Nuclear energy

From Siberia to Kudankulam

Print edition : March 30, 2018

Uranium dioxide powder being sintered in ovens into granules in the NCCP. Photo: Yuri Suleymanov

Fuel rods with nuclear fuel pellets inside stacked on the shop floor at the plant. Photo: Yuri Suleymanov

Nuclear fuel pellets, made of lightly enriched uranium, being polished. These polished pellets of the right geometry are used in the fuel rods. Photo: Yuri Suleymanov

The hexagonal grid separator which holds the nuclear fuel rods in place when the rods are bundled into fuel assemblies. Photo: Yuri Suleymanov

Close-up of nuclear fuel pellets. Photo: Yuri Suleymanov

Nuclear assemblies getting ready with grid separators. Photo: Yuri Suleymanov

Fully assembled, they are ready for export for use in the reactors at Kudankulam. Photo: Yuri Suleymanov

Alexey V. Zhiganin, Director General, NCCP. Photo: By Special Arrangement

The nuclear fuel for the reactors at Kudankulam comes from the NCCP at Novosibirsk in Siberia after a complex process.

THE sun shone bright in a clear, blue November sky, but it was not warm enough to melt the mounds of snow that had formed around the trees. The temperature was about −10° Celsius. We, a group of reporters from India, were at Novosibirsk in the heart of Siberia, situated on the banks of the Ob, the longest river in the Russian Federation, to visit the Novosibirsk Chemical Concentrates Plant (NCCP).

The NCCP is one of the world’s leading manufacturers of nuclear fuel for power stations and research reactors in Russia and several other countries. It supplies fuel assemblies for the first two Russian VVER-1000 reactors at the Kudankulam Nuclear Power Plant (KKNPP) in Tirunelveli district, Tamil Nadu, which use enriched uranium as fuel and light water as both coolant and moderator. The fuel assemblies reaching Kudankulam are finished products, which are packed with pellets made of low enriched uranium. Fuel assemblies with a new configuration, more fuel content and extra weight will reach the Kudankulam-1 and 2 reactors soon.

The NCCP will also supply fuel assemblies for the third and fourth VVER-1000 reactors that are under construction at Kudankulam and the fifth and sixth reactors for which India and Russia signed agreements in 2017. Nuclear Power Corporation of India Limited (NPCIL), which built the first two Russian reactors at Kudankulam, will build the other four units too.

The shop floors of the NCCP were a hub of activity: uranium dioxide powder was being sintered in massive flames; uranium pellets were being checked for their geometry; and metallic fuel rods were undergoing inspection to detect minute cracks. Some of the shop floors were being overhauled to house more modern machines.

“We are on the way to giving ourselves a new image,” said Alexey V. Zhiganin, Director General, NCCP. “Novosibirsk Chemical Concentrates Plant, an enterprise of TVEL Fuel Company of Rosatom, is the only producer of nuclear fuel for Kudankulam. We are quite happy with the results of our cooperation [with India].”

Visits to the Kaluga Nuclear Power Region in Obininsk, 110 km from Moscow, where the world’s first nuclear power reactor is located, and to the NCCP at Novosibirsk, 3,500 km from Moscow, were a revelation. The Russian Federation has attained mastery in every aspect of nuclear power generation: prospecting for uranium and enriching it; designing, building and running power and experimental reactors; reprocessing of spent fuel; and decommissioning of nuclear weapons or reactors. It is the only country in the world which has a fleet of ice-breakers propelled by nuclear power reactors.

At the top of the Russian nuclear power enterprise is Rosatom, the Russian state atomic energy corporation, which brings together more than 300 enterprises, including all civil nuclear power companies and research organisations. It ranks first in the world in building nuclear power reactors. Its subsidiaries are engaged in building eight nuclear power reactors in Russia and 36 reactors in 13 countries, including Bangladesh, Bulgaria, China, Egypt, Finland, Hungary, Iran and India. These reactors are of VVER-1000 or VVER-1200 category, with an installed capacity of 1,000 MWe or 1,200 MWe each.

The NCCP comes under TVEL Fuel Company, the fuel division of Rosatom. TVEL’s main activity is to develop, produce and sell nuclear fuel to power reactors and research reactors in Russia and abroad. It manufactures associated nuclear and non-nuclear products too. TVEL supplies nuclear fuel to 76 power reactors in Russia and 15 other countries in Europe and Asia, and 30 research reactors worldwide. It commands 17 per cent of the global nuclear fuel market and supplies about 30 per cent of the global demand for enriched uranium.

Its array of facilities situated across Russia produce nuclear fuel and components for a variety of Russian reactors such as VVER-400, VVER-1000, VVER-1200, RBMK-1000; breeders or what are called fast-neutron reactors such as BN-600 and BN-800; and reactors used in research and in propelling submarines and ice-breakers.

Russian expertise

According to a publication called TVEL, Main Facts, the structural basis of nuclear fuel is the fuel rod. It is a hermetically sealed metal tube containing a fissionable substance (mostly sintered uranium dioxide) in the form of cylindrical pellets. These fuel rods may have different structures and sizes, depending on the reactor type. For instance, the VVER-1000 reactor has fuel rods that are 3.5 metres tall and 9.1 mm in diameter. The shell of the fuel rods is made of zirconium-niobium alloy. Fuel rods are joined together to form fuel assemblies.

The NCCP plant is situated on 120 hectares in the centre of Novosibirsk town and its manufacturing core is spread over 30 hectares. The NCCP features a museum too, with exhibits and photographs that help a visitor trace its history. On display is a photograph of the visit to NCCP in 2009 by Anil Kakodkar, then Chairman, Atomic Energy Commission (AEC); S.K. Jain, then Chairman and Managing Director, NPCIL; S. Basu, now Chairman, AEC; and others. “They visited our plant to see the production of fuel for the Kudankulam reactors,” the museum curator said.

The Novosibirsk plant was built in 1948 when the Soviet Union decided to build a second chemical concentrates plant, after the one located in Moscow. Young engineers and workers from all over the Soviet Union congregated in Novosibirsk to build the plant. The fuel assembly manufactured in those days had aluminium cladding. In 1958, the NCCP started producing lithium products, which are mainly used in light alloy metallurgy and chemical, nuclear, organic synthesis and other industries. “Lithium production is of vital importance in strengthening the plant’s image,” Zhiganin said. Fuel assemblies made of aluminium cladding were in production from 1952 to 1992.

With the break-up of the Soviet Union in the 1990s and an ensuing financial crisis, the NCCP even resorted to making aluminium kitchenware and trolleys. In 1974, the plant started manufacturing fuel assemblies for research reactors. “Our fuel assemblies are so good that we produce nuclear fuel for 12 types of research reactors,” an NCCP engineer said. In 2014, the NCCP’s process for manufacturing low enriched uranium-silica fuel for research reactors of the Western origin was certified, said Alexander Evseer, its Deputy Director General, Production Directorate. The NCCP adheres strictly to the emission standards prescribed by the International Atomic Energy Agency (IAEA). “In 2016, the emission of radioactive substances from the NCCP into the environment was only 21.1 per cent of the prescribed limits.... The Russian legislation on emissions into the environment is in harmony with international standards. Our legislation is in strict accordance with the IAEA standards on environmental pollution,” Zhiganin said.

Complex process

Visits to various shop floors revealed that the manufacture of nuclear fuel assemblies was a complex process. There are special installations where uranium hexafluoride gas is converted into liquid. Chemicals are added to this liquid at a specific temperature and pressure to produce concentrated hexafluoride and uranium dioxide. The uranium dioxide, separated from the mixture and condensed, is then processed into a powder through a series of processes.

The powder is sintered in ovens. Then, it is granulated into small grains using machines. These granules are pressed into cylindrical pellets in big, rotating machines. The pellets are again pressed in machines where they acquire their own geometry at high temperature, depending on the reactors in which they will be used as fuel.

“If the geometry is not perfect, the fuel pellets will be sent back to the machine. We have automated optical systems which can detect the defects in the geometry,” said Viacheslav V. Leonov, International Communications Manager, TVEL. The pellets again undergo polishing and are subjected to final checks on their geometry.

These polished fuel pellets with perfect geometry reach another shop floor in small boxes. Empty tubes, made of zirconium-niobium, reach the same shop floor from another facility. Here, the seamless tubes are fuelled with pellets and they become fuel rods. After checking for cracks, the rods are filled with helium gas and welded at the top and the bottom. The helium gas is meant to maintain the pressure inside the fuel rods. They are then inspected to ensure that the format of the pellets inside the tube is maintained. The pellets are then checked to see whether their enrichment level is correct.

At another facility, the finished fuel rods are treated with special chemicals. These are bundled together to form fuel assemblies. A machine called “pusher” accurately pushes the fuel rods to make assemblies. The bundles are held in place by what is called separation grids. A series of seven robots weld the separation grids onto fuel rods to hold them in place. The separation grids are also checked for their geometry.

The fuel assemblies then undergo thermal processing in high temperatures. Depending on the reactor for which they are used, the fuel assemblies are hexagonal, square or circular in shape. They again undergo a final inspection in rooms whose walls are made of high-quality glass.

It is these fuel assemblies which have passed all the tests that are loaded into the reactor to generate electricity.

NCCP officials were keen to show us the fuel assemblies that are currently supplied to the two reactors at Kudankulam and the new ones which will later power units 3 and 4.

The extant fuel assemblies, called YTBC, are packed with 489.8 kg of enriched uranium pellets. The fuel assemblies are 3.53 metres long. Their life is five years. The new fuel assemblies, which will be supplied to the Kudankulam reactors, are called TBC-2M. These are 3.6 metres long and they weigh 527 kg each. Their lifetime in a reactor is seven years.

The construction of the third and fourth Russian reactors at Kudankulam is under way. “Construction of the reactor and turbine buildings, and hydro structures are in full swing,” an NPCIL official said. Prime Minister Narendra Modi and President Vladimir Putin of the Russian Federation inaugurated the laying of the foundation for Kudankulam 3 and 4 on October 15, 2016, through video conference. The first pour of the concrete for these two units, which signals the start of the full-fledged construction work, took place on June 29, 2017. Kudankulam 3 and 4 will cost more than Rs.39,500 crore.

On June 1, 2017, during the annual Indo-Russian summit at Saint Petersburg, the Atomstroyexport group of companies coming under Rosatom and the signed the general framework agreement for building the fifth and the sixth VVER-1000 units at Kudankulam. On July 13, 2017, an approval for three key contracts for building them was obtained from Rosatom, and the Indian Finance Ministry and the Economic Development Ministry of the Russian Federation. Six days later, NPCIL’s board of directors approved the signing of these three contracts. Thus, Kudankulam will ultimately have six reactors with a total installed capacity of 6,000 MWe. When it is completed, Kudankulam will be the biggest nuclear power park in India.

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