The Return of Elena
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#269September 2023

The Return of Elena

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Elena AM is a pilot nuclear thermoelectric plant under development at the Kurchatov Institute on commission from Rosatom. The design of the reactor and critical equipment will be ready by the end of 2024.

Elena in the Pacific

It was the 1960s when the Soviet engineers conceived the idea of making a self-contained nuclear power plant capable of operating for up to 10 years without maintenance. Its detailed design was finalized in 1975, followed by the commissioning of a unit called Gamma in 1982. It used a water-cooled water-moderated self-controlled reactor as a source of thermal energy and relied on natural circulation in the primary and secondary circuits for heat removal. Thermal energy was converted to electricity using a thermoelectric principle.

In a thermoelectric generator, heat is directly converted into electricity: temperature differences between two conductors create voltage differences. Gamma’s thermoelectric modules were of the Field-tube type (a pipe placed inside another); semiconductor batteries were made of low-temperature ternary alloys. Gamma could generate 220 kW of thermal power and 6.6 kW of electricity. The entire unit was placed in a water pool for heat removal and biological protection. Natural coolant circulation and thermoelectric conversion were both revolutionary ideas and innovative solutions for that time.

In 1989, the Far Eastern Division of the USSR Academy of Sciences proposed to develop a pilot thermoelectric cogeneration plant to supply heat and power to a research station operated by the Pacific Oceanological Institute near Elena Bay on Popov Island. The plant was named Elena after the bay. Front-end engineering design was completed by early 1990. Elena was capable of generating 880 kW of electricity and 3 MW of heat. Key structural and technical solutions were taken over from Gamma. However, the project was never put into practice  due to a lack of finance and poor economic conditions in the country.

Elena’s revival

The new plant developed by Kurchatov Institute on commission from Rosatom is called Elena AM. The acronym ‘AM’ stands for ‘automated and upgraded’. It is designed to serve as a source of heat in remote and hard-to-access regions that have no heat networks and are too distantand costly to supply with conventional fossil fuels.

Elena AM has a designed thermal capacity of 7 MW and a natural circulation of coolant (water) in its two circuits. The service life of the equipment under development will be 40 years. The 120 cm high reactor core will consist of 241 assemblies with fuel enriched to no more than 19.5%. Its water-cooled water-moderated reactor will be self-controlled across the full spectrum of electrical and thermal loads due to a negative temperature reactivity effect (the higher the temperature, the lower is the reactivity) and a burnable absorber.

The thermoelectric generator of the plant will have a minimum power generation capacity of  200 kW. The plant will operate in a load following mode with daily output variations from 20% to 100% of its nominal capacity. The electricity produced is expected to be sufficient for plant needs and nearby consumers.

Another important feature of the plant is its maintenance-free design. Elena AM will be equipped with fully automated I&C and auxiliary systems.

A steel pool filled with water will serve as a supporting structure for the plant’s core equipment. The pool will also perform a biological protection function by absorbing ionizing radiation. Due to its small capacity, the plant stores little heat: the temperature differences between fuel and water do not exceed 50℃. With no pumps or valves, the plant will be more reliable as there is no part that can go down. Elena AM will be able to operate during and after earthquakes of an 8-point intensity on the MSK-64 scale and remain safe after a 9-point intensity earthquake. Besides, it will be capable of withstanding a crash of a 20-ton airplane moving at 215 m/s. Beyond-design-basis estimates for a 200-ton airplane crashing at no more than 100 m/s will also be made.

The plant will operate 350 days a year and then be shut down for two weeks for diagnostics and maintenance. Maintenance and repairs are planned to be done annually by a dedicated mobile team during the two-week break.

For now, Elena AM is in the development phase. Its specifications will be refined as the development activities move forward.