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TBM Program implementation in ITER
Fusion Engineering and Design 85 (2010) 2005–2011
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TBM Program implementation in ITER V.A. Chuyanov ∗ , D.J. Campbell, L.M. Giancarli ITER Organization, CS 90 046, 13067 St Paul Lez Durance Cedex, France
a r t i c l e
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Article history: Available online 5 August 2010 Keywords: TBM Breeding blankets Tritium production IRP
a b s t r a c t Tritium breeding blanket testing is an important element in the ITER mission. Up to six different concepts for tritium breeding blanket systems, referred to as Test Blanket Systems (TBS), will be tested in three equatorial ports of ITER. Successful TBS experiments in ITER represent an essential step on the path to DEMO for all the ITER Members’ fusion development plans. The ITER Members are in charge of the design, manufacturing and delivery of the TBSs to the ITER site. The IO has responsibility for preparing the necessary interfaces required for the installation of the TBSs. Moreover, the TBM Program has to be fully integrated in the ITER Research Plan and its testing objectives have to be synchronized with the planned ITER operations. The paper addresses the major implementation steps of the TBM Program in ITER, including the organizational aspects, its integration into the ITER Research Plan and the Operational Plan, the licensing procedure and also gives a short overview of the TBS/ITER interfaces issues. © 2010 V.A. Chuyanov. Published by Elsevier B.V. All rights reserved.
1. Introduction Tritium breeding blanket testing is an important element in the ITER mission. Up to six different concepts for tritium breeding blanket systems, referred to as Test Blanket Systems (TBS), will be tested in three equatorial ports of ITER. The TBS testing has to demonstrate that tritium can be produced in the blanket and extracted at a rate equal to tritium consumption in the plasma and that, at the same time, heat can be extracted from the blanket at temperatures high enough for efficient electricity generation. Successful TBS experiments in ITER represent an essential step on the path to DEMO for all the Parties’ fusion development plans [1]. The TBSs functional characteristics are dictated by the operational conditions and requirements expected in a DEMO reactor and, in this sense, they differ from the other ITER components. However, they must be fully integrated in the tokamak; therefore they must be compatible with the systems and operational procedures of ITER and the operating plan. Moreover, TBS testing must not endanger ITER performances, safety and reliability. Provided these constraints for TBSs are satisfied, the ITER Organization (IO) has responsibility for preparing the necessary interfaces required for the installation of the TBSs. In addition, the TBM Program has to be fully integrated into the ITER Research Plan and its testing objectives have to be synchronized with the planned ITER operations. In particular, the issue of the impact of the TBMs’
∗ Corresponding author. Tel.: +33 4 42 31 73; fax: +33 4 42 26 00. E-mail addresses: [email protected], [email protected] (V.A. Chuyanov).
ferromagnetic structural material on plasma performance has to be carefully assessed in order to establish the limit of acceptability for the ferromagnetic mass inside the TBMs. The ITER Members are in charge of the design, manufacturing and delivery of the TBSs to the ITER site. The ITER Council has recently created a specific high level body, the TBM Program Committee. It is charged with the governance of the TBM Program to ensure, in particular, that the selected TBSs will be delivered on time on the ITER site and to establish a credible R&D validation program to guarantee a sufficient TBS reliability. The paper addresses the major implementation steps of the TBM Program in ITER, including the organizational aspects, its integration into the ITER Research Plan and the Operational Plan, and gives an overview of the TBS/ITER interfaces issues. 2. Technical contents of the ITER TBM Program The ITER Council supported the undertaking of the TBM Program under the framework of the ITER Agreement in the IC-2 meeting in June 2008 and requested that the IO implement the TBM Program in ITER. Up to six concepts for various tritium breeding blanket systems, referred to as Test Blanket Systems (TBS), will be tested simultaneously. Each TBS consists of a Test Blanket Module (TBM), installed within the port directly facing the plasma, and several ancillary systems such as the cooling system, tritium circuits, and specific measurement and control equipment. The TBMs will be installed in 3 dedicated equatorial ports of ITER (ports 2, 18, and 16) in direct proximity to the plasma. The TBMs will be inserted in a 20 cm-thick water-cooled steel frame
0920-3796/$ – see front matter © 2010 V.A. Chuyanov. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.fusengdes.2010.07.005
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that acts as the unique interface with the vacuum vessel port extension. At present, the following six independent TBSs are planned to be installed in ITER: (1) In Equatorial Port # 16: the Helium Cooled Lithium Lead (HCLL) TBS and the Helium Cooled Pebble Bed (HCPB) TBS. The HCLL TBM uses the liquid metal LiPb as tritium breeder and neutron multiplier and Helium as coolant. The HCPB TBM uses a Lithiated Ceramic as tritium breeder, Beryllium as neutron multiplier, and Helium as coolant. (2) In Equatorial Port #18: the Water Cooled Solid Breeder (WCSB) TBM and the Dual Coolant Lithium Lead (DCLL) TBM. The WCSB TBM uses a Lithiated Ceramic as tritium breeder, Beryllium as neutron multiplier, and pressurized water as coolant. The DCLL TBM uses the liquid metal LiPb as tritium breeder, neutron multiplier and also as coolant for the breeder region. Helium is used to cool the structures. (3) In Equatorial Port # 2: the Helium Cooled Solid Breeder (HCSB) TBM and the Lithium Lead Ceramic Breeder (LLCB) TBM. The HCSB TBM uses a Lithiated Ceramic as tritium breeder, Beryllium as neutron multiplier, and Helium as coolant. The LLCB TBM uses the liquid metal LiPb as tritium breeder, neutron multiplier and also as coolant for the breeder region. Helium is used to cool the structures and a Lithiated Ceramic is used as an additional breeder.
tion, in particular in relation with machine availability and performances; • monitoring the activities of the Members on the TBS-related activities, in particular on the aspects concerning planning and quality assurance. The IMs are responsible for: • specifying and performing the TBS-related required R&D; • specifying and designing the TBSs and the corresponding TBMassociated shields, procuring and delivering them on the ITER site, bearing the associated cost; • defining the contents, the objectives and the planning of the TBM Test Program and interpreting the obtained results; • shipping the irradiated TBMs from the ITER site to some appropriate facilities and performing any required post-irradiation examinations. To be noted that TBSs will remain the property of the originating IM throughout the whole TBS lifetime (manufacturing, operation, dismantling and waste disposal). Each TBS is developed under the responsibility of one IM who nominates the TBM Leader (TL). The integration of two TBMs in each ITER Port is under the responsibility of one of the two concerned IMs that jointly nominate a Port Master (PM). Each IM may create an official partnership with other IMs for jointly developing a given TBS.
The structural material for all the TBMs is Reduced-Activation Ferritic/Martensitic (RAFM) steel, which is a ferromagnetic material. It should be noted that the above list of TBMs could require modifications as a function of the results of the on-going R&D on breeding blankets, which will continue throughout the ITER construction phase.
3.2. Governing Committees and Arrangements
3. Governance of the TBM Program and corresponding responsibilities
• implementation of the design changes and facilities required for hosting the TBMs; • approach to safety and control issues; • interaction with basic ITER plasma parameters and the ITER Research Plan; • possible impact on ITER Project Schedule.
The TBM Program is now undertaken under the framework of the ITER Agreement and is technically fully integrated in ITER and its corresponding research plan. However, the specificity of the TBM Program requires a particular organization during both ITER construction and operation. 3.1. TBM Program responsibilities The sharing of responsibilities between IO and ITER Members (IMs) is different from those for the other ITER components. The IO is responsible for: • hosting and operating the six TBSs in the ITER facility by ensuring that adequate space and handling facilities (including hot cell) shall be available; • defining the acceptance criteria for the TBSs and verifying them before installation in the ITER facility. It shall approve milestones for R&D, manufacturing, quality assurance and safety requirements in view of timely delivery of the TBMs; • commissioning, licensing, operation, replacement and maintenance of the TBSs; • dismantling and temporarily storing irradiated components and equipment in the hot cell, in view of shipping them to other appropriate installations; • designing and procuring the common port frame(s) and dummy TBMs; • ensuring that the presence and the operation of TBSs shall not have a significant impact on the ITER opera-
As for all other ITER activities, all activities concerning the interfaces between the TBM Program and ITER are dealt with by the ITER Science and Technology Advisory Committee (STAC) and Management Advisory Committee (MAC). These activities concern in particular:
Additionally, the IC has created the TBM Program Committee (TBM-PC) that discusses and approves all TBM-related technical and organizational activities, including TBM system selection, TBM Program plan and milestones, and TBM partnerships. It is also charged with proposing a recovery plan in case of delays. The TBMPC is formally established as an Advisory Committee to the IC on the TBM Program. The first meeting of the TBM-PC took place in March 2009 under the chairmanship of Prof. S. Konishi. It is composed of one member and up to three experts per IM. During its first meeting the TBM-PC recommended to IC the TBM port allocation given in chapter 2. The TBM-PC also nominated the TL for each TBS, with the exception of the DCLL TBS, for which it was nominated an “Interfaces coordinator” that is charged, as are all other TLs, to provide all required TBS data to IO, but, for the time being, without commitment on the delivery of the TBS. Since the two TBSs in each ITER port need to share most port cell equipment and tools, to agree on design and manufacturing of common parts, and to follow the same schedule constraints (e.g., installation and/or replacement at the same time), it is essential to nominate for each port a PM responsible for these integration aspects. Therefore, the TBM-PC also nominated the PMs with the exception of the PM for port #2, for which discussions are still ongoing.
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In order to ensure the timely delivery of the TBSs on the ITER site and to allow all the required IO monitoring activities, for each TBS an Arrangement will have to be signed as soon as possible between the IO and the relevant IM. This replaces the Procurement Arrangements used for all the other ITER components. These arrangements will include, for example, milestones, procedures for quality control, procedures for data exchange, and applicable Intellectual Properties Rights (IPR). 3.3. Technical organizational structure Each TBS is expected to operate independently. However, many interactions, interfaces and even common components are expected between the two TBSs located in the same ITER port. Therefore, the IO has decided to define three projects, corresponding to the three TBM Ports. Each project includes the TBM port plug with the two TBMs and all connection pipes and components corresponding to the two TBSs. Common parts are, for example, the pipe forest in the VV/bioshield interspace, the bio-shield plug, the Ancillary Equipment Unit (AEU), the pipe bundle through the corresponding shaft, and the location of the cooling circuit and tritium circuit components. Moreover, common aspects encompass replacement/maintenance operations and remote handling strategy, operation and treatment in the hot cell facility, and of course installation and replacement strategy. In order to run the three projects, the IO has created three Port Management Groups: PMG-2, PMG-16 and PMG-18, corresponding, respectively to the ITER ports #2, #16 and #18. The members of each PMG are the IO/TBM RO, the corresponding the PM, the two TLs and all appropriate experts from the IO and from all the IMs involved in the activities for the corresponding TBSs. The first PMG meetings have been held during summer 2009. The PMGs are charged with managing the technical aspects of the corresponding TBSs, including: (i) provision of information on the TBS interfaces with ITER systems and operation; (ii) assessment of TBS integration aspects and PM proposals, in particular, in the port cell area; (iii) monitoring of TBS R&D, design and manufacturing; (iv) assessment of safety aspects, human access requirements and RAMI (reliability, availability, maintainability, inspectability); (v) agreement on quality assurance management; (vi) provision of detailed planning and milestones, based on the general TBS milestones defined by the TBM-PC; (vi) review of technical documentation on TBSs. Within the IO, the TBM Program is managed by the FST/TBM group and this is supported by the appropriate experts from other ITER Departments in very different areas of expertise such as: (i) frame design and procurement, (ii) remote handling; (iii) instrumentation and CODAC; (iv) cooling systems; (v) tritium plant; (vi) drawings and CAD equipment; (vii) hot cell facility; (viii) codes and standards; (ix) construction, buildings and services; (x) safety and licensing; (xi) quality assurance. 4. The expected outcomes of the TBM Program and its integration in the ITER Research Plan 4.1. Testing capabilities and limitations ITER may be the only opportunity for testing breeding blankets mock-ups in a real fusion environment before the construction of a DEMO reactor, ensuring: (i) in the initial H/He plasma phase: relevant magnetic fields, relevant plasma regimes (e.g., H-mode), surface heat fluxes, and disruption-induced loads;
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(ii) in the D plasma phase: additional low neutron fluxes appropriate for neutron measurements and neutron analyses verification; and, (iii) in the following DT plasma phase: additional DEMO-relevant 14 MeV-neutron flux, volumetric heat, and tritium production with corresponding T-management capabilities.
The most important limitation for blanket testing in ITER is that the magnitude of neutron flux and volumetric power density is lower than that expected in a DEMO reactor and that the ITER operation features relatively short pulse length (compared to the quasi-continuous operation expected in DEMO). The countermeasure is that, for each selected blanket concept, several TBMs have to be developed making use of “engineering scaling” for testing specific “act-alike” TBMs during the different ITER-phases in order to address the different aspects of the TBM performances (neutronics, thermo-mechanics, thermo-hydraulics, etc.). Of course, not all the problem may be resolved with the testing. Neutron fluence in ITER is definitely too low (up to 3 dpa after 20 years of operation compared with about 70 dpa expected in DEMO for 2 years of operation) and, therefore, long term irradiation effects on materials cannot be tested in ITER, but will have to be determined in another dedicated facility (e.g., IFMIF). Because of the use of ferromagnetic RAF/M steel as TBM structural material, the presence of TBMs produces additional localized magnetic field perturbations in the TBM Port area. A special experiment has been recently performed at the D3D tokamak to model the effect produced by a pare of TBMs in one port [3]. No effects on breakdown, start-up and L-mode operation have been observed. The effects start to appear in H-mode and grow with increase of plasma pressure. The observed direct effect of a single localized perturbation on energy confinement at D3D is small for perturbations typical for TBMs in ITER. However, some other effects, like slowing down of the plasma rotation, are significant. Consequences of these effects and their extrapolation to ITER conditions are not yet fully understood. Analysis of the D3D results, associated uncertainties (the TBMs will be installed in 3 ports) and other R@D done up to now leads to the following conclusions.
(1) The TBMs as now designed may be installed from the beginning of ITER operation. They will not affect start-up and operation in L-mode. (2) To minimize the risk of interference with high Q operations, the TBM designs for high Q operation should be optimized to reduce the TBM-induced ripple by mass reduction as much as reasonably achievable. (3) Unless it will be clearly demonstrated with further R@D and initial ITER experiments that the available TBMs will not affect reaching QDT = 10, they will be removed during the major shutdown prior to first DT operation and replaced with dummy non-ferromagnetic TBMs. (4) The TBMs will be recessed ∼12 cm beyond the minimum major radius of the first wall at the outboard midplane. Further recess would affect too negatively the neutron flux available for TBM. (5) Local TBM correction coils are unacceptable. Without neutron shielding they have a very limited lifetime (<2 years) due to neutron irradiation. The shielding required (>40 cm) to increase the lifetime >2 years reduces the neutron flux to the TBM by 30–50%. This would make the tritium measurements difficult to interpret and jeopardize the TBM mission.
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Fig. 1. TBM testing plan during ITER operation.
4.2. Main general objectives Taking into account these limitations, the major overall testing objectives are the following: (i) validation of structural integrity theoretical predictions under combined and relevant thermal, mechanical and electromagnetic loads, (ii) validation of tritium breeding predictions, (iii) validation of tritium recovery process efficiency and Tinventories in blanket materials, (iv) validation of thermal predictions for strongly heterogeneous breeding blanket concepts with volumetric heat sources, and (v) demonstration of the integral performance of the blankets systems. TBSs have to be installed early in ITER operation because very important data have to be obtained during the non-nuclear phase (H/He phase). The main results expected in the non-nuclear phase are the following: (i) demonstration of the structural integrity of the TBM structures and attachment during disruptions and Vertical Displacement Events (VDE); (ii) assessment of the impact on RAF/M steel, used as a structure for most TBMs, on magnetic field distortion and confirmation of its influence on plasma confinement; (iii) demonstration of all the functionalities of the TBM systems;
(iv) essential operating data necessary to guarantee adequate reliability of the TBSs operation during the nuclear phase. 4.3. TBM Program integration in the ITER Research Plan In the operation of the TBSs, the successful operation of the Tokamak and accompanying physics experiments is essential so that the TBM program needs to be flexible enough to adjust, if necessary, to the needs of the rest of the ITER program. This includes start-up and shutdown and the adjustment to different un-scheduled down times. The TBM testing programme is expected to run from the H/He Phase, throughout the D, DT1 and the initial DT2 Phases (see Fig. 1). It is expected that installation of most TBMs will be started in 2019 immediately after achieving the first plasma. In any case, all TBMs are expected to be installed by the middle of 2022. After 2022, there is a last H/He phase of 1.5 years, then a D-phase for 16 months until mid-2026. Although low levels of tritium will be introduced into plasmas in 2026, experimentation with 50:50 DT fuel mixtures will start at the beginning of 2027, and this phase of operation (denoted DT1) will last until mid-2028. This is followed by the DT2 phase (expected to be a sequence of 2-year periods, made of 8 months shutdown and 16 months operation). The adopted approach for the TBM testing program is to consider it as “piggy back” experiments in which the TBMs will be exposed to series of ITER plasma discharges, within the constraint that the presence of TBMs should not impede the discharges and the testing goals of the specific physics experiment. There will be no specific requirements on pulse parameters from the TBM Program before 2026. After this, a special sequence of long pulses will be designed
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to achieve maximum fluence with minimum total dwell time. Reliability of TBMs must not place any additional limitations on the physics program. In ITER, “nuclear operation” begins with the use of DT fuel for tokamak experiments (early 2027). However, since the tritium plant must be commissioned with tritium in advance of the use of DT fuel, and to avoid duplication of certain T-Plant subsystems, the nuclear phase of operation of the ITER facility will actually begin with the introduction of the first tritium into the T-Plant in early 2025. From the point of view of the TBM Program, for each of the 6 TBS types, it is planned to have up to four TBM versions, which will be tested in two main phases, a first phase that can be called the “learning” phase and a second phase that can be called the “DEMOrelevant data acquisition” phase. The “learning” phase includes the last H/He phase and the Dphase. Lasting about 4 calendar years, it may need 2 different TBM versions, and it is mainly devoted to: • Verification/qualification of the TBSs operation in ITER operational environment. This includes: (i) to check on how to operate the various ancillary systems such as: (a) cooling systems, including pressure drops in TBMs and connection pipes, effects on CS pipe thermal expansion; (b) liquid metal systems including impact of MHD effects and filling and draining procedures; (c) tritium-detritiation systems (using D); (d) CODAC systems and connection with the Central Safety System and the (investment protection) Central Interlock System; (ii) to verify port plugs mounting/dismounting operations, RH handling systems and related operations including in the hot cell; (iii) to check the effects of magnetic field in all dynamic equipment associated with TBSs (e.g. pumps, valves, diagnostics, etc.). • Identification of the operational margins covering all possible operating conditions and their confirmation/justification; validation of TBM integrity. • Resolution of all ITER/TBS interface issues such as: (a) impact of ferromagnetic structures on plasma confinement and ion losses; (b) demonstration of the capability of TBMs to withstand plasma disruptions; (c) checking of tolerances with other components; (d) checking interferences with other ITER systems. • Collection of operating data necessary to guarantee adequate reliability of the TBSs components operation during the nuclear phase, including data concerning the required TBMs replacement operation. • Initiation of preliminary measurements on TBM neutronic responses in order to verify and validate neutronic calculations. • Demonstration of the coolant capability of the TBMs first wall. The “DEMO-relevant data acquisition” phase includes the whole DT1 phase and the first period of the DT2 phase (DT2-1). It lasts about 4 calendar years and it may need two further versions of the TBMs. It is mainly devoted to obtaining from the TBSs all data and information needed for the design and manufacture of the corresponding DEMO breeding blanket. The main expected achievements are the following: • Validation of the capability of the neutronic codes and existing nuclear data to predict TBM nuclear response, including neutron fluxes and spectra, the tritium production rate, nuclear heat deposition, neutron multiplication and shielding efficiency. • Investigation of the TBMs thermo-mechanical behaviour at relevant temperatures, taking into account, for the first time, appropriate volume heat sources; assessment of adopted fabrication technologies, in particular for joints, and the validation of the adopted manufacturing processes under low-level irradiation; additional information for solid breeder TBMs on the thermo-
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mechanics of pebble beds and for liquid breeder TBMs on tritium permeation barriers (either coatings or natural oxide layers). • Demonstration of the operational behaviour of the blanket components for heat extraction and for tritium management, including, for instance, the assessment of tritium permeation and of methods for its reduction, of tritium extraction and coolant purification. • Performance of an integrated test campaign in order to extend the reliability and operational performances database for the tested breeding blankets in a DT fusion device under DEMO-relevant operating conditions (except for neutron fluence) for an extended period of time. It is assumed here to have the same approach for all six selected TBSs. This approach has therefore to be considered as “generic”. In reality, some differences can be expected from one TBS to another. Such differences will be assessed in the future. The possibility to extend the scope of tests associated with a given version of TBM or to combine 2 TBM versions into a single one is not precluded at this stage of the assessment. It is assumed that all four TBM versions will share the same basic architecture, in particular their structural part (including the attachment system), whose design will be qualified during the testing programme in laboratory facilities before TBM commissioning and checked/monitored step-by-step during the different phases of ITER operation. This strategy ensures a relatively stable interface between the TBM and ITER during the whole operation time, with benefits for the availability and safety of the machine. An important difference in the design of each version will concern the integration of the specific instrumentation and the design of internals; in particular of the breeding zone that could be modified for testing optimized design variants or to achieve the required testing conditions; for example, the thickness of the breeder material could be increased to achieve DEMO-relevant temperatures, and the 6Li enrichment could be modified to obtain the desired test conditions. Each TBM will include a monitoring system of all the features relevant for the control and safe operation of the TBM systems. This includes coolant and liquid metal circuit inlet and outlet temperatures (including by-pass in the case of He cooling), pressure measurements in coolant and liquid metal circuits, mass flow rates and neutronics responses inside the fluids (for D- and DT-phases). The TBM ancillary equipment will also have to be adapted to the different loading conditions to which the various TBMs tested in the different ITER operational phases are submitted. 5. Overview of the main ITER/TBS interfaces The TBS components are located in various areas of the Tokamak Complex as shown in the scheme of Fig. 2. A preliminary assessment of the interfaces between the TBSs and ITER was started several years ago [2]. These interfaces have been significantly revised in the last year [3]. This chapter is a short overview of the main results of this recent work. 5.1. TBM port cells The TBMs are located in the in the port plugs inside the TBM equatorial ITER ports. All feeding pipes and measurement systems are coming from the back side. Before reaching the TBMs, all connections for coolant systems, tritium extraction systems, liquid metal systems and measurement systems cross the VV boundary and the Biological shield boundary in order to be connected with several systems located in the corresponding port cells. Components of both TBSs will be located on a special common structure,
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Fig. 2. Scheme of the TBS ancillary equipment (example of the HCLL TBS) with the indication of their locations in the Tokamak Complex.
called Ancillary Equipment Unit (AEU), which can be removed and maintained in the hot cell facility as a unique component. Other connections start from the port cells and go to other locations of the Tokamak complex. The port cell areas behind the TBM port plugs for ports #2, #16, and #18 are allocated to the Test Blanket Systems and will be used for hosting the so-called Ancillary Equipment Units (AEUs). 5.2. TBS cooling circuits components and connection pipes Although some cooling circuit (CC) components are located on the AEU, most of the CC components are located in other parts of the Tokamak Complex. For each TBS, the required footprint for accommodating the cooling circuit components and the associated coolant purification systems components is estimated to be between 80 and 90 m2 . Two areas have been identified for such purposes: an area of about 220 m2 at level 3 of the Tokamak building neighboring the CVCS area to be used for the components of two TBS CCs, and an area of about 480 m2 in the TCWS vault annex at level 4 of the tritium building to be used for the components of the other four TBS CCs. Connecting pipes will have to pass through the corresponding shaft and cross several room of Tokamak and tritium buildings. During TBSs operation, inlet/outlet temperatures are 300C-500C for He-systems and 270C-325C for the water system. Therefore, such high-temperatures pipes require several bends for thermal stresses release and thermal insulation. 5.3. Space reservation for TBS tritium circuits components and connection pipes In the present tritium Building design, an area of 312 m2 has been allocated for the six TBS tritium circuits components (including glove boxes). Connecting pipes are expected to be at room temperatures and link the port cell areas to the tritium building. 5.4. Space reservation for TBS Program in the hot cell facility The TBM Program is expected to make a large use of the hot cell facility. The refurbishment of the TBMs will occur off-line. For each TBM, it is expected to have up to 3 replacements in the first 10 years of TBS operation. The TBMs will be refurbished in pair for
each port. To replace the TBMs, each TBM port plug will be removed from the VV using the ITER Equatorial Cask Transport System and delivered to an appropriated area of the hot cell facility. A new TBM port plug, containing two new TBMs will be available for immediate installation in the TBM equatorial port. Pre-installation tests will be performed in the port plug test facility. Specific areas have been allocated for the refurbishment of TBM port plugs and AEUs and also for performing the necessary operations on TBMs before their shipping outside the ITER site for post-irradiation examinations. The TBM Program requirements, derived from the TBM testing plan and from the adopted maintenance strategy, have been taken into account in the present design of the HCF.
6. Licensing and quality plan Being a part of ITER, TBMs now must go through the same process of licensing as the ITER facility. The first step in this direction has already been completed and TBSs have been mentioned in safety documents presented to French authorities in the past. The present strategy for the TBM Program is to assume that all accidental sequences that could involve TBMs remain within the envelope cases assessed for ITER. Of course this statement has to be proved by appropriate analyses. The TBSs are included in the ITER RPrS (Rapport Preliminaire de Surété) that will be issued in spring 2010. The main TBSs data that are included in the RPrS are the following: (a) TBSs conceptual design description (“envelope design” for components not yet fully defined). (b) Description of the operational status of the various TBS components with their relation to the status of ITER (e.g., pulses, short and long shutdowns, stand-by). (c) Results of the main safety analyses. (d) The maximum expected operational releases have to be identified qualitatively and quantitatively for T, ACP and chemical. Expected coolant and chemical release have to be identified. (e) List of all TBS components and their preliminary safety classification (to be confirmed later). (f) Definition of the main interfaces with other relevant ITER systems (e.g., tritium plant).
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(g) Maximum expected tritium inventories in all systems and components (e.g., cooling systems, purge gas systems, liquid metal systems). (h) Maximum expected Activation Inventories in all systems and components. (i) Maximum expected dose rates in the various locations of the TBSs components (e.g., port cell, CCs locations, hot cell). (j) Waste management aspects such as the list of all elements not yet included in the ITER list and their waste management approach. TBSs components should comply with rules for Pressurized and Nuclear Pressurized Equipment (ESP & ESPN rules). This requirement implies that TBSs design and manufacturing should be validated by a notified body. It also implies that the ESPN classification has to be assigned to all TBSs components in mid-2010 at the latest. Concerning the TBMs, the validation by a notified body can be obtained only after the completion of the on-going qualification test program for the TBM structural materials (both for non-irradiated and irradiated materials up to 3 dpa). Proposals of QA systems should also be presented in 2010, including QA classification for TBSs components. It has to be stressed that the TBM Program corresponds to a special type of activity not yet included in the present ITER contractual framework (i.e., procurement arrangements, tasks, and contracts). In the TBM Program, IMs are responsible for the functional specifications and for the design and manufacturing of the TBSs, while the IO is responsible for the operation. An arrangement has to be signed as soon as possible between the IO and each IM responsible for a TBS (see chapter 3). In these arrangements, the details of the QA procedure and of the quality plan (QP) have to be mentioned. It is expected that they will be quite similar to the QA procedure applied to the procurement arrangements. For each TBS, the QP shall be applied after the signature of the IO/TBM IM arrangement. The QP shall identify: (i) the specific allocation of resources, duties, responsibilities and authority; (ii) details of all suppli-
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ers/subcontractors and how interfaces will be managed; (iii) the specific procedures, methods and work instructions to be applied; (iv) the specific methods of communication, both formal and informal, to be established between working groups; (v) any access restrictions for IO representatives. 7. Conclusions After several years of discussions the TBM testing program now is included in ITER program. The organizational structure of the program has been identified and is being established. Active cooperation between the ITER Organization and ITER Members responsible for the TBSs testing is required for the successful implementation of the TBM Program. Acknowledgments This paper was prepared as an account of work by or for the ITER Organization. The Members of the Organization are the People’s Republic of China, the European Atomic Energy Community, Republic of India, Japan, Republic of Korea, the Russian Federation, and the United States of America. The views and opinions expressed herein do not necessarily reflect those of the Members or any agency thereof. Dissemination of the information in this paper is governed by the applicable terms of the ITER Joint Implementation Agreement. References [1] L. Giancarli, V. Chuyanov, M. Abdou, M. Akiba, B.G. Hong, R. Lässer, et al., Breeding blanket modules testing in ITER: an International Program on the Way to DEMO, Fusion Engineering & Design 81 (2006) 393–405. [2] V.A. Chuyanov, L.M. Giancarli, C.S. Kim, C.P.C. Wong, The integration of TBM systems in ITER, Proceeding ISFNT-8, Fusion Engineering & Design 83 (2008) 817–818. [3] J.A. Snipes, M.J. Schaffer, P. Gohil, P. de Vries, M.E. Fenstermacher, T.E. Evans, et al., Proc. 37th EPS Conf. on Plasma Phys, Dublin, (2010) P1.1093.
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TBM Program implementation in ITER V.A. Chuyanov ∗ , D.J. Campbell, L.M. Giancarli ITER Organization, CS 90 046, 13067 St Paul Lez Durance Cedex, France
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Article history: Available online 5 August 2010 Keywords: TBM Breeding blankets Tritium production IRP
a b s t r a c t Tritium breeding blanket testing is an important element in the ITER mission. Up to six different concepts for tritium breeding blanket systems, referred to as Test Blanket Systems (TBS), will be tested in three equatorial ports of ITER. Successful TBS experiments in ITER represent an essential step on the path to DEMO for all the ITER Members’ fusion development plans. The ITER Members are in charge of the design, manufacturing and delivery of the TBSs to the ITER site. The IO has responsibility for preparing the necessary interfaces required for the installation of the TBSs. Moreover, the TBM Program has to be fully integrated in the ITER Research Plan and its testing objectives have to be synchronized with the planned ITER operations. The paper addresses the major implementation steps of the TBM Program in ITER, including the organizational aspects, its integration into the ITER Research Plan and the Operational Plan, the licensing procedure and also gives a short overview of the TBS/ITER interfaces issues. © 2010 V.A. Chuyanov. Published by Elsevier B.V. All rights reserved.
1. Introduction Tritium breeding blanket testing is an important element in the ITER mission. Up to six different concepts for tritium breeding blanket systems, referred to as Test Blanket Systems (TBS), will be tested in three equatorial ports of ITER. The TBS testing has to demonstrate that tritium can be produced in the blanket and extracted at a rate equal to tritium consumption in the plasma and that, at the same time, heat can be extracted from the blanket at temperatures high enough for efficient electricity generation. Successful TBS experiments in ITER represent an essential step on the path to DEMO for all the Parties’ fusion development plans [1]. The TBSs functional characteristics are dictated by the operational conditions and requirements expected in a DEMO reactor and, in this sense, they differ from the other ITER components. However, they must be fully integrated in the tokamak; therefore they must be compatible with the systems and operational procedures of ITER and the operating plan. Moreover, TBS testing must not endanger ITER performances, safety and reliability. Provided these constraints for TBSs are satisfied, the ITER Organization (IO) has responsibility for preparing the necessary interfaces required for the installation of the TBSs. In addition, the TBM Program has to be fully integrated into the ITER Research Plan and its testing objectives have to be synchronized with the planned ITER operations. In particular, the issue of the impact of the TBMs’
∗ Corresponding author. Tel.: +33 4 42 31 73; fax: +33 4 42 26 00. E-mail addresses: [email protected], [email protected] (V.A. Chuyanov).
ferromagnetic structural material on plasma performance has to be carefully assessed in order to establish the limit of acceptability for the ferromagnetic mass inside the TBMs. The ITER Members are in charge of the design, manufacturing and delivery of the TBSs to the ITER site. The ITER Council has recently created a specific high level body, the TBM Program Committee. It is charged with the governance of the TBM Program to ensure, in particular, that the selected TBSs will be delivered on time on the ITER site and to establish a credible R&D validation program to guarantee a sufficient TBS reliability. The paper addresses the major implementation steps of the TBM Program in ITER, including the organizational aspects, its integration into the ITER Research Plan and the Operational Plan, and gives an overview of the TBS/ITER interfaces issues. 2. Technical contents of the ITER TBM Program The ITER Council supported the undertaking of the TBM Program under the framework of the ITER Agreement in the IC-2 meeting in June 2008 and requested that the IO implement the TBM Program in ITER. Up to six concepts for various tritium breeding blanket systems, referred to as Test Blanket Systems (TBS), will be tested simultaneously. Each TBS consists of a Test Blanket Module (TBM), installed within the port directly facing the plasma, and several ancillary systems such as the cooling system, tritium circuits, and specific measurement and control equipment. The TBMs will be installed in 3 dedicated equatorial ports of ITER (ports 2, 18, and 16) in direct proximity to the plasma. The TBMs will be inserted in a 20 cm-thick water-cooled steel frame
0920-3796/$ – see front matter © 2010 V.A. Chuyanov. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.fusengdes.2010.07.005
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that acts as the unique interface with the vacuum vessel port extension. At present, the following six independent TBSs are planned to be installed in ITER: (1) In Equatorial Port # 16: the Helium Cooled Lithium Lead (HCLL) TBS and the Helium Cooled Pebble Bed (HCPB) TBS. The HCLL TBM uses the liquid metal LiPb as tritium breeder and neutron multiplier and Helium as coolant. The HCPB TBM uses a Lithiated Ceramic as tritium breeder, Beryllium as neutron multiplier, and Helium as coolant. (2) In Equatorial Port #18: the Water Cooled Solid Breeder (WCSB) TBM and the Dual Coolant Lithium Lead (DCLL) TBM. The WCSB TBM uses a Lithiated Ceramic as tritium breeder, Beryllium as neutron multiplier, and pressurized water as coolant. The DCLL TBM uses the liquid metal LiPb as tritium breeder, neutron multiplier and also as coolant for the breeder region. Helium is used to cool the structures. (3) In Equatorial Port # 2: the Helium Cooled Solid Breeder (HCSB) TBM and the Lithium Lead Ceramic Breeder (LLCB) TBM. The HCSB TBM uses a Lithiated Ceramic as tritium breeder, Beryllium as neutron multiplier, and Helium as coolant. The LLCB TBM uses the liquid metal LiPb as tritium breeder, neutron multiplier and also as coolant for the breeder region. Helium is used to cool the structures and a Lithiated Ceramic is used as an additional breeder.
tion, in particular in relation with machine availability and performances; • monitoring the activities of the Members on the TBS-related activities, in particular on the aspects concerning planning and quality assurance. The IMs are responsible for: • specifying and performing the TBS-related required R&D; • specifying and designing the TBSs and the corresponding TBMassociated shields, procuring and delivering them on the ITER site, bearing the associated cost; • defining the contents, the objectives and the planning of the TBM Test Program and interpreting the obtained results; • shipping the irradiated TBMs from the ITER site to some appropriate facilities and performing any required post-irradiation examinations. To be noted that TBSs will remain the property of the originating IM throughout the whole TBS lifetime (manufacturing, operation, dismantling and waste disposal). Each TBS is developed under the responsibility of one IM who nominates the TBM Leader (TL). The integration of two TBMs in each ITER Port is under the responsibility of one of the two concerned IMs that jointly nominate a Port Master (PM). Each IM may create an official partnership with other IMs for jointly developing a given TBS.
The structural material for all the TBMs is Reduced-Activation Ferritic/Martensitic (RAFM) steel, which is a ferromagnetic material. It should be noted that the above list of TBMs could require modifications as a function of the results of the on-going R&D on breeding blankets, which will continue throughout the ITER construction phase.
3.2. Governing Committees and Arrangements
3. Governance of the TBM Program and corresponding responsibilities
• implementation of the design changes and facilities required for hosting the TBMs; • approach to safety and control issues; • interaction with basic ITER plasma parameters and the ITER Research Plan; • possible impact on ITER Project Schedule.
The TBM Program is now undertaken under the framework of the ITER Agreement and is technically fully integrated in ITER and its corresponding research plan. However, the specificity of the TBM Program requires a particular organization during both ITER construction and operation. 3.1. TBM Program responsibilities The sharing of responsibilities between IO and ITER Members (IMs) is different from those for the other ITER components. The IO is responsible for: • hosting and operating the six TBSs in the ITER facility by ensuring that adequate space and handling facilities (including hot cell) shall be available; • defining the acceptance criteria for the TBSs and verifying them before installation in the ITER facility. It shall approve milestones for R&D, manufacturing, quality assurance and safety requirements in view of timely delivery of the TBMs; • commissioning, licensing, operation, replacement and maintenance of the TBSs; • dismantling and temporarily storing irradiated components and equipment in the hot cell, in view of shipping them to other appropriate installations; • designing and procuring the common port frame(s) and dummy TBMs; • ensuring that the presence and the operation of TBSs shall not have a significant impact on the ITER opera-
As for all other ITER activities, all activities concerning the interfaces between the TBM Program and ITER are dealt with by the ITER Science and Technology Advisory Committee (STAC) and Management Advisory Committee (MAC). These activities concern in particular:
Additionally, the IC has created the TBM Program Committee (TBM-PC) that discusses and approves all TBM-related technical and organizational activities, including TBM system selection, TBM Program plan and milestones, and TBM partnerships. It is also charged with proposing a recovery plan in case of delays. The TBMPC is formally established as an Advisory Committee to the IC on the TBM Program. The first meeting of the TBM-PC took place in March 2009 under the chairmanship of Prof. S. Konishi. It is composed of one member and up to three experts per IM. During its first meeting the TBM-PC recommended to IC the TBM port allocation given in chapter 2. The TBM-PC also nominated the TL for each TBS, with the exception of the DCLL TBS, for which it was nominated an “Interfaces coordinator” that is charged, as are all other TLs, to provide all required TBS data to IO, but, for the time being, without commitment on the delivery of the TBS. Since the two TBSs in each ITER port need to share most port cell equipment and tools, to agree on design and manufacturing of common parts, and to follow the same schedule constraints (e.g., installation and/or replacement at the same time), it is essential to nominate for each port a PM responsible for these integration aspects. Therefore, the TBM-PC also nominated the PMs with the exception of the PM for port #2, for which discussions are still ongoing.
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In order to ensure the timely delivery of the TBSs on the ITER site and to allow all the required IO monitoring activities, for each TBS an Arrangement will have to be signed as soon as possible between the IO and the relevant IM. This replaces the Procurement Arrangements used for all the other ITER components. These arrangements will include, for example, milestones, procedures for quality control, procedures for data exchange, and applicable Intellectual Properties Rights (IPR). 3.3. Technical organizational structure Each TBS is expected to operate independently. However, many interactions, interfaces and even common components are expected between the two TBSs located in the same ITER port. Therefore, the IO has decided to define three projects, corresponding to the three TBM Ports. Each project includes the TBM port plug with the two TBMs and all connection pipes and components corresponding to the two TBSs. Common parts are, for example, the pipe forest in the VV/bioshield interspace, the bio-shield plug, the Ancillary Equipment Unit (AEU), the pipe bundle through the corresponding shaft, and the location of the cooling circuit and tritium circuit components. Moreover, common aspects encompass replacement/maintenance operations and remote handling strategy, operation and treatment in the hot cell facility, and of course installation and replacement strategy. In order to run the three projects, the IO has created three Port Management Groups: PMG-2, PMG-16 and PMG-18, corresponding, respectively to the ITER ports #2, #16 and #18. The members of each PMG are the IO/TBM RO, the corresponding the PM, the two TLs and all appropriate experts from the IO and from all the IMs involved in the activities for the corresponding TBSs. The first PMG meetings have been held during summer 2009. The PMGs are charged with managing the technical aspects of the corresponding TBSs, including: (i) provision of information on the TBS interfaces with ITER systems and operation; (ii) assessment of TBS integration aspects and PM proposals, in particular, in the port cell area; (iii) monitoring of TBS R&D, design and manufacturing; (iv) assessment of safety aspects, human access requirements and RAMI (reliability, availability, maintainability, inspectability); (v) agreement on quality assurance management; (vi) provision of detailed planning and milestones, based on the general TBS milestones defined by the TBM-PC; (vi) review of technical documentation on TBSs. Within the IO, the TBM Program is managed by the FST/TBM group and this is supported by the appropriate experts from other ITER Departments in very different areas of expertise such as: (i) frame design and procurement, (ii) remote handling; (iii) instrumentation and CODAC; (iv) cooling systems; (v) tritium plant; (vi) drawings and CAD equipment; (vii) hot cell facility; (viii) codes and standards; (ix) construction, buildings and services; (x) safety and licensing; (xi) quality assurance. 4. The expected outcomes of the TBM Program and its integration in the ITER Research Plan 4.1. Testing capabilities and limitations ITER may be the only opportunity for testing breeding blankets mock-ups in a real fusion environment before the construction of a DEMO reactor, ensuring: (i) in the initial H/He plasma phase: relevant magnetic fields, relevant plasma regimes (e.g., H-mode), surface heat fluxes, and disruption-induced loads;
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(ii) in the D plasma phase: additional low neutron fluxes appropriate for neutron measurements and neutron analyses verification; and, (iii) in the following DT plasma phase: additional DEMO-relevant 14 MeV-neutron flux, volumetric heat, and tritium production with corresponding T-management capabilities.
The most important limitation for blanket testing in ITER is that the magnitude of neutron flux and volumetric power density is lower than that expected in a DEMO reactor and that the ITER operation features relatively short pulse length (compared to the quasi-continuous operation expected in DEMO). The countermeasure is that, for each selected blanket concept, several TBMs have to be developed making use of “engineering scaling” for testing specific “act-alike” TBMs during the different ITER-phases in order to address the different aspects of the TBM performances (neutronics, thermo-mechanics, thermo-hydraulics, etc.). Of course, not all the problem may be resolved with the testing. Neutron fluence in ITER is definitely too low (up to 3 dpa after 20 years of operation compared with about 70 dpa expected in DEMO for 2 years of operation) and, therefore, long term irradiation effects on materials cannot be tested in ITER, but will have to be determined in another dedicated facility (e.g., IFMIF). Because of the use of ferromagnetic RAF/M steel as TBM structural material, the presence of TBMs produces additional localized magnetic field perturbations in the TBM Port area. A special experiment has been recently performed at the D3D tokamak to model the effect produced by a pare of TBMs in one port [3]. No effects on breakdown, start-up and L-mode operation have been observed. The effects start to appear in H-mode and grow with increase of plasma pressure. The observed direct effect of a single localized perturbation on energy confinement at D3D is small for perturbations typical for TBMs in ITER. However, some other effects, like slowing down of the plasma rotation, are significant. Consequences of these effects and their extrapolation to ITER conditions are not yet fully understood. Analysis of the D3D results, associated uncertainties (the TBMs will be installed in 3 ports) and other R@D done up to now leads to the following conclusions.
(1) The TBMs as now designed may be installed from the beginning of ITER operation. They will not affect start-up and operation in L-mode. (2) To minimize the risk of interference with high Q operations, the TBM designs for high Q operation should be optimized to reduce the TBM-induced ripple by mass reduction as much as reasonably achievable. (3) Unless it will be clearly demonstrated with further R@D and initial ITER experiments that the available TBMs will not affect reaching QDT = 10, they will be removed during the major shutdown prior to first DT operation and replaced with dummy non-ferromagnetic TBMs. (4) The TBMs will be recessed ∼12 cm beyond the minimum major radius of the first wall at the outboard midplane. Further recess would affect too negatively the neutron flux available for TBM. (5) Local TBM correction coils are unacceptable. Without neutron shielding they have a very limited lifetime (<2 years) due to neutron irradiation. The shielding required (>40 cm) to increase the lifetime >2 years reduces the neutron flux to the TBM by 30–50%. This would make the tritium measurements difficult to interpret and jeopardize the TBM mission.
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Fig. 1. TBM testing plan during ITER operation.
4.2. Main general objectives Taking into account these limitations, the major overall testing objectives are the following: (i) validation of structural integrity theoretical predictions under combined and relevant thermal, mechanical and electromagnetic loads, (ii) validation of tritium breeding predictions, (iii) validation of tritium recovery process efficiency and Tinventories in blanket materials, (iv) validation of thermal predictions for strongly heterogeneous breeding blanket concepts with volumetric heat sources, and (v) demonstration of the integral performance of the blankets systems. TBSs have to be installed early in ITER operation because very important data have to be obtained during the non-nuclear phase (H/He phase). The main results expected in the non-nuclear phase are the following: (i) demonstration of the structural integrity of the TBM structures and attachment during disruptions and Vertical Displacement Events (VDE); (ii) assessment of the impact on RAF/M steel, used as a structure for most TBMs, on magnetic field distortion and confirmation of its influence on plasma confinement; (iii) demonstration of all the functionalities of the TBM systems;
(iv) essential operating data necessary to guarantee adequate reliability of the TBSs operation during the nuclear phase. 4.3. TBM Program integration in the ITER Research Plan In the operation of the TBSs, the successful operation of the Tokamak and accompanying physics experiments is essential so that the TBM program needs to be flexible enough to adjust, if necessary, to the needs of the rest of the ITER program. This includes start-up and shutdown and the adjustment to different un-scheduled down times. The TBM testing programme is expected to run from the H/He Phase, throughout the D, DT1 and the initial DT2 Phases (see Fig. 1). It is expected that installation of most TBMs will be started in 2019 immediately after achieving the first plasma. In any case, all TBMs are expected to be installed by the middle of 2022. After 2022, there is a last H/He phase of 1.5 years, then a D-phase for 16 months until mid-2026. Although low levels of tritium will be introduced into plasmas in 2026, experimentation with 50:50 DT fuel mixtures will start at the beginning of 2027, and this phase of operation (denoted DT1) will last until mid-2028. This is followed by the DT2 phase (expected to be a sequence of 2-year periods, made of 8 months shutdown and 16 months operation). The adopted approach for the TBM testing program is to consider it as “piggy back” experiments in which the TBMs will be exposed to series of ITER plasma discharges, within the constraint that the presence of TBMs should not impede the discharges and the testing goals of the specific physics experiment. There will be no specific requirements on pulse parameters from the TBM Program before 2026. After this, a special sequence of long pulses will be designed
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to achieve maximum fluence with minimum total dwell time. Reliability of TBMs must not place any additional limitations on the physics program. In ITER, “nuclear operation” begins with the use of DT fuel for tokamak experiments (early 2027). However, since the tritium plant must be commissioned with tritium in advance of the use of DT fuel, and to avoid duplication of certain T-Plant subsystems, the nuclear phase of operation of the ITER facility will actually begin with the introduction of the first tritium into the T-Plant in early 2025. From the point of view of the TBM Program, for each of the 6 TBS types, it is planned to have up to four TBM versions, which will be tested in two main phases, a first phase that can be called the “learning” phase and a second phase that can be called the “DEMOrelevant data acquisition” phase. The “learning” phase includes the last H/He phase and the Dphase. Lasting about 4 calendar years, it may need 2 different TBM versions, and it is mainly devoted to: • Verification/qualification of the TBSs operation in ITER operational environment. This includes: (i) to check on how to operate the various ancillary systems such as: (a) cooling systems, including pressure drops in TBMs and connection pipes, effects on CS pipe thermal expansion; (b) liquid metal systems including impact of MHD effects and filling and draining procedures; (c) tritium-detritiation systems (using D); (d) CODAC systems and connection with the Central Safety System and the (investment protection) Central Interlock System; (ii) to verify port plugs mounting/dismounting operations, RH handling systems and related operations including in the hot cell; (iii) to check the effects of magnetic field in all dynamic equipment associated with TBSs (e.g. pumps, valves, diagnostics, etc.). • Identification of the operational margins covering all possible operating conditions and their confirmation/justification; validation of TBM integrity. • Resolution of all ITER/TBS interface issues such as: (a) impact of ferromagnetic structures on plasma confinement and ion losses; (b) demonstration of the capability of TBMs to withstand plasma disruptions; (c) checking of tolerances with other components; (d) checking interferences with other ITER systems. • Collection of operating data necessary to guarantee adequate reliability of the TBSs components operation during the nuclear phase, including data concerning the required TBMs replacement operation. • Initiation of preliminary measurements on TBM neutronic responses in order to verify and validate neutronic calculations. • Demonstration of the coolant capability of the TBMs first wall. The “DEMO-relevant data acquisition” phase includes the whole DT1 phase and the first period of the DT2 phase (DT2-1). It lasts about 4 calendar years and it may need two further versions of the TBMs. It is mainly devoted to obtaining from the TBSs all data and information needed for the design and manufacture of the corresponding DEMO breeding blanket. The main expected achievements are the following: • Validation of the capability of the neutronic codes and existing nuclear data to predict TBM nuclear response, including neutron fluxes and spectra, the tritium production rate, nuclear heat deposition, neutron multiplication and shielding efficiency. • Investigation of the TBMs thermo-mechanical behaviour at relevant temperatures, taking into account, for the first time, appropriate volume heat sources; assessment of adopted fabrication technologies, in particular for joints, and the validation of the adopted manufacturing processes under low-level irradiation; additional information for solid breeder TBMs on the thermo-
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mechanics of pebble beds and for liquid breeder TBMs on tritium permeation barriers (either coatings or natural oxide layers). • Demonstration of the operational behaviour of the blanket components for heat extraction and for tritium management, including, for instance, the assessment of tritium permeation and of methods for its reduction, of tritium extraction and coolant purification. • Performance of an integrated test campaign in order to extend the reliability and operational performances database for the tested breeding blankets in a DT fusion device under DEMO-relevant operating conditions (except for neutron fluence) for an extended period of time. It is assumed here to have the same approach for all six selected TBSs. This approach has therefore to be considered as “generic”. In reality, some differences can be expected from one TBS to another. Such differences will be assessed in the future. The possibility to extend the scope of tests associated with a given version of TBM or to combine 2 TBM versions into a single one is not precluded at this stage of the assessment. It is assumed that all four TBM versions will share the same basic architecture, in particular their structural part (including the attachment system), whose design will be qualified during the testing programme in laboratory facilities before TBM commissioning and checked/monitored step-by-step during the different phases of ITER operation. This strategy ensures a relatively stable interface between the TBM and ITER during the whole operation time, with benefits for the availability and safety of the machine. An important difference in the design of each version will concern the integration of the specific instrumentation and the design of internals; in particular of the breeding zone that could be modified for testing optimized design variants or to achieve the required testing conditions; for example, the thickness of the breeder material could be increased to achieve DEMO-relevant temperatures, and the 6Li enrichment could be modified to obtain the desired test conditions. Each TBM will include a monitoring system of all the features relevant for the control and safe operation of the TBM systems. This includes coolant and liquid metal circuit inlet and outlet temperatures (including by-pass in the case of He cooling), pressure measurements in coolant and liquid metal circuits, mass flow rates and neutronics responses inside the fluids (for D- and DT-phases). The TBM ancillary equipment will also have to be adapted to the different loading conditions to which the various TBMs tested in the different ITER operational phases are submitted. 5. Overview of the main ITER/TBS interfaces The TBS components are located in various areas of the Tokamak Complex as shown in the scheme of Fig. 2. A preliminary assessment of the interfaces between the TBSs and ITER was started several years ago [2]. These interfaces have been significantly revised in the last year [3]. This chapter is a short overview of the main results of this recent work. 5.1. TBM port cells The TBMs are located in the in the port plugs inside the TBM equatorial ITER ports. All feeding pipes and measurement systems are coming from the back side. Before reaching the TBMs, all connections for coolant systems, tritium extraction systems, liquid metal systems and measurement systems cross the VV boundary and the Biological shield boundary in order to be connected with several systems located in the corresponding port cells. Components of both TBSs will be located on a special common structure,
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Fig. 2. Scheme of the TBS ancillary equipment (example of the HCLL TBS) with the indication of their locations in the Tokamak Complex.
called Ancillary Equipment Unit (AEU), which can be removed and maintained in the hot cell facility as a unique component. Other connections start from the port cells and go to other locations of the Tokamak complex. The port cell areas behind the TBM port plugs for ports #2, #16, and #18 are allocated to the Test Blanket Systems and will be used for hosting the so-called Ancillary Equipment Units (AEUs). 5.2. TBS cooling circuits components and connection pipes Although some cooling circuit (CC) components are located on the AEU, most of the CC components are located in other parts of the Tokamak Complex. For each TBS, the required footprint for accommodating the cooling circuit components and the associated coolant purification systems components is estimated to be between 80 and 90 m2 . Two areas have been identified for such purposes: an area of about 220 m2 at level 3 of the Tokamak building neighboring the CVCS area to be used for the components of two TBS CCs, and an area of about 480 m2 in the TCWS vault annex at level 4 of the tritium building to be used for the components of the other four TBS CCs. Connecting pipes will have to pass through the corresponding shaft and cross several room of Tokamak and tritium buildings. During TBSs operation, inlet/outlet temperatures are 300C-500C for He-systems and 270C-325C for the water system. Therefore, such high-temperatures pipes require several bends for thermal stresses release and thermal insulation. 5.3. Space reservation for TBS tritium circuits components and connection pipes In the present tritium Building design, an area of 312 m2 has been allocated for the six TBS tritium circuits components (including glove boxes). Connecting pipes are expected to be at room temperatures and link the port cell areas to the tritium building. 5.4. Space reservation for TBS Program in the hot cell facility The TBM Program is expected to make a large use of the hot cell facility. The refurbishment of the TBMs will occur off-line. For each TBM, it is expected to have up to 3 replacements in the first 10 years of TBS operation. The TBMs will be refurbished in pair for
each port. To replace the TBMs, each TBM port plug will be removed from the VV using the ITER Equatorial Cask Transport System and delivered to an appropriated area of the hot cell facility. A new TBM port plug, containing two new TBMs will be available for immediate installation in the TBM equatorial port. Pre-installation tests will be performed in the port plug test facility. Specific areas have been allocated for the refurbishment of TBM port plugs and AEUs and also for performing the necessary operations on TBMs before their shipping outside the ITER site for post-irradiation examinations. The TBM Program requirements, derived from the TBM testing plan and from the adopted maintenance strategy, have been taken into account in the present design of the HCF.
6. Licensing and quality plan Being a part of ITER, TBMs now must go through the same process of licensing as the ITER facility. The first step in this direction has already been completed and TBSs have been mentioned in safety documents presented to French authorities in the past. The present strategy for the TBM Program is to assume that all accidental sequences that could involve TBMs remain within the envelope cases assessed for ITER. Of course this statement has to be proved by appropriate analyses. The TBSs are included in the ITER RPrS (Rapport Preliminaire de Surété) that will be issued in spring 2010. The main TBSs data that are included in the RPrS are the following: (a) TBSs conceptual design description (“envelope design” for components not yet fully defined). (b) Description of the operational status of the various TBS components with their relation to the status of ITER (e.g., pulses, short and long shutdowns, stand-by). (c) Results of the main safety analyses. (d) The maximum expected operational releases have to be identified qualitatively and quantitatively for T, ACP and chemical. Expected coolant and chemical release have to be identified. (e) List of all TBS components and their preliminary safety classification (to be confirmed later). (f) Definition of the main interfaces with other relevant ITER systems (e.g., tritium plant).
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(g) Maximum expected tritium inventories in all systems and components (e.g., cooling systems, purge gas systems, liquid metal systems). (h) Maximum expected Activation Inventories in all systems and components. (i) Maximum expected dose rates in the various locations of the TBSs components (e.g., port cell, CCs locations, hot cell). (j) Waste management aspects such as the list of all elements not yet included in the ITER list and their waste management approach. TBSs components should comply with rules for Pressurized and Nuclear Pressurized Equipment (ESP & ESPN rules). This requirement implies that TBSs design and manufacturing should be validated by a notified body. It also implies that the ESPN classification has to be assigned to all TBSs components in mid-2010 at the latest. Concerning the TBMs, the validation by a notified body can be obtained only after the completion of the on-going qualification test program for the TBM structural materials (both for non-irradiated and irradiated materials up to 3 dpa). Proposals of QA systems should also be presented in 2010, including QA classification for TBSs components. It has to be stressed that the TBM Program corresponds to a special type of activity not yet included in the present ITER contractual framework (i.e., procurement arrangements, tasks, and contracts). In the TBM Program, IMs are responsible for the functional specifications and for the design and manufacturing of the TBSs, while the IO is responsible for the operation. An arrangement has to be signed as soon as possible between the IO and each IM responsible for a TBS (see chapter 3). In these arrangements, the details of the QA procedure and of the quality plan (QP) have to be mentioned. It is expected that they will be quite similar to the QA procedure applied to the procurement arrangements. For each TBS, the QP shall be applied after the signature of the IO/TBM IM arrangement. The QP shall identify: (i) the specific allocation of resources, duties, responsibilities and authority; (ii) details of all suppli-
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ers/subcontractors and how interfaces will be managed; (iii) the specific procedures, methods and work instructions to be applied; (iv) the specific methods of communication, both formal and informal, to be established between working groups; (v) any access restrictions for IO representatives. 7. Conclusions After several years of discussions the TBM testing program now is included in ITER program. The organizational structure of the program has been identified and is being established. Active cooperation between the ITER Organization and ITER Members responsible for the TBSs testing is required for the successful implementation of the TBM Program. Acknowledgments This paper was prepared as an account of work by or for the ITER Organization. The Members of the Organization are the People’s Republic of China, the European Atomic Energy Community, Republic of India, Japan, Republic of Korea, the Russian Federation, and the United States of America. The views and opinions expressed herein do not necessarily reflect those of the Members or any agency thereof. Dissemination of the information in this paper is governed by the applicable terms of the ITER Joint Implementation Agreement. References [1] L. Giancarli, V. Chuyanov, M. Abdou, M. Akiba, B.G. Hong, R. Lässer, et al., Breeding blanket modules testing in ITER: an International Program on the Way to DEMO, Fusion Engineering & Design 81 (2006) 393–405. [2] V.A. Chuyanov, L.M. Giancarli, C.S. Kim, C.P.C. Wong, The integration of TBM systems in ITER, Proceeding ISFNT-8, Fusion Engineering & Design 83 (2008) 817–818. [3] J.A. Snipes, M.J. Schaffer, P. Gohil, P. de Vries, M.E. Fenstermacher, T.E. Evans, et al., Proc. 37th EPS Conf. on Plasma Phys, Dublin, (2010) P1.1093.