1 Presented by Alice Ying Helium Cooled Ceramic Breeder (HCCB) Blanket Concept: Design and Test Plan 1.US HCCB efforts With contributions to Phase 1 activities M. Abdou, P. Calderoni, S. Reyes, R. Kurtz, S. Sharafat, S. Willms, M. Youssef A. Abou-Sena, Z. An, E. Kim, G. Wen 2.Working SubGroup-1 (WSG-1) TBWG presentations WSG-1 is led by L.V. Boccaccini (FZK) TBM Costing Kickoff Meeting INL, August 10-12, 2005

2 Deliver TBM to ITER (in 2012) on Day-one (office of science strategic plan) Top Level Objectives of the Test Program 1) First integrated experimental demonstration of the principles of tritium self-sufficiency 2) Breeding technology for producing the tritium necessary for extended operation of ITER 3) Critical experimental data on the feasibility, constraints, and potential of the DT cycle for fusion systems (including conducting shells, passive coils, coatings/thick armors/FW for improving plasma physics performance) Specifics i)validation of TBM 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 T-inventories 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.

3 All ITER Parties have selected HCCB concept as one of their TBM/DEMO options The main features of the proposed HCCB blankets are very similar … 1.Helium as coolant at a pressure of ~8 MPa and temperatures in the range 300°C- 500°C. 2.Use of a ferritic/ferritic-martensitic steel as structural material. Its design limit of about 550°C dictates the max temperature of helium. 3.Use of the ceramic breeder in the form of a pebble bed including single sized or binary pebble beds of Li ceramics such as Li 4 SiO 4 or Li 2 TiO 3 (Li 2 O). 4.Use of Be as multiplier in the form of a pebble bed (single sized or binary) or as a solid porous body. 5.Breeder material and Be are purged by a low pressure ( MPa) flow of helium that extracts the T produced.  Most likely, a low temperature WCCB (water-cooled CB) blanket will be the breeding blanket option during the 2 nd phase of ITER operations if in- situ tritium productions become necessary and desired

4 --- but 6 different concepts are under investigation, characterized by different configurations BOT (Breeder Out of Tubes) or BIT (Breeder in Tubes) concepts among the BOT concepts: –different kind of pebble bed configuration (parallel, perpendicular to the FW), –different bed typology (single sized or binary), –different materials: use of graphite reflector to reduce the amount of Be or use of Be in a porous solid form. Particular design requirements: use of the structural box to withstand the full helium pressure or use of vertical segmentations to reduce EM forces.

5 Box structure to withstand high pressure He during accidents BOT/pebble bed perpendicular to the FW

6 Moreover, the testing strategies vary according to Parties’ views on DEMO’s development: EU proposes a strategy oriented to a “fast track” approach assuming that ITER is the unique step to the DEMO reactor. In this strategy, the ITER tests have a particular meaning: they have to provide as much information as possible on the behavior of the selected system, and for this reason, any technical expedient is adopted in order to reduce the extrapolation gap between ITER and DEMO.  The consequence of this strategy is the use of large TBMs (about 1 m 2 of surface exposed to the plasma) with relevant geometrical similitude and the simulation of DEMO relevant values for the primary testing parameters. The US considers ITER an important fusion testing device for performing initial fusion “break-in” tests, including calibration and exploration of the fusion environment. Part of the fusion environment exploration is the screening of a number of configurations. In addition, the US believes a dedicated fusion component test facility is necessary to reduce the high risk of initial DEMO operation.  The US does not propose to test independently a specific configuration, but rather to evaluate several options of blanket arrangement in co- operation with other parties. The other strategies proposed by the Parties fall between these two positions.

7 Space availability requires an international coordinated testing program The number of independent TBMs that can be present in one port simultaneously strictly depends on the space availability in the port cell area, where spaces are necessary not only for TBM pipe penetrations but also for remote handling tools, frame coolant pipes, and auxiliary systems. It is further limited by space availability in the TCWS building, Tritium building, and Hot Cell building. The maximum external size of the container is 2.62 m (W) x 6.5 m (L) x 3.68 m (H). Port Plug Port Cell

8 Schemes to arrive at a Coordinated Testing Program under discussion 1) An aggressive, international co-operation with the objective of having an international program of blanket development. This is of course the most effective method, but also the most difficult to implement. It requires a broader official agreement among the involved IPs, with the goal of developing this line of blanket components up to the DEMO reactor. 2) Partial international agreements for co-operation especially during the first couple of years of ITER operations. The objective can be to design common TBM objects to produce data that can be used for the development of later independent TBMs or DEMO blanket concepts. Some proposals in this direction have been already presented. 3) Time sharing of a testing place, allowing the IPs to test their own concepts independently. This strategy allow the testing of more concepts, but has the consequence of reducing the testing time available for each IP. A common effort is in any case necessary to develop and operate part of the fixed equipment like the HCS or common standardized interfaces.

9 Testing strategy calls for different issues to be addressed in alignment with ITER operational plan HH-plasma DD-plasma Low Duty D-T High Duty D-T First wall structural response and transient EM/ disruption tests Neutronics and tritium production rate prediction tests Tritium release, thermomechanical interaction and design evaluation tests Initial study of irradiation effects on performance (local magnetic field, eddy current distribution, forces, and torques) (Passive methods on tritium production rate, energy spectrum) Look-Alike/ITER Optimized Act-Alike/ITER Constraint 3 to 4 unit cell arrays /submodules will be placed in ITER over the first 10 years of ITER testing EM/S NT TM PI

10 Example coordinated testing program under discussion This example assumes that three half ports are dedicated to this line of blanket testing (two half-port positions in port A plus a half-port position in port C.) Each TBM is assumed to occupy half a port and can be replaced at most once per year Modules with common helium feeds, but containing sub-modules of different party’s design, or designed in co-operation with different parties, are considered as examples for Locations 1 and 2, respectively. In Location 3, the example shown assumes that only home TBMs will be tested (consequently, a full time sharing approach.)

11 We proposed two collaboration schemes to help to achieve a coordinated testing program Scheme No. 2: Co-Design and Fabrication of Submodule/module TBM In this scheme, the submodule would have to be expanded to a module due to a limited space for penetration Each unit cell size~ 0.2 x 0.2 x 0.4 m 3 Scheme No. 1: inserting three “US” unit cells into the EU HCPB structural box

12 KO has expressed a similar interest in a collaborative testing program in ITER Test Modules Description Electro- Magnetic Sub-module  Installation for day one operation  Size : to be determined through discussion with host TBM  Utilizing HCS of host TBM Neutron Tritium Sub- module  Installation in D-D and D-T phase operation  Size : to be determined through discussion with host TBM  Ancillary systems are to be shared with host TBM  NMS & TMS Thermo- Mechanical TBM 1  Installation in D-T phase operation  Size : ½ port  Ancillary systems are to be shared with other party Thermo- Mechanical TBM 2  Installation in D-T phase operation (for the last 2 years)  Size : ½ port  Ancillary systems are to be shared with other party Test Plan of KO HCSB submodule and TBM

13 JA has not yet explicitly expressed its role in the collaborative testing program The concept is not practical due to the numbers of service pipes. EBW at rear wall 1st breeder 1st multiplier 2nd breeder 2nd multiplier 3rd breeder 3rd multiplier Horizontal View BOT/Layered configuration 3 sub-module structure for internal pressure durability and structure similarity with DEMO blanket (slit structure for electro- magnetic force reduction). JA Solid Breeder He Cooled TBM 3 x Large penetrations/pipes (up to ~100 mm OD) 1 x penetration for Instrumentation (up to ~80 mm OD) 7 x small penetrations (~35 mm OD)

14 China hopes to equally share space with other ITER parties under TBWG framework, and expects to deliver a HCCB TBM to ITER on day one. Integration view of structure design Structural Material: EUROFER mm 9 (3 x 3) Sub-modules 890mm 630mm –0.260m in poloidal –0.190m in toroidal –0.420m in radial Within WSG-1’s content, this TBM program is illustrated as Location 3 of the draft Table

15 RF concepts emphasizing BIT approach 1-beryllium briquette; 2-cooling channel; 3- ceramic breeder; 4-holes for attachment rods; 5-coolant inlet; 6-coolant outlet; 7-purge-gas outlet; 8-purge-gas inlet Coil BIT option beryllium briquette; 2-ceramic pebble-bed; 3-ceramic pellets; 4-gauze elements. Pebble bed + pellet option Straight BIT option Within WSG-1’s content, this TBM program is illustrated as Location 3 of the draft Table

16 Scheme 1: inserting three “US” unit cells into the EU HCPB structural box Cooling to each unit cell is done by unit cell array manifold Added complexity could be manageable: Four pipes are added into the piping system to provide separate cooling and purge gas lines to the test units Associated ancillary components to be arranged in the port cell area

17 Neutronics Unit Cell Design Details Helium 8 MPa T in : 100 o C T out : 300 o C Tritium measurements: 1. Pellet specimens are used for local tritium production rate measurements 2. Run hot helium into the breeding zones to collect tritium (global) during ITER dwell Providing a range of tritium production profiles for verifying neutronics code calculation procedures To achieve a good spatial resolution on local tritium production rate measurement To freeze tritium during ITER testing

18 Thermomechanics Unit Cell Design Details Helium 8 MPa T in : 350 o C T out : 500 o C Total heat generation inside the unit cell ~ 35.8 kW He-coolant flow rate: kg/s per unit cell Skelton View DEMO act-alike design approach: reproducing temperature magnitude and gradient within the blanket pebble bed regions

19 A larger scale of participation is to co-design and fabrication of a TBM module with other party(ies) The design combines layer and edge-on configurations in one physical unit with its own first wall structural box Low T operation during ITER burn: He T in /T out : 100/300 o C Low temperature helium cools breeder zone first before cooling the first wall; breeder zone < 350 o C  Neutronics and tritium production rate prediction (NT) tests Tritium measurements: 1.Pellet specimens are used for local tritium production rate measurements 2.Run hot helium into the breeding zones to collect tritium during ITER dwell Can be one of the three submodules of the JA’s TBM

20 Modification to a typical DEMO FW coolant routing scheme is needed in designing the ITER TBM FW h=5890 W/m 2 -K Max Temp: 523 o C In general, ITER TBM is smaller in size than a typical DEMO module (short flow path, larger flow area per M 2 FW) Uncertain ITER surface flux distribution Disproportional heat distribution between surface heat and neutron loads: By-pass flow is considered to further increase He velocity (for TM/PI Modules) ITER FW heat flux at the mid- plane : Nominal: 0.11 MW/m 2 Peak: 0.5 MW/m 2 Average: 0.3 MW/m 2 5 coolant channels per flow path connected in series

21 Engineering scaling rules are applied for TBM design in order to achieve DEMO-like operating conditions under a reduced neutron wall load (0.78 vs 2- 3 MW/m 2 ) Elastic modulus (MPa) Temperature profile at 400 s von Mise’s stresses (focused on beryllium PB region) Predicted high stress zone (~20MPa) occurs at the corner of the coolant plate MARC Model Breeder zone Beryllium zone Finite element based pebble bed thermomechanics analysis

22 A “qualified” structural material fabrication technology is also needed for breeder zone coolant plates in addition to FW box Layer Design Configuration Edge-on Design Configuration (2 paths)

23 Purge-gas delivery and collection systems are integrated into the bottom and upper end caps Bottom end cap Upper end cap 91 cm First Wall  Not only heat but also tritium produced inside the breeder zone needs to be brought out [more structural fabrication issues] Purge gas flows vertically and radially through different breeding zones to remove tritium

24 There will be ancillary conditioning equipment and measurement systems located in the port cell area A coordinated test program requires a standardization of the TBM/frame interface and an integrated layout of the port cell equipments.

25 Summary An initial framework to achieve a coordinated testing program for HCCB blanket TBMs has been established. This includes: –Cooperation in the design/manufacturing/testing of “common” TBMs. –Use of sub-modules inside the testing program of another IP; this will allow testing of different concepts in smaller test objects, but will require strong cooperation among partners in the design of a common supporting structure. –Preparation of common tests that can be useful for different program; design of common equipment and sharing of results –Standardization of the TBM/frame interface –Common use of the port cell equipment (integrated layout); –Common use of one or more helium coolant systems. The US is expected to play a strong supporting role in the ITER WSG-1 testing program through cost sharing of common auxiliary systems and delivery of about one-third of half-port size helium-cooled ceramic breeder unit cells/submodule. Need “routes” to realize formal collaborative agreements among the parties (Bilateral or multi-lateral).