Jeremy Corbyn MP speaking at CND rally

The speaker expresses gratitude to attendees and acknowledges the efforts of peace campaigners, including Millie Miller. They recount attending a conference in Vienna focused on the humanitarian effects of war, highlighting Austria's stance against nuclear weapons and the global call for disarmament.

What does the phrase 'Two barriers united for peace' imply in the context of the speech?

What was the impact of a nuclear explosion as discussed by the scientists and peace campaigners?