With work on 4 more power reactors going on fast, Kudankulam in Tamil Nadu is all set to become as large a nuclear power generator as Europe’s biggest power plant in Zaporizhzhia. The Ukrainian city has 6 reactors with a capacity of 1,000 MW each, making it the biggest nuclear power plant in Europe.

Unlike Zaporizhzhia which is a big city in Ukraine, Kudankulam is a small village on the Bay of Bengal coast in Tirunelveli district, but like Zaporizhzhia it will also have 6 reactors each with a capacity of 1,000 MW.

Zaporizhzhia was in news recently as Russia attacked places close to the nuclear plant thereby raising questions whether there will be another Chernobyl.  

On April 3, Russia-based AEM-Technologies Izhora, a part of the machine-building division of Rosatom, shipped a pressuriser for Reactor 5 of the Kudankulam Nuclear Power Project.

The pressuriser has been shipped after it passed the mandatory tests, and would reach Kudankulam after covering a distance of 17,000 km via sea.

The pressuriser, weighing about 187.50 tonnes, is a primary circuit equipment of the VVER 1,000 MWe reactor. VVER is the Russian abbreviation that stands for ‘water-water energy reactor’. The pressuriser is responsible for creating and maintaining pressure and coolant volume in the reactor. It is used to limit pressure fluctuations in transient and emergency modes during the operation of a nuclear plant. When assembled, it would be about 14 meters long and 3.30 meters in diameter.

The capacity of the pressuriser is 79 cubic meters, with a wall thickness of 152 millimeters. Hence, this over-sized component is likely to reach the site from VOC Port, Tuticorin, on a barge.

During a hydraulic test, the equipment passed the tightness test at high temperatures and maximum admissible pressure of 24.7 MPa, said Rosatom.

While the KKNPP is operating 2x1,000 MWe VVER, built at the cost of ₹17,270 crore, the Nuclear Power Corporation of India Limited (NPCIL), the project proponent is constructing four more reactors with a similar capacity at Kudankulam with Russian technical know-how, at a cost of ₹89,470 crore.

As of now, Units 1 and 2 are generating power. Since both units started generating power in December 2014 and March 2017 respectively, a total 75,781 million units have been generated.

“In Unit 3, Civil construction work of main buildings like Reactor Building, Reactor Auxiliary Building, Turbine Building, etc. are in progress. Erection of core catcher has been completed. Construction of Inner Containment (IC) up to Elevation (El) +44 Metre (M) completed,” said a senior NPCIL official.

In Unit-4, civil construction work of main buildings like Reactor Building, Reactor Auxiliary Building, Turbine Building are in progress.

In Unit-5, concreting of Foundation Slab of Reactor Building is complete, and further construction works of various buildings are in progress. In Unit-6, construction foundation raft of Reactor Building is complete. Turbine Building raft is also complete, he said.

As per NPCIL, Unit 3 is expected to start generating power by May 2025 and Unit 4 by December 2025. But Units 5 and 6 may start generating power only by 2027 or 2028.

Tamil Nadu is allocated 50% (925MW) of the power generated by the two units, while its neighbouring states share 35% of the residual power, including 442MW for Karnataka, 266MW for Kerala and 67MW for Puducherry. The remaining 15% of the generated power is unallocated and will be added to a central pool.

All the units of Kudankulam are open to International Atomic Energy Agency (IAEA) safety analysts each year. The units in Kudankulam are getting imported fuel and are open to IAEA safety analysis. While Kalpakkam, another power reactor is not open to IAEA analysis as it is for strategic use as per the India-US Nuclear Agreement.

In 2011, there was a big protest from the local people and work in the Units 1 and 2 were stopped for several months before former chief minister J Jayalalithaa set up a committee and assured the local people that the nuclear reactors are safe. And then, work was restarted.

“We faced problems from the locals who refused to allow us to enter the plant for several days. They also received support from various NGOs across the state as well as from Delhi and other states. But after the committee submitted its report, the state government provided support and work began fast and we were able to generate power from Unit 1 on December 31, 2014,” said a former site director.

He said unlike other nuclear power reactors, the reactors at Kudankualm will have fuel for the entire life of a reactor. “Generally, the life of a nuclear reactor is 25 years. All the units in Kudankulam will have fuel for entire life cycle,” said the former director.

Recently, Russia-based TVEL Fuel Company has supplied its first batches of TVS-2M nuclear fuel to two functioning units-1&2 of Kudankulam NPP powered by VVER-1000 reactors.

After refuelling in July 2022, Unit 1 started its operation with an 18-month fuel cycle. With this, TVEL will be fulfilling the agreement with Department of Atomic Energy (DAE)/Nuclear Power Corporation of India Limited (NPCIL) on implementation of TVS-2M nuclear fuel with 18-month operating cycles for units in Kudankulam. The TVS-2M nuclear fuel has several advantages over the old type of fuel previously used.

“Compared to the UTVS fuel model, which was supplied to Kudankulam NPP previously, TVS-2M fuel assemblies have a number of advantages making them more reliable and cost-efficient,” said the director. UTVS is a fuel containing enriched uranium pellets used in nuclear units

The first advantage is the rigidity of a bundle. Because of the welded frame, the fuel assemblies in the reactor core retain their geometry, the spacer grids protect fuel rod cladding from fretting wear (preventing from depressurisation), and the additional spacer grid makes fuel assemblies vibration-resistant.

Secondly, the new fuel has increased uranium capacity. One TVS-2M assembly contains 7.6% more fuel material as compared to UTVS. Besides, the special feature of the Kudankulam fuel in particular is the new generation anti-debris filter ADF-2, efficiently protecting fuel assemblies,” he said.

Considered a clean fuel along with solar and wind, there is a separate transmission line from the Kudankulam Plant to the national grid. This grid uses only wind power, nuclear power and solar power generated from Tamil Nadu.

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