1、STP-NU-045-1ROADMAP TO DEVELOP ASME CODE RULES FOR THE CONSTRUCTION OF HIGH TEMPERATURE GAS COOLED REACTORS (HTGRS) STP-NU-045-1 ROADMAP TO DEVELOP ASME CODE RULES FOR THE CONSTRUCTION OF HIGH TEMPERATURE GAS- COOLED REACTORS (HTGRS) Prepared by: Robert Sims Becht Engineering Revised by: James Neste
2、ll MPR Associates Date of Issuance: June 30, 2012 This report was prepared as an account of work sponsored by U.S. NRC and the ASME Standards Technology, LLC (ASME ST-LLC). Neither ASME, ASME ST-LLC, the authors, nor others involved in the preparation or review of this report, nor any of their respe
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9、 Standards Technology, LLC Three Park Avenue, New York, NY 10016-5990 ISBN No. 978-0-7918-3442-8 Copyright 2012 by ASME Standards Technology, LLC All Rights Reserved Roadmap for ASME HTGR Code Development STP-NU-045-1 iii TABLE OF CONTENTS Foreword . iv 1 VISION STATEMENT . 1 2 BACKGROUND . 2 3 STAK
10、EHOLDERS 3 4 INTRODUCTION AND ORGANIZATION 4 5 PHASE I ACTIVITIES 6 6 ASSUMPTIONS USED IN DEVELOPING THE ROADMAP FOR PHASE II . 7 7 REACTOR DESIGNS AND INFORMATION REQUIRED . 9 8 RESEARCH AND DEVELOPMENT TASKS . 10 9 RECOMMENDED “GLOBAL” ADMINISTRATIVE AND TECHNICAL TASKS FOR PHASES I AND II . 13 10
11、 RECOMMENDED SPECIFIC CODE RULE TASKS FOR PHASE II . 16 11 OVERALL INDUSTRY APPROACH AND ORGANIZATION 21 ASME ST- LLC TASKS 23 APPENDIX 1 LIST OF ACRONYMS AND ABBREVIATIONS . 24 ACKNOWLEDGEMENTS . 26 STP-NU-045-1 Roadmap for ASME HTGR Code Development iv FOREWORD The Roadmap has been developed as a
12、guide to the R ORNL/TM-2007/147, Volume 5 Next Generation Nuclear Plant Phenomena Identification and Ranking Tables (PIRTS), Volume 5: Graphite PIRTS. 8.4 Long Term R Non-safety related; Non-safety related with special treatment. The first and last of these correspond to Class A and B, respectively,
13、 as specified in BPV III-5. Roadmap for ASME HTGR Code Development STP-NU-045-1 15 9.2.6.3.2 Overall philosophy of elevated temperature design rules. For example, determine whether elevated temperature rules should be based on a 60-year life, with periodic surveillance coupon testing to confirm desi
14、gn life. Number of cycles should also be considered and the testing interval should be defined. 9.2.6.4 Determine whether the existing BPV Section III, Division 1, Subsection NF on supports should be modified for the HTGR. It may be better to review and update this subsection rather than writing a n
15、ew book or incorporating the requirements into BPV III-5. 9.2.7 Develop Common Terminology and Units of Measure. A common set of terminology, acronyms, abbreviations and units of measure should be developed for use in all HTGR Code rules. It is suggested that the SI system be the primary units, but
16、provisions for the use of alternative units should be made. STP-NU-045-1 Roadmap for ASME HTGR Code Development 16 10 RECOMMENDED SPECIFIC CODE RULE TASKS FOR PHASE II 10.1 Code Rule Development 10.1.1 The following tasks should be completed to support Code rules development over the Phase II period
17、. 10.1.1.1 Expand the General Requirements Portion of III-5. Based on Section III, Subsection NCA and needs identified by stakeholders, consider whether the Design Specification provided by the Owner should identify items such as anticipated degradation mechanisms and online monitoring or other NDE
18、techniques to detect each type of degradation mechanism in a timely manner for significance assessment and disposition. Examples of degradation mechanisms to be considered include: 10.1.1.1.1 Time/Temperature/Load envelope for each primary loop component including the IHX and reactor pressure vessel
19、 internals. 10.1.1.1.1.1 State whether equipment can be de-pressured when metal temperatures exceed defined limits to reduce stress at high temperatures. 10.1.1.1.2 Corrosion/erosion allowances. 10.1.1.1.2.1 Consider requiring that the Owner document the basis for the corrosion/erosion allowance. Co
20、nsider the need for Code rules with requirements for the testing. 10.1.1.1.3 Change in material properties due to carburization/decarburization. 10.1.1.1.4 Allowance for metal loss due to wear at heat exchanger tube supports and core supports where sliding can occur. 10.1.1.1.4.1 Consider requiring
21、the Owner to document the basis for the allowance for metal loss. The need for Code rules with requirements for the testing should also be considered. 10.1.1.1.5 End-of-life strength and toughness properties for metallic and non-metallic materials that are expected to degrade due to thermal aging, r
22、adiation, and interaction with the environment. Such properties may be in a range rather than a single set of values because of the operation of several types of degradation mechanisms. 10.1.1.1.5.1 Consider requiring the Owner to document the basis for the end-of-life properties. The need for Code
23、rules with requirements for the testing should also be considered. 10.1.1.1.6 Beginning-of-life and end-of-life emissivity for components. 10.1.1.1.6.1 Consider requiring the Owner to document the basis for the end-of-life emissivity. The need for Roadmap for ASME HTGR Code Development STP-NU-045-1
24、17 Code rules with requirements for the testing should also be considered. 10.1.1.2 Correct and Extend Allowable Stresses Values. 10.1.1.2.1 Correct errors in the Type 304 and Type 316 allowable stress values identified in ASME ST-LLC Task 6. 10.1.1.2.2 Identify and mitigate low creep rupture streng
25、th of several Type 304 and 316 heats identified in ASME ST-LLC Task 14. 10.1.1.2.3 Extend allowable stress values in Division 5 to 500,000 hours (currently 300,000 hours), as has been initiated in ASME ST-LLC Tasks 13 and 14a. 10.1.1.3 Define Procedures and Material Models for Inelastic Analysis. De
26、signs that do not meet restrictions imposed by Division 5 for simplified inelastic analysis methods and/or do not meet the applicable conservative design limits require a full inelastic analysis. Standardized methods and materials models are required in Division 5 to accomplish this. This is current
27、ly a Subgroup ETD Task Force work topic. 10.1.1.4 Address Negligible Creep and Creep-Fatigue Rules for Mod 9Cr and the Low Alloy Steels A508 and A533. The strain softening behavior of Mod 9Cr makes the negligible creep rules in Division 5 impossible to implement and the creep-fatigue rules overly co
28、nservative. There is some evidence that creep effects can be observed in low alloy steels below the 700F BPV III-NH cut-off. Rules that address these issues are required. 10.1.1.5 Develop Reference Stress or Other Methods for Load-Controlled Stress Analysis. Simplified methods that do not require st
29、ress classification are required for efficient component sizing in preliminary designs. 10.1.1.6 Incorporate Alloy 617 into Division 5. 10.1.1.6.1 While Alloy 800H can be successfully used in high temperature reactor service as a pressure boundary material, an alloy with higher creep resistance is r
30、equired for thin sections exposed to reactor outlet temperatures, such as in the compact heat exchanger. There exists a large body of creep test data for nickel base Alloy 617, which facilitates its incorporation into BPV III-5. 10.1.1.6.2 Rules for welding/joining Alloy 617 in thin sheets are requi
31、red for ASME Code Section IX. 10.1.1.6.3 Review ASME material specifications for Alloy 617 plate and sheet, tube, bar stock and forgings for adequate quality for BPV III-5, Class A service. 10.1.1.7 Develop Rules for Compact Heat Exchangers. 10.1.1.7.1 Rules for the design or testing qualification o
32、f the compact heat exchanger are required in Division 5. 10.1.1.7.2 Since there is little experience with compact heat exchanger design, rules may have to be developed over the years. In the STP-NU-045-1 Roadmap for ASME HTGR Code Development 18 meantime, requirements should be incorporated into BPV
33、 III-5 for the qualification of the design by testing. 10.1.1.8 Develop Safety Class B Rules. Class B rules currently in Division 5 are taken directly from Code Case N-253. These rules have not been reviewed in years and may contain errors or inconsistencies. They may require a complete review and p
34、ossible revision to be applicable to the HTGR. 10.1.1.9 Develop Exemption Rules for Creep-Fatigue. Current rules in Division 5 for determining when creep-fatigue interactions need not be considered are complex and time consuming to apply. Revised rules are required to streamline the design process f
35、or components with relatively low stress levels. 10.1.1.10 Coordinate Division 5 with Section XI, Division 2. 10.1.1.10.1 Perform a review of the inservice inspection and testing requirements of the new Section XI, Division 2 to ensure Division 5 design and fabrication rules are consistent with Sect
36、ion XI. This may result in restrictions on weld placement for accessibility and restrictions on the surface geometry of welds for inservice inspections. 10.1.1.10.2 Incorporate creep-fatigue crack growth methods developed in ASME ST-LLC Task 8 into Section XI. 10.1.1.11 Update Rules for Welding and
37、Post-Weld Heat Treatment (PWHT). For materials to be used at temperatures above the “negligible creep” threshold (see paragraphs 10.1.1.4 and 7.1.2.3), consider the need for restrictions on welding and PWHT in addition to those in current ASME Codes (e.g. see API RP 934-A). Some examples of areas wh
38、ere modified rules may be needed: 10.1.1.11.1 Evaluate the need to further restrict the range of temperatures permitted during PWHT. 10.1.1.11.2 Evaluate whether metal temperatures should be measured and recorded during PWHT to ensure that the limits are not exceeded. 10.1.1.11.3 Evaluate the need f
39、or rules for field fabrication and testing. 10.1.1.12 Develop/Update Rules for Structural Brazing, Diffusion Bonding or Other High-Temperature Joining Techniques. If structural brazing, diffusion bonding or other high temperature joining techniques are identified as necessary for the IHX or other co
40、mponents, the rules in Section IX should be reviewed and updated as necessary. 10.1.1.13 Develop Rules for NDE for New and Post-Construction. NDE rules should be developed for new and post construction in parallel. The rules should be similar to those in the current Section III and Section XI (Appen
41、dix VIII) Codes, except that the following potential requirements should be considered: 10.1.1.13.1 For new construction, consider 100% wet fluorescent magnetic particle (WFMT) for pressure boundary welds in carbon and low alloy steel materials and 100% PT for welds in austenitic Roadmap for ASME HT
42、GR Code Development STP-NU-045-1 19 materials. It may be necessary to grind and prepare the welds to be able to detect small flaws. 10.1.1.13.2 For new construction consider requiring UT as the primary volumetric examination technique, with performance demonstration requirements to ensure that small
43、 flaws can be detected and categorized. 10.1.1.13.2.1 Adopt the same UT methodology and performance demonstration requirements for post construction. 10.1.1.13.3 If there are areas where UT cannot be demonstrated to find small flaws, consider RT. However, consider how this method can be used for pos
44、t construction applications. If that is impractical, consider requiring a re-design of the component. 10.1.1.14 Consider the Need for New Construction Rules for Performance Testing of Valves and Systems. It is anticipated that several important valves will operate in a very high temperature (e.g. gr
45、eater than 650C, 1200F) environment. If the ability of a specific valve to block flow is important to the integrity of the plant, it may be desirable to demonstrate the performance of valves in that service by testing prior to installation. If so, this should be covered in the new construction rules
46、. New construction qualification requirements should be covered in the QME rules. In-service testing should be covered in the OM Code rules. 10.1.1.15 Consider the Need for New Construction Rules for Rotating Machinery. It is anticipated that several important items of rotating machinery, such as he
47、lium blowers, circulators and compressors, and turbines will operate in a very high temperature environment. If the proper functioning of a particular machine is important to the integrity of the plant, it may be desirable to demonstrate the performance of a prototype machine in that service prior t
48、o installation. If so, new construction qualification requirements should be covered in the QME rules. In-service testing should be covered in the OM rules (see paragraph 10.1.1.17.3). Consider modifying OM 14 to address components in helium service. 10.1.1.16 Develop Rules for Pressure/Temperature
49、Limits and In-Service Testing. The following tasks should be assigned. 10.1.1.16.1 Preheat prior to pressurization for pressure boundary components that can be subject to embrittlement due to thermal aging (e.g. temper embrittlement and/or radiation embrittlement). 10.1.1.16.2 Testing of valves. The requirements will probably differ from the requirements in the OM Code for LWRs because of the higher operating temperatures. 10.1.1.16.3 In-service testing of circulators (compressors). Existing vibration analysis methods for pumps should be modified. Experience in the petrochemical industry
