NUCLEAR POWER PLANTS

Introduction

Nuclear power is the fifth largest source of electricity in India after coal, gas, and wind power. A Nuclear reactor is a device used to initiate and control sustained nuclear chain reaction. Mainly they are used at nuclear powerplants for electricity generation and in propulsion of ships. Heat from nuclear fission is passed to a working fluid which runs through steam turbines. Just as conventional power stations generate electricity by harnessing the thermal energy released from burning fossil fuels, nuclear reactors convert the energy released by the controlled nuclear fission into thermal energy for further conversion to mechanical or electrical forms.

When a large fissile atomic nucleus such as Uranium-235 or Plutonium-239 absorbs a neutron it may undergo nuclear fission. The heavy nucleus splits into two or lighter nuclei (the fission products), releasing kinetic energy, gamma radiations and free neutrons. A portion of these neutrons later be absorbed by other fissile atoms and trigger further fission events release more neutrons and so on. This is known as nuclear chain reaction.

Methods to control nuclear fission

To maintain a sustained controlled nuclear reaction, for every 2 or 3 neutrons released, only one must be allowed to strike another uranium nucleus. If this ratio is less than one then the reaction will die out; if it is greater than one it will grow uncontrolled (an atomic explosion). A neutron absorbing element must be present to control the amount of free neutrons in the reaction space. Most reactors are controlled by means of control rods that are made of a strongly neutron-absorbent material such as boron or cadmium.

In addition to the need to capture neturons, the neutrons often have too much kinetic energy. These fast neutrons are slowed through the use of a moderator such as heavy water and ordinary water. Some reactors use graphite as a moderator, but this design has several problems. Once the fast neutrons have been slowed, they are more likely to produce further nuclear fissions or be absorbed by the control rod.

Nuclear Power Stations:

1. KAIGA NUCLEAR POWER STATION

Kaiga power station is a nuclear power generating station situated at Kaiga, near the river Kali in Uttar Kannada district of Karnataka, India. The plant has been in operation since March 2000 and is operated by the Nuclear Power Corporation of India. The construction for Kaiga began in 1989. The reactor type is pressurized heavy water reactor. It has four units. The fourth unit went on critical on 27 November 2010. The two oldest units comprise the west half of the site and the two newer units are adjoining the east side of the site. All of the four units are small sized CANDU plants of 220MW.

2. TARAPUR ATOMIC POWER STATION

It is located in Tarapur, Palghar, India. It was constructed initially with two boiling water reactor (BWR) units built by Bechtel and GE under the 1963 123 Agreement between India, the United States and International Atomic Energy Agency. It was the first nuclear power plant in India. The construction of the plant was started in 1962 and the plant went operated in 1969.

3. KAKRAPAR ATOMIC POWER STATION

It is a nuclear power station in India, which lies in the proximity of the city of Vyara in the state of Gujarat which consists of two 220MW pressurized water reactor with heavy water as moderator (PHWR). The construction began in 1984 and the plant went operational in 1993. In 2003, this is declared as the best performing pressurized heavy water reactor.

4. RAJASTHAN ATOMIC POWER STATION

It is located at Rawatbhata in the state of Rajasthan, India. It was started in the year 1963 and the reactor type is pressurized heavy water reactor.

5. NARORA ATOMIC POWER STATION

It is located in Narora, Bulandshahar District in Uttarpradesh, India. The plant houses two reactors, each a pressurized heavy water reactor (PHWR) capable of producing 220MW of electricity. Commercial operation of NAPS-1 began on 1 January 1991, NAPS-2 on 1 July 1992. It is the first ISO-14001 certified atomic power station in Asia.

6. KALPAKKAM ATOMIC POWER STATION

It is located at Kalpakkam about 80km of Chennai, India; is a comprehensive nuclear power production, fuel reprocessing, and waste treatment facility that includes plutonium fuel fabrication for fast breeder reactors. It is also India’s first fully indigenously constructed nuclear power station, with two units each generating 220MW of electricity. The station has reactors housed in a reactor building with double shell contained improving protection also in the case of a loss-of-coolant accident.

7. KUDANKULAM NUCLEAR POWER STATION

It is the single largest nuclear power station in India, situated in Kudankulam in the Tirunelvelli District of Tamilnadu. Construction on the plant began on 31 March 2002. But found several delays due to opposition from local fisherman. KKNPP is scheduled to have six VVER-1000 reactors build in collaboration with Atomstroyexport, the Russian state company, Nuclear Power Corporation of India limited (NPCIL) with an installed capacity of 6,000MW of electricity.

Collected By:

Havyashree G P
Ivy Anjali D'Souza
Lekshmi Priya
Pallavi L

Source: Internet