P. S. Suryanarayana The 25-metre cooling tower was built in 1986 Blast for peace: The cooling tower of the nuclear complex being demolished in Yongbyon on Friday. SINGAPORE: The cooling tower at the Yongbyon complex, suspected to be the nerve centre of North Korea's plutonium-based nuclear weapons programme, was on Friday brought down in a controlled dynamite blast. With that televised "implosion,' North Korea demolished one of its "icons' of nuclear empowerment to make a political statement of disarmament.