UN atomic watchdog chief Rafael Grossi on Wednesday welcomed Iran’s “concrete step” on agreeing to cap its stockpile of highly enriched uranium after Tehran implemented preparatory steps to stop adding to its inventory. “I think this is … a concrete step in the right direction — we have a fact which has been verified by us,” Grossi told reporters in Vienna. “I attach importance to the fact that for the first time… since the distancing of Iran from its past obligations, they are taking a different direction,” he said.