Dmitry Kalmykov is a Ukrainian scientist who has dedicated his life to eliminating environmental disasters, first at Chornobyl and now in Semipalatinsk, in Kazakhstan - formerly the Soviet Union's primary nuclear weapons testing site. He teaches schoolchildren about how bombs were tested, and how – more than 30 years after the site was decommissioned – the community is only really beginning to understand radiation's powerfully harmful effects. Against the backdrop of war in Ukraine and the long shadow of a nuclear conflict across the region, Dmitry debates Kazakhstan's nuclear future with its next generation