
For the tests stipulated by NE-6000 of the Code as delineated in regulatory position C.l.a., the applicable design limits of NE-6000 are specified to provide assurance of pressure-retaining integrity. For tests in addition to the ten tests permitted by NE-6000
of the Code, the design limits for Testing Conditions are specified (i.e., the design limits of NE-3226 of the Code which are identical to those of NE-6000). In addition, the design limits of NE-3131(d) of the Code are applicable since Testing Conditions should be considered in the fatigue evaluation.
 
b.
 
Design limits analogous to the normal and upset operating condition category limits given for ASME  
Code Class 1 components are specified for the loading combinations delineated in regulatory position C.l.b.
 
The exemption provided by NE-313 1(d) of the Code (as outlined in note 5 to the regulatory position) should not be applied to the loadings associated with the vibratory motion of 50 percent of the SSE. Significant stress cycles may result from the occurrence of this seismic event and should be included in the evaluation for cyclic loadings. The loadings delineated in regulatory position C.l .b. are either the design loadings defined in this guide (as supplemented by note 6 to the regulatory position)
combined with the loadings associated with the vibratory motion of 50 percent of the SSE or the loadings that occur from flooding the containment for accident recovery combined with the loadings resulting from the vibratory motion of 50 percent of the SSE.
 
The latter loading combination is applicable only if the containment, or portions thereof, is designed to be flooded after the occurrence of the major accident.
 
Flooding design considerations have usually been applied only for boiling water reactor primary containments.
 
c.
 
For the combination of design loadings and loadings associated with the vibratory motion of the SSE
157-2
 
as delineated in regulatory position C.l.c., the design limits of NE-3131(c)(1) or (2) are specified. NE-3131(c)
of the Code distinguishes in the application of design limits between areas of the containment structure that are integral and continuous and those that are not (e.g.,  
bolted flanges and mechanical joints). For the integral and continuous regions of the containment, an increase in allowable stress intensity is permitted by NE-3131(c)(2) of the Code to accommodate the effects of the SSE. However, NE-3131(cX1)
of the Code permits no increase in allowable stress intensity for noncontinuous and nonintegral areas of the containment under earthquake loadings.
 
d.
 
Jet impingement and associated reactions may occur on the containment structure as a result of the occurrence of postulated piping ruptures within the reactor coolant pressure boundary. When the impact forces from jet impingement and associated reactions are considered in combination with design loadings and loadings associated with the vibratory motion of the SSE, as delineated in regulatory position C.l.d., the allowable stress intensities local to the jet and reaction forces are limited to the values specified in either NE-3131.2(a) or NE-3131.2(b) of the Code. These design limits are applied to accommodate the extreme loadings local to the jet impingement or associated reactions without loss of pressure-retaining integrity.
 
NE-3131.2(a) of the Code restricts the allowable stress intensities to the values of NE-3131(c)(2) in regions of the containment structure that are not integral and continuous and in regions where partial penetration welds form part of the containment system boundary in
.--.
the immediate areas of penetrations and access openings.
 
NE-3131.2(b) of the Code permits the use of 85 percent of the stress intensity values of Appendix F of Section III for areas local to jet impingement and reaction loadings not excluded by NE-3131.2(a).
e.
 
The loading combination delineated in regulatory position C.1.2. encompasses those loadings that produce the greatest potential for shell instability (buckling)  
of containment pressure-retaining components. The design limits of NE-3131.1 of the Code are, specified for this loading combination;
however, if a detailed analysis is performed, note 7 to the regulatory position set forth in this guide applies.
 
The factor of 2 between the critical buckling stress and the applied stress as specified in note 7 is based on generally applied margins used where shell buckling is a design consideration. Design loadings (as combined with loadings associated with the vibratory motion of the SSE) include design external pressure, if applicable, and all other concurrent loadings that induce compressive stresses as outlined in note 8 to the regulatory position.
 
In reference to design external pressure, the condition of concern is the maximum net differential external pressure that occurs across the containment vessel. This loading should be evaluated for all containment designs, but may be significant only for cases in which a limited-leakage concrete shield building with annular space surrounds the steel containment vessel.
 
2.
 
Bellows-Type Expansion Joints that Are Parts or Appurtenances of ASME Code Class MC Vessels a.
 
For the tests stipulated by NE-6000 of the Code as delineated in regulatory position C.2.a., the applicable design limits of NE-6000, as supplemented by NE-3810(b) of the Code, are specified to provide assurance of both pressure-retaining integrity and functional performance. For tests in addition to the ten tests permitted by NE-6000 of the Code, the design limits for Testing Conditions are specified. Note 9 to the regulatory position also applies since Testing Conditions should be evaluated in accordance with the cyclic design requirements of NE-3810 of the Code.
 
b.
 
The applicable design limits of N E-3810 of the Code are specified for each of the following loading combinations as delineated in regulatory position C.2.b:
(1) design loadings combined with loadings associated with the vibratory motion of 50 percent of the SSE, (2)
concurrent loadings associated with flooding the containment for accident recovery and the vibratory motion of 50 percent of the SSE, or (3) design loadings combined with loadings resulting from the occurrence of an SSE
and impact forces resulting from jet impingement and associated reactions.
 
Loadings associated with the vibratory motion of 50 percent of the SSE should be evaluated in accordance with the cyclic design requirements of NE-3810 of the Code as stated in note 10 to the regulatory position. Note 11 to the regulatory position provides consistency between the design limits inherent in using the procedures of NE-3810(e) I or 2 and NE-3810(e) 3 of the Code. In addition, for the reasons given in note
12 to the regulatory position, the requirements of NE-3810(c) of the Code should be met by testing the major structural assemblies in which bellows-type expansion joints are installed.
 
==C. REGULATORY POSITION==
ASME Code'
Class MC components of primary metal containment systems 2 '3 that are completely enclosed within Seismic Category I structures should be designed to withstand the following loading combinations within the design limits specified.
 
1.
 
ASME
Code Class MC
vessels, electrical and mechanical penetration assemblies, and other penetration assemblies (excluding bellows-type expansion joints) that are parts or appurtenances 4 of the vessel:
a.
 
The design limits specified in either NE-6222 or NE-6322 of the Code, as applicable, should not be exceeded when the component is subjected to a hydrostatic test, a pneumatic test, or a leak test, and the design limits of NE-3226(a),  
(b),  
and (c)
plus NE-3131(d) of the Code should not be exceeded when the component is subjected to a hydrostatic test, a pneumatic test, or a leak test in addition to the ten such tests permitted by NE-6222 and NE-6322 of the Code.
 
1.57-3
 
b.
 
The design limits specified in NE-3131(a), (b),
and (d)' of the Code should not be exceeded when the component is subjected to either (1) concurrently applied design loadings6 and loadings associated with the vibratory motion of 50 percent of the Safe Shutdown Earthquake (SSE),
or (2) if applicable, concurrent loadings that result from flooding the containment for accident recovery and the vibratory motion of 50
percent of the SSE.
 
c.
 
The design limits specified in NE-3131(cXI) or  
(2) of the Code, as applicable, should not be exceeded when the component is subjected to concurrently applied design loadings and loadings associated with the vibratory motion of the SSE.
 
d.
 
The design limits specified in either NE-3131.2(a) or (b) of the Code, as applicable, should not be exceeded when the component is subjected to concurrently applied design loadings, loadings associated with the vibratory motion of the SSE, and impact forces resulting from jet impingement and associated reactions.
 
e.
 
The design limits specified in NE-3131.17 of the Code should not be exceeded when the component is subjected to concurrently applied design loadings8 that produce the greatest potential for shell instability and loadings associated with the vibratory motion of the SSE.
 
2.
 
Bellows-type expansion joints that are parts or appurtenances of ASME Code Class MC vessels:
a.
 
The design limits specified in either NE-6222 or NE-6322 of the Code, as applicable, supplemented by the design limits specified in NE-3810(b) of the Code should not be exceeded when the component is subjected to a hydrostatic test, a pneumatic test, or a leak test, and the design limits9 of NE-3226(a), (b), and (c) of the Code should not be exceeded when the component is subjected to hydrostatic test, a pneumatic test, or a leak test in addition to the ten such tests permitted by NE-6222 and NE-6322 of the Code.
 
b.
 
The design limits' 0',1 1,12 specified in NE-3810(a), (d), (e), and (g) of the Code should not be exceeded when the component is subjected to either (1)
concurrently applied design loadings and loadings associated with the vibratory motion of 50 percent of the SSE, or (2) concurrent loadings which result from flooding the containment for accident recovery and the vibratory motion of 50 percent of the SSE, or (3)
concurrently applied design loadings, loadings associated with the vibratory motion of the SSE, and impact forces resulting from jet impingement and associated reactions.
 
-- V
1.57-4
 
DEFINITIONS
ASME Code Class MC Components. Metal containment vessels including parts and appurtenances thereof that are constructed in accordance with the rules of Subsection NE of Section III of the ASME Boiler and Pressure Vessel Code. Parts or appurtenances of the containment vessel that perform a containment pressure boundary function may include mechanical penetration assemblies (including personnel or equipment hatches),
electrical penetration assemblies, piping penetration assemblies, and bellows-type expansion joints.
 
Design Loadings. Includes all static and dynamic loadings used to design the containment vessel such as design loadings associated with specified seismic events (e.g.,  
1/2 SSE and SSE), design loadings that are superimposed from other systems or components, and design pressure and temperature loadings (excluding, for the purposes of this guide, jet impingement and associated reactions) from loss-of-coolant accidents due to the occurrence of postulated piping ruptures within the reactor coolant pressure boundary.
 
Penetration Assemblies. Parts or appurtenances required to permit piping, mechanical devices, and electrical connections to pass through the containment vessel shell or head and maintain leaktight integrity while compensating for such things as temperature and pressure fluctuations and earthquake movements.
 
Primary Metal Containment System.
 
Includes the following components:
1. The containment vessel or vessels;
2.
 
All penetration assemblies or appurtenances not a part of the vessel;
3. All piping systems attached to containment vessel nozzles or to penetration assemblies out to and including all pumps, instrumentation connections, and the valves required to isolate the containment system and provide a pressure boundary for the containment function.
 
Safe Shutdown Earthquake (SSE) That earthquake which produces the vibratory ground motion for which structures, systems, and components important to safety are designed to remain functional.
 
Seismic Category I. Those structures, systems, and components that are designed to remain functional if the SSE occurs.
 
1.57-5
 
NOTES
'Section III of the ASME Boiler and Pressure Vessel Code including that part of the Summer 1973 Addenda that pertains to Class MC components.
 
2Components of primary reactor containment systems are Category I for seismic design purposes in accordance with Regulatory Guide 1.29 (Safety Guide
29), "Seismic Design Classification."
3Piping, pumps, and valves that are defined as components of primary metal containment syltems are constructed in accordance with the rules for either Code Class 1 or Code Class 2 components as required by NE-1100, NE-3500, and NE-3600 of Section III. Any piping penetration assemblies or appurtenances that are not a part of the containment vessel should be constructed in accordance with the rules for Code Class
1 or Code Class 2 components as required by the intended service function. Regulatory Guide 1.48,  
"Design Limits and Loading Combinations for Seismic Category I Fluid System Components," applies to the above components.
 
4Refer to NA-1200 of the Code for definition of parts and appurtenances.
 
SThe exception stated in NE-3131(d),  
"In considering the provisions of NB-3222.4(d),  
consideration need not be given to the effects of earthquake loadings." should not be applied to the loadings associated with the vibratory motion of 50
percent of the SSE.
 
6Includes operating loadings where specified (e.g.,  
parts or appurtenances such as vessel nozzles or piping penetration assemblies with special service conditions). 
The requirements of NE-3113 of the Code should be met. Operating loadings need only be included in those combination of loadings delineated in regulatory positions C.1.b.,C.2.b.(1)., and C.2.b.(2).
'If detailed rigorous analyses of shells that contain the maximum allowable deviation from true theoretical form is performed for instability (buckling) due to loadings that induce compressive stresses, such analyses, considering inelastic behavior, should demonstrate that a factor of at least two exists between the critical buckling stress and the applied stress.
 
'lncludes design external pressure, if applicable (e.g., the condition of concern is the maximum net differential external pressure), plus all static and dynamic loadings that induce compressive stresses.
 
9 Tests in addition to the ten permitted by NE-6222 and NE-6322 of the Code should be evaluated in accordance with cyclic design requirements of NE-38 10
of the code.
 
1 Loadings associated with the vibratory motion of
50 percent of the SSE should be included in the evaluation of the cyclic loadings in accordance with the design requirements of NE-3810 of the Code.
 
" If the procedures of NE-3810(e) I or 2 of the Code are used, the total combined meridional membrane and bending stress due to pressure and deflection should be limited to that which would be allowed for 10 cycles using the procedures of NE-3810(d) of the Code. This limit will provide consistency with the design limits inherent in using the procedures of NE-3810(e)3 of the Code.
 
"2The requirements of NE-3810(c) of the Code should be met by testing the major structural assemblies in which the bellows-type expansion joints are installed (e.g., penetration assemblies). All loadings such as axial compressive loadings that contribute to the instability of the assemblies should be considered. Inclusion of these loadings is particularly important in determining if angulation occurs in major structural assemblies containing two or more bellows-type expansion joints.
 
1.57-6}}


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Latest revision as of 02:06, 17 January 2025

Design Limits and Loading Combinations for Metal Primary Reactor Containment Systems Components
ML003740195
Person / Time
Issue date: 06/30/1973
From:
Office of Nuclear Regulatory Research
To:
References
RG-1.57
Download: ML003740195 (6)
v • d • e


-*-

U.S. ATOMIC ENERGY COMMISSION

REGULATORY GUI

DIRECTORATE OF REGULATORY STANDARDS

REGULATORY GUIDE 1.57 DESIGN LIMITS AND LOADING COMBINATIONS

FOR METAL PRIMARY REACTOR CONTAINMENT SYSTEM COMPONENTS

A. INTRODUCTION

General Design Criterion 2, "Design Bases for Protection Against Natural Phenomena," of Appendix A

to 10 CFR Part 50, "General Design Criteria for Nuclear Power Plants," requires, in part, that the design bases for structures, systems, and components important to safety reflect appropriate combinations of the effects of normal and accident conditions with the effects of natural phenomena such as earthquakes. This guide delineates acceptable design limits and appropriate combinations of loadings associated with normal operation, postulated accidents, and specified seismic events for the design of components of metal primary reactor containment systems. This guide applies to light-water-cooled reactors. The Advisory Committee on Reactor Safeguards has been consulted concerning this guide and has concurred in the regulatory position.

B. DISCUSSION

The design conditions and functional requirements of components which provide a pressure boundary for the primary reactor containment function should be reflected in the application of appropriate design limits (e.g., stress or strain limits) for the most adverse combination of loadings to which these components might be subjected. For components constructed in accordance with Subsection NE (Code Class MC) of Section III *of the American Society of Mechanical Engineers (ASME)

Boiler and Pressure Vessel Code, provision of a design specification is required which stipulates the design requirements for the components (e.g.,

the mechanical and operational loadings).

However, neither Section III nor any other published code or national standard provides adequate guidance for selecting combinations of loadings for design or for identifying Seismic Category I

components (i.e.,

components that should be designed to remain functional under the effects of the Safe Shutdown Earthquake [SSE]). This conclusion is supported by B-1223.4(a) of Appendix B to Section III, "Owner's Design Specification"

which states, in part, "The system's function, the environmental conditions under which these functions are performed, and the loading combinations must be evaluated from the system standpoint. This Section [Il] does not provide guidance in the identification of these system functions, conditions, and loading combinations." It is apparent from a review of recent applications for construction permits in which ASME Code design specifications are reflected that adequate guidance for selecting loading combinations is not presently available. For essentially identical components that perform a containment function, the loading combinations and associated design limits are not consistent among different applications for construction permits.

However, components that perform a primary reactor containment function are identified as Category I for seismic design purposes by Regulatory Guide 1.29 (Safety Guide 29), "Seismic Design Classification."

To further provide a consistent basis for the design of metal containment system components, this guide delineates acceptable design limits for appropriate combinations of loadings. The intent of this guide is to address only the most adverse combinations of loadings resulting from those events or conditions identified herein (e.g., those combinations of loadings that result in the limiting or controlling design condition). These loadings are associated either with conditions for which the containment function is required in combination with specified seismic events (i.e., one-half the SSE and SSE) or with other conditions (appropriately combined with specified seismic events) producing possible mechanisms for failure that could affect the function and/or structural integrity of structures, systems, and components important to safety. Included in the latter USAEC REGULATORY GUIDES

Copies of published guides may be obtained by request indicating the divisions desired to the US. Atomic Energy Commission. Washington, D.C. 20545, Regulatory Guides are issued to describe and make available to the public Attention: Director of Regulatory Standards. Comments n--d suggestions for methods acceptable to the AEC Regulatory staff of implementing specific parts of improvements in these guides are encouraged and should be sent to the Secretary the Commission's regulations, to delineate techniques used by the staff in of the Commission, US. Atomic Energy Commission, Washington, D.C. 20645, evaluating specific problems or postulated accidents, or to provide guidance to Attention: Chief, Public Proceedings Staff.

applicants. Regulatory Guides are not substitutes for regulations and compliance with them is not required. Methods and solutions different from those set out in The guides are issued in the following ten broad divisions:

the guides will be acceptable if they provide a basis for the findings requisite to the issuance or continuance of a permit or license by the Commission.

1. Power Reactors

6. Products

2. Research and Test Reactors

7. Transportation

3. Fuels and Materials Facilities

8. Occupational Health Published guides will be revised periodically, as appropriate, to accommodate

4. Environmental and Siting

9. Antitrust Review comments and to reflect new information or experience.

5. Materials and Plant Protection

10. General JUNE 1973 DE

are the loadings associated with the vibratory motion of the SSE, design external pressure (if applicable), and other loadings that induce compressive stresses. The effects of natural phenomena other than earthquakes, such as tornadoes, hurricanes, and floods, are not considered in this guide. The scope of this guide is limited to primary reactor containment components that are completely enclosed within Seismic Category I

structures (e.g.,

concrete shield buildings).

These structures are often designed to withstand applicable design basis natural phenomena in addition to earthquakes and therefore offer protection against those phenomena for structures, systems, and components located therein. In addition to the loading combinations addressed in this guide, primary reactor containment components enclosed within Seismic Category I

structures should be designed to withstand the effects of pertinent natural phenomena not otherwise protected against.

The approach set forth in this guide is directly related to Section III of the ASME Code. Design limits as specified in Section III are adopted to provide assurance of maintaining the pressure-retaining integrity of the primary reactor containment. Since primary reactor containment is an engineered safety feature whose function is required in the event of loss-of-coolant accidents within the reactor coolant pressure boundary, the ability to withstand the loadings associated with those accidents is, in effect, a normal design condition for the containment. The design limits provided by Subsection NE of Section III of the Code, in recognition of the containment function, are analogous to the normal operating condition category design limits that are applied to ASME Code Class I components. To accommodate extreme loadings such as the impact forces from jet impingement and associated reactions and still maintain pressure-retaining integrity,Section III

selectively provides special design limits.

The primary reactor containment system of metal construction includes all components which perform a containment function such as (1) the containment vessel or vessels,

(2)

penetration assemblies and access openings, and (3)

piping systems attached to the containment vessel nozzles or to penetration assemblies out to and including all pumps and the valves required to isolate the containment. Many of these components, particularly piping, pumps, and valves, perform a dual function, that is, a service function (e.g., steam and feedwater piping) in addition to a containment function.

Subsection NE of Section III of the ASME Code requires that these components be constructed in accordance with the rules for either Code Class I or Code Class 2 piping, pumps, or valves as determined by their intended service function. In addition; Subsection NE states that components performing this dual function shall meet the more stringent requirements for their intended service function or containment function considered independently or in combination. As a result of investigating piping systems that penetrate containment and perform a containment function, it is concluded that the service function requirements for piping, pumps, and valves of these systems are controlling for design purposes. Therefore, as stated in note 3 to the regulatory position set forth in this guide, Regulatory Guide 1.48, "Design Limits and Loading Combinations for Seismic Category I Fluid System Components,"

should apply to the design of Code Class 1 or 2 piping, pumps, and valves that are defined as containment system components, including any piping penetration assemblies or portions thereof that are not a part of the containment vessel. The only components that are classified as ASME Code Class MC (i.e., components constructed in accordance with the rules of Subsection NE of Section III of the Code) are metal containment vessels, including parts and appurtenances thereof. Such parts and appurtenances may include mechanical, electrical, and piping penetration assemblies, and bellows-type expansion joints.

1. ASME Code Class MC Vessels and Penetration Assemblies that are Parts or Appurtenances of the Vessel (Excluding Bellows-Type Expansion Joints).

a.

For the tests stipulated by NE-6000 of the Code as delineated in regulatory position C.l.a., the applicable design limits of NE-6000 are specified to provide assurance of pressure-retaining integrity. For tests in addition to the ten tests permitted by NE-6000

of the Code, the design limits for Testing Conditions are specified (i.e., the design limits of NE-3226 of the Code which are identical to those of NE-6000). In addition, the design limits of NE-3131(d) of the Code are applicable since Testing Conditions should be considered in the fatigue evaluation.

b.

Design limits analogous to the normal and upset operating condition category limits given for ASME

Code Class 1 components are specified for the loading combinations delineated in regulatory position C.l.b.

The exemption provided by NE-313 1(d) of the Code (as outlined in note 5 to the regulatory position) should not be applied to the loadings associated with the vibratory motion of 50 percent of the SSE. Significant stress cycles may result from the occurrence of this seismic event and should be included in the evaluation for cyclic loadings. The loadings delineated in regulatory position C.l .b. are either the design loadings defined in this guide (as supplemented by note 6 to the regulatory position)

combined with the loadings associated with the vibratory motion of 50 percent of the SSE or the loadings that occur from flooding the containment for accident recovery combined with the loadings resulting from the vibratory motion of 50 percent of the SSE.

The latter loading combination is applicable only if the containment, or portions thereof, is designed to be flooded after the occurrence of the major accident.

Flooding design considerations have usually been applied only for boiling water reactor primary containments.

c.

For the combination of design loadings and loadings associated with the vibratory motion of the SSE

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as delineated in regulatory position C.l.c., the design limits of NE-3131(c)(1) or (2) are specified. NE-3131(c)

of the Code distinguishes in the application of design limits between areas of the containment structure that are integral and continuous and those that are not (e.g.,

bolted flanges and mechanical joints). For the integral and continuous regions of the containment, an increase in allowable stress intensity is permitted by NE-3131(c)(2) of the Code to accommodate the effects of the SSE. However, NE-3131(cX1)

of the Code permits no increase in allowable stress intensity for noncontinuous and nonintegral areas of the containment under earthquake loadings.

d.

Jet impingement and associated reactions may occur on the containment structure as a result of the occurrence of postulated piping ruptures within the reactor coolant pressure boundary. When the impact forces from jet impingement and associated reactions are considered in combination with design loadings and loadings associated with the vibratory motion of the SSE, as delineated in regulatory position C.l.d., the allowable stress intensities local to the jet and reaction forces are limited to the values specified in either NE-3131.2(a) or NE-3131.2(b) of the Code. These design limits are applied to accommodate the extreme loadings local to the jet impingement or associated reactions without loss of pressure-retaining integrity.

NE-3131.2(a) of the Code restricts the allowable stress intensities to the values of NE-3131(c)(2) in regions of the containment structure that are not integral and continuous and in regions where partial penetration welds form part of the containment system boundary in

.--.

the immediate areas of penetrations and access openings.

NE-3131.2(b) of the Code permits the use of 85 percent of the stress intensity values of Appendix F of Section III for areas local to jet impingement and reaction loadings not excluded by NE-3131.2(a).

e.

The loading combination delineated in regulatory position C.1.2. encompasses those loadings that produce the greatest potential for shell instability (buckling)

of containment pressure-retaining components. The design limits of NE-3131.1 of the Code are, specified for this loading combination;

however, if a detailed analysis is performed, note 7 to the regulatory position set forth in this guide applies.

The factor of 2 between the critical buckling stress and the applied stress as specified in note 7 is based on generally applied margins used where shell buckling is a design consideration. Design loadings (as combined with loadings associated with the vibratory motion of the SSE) include design external pressure, if applicable, and all other concurrent loadings that induce compressive stresses as outlined in note 8 to the regulatory position.

In reference to design external pressure, the condition of concern is the maximum net differential external pressure that occurs across the containment vessel. This loading should be evaluated for all containment designs, but may be significant only for cases in which a limited-leakage concrete shield building with annular space surrounds the steel containment vessel.

2.

Bellows-Type Expansion Joints that Are Parts or Appurtenances of ASME Code Class MC Vessels a.

For the tests stipulated by NE-6000 of the Code as delineated in regulatory position C.2.a., the applicable design limits of NE-6000, as supplemented by NE-3810(b) of the Code, are specified to provide assurance of both pressure-retaining integrity and functional performance. For tests in addition to the ten tests permitted by NE-6000 of the Code, the design limits for Testing Conditions are specified. Note 9 to the regulatory position also applies since Testing Conditions should be evaluated in accordance with the cyclic design requirements of NE-3810 of the Code.

b.

The applicable design limits of N E-3810 of the Code are specified for each of the following loading combinations as delineated in regulatory position C.2.b:

(1) design loadings combined with loadings associated with the vibratory motion of 50 percent of the SSE, (2)

concurrent loadings associated with flooding the containment for accident recovery and the vibratory motion of 50 percent of the SSE, or (3) design loadings combined with loadings resulting from the occurrence of an SSE

and impact forces resulting from jet impingement and associated reactions.

Loadings associated with the vibratory motion of 50 percent of the SSE should be evaluated in accordance with the cyclic design requirements of NE-3810 of the Code as stated in note 10 to the regulatory position. Note 11 to the regulatory position provides consistency between the design limits inherent in using the procedures of NE-3810(e) I or 2 and NE-3810(e) 3 of the Code. In addition, for the reasons given in note

12 to the regulatory position, the requirements of NE-3810(c) of the Code should be met by testing the major structural assemblies in which bellows-type expansion joints are installed.

C. REGULATORY POSITION

ASME Code'

Class MC components of primary metal containment systems 2 '3 that are completely enclosed within Seismic Category I structures should be designed to withstand the following loading combinations within the design limits specified.

1.

ASME

Code Class MC

vessels, electrical and mechanical penetration assemblies, and other penetration assemblies (excluding bellows-type expansion joints) that are parts or appurtenances 4 of the vessel:

a.

The design limits specified in either NE-6222 or NE-6322 of the Code, as applicable, should not be exceeded when the component is subjected to a hydrostatic test, a pneumatic test, or a leak test, and the design limits of NE-3226(a),

(b),

and (c)

plus NE-3131(d) of the Code should not be exceeded when the component is subjected to a hydrostatic test, a pneumatic test, or a leak test in addition to the ten such tests permitted by NE-6222 and NE-6322 of the Code.

1.57-3

b.

The design limits specified in NE-3131(a), (b),

and (d)' of the Code should not be exceeded when the component is subjected to either (1) concurrently applied design loadings6 and loadings associated with the vibratory motion of 50 percent of the Safe Shutdown Earthquake (SSE),

or (2) if applicable, concurrent loadings that result from flooding the containment for accident recovery and the vibratory motion of 50

percent of the SSE.

c.

The design limits specified in NE-3131(cXI) or

(2) of the Code, as applicable, should not be exceeded when the component is subjected to concurrently applied design loadings and loadings associated with the vibratory motion of the SSE.

d.

The design limits specified in either NE-3131.2(a) or (b) of the Code, as applicable, should not be exceeded when the component is subjected to concurrently applied design loadings, loadings associated with the vibratory motion of the SSE, and impact forces resulting from jet impingement and associated reactions.

e.

The design limits specified in NE-3131.17 of the Code should not be exceeded when the component is subjected to concurrently applied design loadings8 that produce the greatest potential for shell instability and loadings associated with the vibratory motion of the SSE.

2.

Bellows-type expansion joints that are parts or appurtenances of ASME Code Class MC vessels:

a.

The design limits specified in either NE-6222 or NE-6322 of the Code, as applicable, supplemented by the design limits specified in NE-3810(b) of the Code should not be exceeded when the component is subjected to a hydrostatic test, a pneumatic test, or a leak test, and the design limits9 of NE-3226(a), (b), and (c) of the Code should not be exceeded when the component is subjected to hydrostatic test, a pneumatic test, or a leak test in addition to the ten such tests permitted by NE-6222 and NE-6322 of the Code.

b.

The design limits' 0',1 1,12 specified in NE-3810(a), (d), (e), and (g) of the Code should not be exceeded when the component is subjected to either (1)

concurrently applied design loadings and loadings associated with the vibratory motion of 50 percent of the SSE, or (2) concurrent loadings which result from flooding the containment for accident recovery and the vibratory motion of 50 percent of the SSE, or (3)

concurrently applied design loadings, loadings associated with the vibratory motion of the SSE, and impact forces resulting from jet impingement and associated reactions.

-- V

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DEFINITIONS

ASME Code Class MC Components. Metal containment vessels including parts and appurtenances thereof that are constructed in accordance with the rules of Subsection NE of Section III of the ASME Boiler and Pressure Vessel Code. Parts or appurtenances of the containment vessel that perform a containment pressure boundary function may include mechanical penetration assemblies (including personnel or equipment hatches),

electrical penetration assemblies, piping penetration assemblies, and bellows-type expansion joints.

Design Loadings. Includes all static and dynamic loadings used to design the containment vessel such as design loadings associated with specified seismic events (e.g.,

1/2 SSE and SSE), design loadings that are superimposed from other systems or components, and design pressure and temperature loadings (excluding, for the purposes of this guide, jet impingement and associated reactions) from loss-of-coolant accidents due to the occurrence of postulated piping ruptures within the reactor coolant pressure boundary.

Penetration Assemblies. Parts or appurtenances required to permit piping, mechanical devices, and electrical connections to pass through the containment vessel shell or head and maintain leaktight integrity while compensating for such things as temperature and pressure fluctuations and earthquake movements.

Primary Metal Containment System.

Includes the following components:

1. The containment vessel or vessels;

2.

All penetration assemblies or appurtenances not a part of the vessel;

3. All piping systems attached to containment vessel nozzles or to penetration assemblies out to and including all pumps, instrumentation connections, and the valves required to isolate the containment system and provide a pressure boundary for the containment function.

Safe Shutdown Earthquake (SSE) That earthquake which produces the vibratory ground motion for which structures, systems, and components important to safety are designed to remain functional.

Seismic Category I. Those structures, systems, and components that are designed to remain functional if the SSE occurs.

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NOTES

'Section III of the ASME Boiler and Pressure Vessel Code including that part of the Summer 1973 Addenda that pertains to Class MC components.

2Components of primary reactor containment systems are Category I for seismic design purposes in accordance with Regulatory Guide 1.29 (Safety Guide

29), "Seismic Design Classification."

3Piping, pumps, and valves that are defined as components of primary metal containment syltems are constructed in accordance with the rules for either Code Class 1 or Code Class 2 components as required by NE-1100, NE-3500, and NE-3600 of Section III. Any piping penetration assemblies or appurtenances that are not a part of the containment vessel should be constructed in accordance with the rules for Code Class

1 or Code Class 2 components as required by the intended service function. Regulatory Guide 1.48,

"Design Limits and Loading Combinations for Seismic Category I Fluid System Components," applies to the above components.

4Refer to NA-1200 of the Code for definition of parts and appurtenances.

SThe exception stated in NE-3131(d),

"In considering the provisions of NB-3222.4(d),

consideration need not be given to the effects of earthquake loadings." should not be applied to the loadings associated with the vibratory motion of 50

percent of the SSE.

6Includes operating loadings where specified (e.g.,

parts or appurtenances such as vessel nozzles or piping penetration assemblies with special service conditions).

The requirements of NE-3113 of the Code should be met. Operating loadings need only be included in those combination of loadings delineated in regulatory positions C.1.b.,C.2.b.(1)., and C.2.b.(2).

'If detailed rigorous analyses of shells that contain the maximum allowable deviation from true theoretical form is performed for instability (buckling) due to loadings that induce compressive stresses, such analyses, considering inelastic behavior, should demonstrate that a factor of at least two exists between the critical buckling stress and the applied stress.

'lncludes design external pressure, if applicable (e.g., the condition of concern is the maximum net differential external pressure), plus all static and dynamic loadings that induce compressive stresses.

9 Tests in addition to the ten permitted by NE-6222 and NE-6322 of the Code should be evaluated in accordance with cyclic design requirements of NE-38 10

of the code.

1 Loadings associated with the vibratory motion of

50 percent of the SSE should be included in the evaluation of the cyclic loadings in accordance with the design requirements of NE-3810 of the Code.

" If the procedures of NE-3810(e) I or 2 of the Code are used, the total combined meridional membrane and bending stress due to pressure and deflection should be limited to that which would be allowed for 10 cycles using the procedures of NE-3810(d) of the Code. This limit will provide consistency with the design limits inherent in using the procedures of NE-3810(e)3 of the Code.

"2The requirements of NE-3810(c) of the Code should be met by testing the major structural assemblies in which the bellows-type expansion joints are installed (e.g., penetration assemblies). All loadings such as axial compressive loadings that contribute to the instability of the assemblies should be considered. Inclusion of these loadings is particularly important in determining if angulation occurs in major structural assemblies containing two or more bellows-type expansion joints.

1.57-6


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