ITER: What India Gets if Fusion Power Works

Fusion is the reaction that powers the Sun. Making it work in a machine needs extreme heat and a way to hold the hot gas in place.

1. What is nuclear fusion?

Fusion means light atoms join to make a heavier atom. In the Sun, hydrogen nuclei collide and fuse into helium. A tiny bit of mass is lost in the process. That lost mass turns into a very large amount of energy.

• Fusion is the energy source of the Sun and the stars.
• The Sun’s core is at about 15,000,000 °C.
• The Sun turns about 600 million tonnes of hydrogen into helium every second.

2. How hot must a fusion machine get?

On Earth the machine must be much hotter than the Sun’s core. ITER says deuterium-tritium fusion needs about 150,000,000 °C in the laboratory. That is ten times the temperature at the Sun’s core.

The live article says “many times hotter than the Sun’s core”. That is correct. The exact figure is about ten times.

Three conditions must be met together.

• Very high temperature.
• Enough plasma particles packed together so that collisions happen.
• Enough confinement time, meaning the plasma is held in place long enough.

3. What is plasma, and what is a tokamak?

At such heat, electrons break away from the nuclei. The gas becomes a plasma. It is often called the fourth state of matter.

A tokamak holds the plasma with strong magnetic fields. The word comes from a Russian phrase meaning “toroidal chamber with magnetic coils”. Its vacuum chamber is shaped like a doughnut.

The plasma never touches the walls. Magnetic coils keep it away from them. Heat from the fusion reaction is absorbed in the walls.

4. Which fuel does fusion use, and where does it come from?

The easiest reaction uses two forms of hydrogen. They are deuterium (D) and tritium (T). The D-T reaction gives the most energy at the “lowest” temperature. It makes one helium nucleus and one neutron.

• Deuterium can be taken from any water. Each cubic metre of seawater holds about 33 grams.
• Tritium is very rare in nature.
• Tritium has a half-life of 12.3 years.
• Today the main source of tritium is heavy-water fission reactors, such as CANDU types. India operates this kind of reactor.

Future plants must make their own tritium. They will do it from lithium inside the machine.

5. How is fusion different from fission?

Fission splits heavy atoms. Fusion joins light atoms. They are different reactions.

• Fission is a chain reaction. A fission core holds several tonnes of radioactive fuel.
• Fusion is not a chain reaction. The whole ITER system holds only a few kilograms of tritium.
• Only a few grams of fuel react at any moment.
• A runaway reaction is impossible. If anything goes wrong, the plasma cools and the reaction stops.

India’s thorium plans are about fission. Fusion is a separate technology.

6. Is fusion free of radioactive waste?

Not quite. The live article says fusion has “no long-lived radioactive waste”. ITER’s wording is narrower. It says fusion plants make no high-activity, long-life waste.

• The “burnt” fuel is helium, which is not radioactive.
• Tritium is radioactive, but only a few grams are used at a time.
• Fast neutrons make the vessel materials radioactive over time.
• That waste is rated very low, low or medium activity.
• Most of its radioisotopes have half-lives under ten years.
• ITER expects the materials to be recyclable within about 100 years.

So the safe line is “no high-activity, long-life waste”. Do not say “no radioactive waste”.

ITER is a research machine, not a power plant. It sits in France but belongs to seven partners.

7. What is ITER, and where is it?

ITER is a large experiment to prove fusion can work as a big, carbon-free energy source. The name is Latin for “The Way”. It is being built at Cadarache, near Saint-Paul-lez-Durance in southern France. The site is about 70 km north-west of Marseille. It covers 42 hectares.

When finished, it will be the world’s largest tokamak. It will have about six times the plasma volume of the biggest machine running today.

8. Who are the members, and who pays what?

There are seven ITER Members. They are China, the European Union, India, Japan, Korea, Russia and the United States.

• Europe pays the largest share of construction cost, about 45.6 percent.
• The other six pay about 9.1 percent each. That includes India.
• About nine-tenths of the value arrives as in-kind parts, not cash.
• All Members share the results and the intellectual property.

9. When did ITER begin?

The idea of a joint fusion experiment dates from 1985. The project then moved in steps.

• 2005: the decision to site ITER in France.
• 2006: the ITER Agreement was signed.
• 2007: the ITER Organization was formally created.
• 2010: building work began on the main site.
• 2012: ITER became a licensed nuclear installation under French law.
• 2020: machine assembly began.

India became a full partner in December 2005. It signed the 2006 agreement with the other six. That is why the live article can call India a founding member.

10. What does the ITER machine look like, and will it make electricity?

ITER is a doughnut-shaped tokamak ringed by superconducting magnets. Its main parts are listed below.

• Plasma volume: 840 cubic metres.
• Vacuum vessel: about 19.4 m across and about 5,200 tonnes.
• Toroidal field magnets: 18 D-shaped coils, each 330 tonnes.
• Cryostat: a steel outer chamber that keeps the magnets very cold. India built it.

ITER will not make electricity. It will heat plasma and measure the fusion power. Machines after ITER must turn that heat into power.

ITER’s main goal is a tenfold power gain. Other machines have set records, but none has reached ITER’s target in a tokamak.

11. What does Q greater than or equal to 10 mean?

Q is the ratio of fusion power made to heating power put in. Q = 1 is breakeven. At breakeven the plasma gives out as much fusion power as it takes in.

ITER is designed for Q of at least 10. That means:

• 50 MW of heating power goes in.
• 500 MW of fusion power comes out of the plasma.

ITER says no magnetic-confinement machine has yet reached Q = 1.

12. How long must the pulses last?

The 2024 press conference gave the goal as 500 MW for 400 seconds. The ITER FAQ gives a range of 400 to 600 seconds. Use 400 seconds as the safe figure, and know the range.

ITER will also test a second mode. It is a steady-state run at a lower gain of Q = 5.

13. What is a burning plasma, and what is tritium breeding?

In a burning plasma, the helium nuclei made by fusion supply enough heat to keep the plasma hot. Outside heating is then needed much less. ITER’s main aim is to study this.

ITER will also test tritium breeding. Neutrons hit lithium and make tritium. The process is meant to run inside the vacuum vessel.

• The test uses lithium-6.
• The world has too little tritium to fuel many plants.
• Worldwide stock from heavy-water reactors does not exceed about 20 kilograms in any year.
• That stock is just enough to fuel ITER’s planned D-T years.

14. What did JET achieve?

JET was a European tokamak at Culham in the UK. It was a large magnetic-fusion machine.

• In 1997, JET made 16 MW of fusion power from 24 MW of heating. That is Q of 0.67.
• Its fusion energy record rose from 22.7 MJ (1997) to 59 MJ (2022 report).
• In 2024, EUROfusion reported a new record of about 69 MJ, from only 0.21 milligrams of fuel.

JET never reached Q = 1. The records measure different things, so do not mix them.

15. What was the NIF ignition result of 2022?

The National Ignition Facility (NIF) is in the United States. It uses lasers, not magnets. On 5 December 2022 it gave 2.05 MJ of laser energy to a fuel target. The fusion output was 3.15 MJ.

The US Department of Energy called this the first controlled fusion experiment to produce more energy than the laser energy used to drive it.

Do not mix this with ITER’s goal. NIF counts laser energy on the target. It does not count the large power drawn from the grid to run the lasers.

16. What about China's EAST and the SPARC project?

EAST is China’s superconducting tokamak at Hefei. On 20 January 2025 it held a high-confinement plasma for 1,066 seconds. The earlier record was 403 seconds, also set by EAST in 2023. This test shows long duration. It does not show energy gain.

SPARC is a private tokamak built by Commonwealth Fusion Systems in the United States. The company says its first goal is Q above 1. It says SPARC will reach that in 2027. That is a company claim. No SPARC result had been reported when this was checked.

ITER is far behind its first plan. The cost figures also differ by source.

17. What was the old schedule?

The 2016 baseline had two main dates.

• First plasma: December 2025.
• Start of deuterium-tritium operation: 2035.

First plasma would have been a short test of a partly built machine. The ITER Director-General called it “rather symbolic” in 2024, according to Physics World.

18. What is the current schedule?

The ITER Council approved a new baseline approach in November 2024. It starts research with a fuller machine.

• 2034: Start of Research Operation, with hydrogen and deuterium plasmas.
• 2036: full magnetic energy. This is a three-year delay.
• 2039: start of deuterium-tritium operation. This is a four-year delay.

The new plan drops the early symbolic first plasma. The project says its mission goals have not changed.

19. Why was ITER delayed?

Several causes added up.

• The Covid-19 pandemic caused supply-chain and quality-control delays.
• Cracks were found in water pipes that cool the thermal shields.
• In early 2022 the French nuclear regulator briefly halted assembly over radiation shielding.
• Some first-of-a-kind components needed repair.

ITER’s FAQ also lists older causes of rising cost. The 2008 design review added new coils. The number of Members grew from four to seven. Steel and concrete prices rose.

20. How much does ITER cost?

No single number is right. Most parts are built in-kind by Members, who do not have to publish their real costs.

• The first estimate, from the 2001 design, was EUR 5 billion for construction.
• ITER’s FAQ says the cost of construction for the seven Members was once evaluated at about EUR 13 billion.
• In 2024, the Director-General said the new plan adds about EUR 5 billion for the ITER Organization. Members were still reviewing it.
• Scientific American reports the latest official estimate at more than 20 billion euros (about 22 billion dollars). Physics World says “tens of billions of euros”.

For an exam, say ITER costs tens of billions and is far over its first estimate.

India’s part is built by the Institute for Plasma Research and Indian companies. The biggest piece is the cryostat.

21. When did India join, and who manages its share?

India joined ITER as a full partner in December 2005. The Institute for Plasma Research (IPR) in Gandhinagar manages India’s part. IPR is an aided institute of the Department of Atomic Energy (DAE).

IPR’s ITER arm is called ITER India. It is the Indian Domestic Agency. It was formed as a specially empowered body in November 2007.

22. What share does India pay, and how?

India pays about 9.1 percent of construction cost. Most of it is not cash. It is delivered as finished parts, called in-kind contributions.

ITER describes India’s work as 14 procurement packages. The cryostat is the largest of them. Indian industry builds the parts under contracts from ITER India.

23. What is the cryostat, and who built it?

The cryostat is a huge stainless-steel vacuum chamber around the ITER vessel and magnets. It keeps the magnets cold. ITER calls it the largest stainless steel high-vacuum pressure chamber ever built.

• Volume: 16,000 cubic metres.
• Weight: 3,850 tonnes.
• Made by Larsen & Toubro at Hazira.
• Planned to ship from India in 54 modules, to be assembled at the ITER site.
• Completed in 2022.

Its 1,250-tonne base was the first big machine part placed in the tokamak pit, in May 2020.

24. What else does India supply?

India’s list goes beyond the cryostat. The Department of Atomic Energy and ITER name these items.

• Cooling water system: it can exchange about 1 gigawatt of heat during a full-power pulse.
• Cryogenic distribution systems.
• In-wall shield blocks, which work as neutron shields inside the vessel.
• Diagnostic neutral beam and other diagnostics.
• Heating systems and their power supplies, which were at prototype and test stage in the latest IPR report.

Indian firms involved include L&T, Inox India, Tata Consulting Engineers and HCL Technologies. L&T also won a direct ITER contract for welding vacuum vessel ports.

25. What does India get back from ITER?

Members get 100 percent of the scientific results, though they pay only part of the cost. They also share the intellectual property.

For India there are other gains.

• Know-how in fusion science and technology.
• Training of a skilled workforce. About 200 people were working on site in 2025.
• Experience that ITER says helps lay the base for an Indian fusion industry.

The government has said India may consider building a fusion reactor of its own in future, based on ITER’s experience and success.

India has its own tokamaks and its own nuclear plan. The 2016 question asks how fusion differs from that plan.

26. What are ADITYA, ADITYA-U and SST-1?

Both machines are at the Institute for Plasma Research in Gandhinagar. IPR says they are the only two tokamaks in India.

• ADITYA is a medium-sized tokamak. It has run at IPR since 1989.
• ADITYA-U is its upgraded version. It routinely runs experiments in support of ITER.
• SST-1 is a superconducting tokamak. It was built for long, steady plasma pulses.

Their plasma durations have been short. An IPR director said they are only a few hundred milliseconds, far shorter than records in China and France.

27. What are India's next fusion plans?

India is thinking of an early use of fusion through a fusion-fission hybrid. In this idea a fusion core drives a sub-critical fission blanket. The Department of Atomic Energy says it could make electricity or burn radioactive waste. It would be a step while India waits for D-T results from ITER.

IPR scientists have proposed a roadmap with three steps.

• SST-Bharat, a mid-sized machine.
• A fusion-fission hybrid reactor.
• A DEMO reactor of about 250 MWe, targeted for the 2060s.

This is a proposal, not an approved project.

28. What is India's thorium plan, and how is it different?

India has limited uranium but one of the largest thorium reserves in the world. So the Department of Atomic Energy built a three-stage nuclear programme. All three stages use fission.

• Stage 1: pressurised heavy water reactors burn natural uranium and make plutonium.
• Stage 2: fast breeder reactors use that plutonium. They also breed uranium-233 from thorium.
• Stage 3: reactors use uranium-233 bred from thorium.

The Prototype Fast Breeder Reactor at Kalpakkam reached first criticality on 6 April 2026. PIB says this took India into stage 2.

Thorium is a fission fuel. ITER’s success does not change it.

29. What did the 2016 question ask, and why is (d) right?

UPSC Civil Services Prelims 2016, GS Paper I, Q79 asked about the “immediate advantage” for India if ITER succeeds. Option (c) is often left out of summaries.

• (a) Use thorium in place of uranium for power generation.
• (b) Attain a global role in satellite navigation.
• (c) Drastically improve the efficiency of its fission reactors.
• (d) Build fusion reactors for power generation.

(d) is the answer. ITER is a fusion test. If it works, members can design fusion power plants.

• (a) is wrong. Thorium use is a fission matter. It belongs to India’s three-stage plan, not to ITER.
• (b) is wrong. Satellite navigation is a different field. ITER has nothing to do with it.
• (c) is wrong. ITER studies fusion. It does not make fission reactors more efficient.

30. What are the exam traps?

Use this checklist.

• ITER is fusion. Thorium and fast breeders are fission.
• ITER is an experiment. It will not make electricity.
• Location: Cadarache, southern France.
• Seven Members: China, EU, India, Japan, Korea, Russia, US.
• India’s share: about 9.1 percent, paid mostly in-kind.
• India’s best-known part: the cryostat, built by L&T at Hazira.
• Goal: Q of at least 10. That is 500 MW from 50 MW of heating.
• Pulse goal: 400 seconds. The FAQ range is 400 to 600 seconds.
• Fuel: deuterium and tritium. Tritium is bred from lithium.
• The “immediate advantage” for India is the ability to build fusion reactors.
• Say “no high-activity, long-life waste”. Do not say “no waste”.
• Current plan: research operation 2034, D-T operation 2039.
• Do not mix records. JET (magnetic), NIF (laser) and EAST (duration) measure different things.