F4E Analysis & Codes Group on behalf of V. Barabasch et al. (ITER IO)

Transcription

1 ITER Department t ITER Codes and Standards F4E Analysis & Codes Group on behalf of V. Barabasch et al. (ITER IO) Petten, 16th April 2010 Slide 1

2 Summary 1) Introduction 2) Main regulatory documents for mechanical components - Quality Order 10 th August Pressure Equipment Directive (PED) - French Order concerning Nuclear Pressure Equipment (ESPN) 3) ITER Pressure and Nuclear Pressure Equipment 4) C&S selection for the ITER Components - ITER Specific Codes - Existing Industrial C&S 5) Conclusions Slide 2

3 Introduction ITER shall observe French nuclear regulations in accordance with: Article 14 of the Agreement on the Establishment t of the ITER organization, Headquarters Agreement with French Government (7 Nov 2007) The radioactive inventory classifies ITER as a Basic Nuclear Installation (French acronym: INB) according to Decree of 11 May 2007 threshold level for tritium: 10 4 TBq (27 g) Specific attention has to be paid to regulations related to mechanical components, in particular to components providing a safety function. Slide 3

4 Introduction ITER, as unique facility, has many types of mechanical equipment. A multi-code approach is applied for the selection of the Codes and Standards (C&S) for the various ITER components. The main reasons for this approach are: the wide variety of the ITER components and loads (e.g. operational temperature from 4 K to ~ 1000K, neutron irradiation effect, etc.), which does not allow to use one existing industrial Code; the unique feature of some ITER systems and components (magnet, in-vessels) for which development of specific criteria is required; the need to make use of some advantages of specific existing Codes to cover the particular ITER operational requirements; some components are nuclear pressure equipment and they shall be designed and manufactured in accordance with French regulation; some components are pressure equipment and they shall be designed and manufactured in accordance with French regulation; some components provide a confinement barrier for a given nuclear inventory; in some case this barrier is also nuclear pressure equipment, in other cases it is not pressure equipment. Slide 4

5 Main regulatory documents for mechanical components Quality Order dated 10 th August 1984 concerning Basic Nuclear Installation design, construction and operation quality Order dated 12 th December 2005 concerning nuclear pressure equipment (ESPN) Decree No dated 13 th December 1999 concerning pressure equipment - introduction of the Pressure Equipment Directive in France (ESP/PED) Slide 5

6 Quality Order, 10 th August 1984 This Order defines the specific activities which shall be implemented by the Operator of a nuclear facility with regards to the safety demonstration. ti Quality Related Activities (QRA) which have an impact on the quality of Safety Important Components shall be identified by Operator and they are related to design, manufacturing, construction and operation of the nuclear facility. The Quality requirements of this order (also requirements of IAEA Safety Standards Series) are implemented in the ITER Quality Assurance Program, which is applicable for the ITER system and components. Same quality requirements must be implemented by the Suppliers and/or Contractors and following chain of subcontractors. Slide 6

7 French Decree concerning pressure equipment - Pressure Equipment Directive 97/23/EC [ESP/PED] ESP/PED applies to the design, manufacture and conformity assessment of pressure equipment and assemblies with a maximum allowable pressure greater than 0.5 bar over atmospheric pressure (1.5 bar absolute). ESP/PED introduces a categorization (Category I IV, Category IV being the highest) of the pressure equipment, depending on the hazard due to pressure, volume of the vessel or diameter of the pipe, type of fluid and temperature. There is an additional category which is Sound Engineering Practice (SEP). For each category the so-called modules for conformity assessment in accordance with the Essential Safety Requirement are established. For equipment in Category II IV the conformity assessment has to be performed by a Notified Body Some equipment operating under a pressure greater than 0.5 bar may fall outside of scope of Directive. Slide 7

8 French Decree concerning pressure equipment - Pressure Equipment Directive 97/23/EC [ESP/PED] ESP/PED formulates Essential Safety Requirements (ESR) which includes technical and legal conditions which have to be satisfied. These requirements are related to the design, manufacture, materials and other specific conditions. The selection of C&S is the responsibility of the Manufacturer; he shall demonstrate that the selected C&S provides conformity with ESR. Generally the use of European Harmonized Standards will give the presumption of conformity with ESR, however other C&S can be used. After completion of the conformity assessment the Manufacturer shall declare conformity and issue a CE mark. Pressure equipment are subject to the provisions applicable to operation (in-service inspection) and re-qualification, as required. Slide 8

9 French Order concerning nuclear pressure equipment [ESPN] Definition of Nuclear Pressure Equipment: is pressure equipment as defined d in accordance with PED/ESP; is used in a Basic Nuclear Installation; directly ensures containment of radioactive substances, and in case of failure leads to release of activity it above 370 MBq. ESPN has practically extended the application of the methodology of ESP/PED (ESR, conformity modules, etc.). ESPN has double classification of the equipment: Pressure hazard based on PED rules, Category I IV, and Category 0 (equivalent to SEP); Nuclear level - N1, N2 and N3. Slide 9

10 French Order concerning nuclear pressure equipment [ESPN] ESPN includes some additional requirements to ESR depending on the nuclear level of the equipment. As far as C&S are concerned, the ESPN does not define specific requirements for the selection of the Codes, but requires that the conformity with ESR shall be demonstrated. Manufacturer of the equipment shall select an applicable Code which is used as a tool for demonstrating conformity with Essential Safety Requirements. The ESPN defines also rules for maintenance and monitoring, periodic inspections, installation and operation and periodic re-qualifications of nuclear pressure equipment. Slide 10

11 ITER Pressure and Nuclear Pressure Equipment The following types of mechanical equipment are identified: 1. Standard pressure (non-nuclear) equipment. The fluid is nonradioactive. Equipment in cryoplant and cryodistribution system Feeders for Magnets, thermal shield and manifolds Heat rejection system of cooling water systems etc. 2. Nuclear pressure equipment as defined in ESPN: Vacuum Vessel and Ports - Category IV, Level N2, ports N3 Equipment in Primary Heat Transfer Systems (heat exchangers, pressurizers, piping, etc.) - Category I - IV, Level N2, N3 Equipment in the Tritium Plant, equipment in Test Blanket Modules systems, etc. - Category 0 - IV, Level N2, N3 etc. Slide 11

12 ITER Pressure and Nuclear Pressure Equipment The following types of equipment are identified: 3. Equipment outside of scope of ESP/PED and consequently from ESPN. Example ITER Divertor. For this equipment the fluid pressure can be considered as:...not significant design factor as defined in ESP/PED. =>For divertor electromagnetic and thermal loads are dominant. A case-by-case analysis is needed for the assessment of applicability ESP/PED for equipment. Slide 12

13 C&S selection for the ITER Components 1) ITER specific Codes: Magnet Structural Design Criteria (MSDC) Structural Design Criteria for In-Vessel Components (SDC-IC) Technical Specifications for non-metallic window and insulating Specifications for design by experiment These Criteria and Specifications have been developed in cooperation with the ITER Parties because there are no available Industrial Codes which can cover specific features of the ITER design and operating conditions. 2) Existing Industrial C&S: ASME Codes RCC-MR, Edition 2007 EN Harmonized Standards, e.g. EN 13445, EN13480 Slide 13

14 C&S selection for the ITER Components ITER Specific Industrial C&S Magnet Structural Design Cit i Structural Design Criteria In-vessel C t Technical Specifications and D i b Experiment Criteria Components Design by RCC-MR Edition 2007 ASME Codes Sec VIII Div 2 B31.33 Etc. EN Standards EN etc. - Structural Components and Welds - Magnet Windings - Bolts, Keys, Supports - Cryogenic piping - Blanket - Divertor - In-vessel parts: diagnostic, heating systems, fuel system, neutral beam - Non-metallic windows diagnostic and heating - Non-metallic insulating bushing - ELMs, VS coils - Armour Joints - Vacuum Vessel - Ports - Port plugs - Penetrations - Cryostat - Cooling Water System - Tritium Plant - Thermal Shield - Neutral beam, - Ex-vessel part diagnostic, heating systems, fuel system - Hot cells and radwaste PE - Cryoplant (parts) - Cryoplant - Cryopumps - Liquid and gas distribution - Manufacturing rules for IVC Note: Selection of C&S for TBM systems is under discussion. Slide 14

15 ITER Specific Codes Magnet Structural Design Criteria The main needs for development of the specific design criteria arise from the unique features of the ITER magnet structure: The magnets operate at 4K-77K, mostly 4K. Yield and ultimate strength are increased, fracture toughness is similar at cryogenic temperature. The loads have a strong cyclic component. Large material thicknesses, up to ~0.4 m, welds, high stresses. In-service inspection is not possible except for a few limited regions. There is extensive use of non-metallic materials especially for bonding and compressive load transmission. Some magnet components combine structural support with an electrical function and the structural limits are controlled by the electrical functionality. Electromagnetic loads cause 3D stress systems, complicated by contact interfaces, which generally need finite element analysis to resolve. There is no previous experience of such a design. These Design Criteria result from extensive assessment of the features of various existing Codes and Standards d (ASME Section VIII, Section III, ASME B31.3, API 579, etc.). Slide 15

16 ITER Specific Codes Magnet Structural Design Criteria The Magnet Structural Design Criteria includes the following four parts. Part I: Main Structural Components and Welds Part II: Magnet Windings (Radial Plates and Conductors) with High and Low Voltage Insulation and Epoxy Filler Part III: Bolts, Keys, Supports and Special Components Part IV: Cryogenic Piping - based on general rules of ASME B31.3 The questions related to the safety factors, the operating loads, residual stresses, non-destructive examination sensitivity and reliability, accuracy of material data relevant to the fracture and fatigue prediction procedures, are very significant at the design and fabrication stage for the magnets than for conventional components. The material requirements are specified in these Criteria. Metallic materials shall be characterized at operational temperature 4 K, except materials used for the helium supply piping system. During fabrication ultrasonic inspection is required for all metallic components, and defect sizes are quantified, with more extensive procedures according to ASME Section XI, Appendix VIII and ASME Section V, Article 4. Slide 16

17 ITER Specific Codes Structural Design Criteria for In-Vessel Components (SDC-IC) SDC-IC contains rules for design of the in-vessel components (blanket, divertor, etc). SDC-IC was developed d in collaboration with ITER Parties. SDC-IC is based on the RCC-MR code. SDC-IC was developed because existing industrial codes are not applicable. In particular, the neutron irradiation affects materials properties, resulting in: time dependent material properties, embrittlement of the material (reduced ductility and fracture toughness), irradiation-induced creep and relaxation swelling (at specific conditions). The geometry of the various components is non-axisymmetric. Distribution of thermal and electromagnetic loads will also be non-axisymmetric. Slide 17

18 ITER Specific Codes Structural Design Criteria for In-Vessel Components (SDC-IC) Currently the scope of SDC-IC is limited to criteria related to design. Further improvements of the design rules are planned with participation of the ITER DAs. It is considered that conventional manufacturing rules (e.g. welding, forming) are based on EN harmonized standards. The consistency of design rules and manufacturing standards is being demonstrated. Slide 18

19 ITER Specific Codes Technical specifications for non-metallic materials The first confinement barrier of the ITER plasma chamber includes windows and other elements with non-metallic materials - safety related function. Materials are fused silica, quartz, sapphire, alumina, CVD diamond etc. Window Assemblies are part of the unpressurized area of the radioactivity confinement barrier (pressure in plasma chamber less than 1.5 b absolute). The ITER Practice for Replaceable Non-Metallic Windows is under development and consists of: Technical Specification document, prescribing: - requirements for design / manufacturing - non-destructive examination / acceptance testing - installation / monitoring / in-service inspection Torus windows Engineering Justification Document -support of the soundness Technical Specification. Existing Practice Document Supporting R&D and Qualification Document [CVD diamond] Slide 19

20 ITER Specific Codes Design-by- Experiment Due to design requirements many components (First Wall/Blanket, Divertor, etc.) include joints of dissimilar materials such as Be/Cu alloy, W/Cu alloys, C/Cu Alloys, Copper/Stainless steel. Taking into account that there is no existing Code addressing these types of components, these joints are being designed based on Design-By-Experiment rules. 30 mm 400 mm These rules are based on practices which are used in various fusion facilities and supported by extensive ITER R&D program. Basically these rules include: Development of joining technologies by manufacture and extensive testing of small scale mock-ups (incl. neutron irradiation), Qualification of most promising technologies by testing of design representative mock-ups including non-destructive examination, determination of allowable defects, fatigue limit, etc. Final manufacture of the components and application of an extensive qualification program before installation in the ITER. Slide 20

21 RCC-MR, Edition 2007 ITER VV and Ports The RCC-MR Code was originally developed as code for mechanical components of fast reactors. On request of the ITER EU DA (EFDA) the scope of the Code was enlarged and include the ITER Vacuum Vessel (VV). The fourth edition of the RCC-MR code has been issued in October Features of RCC-MR Edition 2007: introduction in the Code of European Harmonized standards introduction of requirements of ESP/PED and ESPN improvement of the design rules based on R&D results introduction ti Appendix 19 specific to ITER VV Appendix A19 Vacuum Vessel is classified as a Class 2 welded box structure which allows to reflect the double shell assembly with internal ribs (Section RC3800). Slide 21

22 RCC-MR, Edition 2007 ITER VV and Ports Features of RCC-MR and ITER Vacuum Vessel: Material: from the beginning of the VV design development, austenitic steel type 316L(N)-ITER Grade has been selected from RCC-MR Code. The design of the ITER VV is a box type of structure. Special rules for box types of structure were introduced for Class 2 components. Based on features of box type structure, four categories of welded joints for VV have been proposed. For these different categories, there are different authorized types of welded joints and different requirements for non destructive testing. Rules for bolted joints: Preloaded bolts for pressure e retaining boundaries, Preloaded bolts not for pressure retaining boundaries. Rules for non-preloaded bolts Slide 22

23 ASME Codes Considering the international participation to the project, US codes and standards are widely used across the project. The ASME Codes are familiar to most participants and they are the origin of many other national standards. Use of ASME or other international code is possible for pressure and nuclear pressure equipment, provided that: Manufacturer of equipment provides demonstration of conformity with Essential Safety Requirements for relevant equipment, In many cases this conformance to ESR is assessed by a Notified Body or (Agreed Notified Body) The application of various ASME Codes (Section VIII Div 2, ASME B31.1, 1 etc.) is being analysed to demonstrate the conformity with ESR. Additional technical specifications will be needed to provide conformity with ESR and to demonstrate soundness of design at various Categories events. Slide 23

24 Conclusion ITER will be first fusion facility which is under construction in accordance with safety and licensing requirements for a Basic Nuclear Installation in France. ITER, as unique facility, has many types of mechanical equipment. The multi-code approach is applied in the selection of the Codes for the ITER components. Industrial available codes are generally selected for the ITER components. Among these Codes ASME, RCC-MR, and EN Harmonized standards are proposed for various equipment. For equipment which are not covered by existing Codes, additional Technical Specifications are being developed and they include Magnet Structural Design Criteria, Structural Design Criteria for In-Vessel Components, specification for non-metallic components and design by experiment rules. Slide 24

25 Conclusion Due to application of various C&S, significant attention is being paid to the definition iti of the interfaces between different components and systems which is needed for the overall integration and operation of the ITER facility. In general the basic regulatory documents do not specify particular design and manufacturing Codes. The selected C&S for pressure and nuclear pressure equipment shall provide the conformity with the Essential Safety Requirements, which are formulated for various type of pressure and nuclear pressure equipment. ITER Organization as a nuclear operator shall apply French nuclear regulations, especially the Quality Order, which is applicable for design, construction, operation and decommissioning of ITER. Slide 25

26 Thank you very much!!! Analysis & Codes Group The content of this presentation has been provided by ITER IO Slide 26