ITER is an experimental fusion reactor facility under construction in Cadarache, south of France to prove the feasibility of nuclear fusion as a future source of energy. ITER will work on the “Tokamak” concept where the reaction of hydrogen isotopes Deuterium and Tritium produces energy by the mass-energy conversion principle, thereby proving to be a source of unlimited energy. ITER partners are the European Union, China, India, Japan, South Korea, Russia and the United States of America. European Union being the host party contributes about 45% while the rest of the parties contribute about 9% each. Most of these contributions are through ‘in-kind’ procurement of ITER components. India formally joined the ITER Project in 2005 and the ITER Agreement between the partners was signed in 2006.
ITER Organization (IO) is the central team responsible for construction at site and operation, while the ITER partners created their own domestic agencies to deliver their commitments to ITER. ITER-India is the Indian domestic agency, a specially empowered project of the Institute for Plasma Research (IPR), an aided organization under Dept. of Atomic Energy, Govt. of India. ITER-India is responsible for delivery of the following ITER packages: Cryostat, In-wall Shielding, Cooling Water System, Cryogenic System, Ion-Cyclotron RF Heating System, Electron Cyclotron RF Heating System, Diagnostic Neutral Beam System, Power Supplies and some Diagnostics. Additionally, related R&D and experimental activities are being carried out at the ITER-India laboratory in Gandhinagar, Gujarat.
India’s contribution to ITER includes delivery of 9 in-kind packages to ITER. Each of the package to be delivered involves development of materials, machining, technologies and quality to meet with the stringent nuclear safety norms of the French regulatory board and also ensure that the components work for the life time of ITER.
An overview of the Indian packages to the ITER machine
The cryostat is the outer vacuum shell of the ITER machine and has a height and diameter of 30 m. Due to its dimensions, limitations on road transport and the need for assembly of ITER components within the Cryostat, the Cryostat is divided into four sections of Base, Lower Cylinder, Upper Cylinder and Top lid. Each section, other than the Top lid, is divided vertically into two tiers and each tier has six sectors in the Toroidal plane. The Top lid is divided into thirteen sectors. Several technologies have been developed which include:
Welding across different thickness, ranging from 20 mm to 200 mm
Weld processes to ensure dimension control within 0.3% tolerance
Flatness control of pedestal ring
Special handling of large pieces ~ 100 Tons each
Development of dual operator technique to control distortion in T welds
Development of special Hot wire TIG welding for heavy thickness welds to be carried out at site
Development of weld inspection by Ultrasonic method for thick welds
Cryostat lower cylinder ready for delivery to ITER France
A special workshop has been erected within ITER site to facilitate the fabrication of large sections and their corresponding transfer to the ITER building. The upper cylinder sectors are ready at the manufacturer’s works, for dispatch.
In order to fulfill the cryogenic requirements of ITER, a network of 4000 m cryolines and 7000 m warm line together with 9 cryodistribution boxes is required to transfer cryogens from cryoplants of capacities 75 kW @ 4.5 K and 1 MW @ 80 K. A dedicated Prototype Cryoline (PTCL) test facility has been set up to test and qualify a scaled section of 29 m of prototype cryoline, consisting of six process pipes with an Outer Vacuum Jacket (OVJ) of 600 mm diameter and carrying helium at 4.5 K and at 80 K in the ITER-India laboratory at IPR. The layout includes the 90 degree and 160 degree bends, Tee elements, out of plane section and straight elements. It is 1:1 scale in diameter and 1:5 in length, as compared to the torus and cryostat cryolines for ITER. Two PTCLs, i.e., PTCL-1 and PTCL-2 from two different suppliers were manufactured and tested. Bulk production of the cryolines is underway and 50% of the deliveries have been completed. Installation activities at site are underway.
PTCL-1 and PTCL-2 installed at ITER-India cryogenic laboratory (PTCL : Prototype cryo line)
The Cryodistribution system supplies the Supercritical Helium (SHe) to the superconducting magnets of ITER Central Solenoid (CS), Toroidal Field Coils (TF) and Poloidal Field (PF) Coils, magnet support structure as well as to the cryo pumps. It consists of seven cold boxes. The principal challenge in cryodistribution is the development of cold circulators having mass flow rate of the order 3 kg/s at 4.3 K and 0.15 MPa pressure head. Cold circulators of this rating were not available and required a special development and testing. Two manufacturers having competitive technologies, based on active magnetic bearing and hybrid ceramic ball bearing have designed and manufactured the test cold circulators. A dedicated test has been carried out for the cold circulators in the cryogenic facility of JAEA. The tests established all modes of operation and performance of both types of cold circulators at nominal and maximum operational condition. Functionality has been established for mass flow rates 3 kg/s and maximum pressure head of 0.2 MPa, ensuring reliable cryogenic distribution to the CS, TF and PF magnets and cryopump.
Cold Circulator cartridge
The In Wall Shield (IWS) blocks made out of borated steel (SS304B4, SS304B7)are placed in between the two walls of the ITER vacuum vessel for neutron shielding purposes and ferromagnetic steel (SS430) to reduce the toroidal field ripple. A total of 8809 blocks are to be assembled for the 9 sectors of vacuum vessel and the field joints in between the sectors. The blocks are assemblies of machined plates, each of which is 40 mm thick, made out of borated steel and Ferritic steel. There are about 58000 plates which are to be machined to precision, involving 3-D profiles. These block assemblies use ~ 1,50,000 brackets, spacers, bolts and washers. The developments include:
Use of powder metallurgy route used to produce SS304B7 by Carpenter Technology for better grain structure and boron distribution
Corrosion study for all IWS materials under simulated operating conditions (200 deg. C, 24 bar pressure, water, 5 weeks)
Magnetic permeability control during component machining (Maximum 1.03)
Vibration test for fastener anti-rotation design validation
45% of blocks delivered to KO and EU
IWS block assemblies
The cooling water system under the Indian scope includes the following subsytems:
Component Cooling Water System (CCWS) : Provides cooling water at 31oC, specified flow rate, pressure and water quality
Chilled Water System (CHWS) : Provides chilled water at 6oC, specified flow rate and pressure
Heat Rejection System (HRS): Final heat sink. Also stores the excess heat during pulse operation and rejects the same during dwell period
Fabrication of chillers for water components
The scope of supply includes
10 cells of Cooling Tower: Avg. 510 MW; Peak ~ 1.2 GW
14 Plate type Heat Exchanger: 70 MW each: Possibly at the highest range of design,
6 Air cooled Chillers: 450 kW each and with requirement of seismic qualification for nuclear site which is the first of its kind.
The other challenge is to establish interfaces with buildings, site network and site construction. The delivery under the CWS include ~4500 pipe spools upto 2m diameter, in varying lengths and piping geometries, having ~ 18 km of piping and ~ 105 inch diameter of welding. Till date 90% of the delivery has been completed and includes 2500 spools of pipes and major components- chiller, cooling tower and pumps. The pipes have a special pipe in pipe design due to the site constraint of buried piping.
The scope of the ICRH system includes 9 RF sources each rated for
36-65 MHz, CW operation at 2.5 MW with a VSWR 2.0 OR
40-55 MHz, CW operation at 3 MW with a VSWR of 1.5.
ITER-India test facility for testing amplifier chains with Tetrode and dicrode tubes
Tube development for the RF sources has been undertaken with development of two types of tube viz Tetrode: 1.9 MW/VSWR 1:1/300s and Diacrode: 1 MW/VSWR 1:1/1000s.
Further as no unqiue amplifier chain exists to meet ITER needs, ITER India proposed a layout consisting of two parallel three stage amplifier chains + a combiner circuit on the output side. An R&D program with the mandate to prove the delivery of 2.5/3 MW RF power from the two parallel, three stage amplifier chain, has been launched. For this purpose, a dedicated high power test facility has been set up. It consists of a wide band solid state amplifier (for 35 – 65 MHz, 10 kW) as pre-driver stage, high voltage power supplies (Maximum voltage/current 27 kV/190 A), high power transmission lines (12’’), a 3MW, water cooled dummy load and a local control unit for control and monitoring (approx. 150 analog and digital channels). Demonstration of each chain having the specification of delivering 1.5 MW for 2000s in the 35-65 MHz, at VSWR of 2:1, is the aim of this R&D activity.
The EC scope of supply from India includes 2 gyrotrons sources of 1 MW power output at 170 GHz for a pulse length of 3600s pulse length.
ITER-India test facility for testing amplifier chains with Tetrode and dicrode tubes
A gyrotron test facility (GTF) is currently under development at ITER-India lab to establishing a reliable, integrated system performance. The test facility consists of prototype auxiliary systems including a set of dedicated high voltage power supplies to ensure that the test facility configuration and the environment is close to that of the ITER deliverables. A dedicated 55kV, 110A, PSM based Main High voltage power supply for the gyrotron cathode circuit is in advanced stage of development. A prototype of compact cost effective solution using solid state switch has been prepared and tested as a potential solution for the low current fast switching high voltage gyrotron body power supply.
The ITER diagnostic neutral beam (DNB) is to be used to diagnose He ash content of the ITER plasma during its DT operation phase using the CXRS diagnostic technique. The measurements shall be performed using a 100 keV 20 A neutral hydrogen beam. Production of this beam requires a diagnostic beam line consisting of an 8 driver based RF negative ion source, a neutralizer cell, an electrostatic residual ion dump and a beam dump for beam characterization and optimization. In order to generate the neutral beam with the above mentioned parameters, 100 keV 60A H- beam needs to be extracted and accelerated from the ion source followed by neutralization, separation of un-neutralised ionic beam from the neutral beam and beam characterization followed by transport over 20.7 m from the ion source. The neutralizer, the electrostatic RID and the calorimeter intercept the beam and are subject to high power densities. Each of the components therefore requires special materials, precision machining, welding and inspectability to ensure ITER desired quality standards. As an example of precision machining the most critical 3 grid beam extractor and accelerator system of the ion source requires beamlet aperture positioning accuracy of 50 microns, a flatness control of 0.4 micron and the angle tolerance of 0.011o. The angles in the grid segments help in focusing to ensure minimal beam losses through the duct connecting the diagnostic neutral beam system to the ITER vessel port. The other examples of precision machining include a < 500 mm drift over 1.8 m deep drilled hydraulic channels for the neutralizer and the electrostatic residual ion dump panels. A unique facility having a unique 21 m transport length is under construction at ITER – India lab to operate and characterize neutral beams and hence provide the much needed data base to diagnosticians using the beam for diagnosis.
INTF test facility and neutral beam line components
The power supply package includes power supplies for three packages :
Diagnostic neutral beam : 10 kV, 140 A extraction power supply, 90 kV 70 A acceleration power supply for the diagnostic neutral beam source, 200 kW 1 MHz RF generators, 4 nos. and a 10 kV 60 A power supply for the electrostatic residual ion dump
The ICRH system : Driver stage 8-18 kV 250 kW and end stage 27 kV 2.8 MW power supplies
The ECRH system : 55 kV, 5.5 MW power supply
Indian manufactured 7.2 MW, 100 kV acceleration power supplies on Padova ion source test stand
The developments include
delivery of 7.2 MW, 100 kV acceleration grid power supplies for an neutral beam ion source test bed at Padova, Italy
a transmission line capable of supporting a power transport of 150 MW over 25 m length and accommodates power, hydraulics and RF lines for the Indian test facility
A dual output high voltage power supple for ICRH system which is first of its kind with a unique concept
A prototype of compact cost effective solution using solid state switch has been prepared and tested as a potential solution for the low current fast switching high voltage gyrotron body power supply for the ECRH system
The diagnostic package includes India’s participation in
X-Ray Crystal Spectroscopy (XRCS) : Set of spectrometers (X-ray crystals, Detectors , Vacuum chamber), Calibration source, Instrumentation & Control (I&C)
Electron Cyclotron Emission (ECE) : Set of Michelson Interferometers & Radiometers, Polarization splitter unit, Transmission line, Calibration source, Instrumentation & Control
CXRS : Optical Fibers, Detectors, Visible Spectrometers, Opto-mechanical components like filters, mounts, I&C
Upper Port- 09 (UP#09) : Complex integration with Interspace Support Structure (ISS) & Port Cell Support Structure (PCSS) etc., and customization for CXRS(Edge).
Fourier transform spectrometer at ITER India lab
In order to establish measurement techniques for low loss transmission of ultra-wide band frequency range of 70 GHz – 1000 GHz, a prototype Fourier Transform Spectrometer has been developed to establish in vacuum attenuation calibration for a 8 m transmission length for the transmission line attenuation
One of the important developments in collaboration with NFTDC Hyderabad is the development of ITER grade CuCrZr material with controlled % elemental composition of CuCrZr Cr : 0.6 – 0.8%; Zr : 0.07% to 0.15% ; Cd : 0.01%; Co : 0.05% ; total impurities not to exceed 0.1%. The material has been used in several of the beam line components of the diagnostic neutral beam such as the electrostatic residual ion dump panel elements and the heat transfer elements for the calorimeter panels for beam diagnosis.
Heat transfer elements made from special material - CuCrZr
Institute for Plasma Research, An aided institute of Department of Atomic Energy, Govt. of India, Bhat , Gandhinagar - 382428 Gujarat, India.
ITER will use the well known magnetic confinement scheme called the “tokamak”, to confine the deuterium-tritium plasma. D-T fusion reactions occur when the plasma is heated to about 10 keV or 100 million degrees C. The reaction leads to the creation of alpha particle and energetic neutron with a total released energy of about 17.6 MeV, which is about 1000 times that of the reactants.
The deuterium (heavy hydrogen) is plentiful and can be easily obtained from the sea-water. The abundance of deuterium with respect to hydrogen goes as the ratio 1 : 6400 i.e. 1 D atom in about 6400 atoms of hydrogen in sea water. The tritium fuel can be generated within the reactor blanket itself by using a reaction between neutrons and lithium. There are enough lithium resources around the world and hence the fusion fuel is virtually inexhaustible.
In a fusion reactor, there will only be a very limited amount of fuel inside the reactor at any time. The fusion reaction automatically closes if the plasma temperature is too high. A fusion reactor is inherently safe.
Yes. Although fusion is a nuclear reaction, it is fundamentally different from fission reaction. Fusion does not produce any high-activity/long-lived radioactive products nor any harmful emissions.
India formally joined the ITER Project in 2005 and the ITER Agreement between the partners was signed in 2006.
ITER is a project based on international cooperation. ITER partners are the European Union, China, India, Japan, South Korea, Russia and the United States of America. European Union being the host party contributes about 45% while the rest of the parties contribute about 9% each. Most of these contributions are through ‘in-kind’ procurement of ITER components. India makes significant contribution towards building of ITER through ITER-India, the Indian domestic agency, a specially empowered project of the Institute for Plasma Research (IPR), an aided organization under Dept. of Atomic Energy, Govt. of India.
© Copyrights 2023 Vigyam Samagam
