Divertor and Blanket Systems: Design, Required technologies and Schedule M. Merola

1. Divertor and Blanket Systems: Design, Required technologies and Schedule M. Merola Head of the Internal Components Division The views and opinions expressed herein do not necessarily reflect those of the ITER Organization.

2. ITER Internal Components • Divertor and Blanket directly face the thermonuclear plasma and cover an area of about 210 + 620 m2, respectively. • All these removable components are mechanically attached to the Vacuum Vessel or Vessel Ports. • Max heat released to the internal components during nominal pulsed operation: ~850 MW • Removed by four independent water loops at 4 MPawater pressure, ~70 (inlet), ~120 (outlet) °C Blanket Divertor

3. Overview of Material Mass

4. ITER Divertor • Divertor system main functions : • Exhaust the major part of the plasma thermal power (including alpha power) • Minimize the helium and impurities content in the plasma

5. Divertor Cassette Layout 54 Cassettes in a circular array held in position by two concentric radial rails .

6. Divertor System • Scope • 54 Divertor assemblies • 4320 Heat flux elements • 5 Major systems: • Cassette Body + Integration • Outer Vertical Target • Inner Vertical Target • Dome • Plasma-Facing Comp Tests

7. Power Handling Comparisons

8. Status of Divertor • First Divertor (CFC/W) is well into procurement phase (5 PAs) • PFCs: Last PA signed March 2010. Definition of QA for all parties done. Preparation for prototype manufacturing. • HHF Testing facility in RFDA: PA signed March 2010. Commissioning planned July 2012. • Cassette Body and integration: PA signature 8th May 2012 HHF testing of Plasma Facing Units

9. Divertor Qualification Prototypes • CFC Armoured Areas • 1000 cycles at 10 MW/m2 • 1000 cycles at 20 MW/m2 • W Armoured Areas • 1000 cycles at 3 MW/m2 • 1000 cycles at 5 MW/m2 All 3 Domestic Agencies have been qualified.

10. Status of W Technology R&D in EU 2000 cycles at 15 MW/m2 on W Unirradiated- 1000 cycles x 20 MW/m2 – no failure 200°C, 0.1 and 0.5 dpa in tungsten - Successfully tested up to 18 MW/m2 Most of all the W repaired monoblocks behaved like not-repaired ones

11. Blanket System Functions • Main functions of ITER Blanket System: • Exhaust the majority of the plasma power. • Contribute in providing neutron shielding to superconducting coils. • Provide limiting surfaces that define the plasma boundary during startup and shutdown.

12. Blanket System Modules 7-10 Modules 11-18 Modules 1-6 Shield Block (semi-permanent) FW Panel (separable) Blanket Module 50% 50% 50% 40% 10% ~850 – 1240 mm ~1240 – 2000 mm

13. Design Heat load on blanket • Group 1 : 1 – 2 MW/m²Normal heat flux panels • Group 2 : 3.5 – 5 MW/m²Enhancedheat flux panels

14. First Wall Finger Design Normal Heat Flux Finger: • q’’ = ~ 1-2 MW/m2 • Steel Cooling Pipes • HIP’ing Enhanced Heat Flux Finger: • q’’ < ~ 5 MW/m2 • Hypervapotron • Explosion bonding (SS/CuCrZr) + brazing (Be/CuCrZr) SS Back Plate Be tiles Be tiles SS Pipes CuCrZr Alloy

15. FW Pre-Qualification Requirements • Each DA must demonstrate technical capability prior to start procurement. • 2 phase approach: 2 slopes, 4 facets 6 Fingers in 1 to 1 scale I. Demonstration/validation joining of Be/CuCrZr and SS/CuCrZrjoint (done) II. Semi-prototype production/validation of large scale components (on-going)

16. Shield Block Design • Slits to reduce EM loads and minimize thermal expansion and bowing • Poloidalcoolant arrangement. • Cut-outs at the back to accommodate many interfaces (Manifold, Attachment, In-Vessel Coils). • Basic fabrication method from either a single or multiple-forged steel blocks and includes drilling of holes, welding of cover plates of water headers, and final machining of the interfaces.

17. Blanket Manifold • • A multi-pipe configuration has been chosen, with each pipe feeding one or two BM’s replacing the previous baseline with a large single pipe feeding several BM’s • Higher reliability due to drastic reduction of number of welds and utilization of seamless pipes. • Higher mechanical flexibility of pipes. • Superior leak localization capability due to larger segregation of cooling circuits. • Well established manifold technologies.

18. Tolerances General Tolerances described in Standards do NOT always meet our requirements ISO 2768-1:1989 Tolerances for linear and angular dimensions … ISO 2768-2:1989 Geometrical tolerances ...

19. Key Technology Areas Welded structures made of austenitic steels: NG-TIG, EB, Laser, TIG, MIG, … High heat flux joining technologies (Tungsten, Beryllium, CuCrZr): HIP’ing, brazing, casting, EB Heat Flux Testing of actively cooled components Non-destructive Examinations RX, UT, … Piping, flexible supports for pipes Insulating coatings, Low friction coatings, Anti-size coatings Precise machining, metrology High-Vacuum technologies, Pressure Tests, He Leak Tests

20. Manufacturing / Welding Qualifications • Qualification of Welding Procedure Specification (WPS) • WPS according to EN ISO 15607 and EN ISO 15609-nn • Preliminary WPS is qualified according to EN ISO 15614-nn • Qualification if quality level B achieved • EN ISO 5817 for arc welding • EN ISO 13919 serie for power Beam welding • Welding Procedure Qualification Record (WPQR) • The welding qualification for Quality Class 1 components shall be witnessed by ITER recognized Independent Inspection Authority, e.g. Third Party Inspector. • Welders, operators and NDT personnel shall be qualified (EN 287/ EN1418/ EN 473) • Other equivalent national or international standards and codes may be acceptable subject to the IO’s written approval.

21. NDT of welds in Steel Supports • Surface crack examination • Visual Test for welds (EN 970) • Liquid Penetrant Test for welds (EN 571) N.B. ITER Vacuum Handbook requirement: use of qualified liquid penetrants • Volumetric examination • Radiographic test for welds (EN 1435) • Ultrasonic Test for welds (EN 22825) • Acceptance Criteria • Quality level B of EN ISO5817/ EN ISO 13919 • ITER Vacuum Handbook Attachment 1: Welding • Other equivalent national or international standards and codes may be acceptable subject to the IO’s written approval.

22. Engineering Support Services Design supporting analysis (Electro-Magnetic, thermal, mechanical) Development of component design, including the production of 2D drawings and 3D models. This activity requires the possibility to receive and deliver CAD files in of CATIA_V5 format. Good knowledge and understanding of the codes, standards, and design criteria used in ITER. The work may require the presence of the Contractor’s personnel at the working site of the ITER Organization, for extended periods of time, for the purpose of design review and data gathering.

23. Divertor Procurement Schedule • 17.P2C.RF Divertor Dome: signed 9th June 2009 • 17.P2A.JA Divertor Outer Target: signed 17th June 2009 • 17.P2D.RF Divertor Heat Flux Tests: signed 23rd February 2010 • 17.P2B.EU Divertor Inner Target: signed 22nd March 2010 • 17.P1.EU Divertor Cassette and Integration: signed 8th May 2012 • 17.P2E.EU Divertor Rails: September 2014

24. Blanket Procurement Schedule • 16.P1A.CN/EU/RF Blanket First Wall: November 2013 • 16.P1B.CN/KO Blanket Shield Block: November 2013 • 16.P3.RF Blanket Module Connections: July 2014 • 15.P1A.EU Blanket Manifolds: March 2014

25. Summary and Conclusions • The ITER plasma facing components are one of the most technically challenging components of the ITER machine • An extensive R&D effort has been carried out world-wide to develop suitable high heat flux technologies • Divertor plasma-facing components • Blanket First Wall • The ITER Divertor design and R&D has reached a stage of maturity to allow the start of procurement in June 2009 • Substantial engineering effort (design and analysis) is planned for the Blanket System in 2012 • Key technology areas includes: • Austenitic steel welding (Divertor cassette, Blanket shield block) • Piping (Blanket manifold) • Precise machining of metallic materials (Divertor rails)