Successful test of recycled fuel

17 September 2021

Recycled REMIX nuclear fuel has passed a five-year operational test in Russia and is ready for pilot operation, Rosatom fuel subsidiary TVEL has said. REMIX is designed to reduce uranium consumption and close the fuel cycle using mainstream light-water reactors.

Workers with a fresh VVER-1000 fuel assembly (Image: TVEL)

In mid-2016, three VVER-1000 fuel assemblies made specially with five REMIX rods among their 300 normal rods were loaded into the third reactor at the Balakovo nuclear power plant. Today, Rosatom announced that the trial was successful. "During all five years of testing, our specialists monitored the neutronic and life characteristics of experimental fuel assemblies. There were no deviations from normal operation, which confirms the design properties of the new nuclear fuel," said Yury Ryzhkov, deputy chief engineer for safety and reliability at Balakovo.

The trial fuel assemblies will be examined in more detail at the Research Institute of Atomic Reactors in Dimitrovgrad in around 2023 after they have cooled and the highest levels of radioactivity have subsided.

In the meantime, TVEL's vice president for science and technology Alexander Ugryumov said, "We expect the next step ... should be pilot operation of several fuel assemblies with all REMIX fuel rods." No schedule or specific reactor was mentioned for this next stage of development.

New fuel option

REMIX (from Regenerated Mixture) fuel is made from uranium and plutonium recovered as an unseparated mixture from previously used fuel. They are topped up with low-enriched uranium to give a fuel that performs within the same parameters as normal fuel made only from fresh low-enriched uranium. This means a reactor would not need any modification to start using REMIX.

The cycle of reprocessing, recycling and top-up can be repeated as many as five times, with waste fission products removed each time and vitrified in glass ready for permanent geological disposal. In theory, a new reactor could operate for its whole design life of 60 years on just three REMIX fuel loads, circulating them continuously.

In August last year, Rosatom approved investment to set up a full manufacturing line for REMIX fuel. The uranium-plutonium fuel pellets will be made at the Mining and Chemical Combine in Zheleznogorsk, in the Krasnoyarsk region, where there is already a large storage facility for VVER-1000 fuel. The pellets will be manufactured into finished fuel assemblies at the Siberian Chemical Combine in Seversk in the Tomsk region of Russia.

So far, the REMIX project is focused on creating a new fuel strategy for VVER-1000 reactors. The country also builds and operates newer VVER-1200 units at home and abroad, as well as older RBMK models.

Researched and written by World Nuclear News