Regulatory Guide 1.87

Guidance for Construction of Class 1 Components in Elevated-Temperature Reactors (Supplement to ASME Section III Code Cases 1592, 1593, 1594, 1595, and 1596)

ML003740252
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Issue date:	06/30/1975
From:	Office of Nuclear Regulatory Research
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RG-1.87, Rev 1
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Revision 1 U.S. NUCLEAR REGULATORY COMMISSION June 1975 REGULATORY GUIDE

OFFICE OF STANDARDS DEVELOPMENT

REGULATORY GUIDE 1.87 GUIDANCE FOR CONSTRUCTION 1 OF CLASS 1 COMPONENTS

IN ELEVATED-TEMPERATURE REACTORS

(SUPPLEMENT TO ASME SECTION III CODE CASES 1592, 1593, 1594, 1595, AND 1596)

A. INTRODUCTION

B. 'DISCUSSION

Section 50.55a, "Codes and Standards," of 10 CFR The rules for construction of nuclear components Part 50, "Licensing of Production and Utilization given in Section III of the ASME Boiler and Pressure Facilities," requires, in part, that structures, systems, Vessel Code, including Class 1 nuclear components and components be designed, fabricated, erected, tested, that are covered in Subsection NB of Section III, apply and inspected to. quality standards commensurate with to components at temperatures where creep effects are the importance of the safety functions to be performed. insignificant. Material behavior considerations are General Design Criterion 1, "Quality Standards and limited to either elastic or elastic-plastic response, which, Records," of Appendix A, 2 "General Design Criteria for in effect, provides protection against only time Nuclear Power Plants," to 10 CFR Part 50 permits use independent failure modes such as ductile rupture, gross of recognized codes and standards, provided they are distortion, and fatigue.

identified and evaluated to determine applicability, adequacy, and sufficiency and are supplemented or The service temperatures and load conditions for modified as necessary to ensure a quality product in HTGRs, LMFBRs, and GCFBRs are such that keeping with the required safety function. This guide time-dependent phenomena such as creep and relaxation describes interim licensing guidelines to aid applicants in are important. Subsection NB of Section III does not implementing these requirements with respect to ASME provide adequate guidance for construction of Class 1 components operating at elevated temperatures. components subject to elevated-temperature service.

This guide applies to high-temperature gas-cooled Therefore, as an interim step, the ASME has developed reactors (HTGRs), liquid-metal fast-breeder reactors five Code Cases (1592, 1593, 1594, 1595, and 1596) to (LMFBRs), and gas.cooled fast-breeder reactors provide guidance in this area. Code Cases 1593, 1594, (GCFBRs). 1595, and 1596 were approved on November 5, 1973, as interpretations of the ASME Boiler and Pressure Vessel Code. Code Case 1592 was approved on April 29,

1974.

'As defined in Section III of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME These Code Cases cover design, fabrication and B&PV Code), construction is an all-inclusive term comprising materials, design, fabrication, examination, testing, inspection, installation, examination, testing, and protection against and certification required in the manufacture and installation overpressure. They reflect both time-independent and of components. time-dependent material properties and structural

2 behavior (elastic and inelastic) by considering the Appendix A to 10 CFR Part 50 is directly applicable to water-cooled nuclear power plants; however, as indicated in following modes of failure:

that appendix, the General Design Criteria are considered applicable to other types of nuclear power units and are 1. Ductile rupture from short-term loadings;

intended to provide guidance in establishing principal criteria for such other units. 2. Creep rupture from long-term loadings;

USNRC REGULATORY GUIDES Comments should be sent to the Secretary of the Commission, U.S. Nuclear Regulatory Guides are issued to describe and make available to the public Regulatory Commission, Washington. D.C. 20555, Attention: Docketing and methods acceptable to the NRC staff of implementing specific parts of the Service Section.

Commission's regulations, to delineate techniques used by the staff in evalu.

ating specific problems or postulated accidents. orto provide guidance to appli- The guides are issued in the following ten broad divisions:

cants- Regulatory Guides are not substitutes for regulations, and compliance 1. Power Reactors 6. Products with them is not required. Methods and solutions different from those set Out in 2 Research and Test Reactors 7. Transportation the guides will be acceptable if they provide a basis for the findings requisite to 3. Fuels and Materials Facilities 8. Occupational Health the issuance or continuance of a permit or license by the Commission. 4. Environmental and Siting 9. Antitrust Review Comments and suggestions for improvements in these guides are encouraged 5. Materials and Plant Protection 10- General at all times, and guides will be revised, as appropriate, to accommodate com ments and to reflect new information or experience. This guide was revised as a Copies of published guides may be obtained by written request indicating the result of substantive comments received from the public and additional staff divisions desired to the U.S. Nuclear Regulatory Commission. Washington. D.C.

review 20555. Attention: Director, Office of Standards Development.

3. Creep-fatigue failure; tion of accepted construction practices. However, certain aspects of testing and overpressure protection

4. Gross distortion due to incremental collapse and relative to test liquids and "noncritical" component ratcheting; protection need further clarification as indicated in the regulatory position of this guide.

5. Loss of function due to excessive deformation;

These code cases were developed to supplement

6. Buckling due to short-term loadings; Subsection NB, "Requirements for Class 1 Components," of Section III of the ASME B&PV Code.

7. Creep buckling due to long-term loadings. In some instances, they also refer to use of other ASME

rules such as Appendix E, "Minimum Bolt Cross-Section Consideration of these complex failure modes serves as a Area," Appendix F, "Rules for Evaluation of Faulted basis for developing design methods and procedures to Conditions," Subsection NF, "Component Supports,"

provide adequate protection throughout a reactor and Subsection NG, "Core Support Structures." These lifetime of 30 to 40 years. referenced rules do not include consideration of ele vated-temperature or time-dependcent effects during serv The Code Cases under discussion utilize recently ice life. Therefore, the use of Appendices E or F,

acquired information on material behavior, extended use Subsections NF or NG, or other portions of Section III

of accepted practice, and special consideration of of the ASME B&PV Code should be justified with safety-related aspects of the nuclear system to establish respect to applicability for elevated-temperature service rules of construction for components in elevated when used with these Code Cases. Some representative temperature service. These rules establish procedures areas of concern are repeated stress relaxation, dynamic that are consistent with current knowledge and the state load considerations, deforrhation limits, and irradiation of the art. effects.

Code Case 1592 presents rules for component design A note of caution is also raised concerning Code Case and includes data on material properties. The complex reference to Articles in Subsection NB of Section III of influence of temperature, environment, and geometry on the ASME B&PV Code. The primary problem is that material properties and structural behavior for extended literal compliance with a specific Code Case could time periods requires evaluation of component design by possibly introduce unintended construction practices by analytical techniques. Although present knowledge is referring to a certain Article in Subsection NB that has sufficient to design with a high probability of safe subsequently been superseded by another Code Case. As service, it will be necessary for component designs to an example, Code Case 1593 (in the Reply to Inquiry)

consider and accommodate inservice inspection and refers to fabrication and installation in accordance with surveillance programs. The intent, within the context of the rules of Section III, Article NB-4000. Subparagraph this guide, is to establish that potential access and NB-4223.1 of that Article subsequently references Table coupon-test-material needs for both inspection and NB-3642.1-1 which in turn refers to subparagraph surveillance programs should be considered at the NB-3641.1 of Article NB-3000. However, for Class 1 component design stage. components in elevated-temperature service, Code Case

1592 has replaced Article NB-3000 and, in the process, The provision to consider inservice inspection and the requirements of Table NB-3642.1-1 and sub surveillance test programs at the design stage will allow paragraph NB-3641.1 were changed. This illustrates systematic monitoring of component and material that compliance with one Code Case may inadvertently behavior. This approach will help to detect and assess conflict Yfith another Code Case. Therefore, care should accumulation of damage, excessive deformation, be exercised to determine that referenced Articles in incipient failure, or possible synergistic effects of Subsection NB are consistent with all applicable Code elevated temperature, load conditions, and environment Cases and the supplements of the regulatory position of on materials and components during a design life of 30 this guide.

to 40 years. Additionally, the limited material response data base (tensile, creep, stress rupture, fatigue, etc.) and The rules in Appendix II of Section III of the ASME

lack of prototypical service experience will also be B&PV Code permit component acceptance by means of augmented by results -from ongoing research programs. experimental stress analysis in lieu of analytical techniques. Code Case 1592 establishes intent to extend Construction aspects associated with fabrication and this concept to permit acceptance of elevated installation, examination, testing, and overpressure temperature components by experimental analysis.

protection are covered in Code Cases 1593, 1594, 1595, Detailed guidelines have not been provided; therefore, it and 1596, respectively. These rules generally account for will be necessary to document test procedures and potential safety-related problems during elevated acceptance criteria for experimental analysis of com temperature service by invoking more stringent applica- ponents to be used in elevated-temperature service.

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C. REGULATORY POSITION

inelastic analysis should be included in the PSAR. All

• computer programs used should be identified and The requirements of Code Cases 1592, "Section III, sufficiently described in the PSAR with respect to those Class 1 Components in Elevated Temperature Service," portions utilized to identify basic theory, assumptions,

1593; "Fabrication and Installation of Elevated constitutive relations, extent of verification, limitations, Temperature Components,Section III, Class 1," 1594, and justification of applicability, including validation of

"Examination of Elevated Temperature Components, computer models and modeling techniques.

Section III, Class 1," 1595, "Testing of Elevated Temperature Components,Section III, Class 1,," and b. Identification of whether the strength properties

1596, "Protection Against Overpressure of Elevated used in analysis are minimum, average, or maximum Temperature Components,Section III, Class 1," will be should be included in the PSAR for each part of the used with Section III of the ASME Boiler and Pressure analysis, except where the properties are specified by, or Vessel Code, including Addenda, in evaluating are an integral part of, the analytical method. Where an applications for construction permits, as supplemented option exists; the use of minimum, average, or maximum

• by the following: strength properties relative to critical failure modes, damage laws, and deformation limits should be justified on the basis of increased safety. If the material property

1. General Items. data given in the Code" Case are inadequate (including alteration or extrapolation) for design evaluation of all a. All five Code Cases should be invoked, where modes of failure, the appropriate properties used in applicable, for components 'in high-temperature design should be documented and justified in the PSAR.

gas-cooled reactors, liquid-metal fast-breeder reactors, This material data base, together with a description of and gas-cooled fast-breeder reactors. the methods used to account for environmental effects throughout design life, should be documented in the b. These Code Cases may be used in conjunction PSAR.

with Subsection NB of Section III of the ASME Boiler and Pressure Vessel Code. When other portions of Section III such as Appendices E and F and Subsections c. The acceptability criteria applied as strain, NF and NG are used with these Code Cases, justification deformation, and fatigue limits pursuant to 3250 should of the bases relative to elevated-temperature appli be consonant with the rules of Appendix T of this Code cabilifty should be submitted in the Preliminary Safety Case. When any acceptability criteria or material Analysis Report (PSAR). properties are invoked as alternatives to the rules of

-1 If the requested justification and documentation are Appendix T, the affected areas (material, parts, components, systems, etc.) should be identified, and not available at the time the PSAR is submitted, they justification for such rules should be documented in the should be included in a subsequent submittal, and the PSAR.

PSAR should contain a preliminary discussion of bases and approaches to be utilized and should reference the d. A full description of the buckling analysis appropriate regulatory position paragraph of this guide pursuant to T-1500 should be documented in the PSAR.

such as C.l.b for this item. This procedure should be This should also include the following:

implemented for all paragraphs of this guide that request submittal of information in the PSAR. (1) Indication of the margin for a design factor on load applied throughout service life, in addition to the c. Component designs should accommodate the suggested end-of-life design factor in Table T-1520-1.

required inservice inspection and surveillance programs for material or component integrity. Representative (2) Justification that a process is purely environmental factors should consider the compatibility strain-controlled and not combined with load-controlled of the coolant such as sodium, helium, air, and or significant elastic followup when the strain-controlled contaminants; irradiation effects that might induce design factor in Table T- 15 20-1 is used.

ductility loss; and aging resulting from :prolonged exposure to elevated temperature. (3) Description of the methods used to determine the minimum stress-strain curve suggested in T-1520(c).

2. Code Case 1592 e. The intent of Appendix II (ASME B&PV Code)

a. A description of analysis methods and delineation rules should be used for guidance when design is justified by experimental analysis. A description of procedures of areas that have been subjected to elastic analysis or used for experimental analysis, the evaluation

• Lines indicate substantive changes from previous issue. techniques, and acceptance criteria should be included in I

the PSAR.

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3, Code Case 1593 "noncritical" pursuant to 71 10(aX4) and 7110(b). The evaluation techniques and acceptance criteria used to All Articles of Subsection NB referenced in this Code justify designation as a "noncritical" component should Case should be applied in a manner consistent with all also be included.

applicable elevated-temperature Code Cases and the corresponding supplements in the regulatory position of b. All Articles of Subsection NB referenced in this this guide. Code Case should be applied in a manner consistent with all applicable elevated-temperature Code Cases and the

4. Code Case 1594 corresponding supplements in the regulatory position of this guide.

All Articles of Subsection NB referenced in this Code Case should be applied in a manner consistent with all c. The potential overpressure due to failure of a applicable elevated-temperature Code Cases and the system component in 7121(d) should include corresponding supplements in the regulatory position of consideration of pressure from an adjacent system by this guide. leaks or chemical reaction or both.

S. Code Case 1595 d. For those reactors using liquid sodium as the coolant, a description of the methods used to determine a. The "nonhazardous liquid" in 6212(a) should be overpressure resulting from possible shock loads nonhazardous relative to possible reactions between mentioned in 7122 should appear in the Overpressure residual test liquid and the normal coolant fluid and Protection Report. This should include a definition of nonhazardous with respect to deleterious effects to the what constitutes rapid valve closure relative to component (material) such as corrosion by either the pressure-wave velocity and valve closing time. A

test liquid or a fluid created by reaction of test liquid description of how the pressure shock and momentum and coolant. Appropriate posttest procedures that ensure change effects have been accounted for with respect to proper draining and drying may be instituted in some pressure relief, piping design, and support systems instances where a potential test liquid would be should also be included.

excluded from use because of the aforementioned effects. When a test liquid is considered "nonhazardous"

D. IMPLEMENTATION

as a result of such prescribed posttest procedures, the posttest procedures should be documented in the PSAR The purpose of this section is to provide information and included as part of the Data Report Form required to applicants and licensees regarding the INRC staffs by NA-8400 of the ASME B&PV Code. All areas subject plans for utilizing this regulatory guide.

to these procedures should be identified in the PSAR.

Except in those instances in which the applicant b. All Articles of Subsection NB referenced in this proposes an alternative method for complying with Code Case should be applied in a manner consistent with specified portions of the Commission's regulations, the all applicable elevated-temperature Code Cases and the method described herein will be used in the evaluation corresponding supplements in the regulatory position of of submittals for construction permit applications this guide. docketed after January 1, 1976.

6. Code Case 1596 If an applicant wishes to use this regulatory guide in developing submittals for applications docketed on or.

a. The Overpressure Protection Report should before January 1, 1976, the pertinent portions of the indicate those components considered to be application will be evaluated on the basis of this guide.

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