Not only is it not fast, Vitrification is still just a decades-old folk-tale that sounds good (and 'promising'). In 2018 an "experiment" at PNNL reported that

Not only is it not fast, Vitrification is still just a decades-old folk-tale that sounds good (and 'promising'). In 2018 an "experiment" at PNNL reported that "Dangerous radioactive waste has been trapped inside solid glass in a first-of-its-kind demonstration". Only time will tell how real that prospect is. https://www.livescience.com/62623-radioactive-waste-trapped-in-glass.html https://www.livescience.com/62623-radioactive-waste-trapped-...