A long-scheduled repair and maintenance outage at Russia’s Balakovo 3 (a 950MWe VVER) ended on 31 March.
Extensive work was carried out to modernise the equipment to increase reliability and safety. Two steam generators were replaced, which will improve the thermo-hydraulic characteristics of the reactor.
Balakovo 3 is testing Russia’s Remix (regenerated mixture) fuel, which reduces the consumption of natural uranium. Remix fuel is a combination of mixed-oxide (mox) fuel and fuel with a mix of fresh and recycled uranium.
In 2016, several fuel assemblies were loaded into the core of Balakovo 3 each containing six elements with Remix fuel and pilot operation is continuing.
“According to developers, the savings in natural uranium can be about 22%,” said Vladimir Dergachev, head of the nuclear safety and reliability department at Balakovo.
“The neutron spectrum of Remix fuel does not differ from the neutron spectrum of ordinary uranium fuel, which means it can be used in conventional reactors without making additional changes to their design and additional safety measures,” he added.
Remix fuel is a unique domestic development of Russia's VG Khlopin Radium Institute.
Safety-wise, the new fuel elements do not differ from those based on uranium dioxide with a maximum input enrichment of 5%.
The strategic objective Remix fuel is to close the nuclear fuel cycle. In 2021, the test assemblies will be removed from the reactor and transferred to the holding pool for 1.5 years to reduce radioactivity. In 2023, they will be delivered to the Research Institute of Atomic Reactors in Dimitrovgrad for analysis and further research.
Remix fuel is being tested at Russia's Balakovo nuclear power plant (Credit: Rosenergoatom)