Where Nuclear fusion generally takes place ?

 SET:S&T:NUCLEAR FUSION:ITER:21112025 

Topic : S&T:NUCLEAR FUSION (for G S 

Papers) {Prepared on 21 .11.2025 } 

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TOPIC : NUCLEAR FUSION:ITER: for UPSC(CSE)(Prelims) Exams. ,2026 QUESTIONS & ANSWERS 

1)Question: What is the meaning of ITER in Latin? 

Ans : The way 

2)Question: Expand ITER? 

Ans : International Thermonuclear Experimental Reactor 

3)What is the objective of ITER ? 

Ans : The objective of the International Thermonuclear Experimental Reactor (ITER) is to demonstrate experimentally the feasibility of controlled nuclear fusion as an alternate source of virtually limitless and clean energy.

4)What happens in Nuclear Fusion ? 

Ans : In nuclear fusion ,two light nuclei such as deuterons combine to form a bigger nucleus 

5)Where Nuclear fusion generally takes place ? 

Ans : Nuclear fusion is the process that has been powering our sun and stars

since ages. 

6)What happens in nuclear fusion ? 

Ans : When the nuclei of the two isotopes of Hydrogen, i.e., Deuterium (D) and Tritium (T), fast enough to overcome the Coulomb repulsion (both nuclei being positively charged), collide they fuse together to convert into a Helium nucleus and a neutron . The mass of the reactants slightly exceeds the combined mass of the products with the mass difference being released as energy following ΔE=Δmc2, the famous formula of Einstein. Each reaction produces 17.6 MeV of energy, 14.1 MeV of the neutron and 3.5 MeV of the He-4 nucleus. The energy generated can be converted into heat and finally, electricity. 

7)Where Deuterium is available ? 

Ans : Deuterium is available from seawater and Tritium can be generated within the reactor by blankets containing lithium salts. Barely a gram of gaseous fuel is within the reactor at any given time (e.g., the input and exhaust approximately same at 30 milligrams/sec of D or T for a 1000 m3 reaction volume). The yield of the D-T fusion reactions is the highest and requires temperatures in excess of 100 million Kelvin. ( At such temperatures the matter is fully ionized (and known as plasma, the 4th state of matter) 

8)How ITER is being constructed ? 

Ans : International Thermonuclear Experimental Reactor (ITER) is a collaboration of 35 nations launched in 1985.It is located in France. 

9)ITER aims at what ? 

Ans : It aims to build the world’s largest tokamak to prove the feasibility of fusion as a large-scale and carbon-free source of energy. 

10)Where ITER is located ?

Ans : ITER is located at Saint-Paul-Lez-Durance, in the south of France. 11)What is the contribution of India in ITER? 

Ans : Industrial capability and Indian domestic effort in Fusion Research were the stepping stones for India being invited to join this prestigious scientific collaboration. EU, being the host, contributes 45% of the project; all other members including India contribute 9.09% of the project. In kind contribution from participating nations is a key feature of ITER whereby industries from all members have the opportunity to develop key technologies for future reactors. 

12) Sun contains mostly what for nuclear fusion ? 

Ans : Hydrogen . Hydrogen nuclei combine to form helium and release energy. This process gives the Sun such a large amount of energy 

13)Under what circumstances, Hydrogen fuses to form Helium ? 

Ans : If the temperature is very high (i.e., about 10 to the power of 7 degrees Celsius 

14)But in the laboratory, how these protons start fusion ? 

Ans : It starts with heavy Hydrogen which is called deuterium . The deuterium nucleus contains a proton and a neutron. 

15)What is Tritium ? 

Ans : It is also an isotope of Hydrogen. 

16)In the laboratory, with the mixture of deuterium and tritium fusion reaction can be observed. This fusion reaction releases Helium and neutron and 17.6MeV energy. 

17) What is a Hydrogen Bomb ? 

Ans : Hydrogen bomb is also called as a fission-fusion bomb. 

After the fission explosion happens it causes a heating of hydrogen and basically sets off a series of further nuclear reactions.It's often called a two-stage atomic

bomb. It's very similar to what goes on in the sun 

18)Who invented the Hydrogen bomb ? 

Ans : Edward Teller, USA in 1952 

19)What is the name of India’s first Tokamak ? Where it is located ? 

Ans:India’s first Tokamak called ADITYA was commissioned in 1989 at the Institute for Plasma Research, Gandhinagar, Gujarat 

20) Give details of small tokamak ADITYA ? 

Ans : ADITYA is a small tokamak producing about 0.4 m3 of Hydrogen plasma and has been extensively used to make significant contributions in understanding plasma. behaviour in its over 30 years of operation. Generation of intermittent disruptions in plasma was first reported from experiments in ADITYA which is a major subject in fusion plasma experiments. 

21) What are the goals of ITER in France? 

Ans : ITER aims to build and demonstrate the following to lay the foundations for tokamak-based fusion power plants: 

i)To produce 500 MW of fusion power from 50 MW of input heating power Q≥10. 

ii)To sustain fusion through internal heating, i.e., self-sustained reaction. 

iii) To demonstrate the feasibility of producing tritium, as well as heat-extraction to mimic a real fusion power plant environment. 

iv) To control the plasma and fusion reactions to establish the safety of a fusion device. 

v) To test technologies such as heating, control, diagnostics, cryogenics and remote maintenance to bridge the gap between today’s smaller-scale experimental fusion device and fusion power plants of the future 

Ans : All the above 

22) What is Tokamak? 

Ans : One of the most popular ways to demonstrate and establish nuclear

fusion in the laboratory is by confining plasma in a very strong magnetic field produced in a donut shaped machine called the Tokamak. The history of Tokamaks dates to the 1950s with the design of the first device proposed by Andrei Sakharov and Igor Tamm. The first reports on plasma with a temperature of 11.6 million Kelvin came in from T-3 Tokamak, Moscow in 1968.