The organization responsible for the design, construction, commissioning, and operation of nuclear power reactors in India is the Nuclear Power Corporation of India Limited (NPCIL).

NPCIL is a government-owned corporation created in 1987 under the Department of Atomic Energy (DAE) to undertake nuclear power projects in the country. It is the only organization in India that is authorized to operate nuclear power plants and carry out related activities.

Below are the key points explaining why NPCIL is responsible for these tasks:

1. Design:
NPCIL is responsible for the design of nuclear power reactors in India. It collaborates with various international organizations and utilizes their expertise to develop safe and efficient reactor designs.

2. Construction:
NPCIL undertakes the construction of nuclear power plants in India. It manages all aspects of the construction process, including site selection, procurement of equipment and materials, and construction supervision.

3. Commissioning:
Once the construction is complete, NPCIL is responsible for commissioning the nuclear power reactors. This involves conducting various tests and inspections to ensure the plant is ready for operation.

4. Operation:
NPCIL operates the nuclear power reactors in India. It employs trained personnel who are responsible for the day-to-day operation of the plants, including monitoring and controlling the reactors, ensuring safety protocols are followed, and optimizing power generation.

5. Regulation:
While NPCIL is responsible for the operation of nuclear power reactors, it is overseen by the Atomic Energy Regulatory Board (AERB), which is an independent regulatory body. AERB ensures that NPCIL follows all safety regulations and guidelines to protect public health and the environment.

In summary, NPCIL, under the Department of Atomic Energy, is responsible for the design, construction, commissioning, and operation of nuclear power reactors in India. It plays a crucial role in India's nuclear power program by harnessing nuclear energy for sustainable and clean electricity generation.

Answer:

The correct answer is option 'b) Nuclear Power Corporation of India Limited (NPCIL)'.

Explanation:

Nuclear power plays a significant role in India's energy mix, and the responsibility for the design, construction, commissioning, and operation of nuclear power reactors in the country lies with the Nuclear Power Corporation of India Limited (NPCIL).

1. Role of NPCIL:
- The NPCIL is a government-owned corporation established in 1987 under the Companies Act 1956. It is responsible for operating nuclear power plants and implementing nuclear power projects in India.
- NPCIL's primary objective is to contribute to the development of nuclear power technology, harness nuclear energy for power generation, and undertake the construction, operation, and maintenance of nuclear power reactors.

2. Organization under which NPCIL operates:
- NPCIL operates under the administrative control of the Department of Atomic Energy (DAE), which is responsible for the development, control, and use of atomic energy for the country's welfare.
- The DAE is a department under the Prime Minister's Office and provides overall guidance and support to the NPCIL in its activities.

3. Achievements of NPCIL:
- NPCIL has successfully designed, constructed, and commissioned several nuclear power reactors in India, contributing significantly to the country's power generation capacity.
- It operates 22 commercial nuclear power reactors with a total installed capacity of 6,780 MW. These reactors are spread across different locations in the country, including Tarapur, Rajasthan, Madhya Pradesh, Gujarat, Tamil Nadu, and Karnataka.
- NPCIL has also been involved in the construction of new reactors, including the indigenously designed Pressurized Heavy Water Reactors (PHWRs) and Light Water Reactors (LWRs) with international cooperation.

4. Safety and regulatory oversight:
- While NPCIL is responsible for the operation of nuclear power reactors, the regulatory oversight and safety aspects are handled by the Atomic Energy Regulatory Board (AERB).
- AERB is an independent regulatory body established under the Atomic Energy Act, 1962. It ensures that nuclear installations in the country are operated safely and securely.
- AERB sets the safety standards, reviews the design and safety features of nuclear power reactors, and conducts inspections and assessments to ensure compliance with safety regulations.

In conclusion, the Nuclear Power Corporation of India Limited (NPCIL) is the organization responsible for the design, construction, commissioning, and operation of nuclear power reactors in India. It operates under the administrative control of the Department of Atomic Energy (DAE) and works closely with the Atomic Energy Regulatory Board (AERB) to ensure the safety and security of nuclear installations in the country.