The time has come for the first refuelling of the second reactor on the Akademik Lomonosov floating nuclear power plant. The last time nuclear fuel was loaded into the floating power unit was in October 2018 in Murmansk. As with nuclear icebreakers, refuelling the ship's reactor is a separate process that takes several months.

The floating nuclear power plant is one of modern engineering's marvels, with over half a century of history. The first ideas for creating small-capacity nuclear power plants to supply remote settlements appeared back in the 1970s. It was envisioned that these would be land-based facilities housing ship reactors with capacities from 6 to 100 MW. These projects didn't progress beyond paper, nor did later ideas to use decommissioned nuclear submarines for electricity generation. However, this idea proved unfeasible—the advantages of using nuclear submarines were negated by implementation complexities and operational difficulties. In 2006, when the imminent decommissioning of the Bilibino Nuclear Power Plant became apparent, a decision was made to build a floating power unit in the form of a ship. In 2015, construction of coastal infrastructure began in Pevek, and in 2018, the Akademik Lomonosov left the Baltic Shipyard.

The floating power unit is equipped with two KLT-40S reactors. They can supply 70 MW of electricity and up to 50 Gcal/hour of thermal energy for water heating to coastal networks. It produces 240 tons of steam per hour at 290 degrees Celsius, and electricity is supplied at 10 kV. Today, Akademik Lomonosov replaces the gradually retiring capacities of Bilibino NPP and Chaunskaya CHPP, while also supplying power to mining companies in Western Chukotka and the Baimskaya ore zone. The KLT-40S operates on fuel with uranium enriched to only 20%, meeting IAEA radiation safety standards.

The floating nuclear power plant's core is made of fuel element cassettes, allowing it to be compact while increasing its energy capacity. Unlike land-based reactors where fuel elements are partially replaced every 12–18 months, in the KLT-40S and other ship reactors, the entire cassette is removed and a new one loaded. This is a very complex and critical procedure—first, the old fuel elements are removed from the core and isolated, then the steam generators and related equipment are repaired, and finally, the new cassette is loaded. The fuel elements themselves had to be transported from Elektrostal near Moscow to Pevek, which is a very challenging undertaking in itself. Despite the new fuel elements being practically radiation-free, they must be transported with extreme caution, which is quite difficult in Far North conditions. We wrote about how nuclear icebreakers are refuelled and what is done with spent fuel here.

The process of refuelling Akademik Lomonosov has stretched over two years—in 2023, one reactor was recharged, and this year, they started on the remaining one. However, there's hope that in the foreseeable future, floating nuclear power plants and nuclear icebreakers may need refuelling less frequently—scientists from Tomsk Polytechnic University have calculated the conversion of small nuclear power plants to thorium-uranium fuel. According to experts, if in addition to using a new type of energy source, the fuel element diameter is slightly increased, the duration of NPP operation without refuelling can be extended by almost 75%. Calculations were performed for KLT-40S reactors. In fact, if it's possible to extend the fuel elements' service life to 8 years, it will be a tremendous success and cost saving.

By the way, the refuelling work on Akademik Lomonosov and the overall operation of the floating nuclear power plant is being watched by almost the entire world. For example, the Russian Arctic experience has interested members of the Association of Southeast Asian Nations. They also have remote areas where it's much easier to provide electricity from a coastal nuclear power plant than to build stationary facilities.

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