by Marina MALYGINA, journalist

In early 2012, a "dry" (air-cooled) storage facility for spent nuclear fuel was put into operation at the Mining and Chemical Industrial Complex in Zheleznogorsk, Krasnoyarsk Territory. It is a powerful production facility of the nuclear industry designed for 38,0001 of radiation "wastes" of Leningrad, Kursk and Smolensk atomic power plants and also Bulgarian and Ukrainian plants built according to our designs. They will be put in special sealed stainless steel canisters, which will provide their complete autonomy and safety during storage for more than 50 years.

Today 32 power units of 24.2 GW total capacity operate in Russia. They produce about 16 percent of the country's electric power. It is planned to build up the nuclear power production further on. In line with the Federal target program for the advancement of the power industry sector, 26 new plants will be put into operation by 2025, which will increase a share of energy produced by nuclear power plants to 25 percent. It means that quantity of spent nuclear fuel (or SNF as it is usually called among specialists) will be ever-growing. The majority of states with developed infrastructure in this sector (Russia is no exception here) decided to prolong its storage life after its "service" in the reactor is over.

At the first stage such fuel is kept in an aqueous medium in near-reactor pools, thus decreasing residual heat (to 2-10 kW) and decomposition of the most active

short-lived iodine-131, xenon-133 and other radionuclides. After expiry of a conditioning period (usually it takes 1-3 years), it is transported to a plant for radiochemical processing. In our country final handling operations with fuel unloaded from water-cooled power and high-power channel-type reactors are mainly concentrated at the Mining and Chemical Industrial Complex in Zheleznogorsk.

The said enterprise has a rich history. The construction started on the right bank of the Yenisei river (50 km from Krasnoyarsk) in 1950. It was constructed at the depth of 200 m under the rocky ground for protection from a possible strike from the air (area of its underground premises makes up about 7 mln m³): at that time weapongrade plutonium was produced from natural uranium there.

From 1958 to 1964 three reactor plants of the AD, ADE-1 and ADE-2 types were installed there. The first two were designed solely for plutonium production and were stopped under the conversion program in 1992, and the third dual-purpose production uraniumgraphite reactor performed not only defense but also economic targets, namely, produced heat and electric power for Zheleznogorsk. It was put into operation in 1964 together with a technological complex of an underground nuclear heat and power plant and became the third nuclear power plant built in the USSR, but in 2010 ADE-2 was taken out of operation.

While the nuclear stockpiles in our country were gradually decreasing (since the 1980s), the production activity of this industrial complex was increasingly turning to conversion lines, in particular, storing of spent fuel in a "wet" (water) depository of 6,000 t capacity put into operation in 1985, with a possibility of its further using at the RT-2 plant. Construction of such production facility was started, but further computations of the nuclear administration proved that processing of spent nuclear fuel was economically inexpedient, at least, at the current stage of the nuclear power development, as it required substantial initial investments to production facilities and further expenses for burial of the processed products in volumes exceeding the initial ones. Therefore, the problem of a further "fate" of spent nuclear fuel, i.e. its processing or permanent storage, was solved in our country, like in most countries of the world, in favor of the latter. A design of a "dry" depository in place

of the RT-2 plant was initiated in 2003. It differed favorably technically and economically from the previous pool-type technologies.

The progress of the project was complicated. The main construction works started only in 2006, but were actually suspended two years later until Rosatom changed the main contractor when the private Group E4 engineering company (Moscow) obtained a contract through a qualification selection. According to Mikhail Abyzov, chairman of the company board of directors, he received the project when its implementation was actually one year behind schedule. Nevertheless, this lag was liquidated and a complicated engineering complex was constructed in due time. On December 19, 2011, Sergei Kiriyenko, Director General of Rosatom signed an acceptance certificate, and in January 2012 the first stage of the unique "dry" depository for spent nuclear fuel was commissioned.

It must be admitted that this event was expected: the near-station "wet" depositories of Leningrad, Kursk and Smolensk nuclear power plants were almost filled to the limit. Should the startup of the complex in Zheleznogorsk have dragged on, their work presumably would have stopped already in the following six months. But now a

base for further dynamic development of our nuclear industry is secured.

Sergei Kiriyenko said after his visit to the complex: "The complex of nuclear fuel 'dry' depository is really unique, it has no parallel in the world. By using modern radiation safety monitoring systems the new depository will provide reliable conservation of nuclear fuel for over 50 years." He added that construction of the project by the Group E4 company became a vivid example of state-private partnership testifying that private companies possessed required competence, qualification and experience, and are ready to and can implement the most complicated projects of the nuclear power purpose.

The 270 m long complex, about 35 m wide and about 40 m high consists of two rooms for storage and packing in canisters and can hold 38,000 t of spent fuel from high-power channel-type and water-cooled power reactors mainly used now at national nuclear power plants. The building's frame is strengthened with 85,000 m³ reinforced concrete, which provides the project's resistance to external influence (aircraft crash, blast wave, earthquake, hurricane, tornado) at least for 100 years.

The "dry" depository of a chamber type is designed for acceptance of fuel with a burnout fraction up to 50 GW • day/tU. It gets there after conditioning in water in "covers", which are put later in metal canisters, each designed for three assemblies of water-cooled power

reactors (or 30 capsules with bundles of fuel elements of high-power channel-type reactors). The latter are sealed by welding and after vacuum drying of inner fuel assemblies are filled with helium. It should be noted that just due to such exclusive technology used only here any penetration of radioactive substances into the environment is excluded. Then, specialists check the welded seam for tightness and transport the canister by a reloading machine to the storage pocket (metal pipe fixed on chamber covers). The pocket allows installation of two such canisters, one above the other, then the pocket is closed with a protector plug and welded to secure tightness.

Heat elimination providing safe thermal conditions of storage takes place by means of atmospheric air convection. It decreases the operating costs to the maximum as compared with conventional depositories of a pool-type. The geometry of fuel placing guarantees subcriticality of the system (fission chain reaction is impossible) in the conditions of normal operation and even in case of emergencies. By estimates, radioactivity discharge will make up tenth parts of permissible values.

According to specialists, a "dry" depository is to be filled in 8-10 years, but with the permanently improving technology of fuel capacity, it can exhaust its resources even in 5 years. Therefore, it is planned to construct one more line of the industrial complex and also PT-2 processing plant in Zheleznogorsk. An experimental demonstration center of 250 t annual capacity for recycling (reutilization) of nuclear fuel, a kind of a base for creation of a full-scale plant for handling of spent nuclear fuel, is scheduled to be put into operation in 2015-2017.

All is well except the endless debates about wastes transportation from nuclear power plants to the Mining and Chemical Industrial Complex. According to the Rosatom program designed for 2025, the Krasnoyarsk Territory will accept for burial three trains with radioactive materials monthly already in near future. Ecologists maintain that in case of a railway accident, the situation can follow the "Chernobyl scenario". To put it otherwise, one cannot rule out a technogenic catastrophe with radioactivity discharge like the one at the Chernobyl nuclear power plant (Ukraine) in 1986.

Pyotr Gavrilov, Dr. Sc. (Tech.), Director General of the Mining and Chemical Industrial Complex dispelled these conjectures at a press conference in January of 2012. He said that for 66 years of existence of the nuclear industry in Russia, the transportation of nuclear fuel had been performed by specialized organizations providing an unprecedented level of safety throughout the fuel transportation route. Spent nuclear fuel is carried in transport packages by special trains marked with a letter, which run without stops at intermediate stations. He stressed: "Transport packages undergo pop-up and other tests, which exclude seal failure. They include falls to a hard surface from a 9 m height on a special 1 m pin, burning in open flame at 800°C for 30 min, and location of the container at a depth of 200 m under water for 2 hours."

The RAS Moscow Institute for Problems of Safe Development of Nuclear Power Engineering shares

Gavrilov's point of view. Rafael Arutyunyan, Dr. Sc. (Phys. & Math.), deputy director of this institute told the Gazeta.Ru newspaper on March 19, 2012: "Safe handling of spent nuclear fuel is a closed subject never causing problems for the environment and ecology... There were no and cannot be any grave consequences for people and ecology when reloading, storing and processing spent nuclear fuel. The transported fuel possesses low heat isolation and is carried in super-strong containers, therefore nothing with it can cause any serious accident or catastrophe."

On April 5, 2012, the first train with two transport containers of spent fuel of about 16 t (in units of uranium dioxide) from the Leningrad nuclear power plant came to Zheleznogorsk. The strict dosimetric control conducted in the presence of representatives of the Federal Service for Ecological, Technological and Nuclear Inspectorate by workers of the Mining and Chemical Industrial Complex showed that radiation background was more than 80 times lower than the set standard and almost twice as less as that at a cruising altitude for aircraft. It means that transport packages completely fulfil their functions and guarantee radiation safety criteria, and that with appreciable margin.

On arrival of the first wagon Pyotr Gavrilov said: "A new history of our industrial complex begins with this moment. Two years ago, in April of 2010, the last commercial uranium-graphite reactor ADE-2 was stopped at the Mining and Chemical Industrial Complex. But today begins commercial operation of a new high-capacity production facility of nuclear industry." After the first wagon entered the receiving department and was prepared for unloading, the protective flaps of a rail conveyer opened, and the shift personnel set about to implement technological operations. The "dry" depository of the Mining and Chemical Industrial Complex joined the existing enterprises of the nuclear power complex of the country.

The unique engineering and technological solutions used in Zheleznogorsk (methods of "dry" storage providing long-term safe conditioning, temperature control below 300-350°C on fuel-element casings in inert gas, passive method of heat elimination, a possibility of convenient and rapid identification of a radioactive contamination source) place our country among leaders in handling of spent nuclear fuel. It is not accidental that a number of foreign countries got interested in the Russian experience. Spain and some other countries of the European Union plan to construct production complexes similar to that in Zheleznogorsk. American specialists also visited Zheleznogorsk. In January of 2012, the US Department of Energy received recommendations on construction of a similar centralized "dry" depository instead of a deep geological burial of radioactive wastes in the salt mines of Yucca Mountain (Nevada).

Illustrations from the Krasnoyarsk social and business publication Dela.ru and other Internet sources