Regulatory Guide 1.57: Difference between revisions

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{{Adams
{{Adams
| number = ML070310029
| number = ML003740195
| issue date = 03/11/2007
| 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 = Shaukat S
| author name =  
| author affiliation = NRC/RES/DFERR/DDERA/MSEB
| author affiliation = NRC/RES
| addressee name =  
| addressee name =  
| addressee affiliation =  
| addressee affiliation =  
| docket =  
| docket =  
| license number =  
| license number =  
| contact person = Shaukat K, RES/DFERR/ERA/MS, 415-6592
| contact person =  
| case reference number = DG-1158
| document report number = RG-1.57
| document report number = RG-1.057, Rev 1
| package number = ML070240106
| document type = Regulatory Guide
| document type = Regulatory Guide
| page count = 13
| page count = 6
}}
}}
{{#Wiki_filter:The U.S. Nuclear Regulatory Commission (NRC) issues regulatory guides to describe and make available to the public methods that the NRC staff considers acceptable for use in implementing specific parts of the agencys regulations, techniques that the staff uses in evaluating specific problems or postulated accidents, and data that the staff need in reviewing applications for permits and licenses.  Regulatory guides are not substitutes for regulations, and compliance with them is not required.  Methods and solutions that differ from those set forth in regulatory guides will be deemed acceptable if they provide a basis for the findings required for the issuance or continuance of a permit or license by the Commission.
{{#Wiki_filter:-*-  
 
U.S. ATOMIC ENERGY COMMISSION  
This guide was issued after consideration of comments received from the public.  The NRC staff encourages and welcomes comments and suggestions in connection with improvements to published regulatory guides, as well as items for inclusion in regulatory guides that are currently being developed.  The NRC staff will revise existing guides, as appropriate, to accommodate comments and to reflect new information or experience.  Written comments may be submitted to the Rules and Directives Branch, Office of Administration, U.S. Nuclear Regulatory Commission, Washington, DC
REGULATORY GUI
20555-0001.
¶
 
DIRECTORATE OF REGULATORY STANDARDS
Regulatory guides are issued in 10 broad divisions:  1, Power Reactors; 2, Research and Test Reactors; 3, Fuels and Materials Facilities;
REGULATORY GUIDE 1.57 DESIGN LIMITS AND LOADING COMBINATIONS  
4, Environmental and Siting; 5, Materials and Plant Protection; 6, Products; 7, Transportation; 8, Occupational Health; 9, Antitrust and Financial Review; and 10, General.
FOR METAL PRIMARY REACTOR CONTAINMENT SYSTEM COMPONENTS
 
Requests for single copies of draft or active regulatory guides (which may be reproduced) should be made to the U.S. Nuclear Regulatory Commission, Washington, DC 20555, Attention: Reproduction and Distribution Services Section, or by fax to (301) 415-2289; or by email to Distribution@nrc.gov.
 
Electronic copies of this guide and other recently issued guides are available through the NRCs public Web site under the Regulatory Guides document collection of the NRCs Electronic Reading Room at http://www.nrc.gov/reading-rm/doc-collections/ and through the NRCs Agencywide Documents Access and Management System (ADAMS) at http://www.nrc.gov/reading-rm/adams.html, under Accession No. ML070310029.
 
U.S. NUCLEAR REGULATORY COMMISSION  
 
REGULATORY GUIDE
OFFICE OF NUCLEAR REGULATORY RESEARCH
 
March 2007 Revision 1
 
REGULATORY GUIDE 1.57 (Draft was issued as DG-1158, dated October 2006)
 
DESIGN LIMITS AND LOADING COMBINATIONS  
FOR METAL PRIMARY REACTOR CONTAINMENT  
SYSTEM COMPONENTS  


==A. INTRODUCTION==
==A. INTRODUCTION==
This regulatory guide describes an approach that the staff of the U.S. Nuclear Regulatory Commission (NRC) considers acceptable for use in satisfying the requirements of General Design Criteria (GDC) 1, 2, 4, and 16, as specified in Appendix A, General Design Criteria for Nuclear Power Plants, to Title 10, Part 50, of the Code of Federal Regulations (10 CFR Part 50), Domestic Licensing of Production and Utilization Facilities (Ref. 1).  Specifically, 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 performed.
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.
To augment those requirements, 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 function.  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 occurrence. Similarly, 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 compatible with environmental conditions associated with normal operation, maintenance, testing, and postulated accidents, including loss-of-coolant accidents (LOCAs).
 
Rev. 1 of RG 1.57, Page 2 In addition, GDC 16, Containment Design, requires that the reactor containment and its associated systems be provided to establish an essentially leaktight 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 conditions. Finally, 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 50.44 provides the requirements for combustible gas control for currently-licensed reactors and for future water-cooled reactor applicants and licensees. This regulatory guide describes an approach acceptable to the NRC staff to consider the structural loads involved and determine the containment response to demonstrate the containment structural integrity.
 
Moreover, leaktightness of the containment structure must be tested at regular intervals during the life of the plant, in accordance with the provisions of 10 CFR Part 50, Appendix J, Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors.  In addition, for certain reactors specified in 10 CFR 50.34(f), 10 CFR 50.34(f)(3)(v)(A) and (B) require 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 actuations.
 
Meeting these criteria 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 condition.
 
This regulatory guide contains information collections, covered by the requirements of 10 CFR
Part 50, that the Office of Management and Budget (OMB) approved under OMB control number 3150-0011.
 
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 number.
 
Rev. 1 of RG 1.57, Page 3


==B. DISCUSSION==
==B. DISCUSSION==
Background The American Society of Mechanical Engineers (ASME) publishes the Rules for Construction of Nuclear Facility Components, as Section III of the ASME B&PV Code (Ref. 2).1 In that section, 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 concrete (ASME B&PV Code Section III, Division 1, is hereinafter referred to as the Code). 
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)  
However, the existing industry codes and standards are 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 reactors. 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).  
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.


The NRC is committed to the use of industry consensus codes and standards for the design, construction, and licensing of commercial nuclear power reactors facilities. 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 containments.  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 functions. 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.
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.


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 inerted atmosphere.  10 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 integrity.  10 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 occur.
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.


10 CFR 50.44(c)(3) requires that future water-cooled reactors containments that do not rely upon an inerted 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 integrity.  10 CFR 50.44(c)(5) requires that for future water-cooled reactors containments, an applicant must perform an analysis that demonstrates containment structural integrity.  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 involved.  The analysis must address an accident that releases hydrogen generated from 100 percent fuel clad-coolant reaction accompanied by hydrogen burning.
===1. Power Reactors ===


1 ASME Boiler and Pressure Vessel Code, Section III, Nuclear Components, Division 1, including that part of the Summer 2003 Addenda.
===6. Products ===
2. Research and Test Reactors


Rev. 1 of RG 1.57, Page 4 To address the requirements of 10 CFR 50.34(f) and 10 CFR 50.44(b) and (c), Regulatory Position C.1.2.3.3 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 dioxide.
===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.


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 subjected.  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 components.
5. Materials and Plant Protection
10. General JUNE 1973 DE


In Appendix B to the Code, entitled Owners 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 considered. 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.
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.


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 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 safety.
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.


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 stresses.  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 building.  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 primary reactor containment system of metal construction includes all components which perform a containment function such as (1) the containment vessel or vessels,  
 
(2)  
The approach set forth in this guide is directly related to Section III of the Code.  Design limits as specified in Section III are adopted to provide assurance of maintaining the pressure-retaining integrity of the primary reactor containment.  The primary reactor containment system of metal construction includes all components that perform a containment function, such as (1) the containment vessel(s),  
penetration assemblies and access openings, and (3)  
(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 containment.
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.
 
Rev. 1 of RG 1.57, Page 5 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 thereof.2  Such parts and appurtenances may include mechanical, electrical, and piping penetration assemblies,3 bellows-type expansion joints, and access openings.  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-1120. 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.


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. 3), as they relate to metal containments and liners of concrete containments.
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.


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


New guidelines for the ultimate capacity of steel containments are added in this regulatory guide in order to be consistent with the current staff position. These guidelines are being considered for inclusion in the update to Section 3.8.2, Steel Containment, of NUREG-0800, Standard Review Plan
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
[SRP] for the Review of Safety Analysis Reports for Nuclear Power Plants (Ref. 4).  
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.


2 Refer to NCA-9200 of the Code for definitions of parts and appurtenances.
b.


3 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 leaktight integrity, while compensating for such things as temperature and pressure fluctuations and earthquake movements.
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.


Rev. 1 of RG 1.57, Page 6  
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.


==C. REGULATORY POSITION==
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.
1.


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


For earthquake engineering criteria, 10 CFR Part 50, Appendix S, Earthquake Engineering Criteria for Nuclear Power Plants, would be applicable for the operating-basis earthquake (OBE)
c.
and safe-shutdown earthquake (SSE).  In this manner, 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 damage.


Code Class MC components of primary metal containment systems that are completely enclosed within Seismic Category I structures4 should be designed to withstand the following loads and loading combinations within the specified design limits.
For the combination of design loadings and loadings associated with the vibratory motion of the SSE
157-2


1.1 Loads D -------Dead loads.
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.


L--------Live loads, including all loads resulting from platform flexibility and deformation and from crane loading, if applicable.
d.


Pt -------Test pressure.
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.


Tt -------Test temperature.
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.


To-------Thermal effects and loads during startup, normal operating, or shutdown conditions, based on the most critical transient or steady-state condition.
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.


Ro-------Pipe reactions during startup, normal operating, or shutdown conditions based on the most critical transient or steady-state condition.
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.


Po-------External pressure loads resulting from pressure variation either inside or outside containment.
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.


E--------Loads generated by the operating-basis earthquake including sloshing effects, if applicable.
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.


E-------Loads generated by the SSE, including sloshing effects.
2.


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.5 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
Bellows-Type Expansion Joints that Are Parts or Appurtenances of ASME Code Class MC Vessels a.


4 Components of primary reactor containment systems are Seismic Category I for seismic design purposes in accordance with Regulatory Guide 1.29, Seismic Design Classification (Ref. 5). Seismic Category I SSCs are designed to remain functional if the SSE occurs.
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.


5 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 postulated.  For all other load combinations involving a loss of coolant accident (LOCA), the design-basis LOCA is postulated.
b.


Rev. 1 of RG 1.57, Page 7 Ps -------All pressure loads that are caused by the actuation of safety relief valve (SRV) discharge, including pool swell and subsequent hydrodynamic loads.
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.


Ts-------All thermal loads that are generated by the actuation of SRV discharge, including pool swell and subsequent hydrodynamic thermal loads.
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.


Rs-------All pipe reaction loads that are generated by the actuation of SRV discharge, including pool swell and subsequent hydrodynamic reaction loads.
==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.


Yr-------Equivalent static load on the structure generated by the reaction on the broken pipe during the design-basis accident.
1.
 
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.
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.


FL-------Load generated by the post-LOCA flooding of the containment, if any.
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.


Pg1------ Pressure resulting from an accident that releases hydrogen generated from 100% fuel clad metal-water reaction.
1.57-3


Pg2------Pressure resulting from uncontrlooed hydrogen burning.
b.


Pg3------Pressure resulting from post-accident inerting, assuming carbon dioxide is the inerting agent.
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.


See Regulatory Guide 1.7 (Ref. 6) for additional guidance about the pressure load Pg3 due to combustible gas concentration.
c.


1.2 Loading Combinations and Design Limits The specified loads and load combinations are acceptable if found to be in accordance with the following guidance.  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:
The design limits specified in NE-3131(cXI) or  
1.2.1 Testing Condition This includes the testing condition of the containment to verify its leak integrity.  In this case, the loading combination includes: 
(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 + L + Tt + Pt
1.2.2 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 plant. Such loads include design pressure, design temperature, and the design mechanical loads generated by the design-basis accident.  In this case, the loading combination includes: 
D + L + Pa + Ta + Ra


Rev. 1 of RG 1.57, Page 8
d.
1.2.3 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 condition.  The loads may be combined by their actual time history of occurrence, taking into consideration their dynamic effect upon the structure.


1.2.3.1 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 Loadings. The loading combinations corresponding to these limits include the following:
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.
(1)
Normal operating plant condition D + L + To + Ro + Po
(2)
Operating plant condition in conjunction with multiple SRV actuations D + L + Ts + Rs + Ps
(3)  
Loss-of-coolant accident D + L + Ta + Ra + Pa
(4)
Multiple SRV actuations in combination with a small- or intermediate-break accident D + L + Ta + Ra + Pa + Ts + Rs + Ps
(5)  
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
(6)
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
1.2.3.2 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 operational.  The loading combinations corresponding to these limits include the following:
(1)
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
 
Rev. 1 of RG 1.57, Page 9
(2)
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
(3)
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
(4)
Loss-of-coolant accident in combination with a single active component failure causing one SRV discharge D + L + Ta + Pa + Ra + Ts + Rs + Ps
1.2.3.3 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 required.  The loading combinations corresponding to these limits include the following:
(1)
Loss-of-coolant accident in combination with the SSE
D + L + Ta + Ra + Pa + E
(2)
Operating plant condition in combination with the SSE  
D + L + To + Ro + Po + E
(3)
Multiple SRV actuations in combination with a small- or intermediate-break accident and SSE 
D + L + Ta + Ra + Pa + Ts + Rs + Ps + E
(4)
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.]
(5)
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.]


Rev. 1 of RG 1.57, Page 10
e.
1.2.3.4 Level D Service Limits These service limits include other applicable service limits and loadings of dynamic nature for which the containment function is required.  The load combinations corresponding to these limits include the following:
(1)
Loss-of-coolant accident in combination with the SSE and local dynamic loadings D + L + Ta + Ra + Pa + Yr + Yj + Ym + E
(2)
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'
(3)
Post-LOCA flooding of the containment in combination with the operating-basis earthquake D + L + FL + E
1.3 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.


1.4 Treatment of Buckling Effects Earthquake, thermal, and pressure loads require consideration of buckling of the shell.  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
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.
Code Case N-284-2, pending endorsement in Regulatory Guide 1.84 (Ref. 7).6  An acceptable approach to this problem is to perform a nonlinear analysis.


2.
2.


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


Ultimate Capacity of Concrete Containment
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.


A nonlinear finite element analysis should be performed to determine the ultimate capacity of the containment.  Additional information guidance is provided in the SRP 3.8.2.
b.


6 Code Case N-284, Metal Containment Shell Buckling Design Methods, Class MC Section III, Division 1, is currently being revised.  Revision 1 of N-284 is unacceptable to the NRC, as discussed in Regulatory Guide 1.193 (Ref. 8).  Revision 2 of N-284 is correcting errata, misprints, recommendations, and errors identified by the NRC staff, and is expected to be approved when it is published.
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.


Rev. 1 of RG 1.57, Page 11
-- V
1.57-4


==D. IMPLEMENTATION==
DEFINITIONS
The purpose of this section is to provide information to applicants and licensees regarding the NRC staffs plans for using this regulatory guide.  No backfitting is intended or approved in connection with its issuance.
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.


Except in those cases in which an applicant or licensee proposes or has previously established an acceptable alternative method for complying with specified portions of the NRCs regulations, the methods to be described in the active guide will reflect public comments and will be used in evaluating
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) submittals in connection with applications for construction permits, standard plant design certifications, operating licenses, early site permits, and combined licenses; and (2) submittals from operating reactor licensees who voluntarily propose to initiate system modifications if there is a clear nexus between the proposed modifications and the subject for which guidance is provided herein.
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.


REGULATORY ANALYSIS / BACKFIT ANALYSIS
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.


The regulatory analysis and backfit analysis for this regulatory guide are available in Draft Regulatory Guide DG-1158, Design Limits and Loading Combinations for Metal Primary Reactor Containment System Components (Ref. 9).  The NRC issued DG-1158 in October 2006 to solicit public comment on the draft of this Revision 1 of Regulatory Guide 1.57.
Primary Metal Containment System.


Rev. 1 of RG 1.57, Page 12 REFERENCES
Includes the following components:
1.
1. The containment vessel or vessels;
 
U.S. Code of Federal Regulations, Title 10, Energy, Part 50, Domestic Licensing of Production and Utilization Facilities.7 
2.
2.


ASME Boiler & Pressure Vessel Code, Section III, Rules for Construction of Nuclear Facility Components, Division 1, Subsection NE, Class MC Components, 2001 Edition with 2003 Addenda, American Society of Mechanical Engineers, New York, New York.8
All penetration assemblies or appurtenances not a part of the vessel;
3.
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.
 
ASME Boiler & Pressure Vessel Code, Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, 2001 Edition with 2003 Addenda, American Society of Mechanical Engineers, New York, New York.
 
4.
 
NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants, U.S. Nuclear Regulatory Commission, Washington, DC.5
5.
 
Regulatory Guide 1.29, Seismic Design Classification, U.S. Nuclear Regulatory Commission, Washington, DC.9 
6.
 
Regulatory Guide 1.7, Control of Combustible Gas Concentrations in Containment, U.S.
 
Nuclear Regulatory Commission, Washington, DC.
 
7.


Regulatory Guide 1.84, Design, Fabrication, and Materials Code Case Acceptability, ASME
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.
Section III, U.S. Nuclear Regulatory Commission, Washington, DC.


7 All NRC regulations listed herein are available electronically through the Electronic Reading Room on the NRCs public Web site, at http://www.nrc.gov/reading-rm/doc-collections/cfr/. Copies are also available for inspection or copying for a fee from the NRCs Public Document Room at 11555 Rockville Pike, Rockville, MD; the PDRs mailing address is USNRC PDR, Washington, DC 20555; telephone (301) 415-4737 or (800) 397-4209; fax (301) 415-3548;
Seismic Category I. Those structures, systems, and components that are designed to remain functional if the SSE occurs.
email PDR@nrc.gov.


8 Copies of the Code and addenda thereto may be obtained from the American Society of Mechanical Engineers, Three Park Avenue, New York, New York  10016-5990.
1.57-5


5 All NUREG-series reports listed herein were published by the U.S. Nuclear Regulatory Commission.  Copies are available for inspection or copying for a fee from the NRCs Public Document Room at 11555 Rockville Pike, Rockville, MD; the PDRs mailing address is USNRC PDR, Washington, DC 20555; telephone (301) 415-4737 or
NOTES
(800) 397-4209; fax (301) 415-3548; email PDR@nrc.gov.  Copies are also available at current rates from the U.S.
'Section III of the ASME Boiler and Pressure Vessel Code including that part of the Summer 1973 Addenda that pertains to Class MC components.


Government Printing Office, P.O. Box 37082, Washington, DC 20402-9328, telephone (202) 512-1800; or from the National Technical Information Service (NTIS) at 5285 Port Royal Road, Springfield, Virginia 22161, online at http://www.ntis.gov, by telephone at (800) 553-NTIS (6847) or (703) 605-6000, or by fax to (703) 605-6900.
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.


NUREG-0800 is also available electronically through the Electronic Reading Room on the NRCs public Web site, at http://www.nrc.gov/ reading-rm/doc-collections/nuregs/.
4Refer to NA-1200 of the Code for definition of parts and appurtenances.
9 All regulatory guides listed herein were published by the U.S. Nuclear Regulatory Commissio


====n. Where an ADAMS ====
SThe exception stated in NE-3131(d),
accession number is identified, the specified regulatory guide is available electronically through the NRCs Agencywide Documents Access and Management System (ADAMS) at http://www.nrc.gov/reading-rm/adams.html.
"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.


All other regulatory guides are available electronically through the Electronic Reading Room on the NRCs public Web site, at http://www.nrc.gov/reading-rm/doc-collections/reg-guides/.  Single copies of regulatory guides may also be obtained free of charge by writing the Reproduction and Distribution Services Section, ADM, USNRC, Washington, DC 20555-0001, or by fax to (301)415-2289, or by email to DISTRIBUTION@nrc.gov. Active guides may also be purchased from the National Technical Information Service (NTIS) on a standing order basis. Details on this service may be obtained by contacting NTIS Error! Main Document Only.at 5285 Port Royal Road, Springfield, Virginia
6Includes operating loadings where specified (e.g.,
22161, online at http://www.ntis.gov, by telephone at (800) 553-NTIS (6847) or (703) 605-6000, or by fax to (703)  
parts or appurtenances such as vessel nozzles or piping penetration assemblies with special service conditions).   
605-6900.  Copies are also available for inspection or copying for a fee from the NRCs Public Document Room (PDR), which is located at 11555 Rockville Pike, Rockville, Maryland; the PDRs mailing address is USNRC PDR,  
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).
Washington, DC 20555-0001.  The PDR can also be reached by telephone at (301) 415-4737 or (800) 397-4209, by fax at (301) 415-3548, and by email to PDR@nrc.gov.
'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.


Rev. 1 of RG 1.57, Page 13
'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.
8.


Regulatory Guide 1.193, ASME Code Cases Not Approved for Use, U.S. Nuclear Regulatory Commission, Washington, DC.
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.


9.
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.


Draft Regulatory Guide DG-1158, Design Limits and Loading Combinations for Metal Primary Reactor Containment System Components, U.S. Nuclear Regulatory Commission, Washington, DC.10
" 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.


10 
"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.
Draft Regulatory Guide DG-1158 is available electronically under Accession #ML063000278 in the NRCs Agencywide Documents Access and Management System (ADAMS) at http://www.nrc.gov/reading-rm/adams.html.


Copies are also available for inspection or copying for a fee from the NRCs Public Document Room (PDR), which is located at 11555 Rockville Pike, Rockville Maryland; the PDRs mailing address is USNRC PDR, Washington, DC
1.57-6}}
20555-0001. The PDR can also be reached by telephone at (301) 415-4737 or (800) 397-4209, by fax at (301)
415-3548, and by email to PDR@nrc.gov.}}


{{RG-Nav}}
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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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