Nuclear power plant manufacturers, such as Westinghouse and Framatome, are developing safer nuclear reactors that use so-called accident-tolerant fuels that are less likely to overheat — and if they do, will produce very little or no hydrogen. As Scientific American reports, commercial reactors use small pellets of uranium dioxide stacked inside long cylindrical rods made of zirconium alloy, which “allows the neutrons generated from fission in the pellets to readily pass among the many rods submerged in water inside a reactor core, supporting a self-sustaining, heat-producing nuclear reaction.” The problem is that if the zirconium overheats, it can react with water and produce hydrogen, which can explode. From the report: In some of the variations, the zirconium cladding is coated to minimize reactions. In others, zirconium and even the uranium dioxide are replaced with different materials. The new configurations could be slipped into existing reactors with little modification, so they could be phased in during the 2020s. Thorough in-core testing, which has begun, would have to prove successful, and regulators would have to be satisfied. In a bonus, the new fuels could help plants run more efficiently, making nuclear power more cost-competitive — a significant motivation for manufacturers and electric utilities because natural gas, solar and wind energy are less expensive.
Russia is also deploying other safety measures; recent installations at home and abroad by the state-run company Rosatom have newer “passive” safety systems that can squelch overheating even if electrical power at the plant is lost and coolant cannot be actively circulated. Westinghouse and other companies have incorporated passive safety features into their updated designs as well. Manufacturers are also experimenting with “fourth generation” models that use liquid sodium or molten salt instead of water to transfer heat from fission, removing the possibility of dangerous hydrogen production. China reportedly intends to connect a demonstration helium-cooled reactor to its grid this year.
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