Laxity in the Ukrainian nuclear industry

"Ukraine has been experimenting with American-made clones of Russian fuel assemblies since 2005. That was the year that Energoatom shipped six TVS-WR assemblies manufactured by Westinghouse to the South Ukraine nuclear plant and began their pre-installation inspection. As a result of their experiments, it was concluded that the American fuel assemblies were defective. However, they still decided to proceed to the next stage of the experiment – the annual loading of the reactor using this fuel. In 2008, Energoatom and a Swedish subsidiary of Westinghouse signed an agreement to supply the South Ukraine nuclear plant with enough American fuel for the scheduled annual partial refueling of the three reactors from 2011 to 2015.

However, as early as April 2012, malfunctions in the American assemblies were noted at the reactors of the South Ukraine nuclear plant. In an emergency procedure, all the TVS-WR assemblies were completely unloaded from the reactors after they were found to be damaged, mainly due to structural flaws in the spacer grids. As a result, in 2013, following a thorough inspection, Ukraine’s State Nuclear Regulatory Inspectorate instituted a total ban on the use of American fuel at Ukrainian nuclear plants.

But the victory of the Revolution of Dignity has once again cleared the path for American TVS-WRs to be used in Ukraine. In April 2014, Kiev carefully reassembled the torn-up scraps of its old contract with Westinghouse and decided to give things another go. The media reported that American fuel was subsequently loaded into reactor no. 3 at the South Ukraine nuclear plant (March 2015), reactor no. 5 at the Zaporizhia nuclear plant (June 2016), and reactor no. 2 at the South Ukraine nuclear plant (August 2017). The consequences were soon evident."

https://southfront.org/get-ready-new-chernobyl-ukraine/