The UN Treaty on the Prohibition of Nuclear Weapons (TPNW) officially comes into force tomorrow.
Among those who will be joining a bell ringing celebration to mark the move will be internationally renowned campaigner Angie Zelter, of Knighton, Powys, and Joan Meredith, of Malpas near Whitchurch.
They are founders of the Trident Ploughshares disarmament campaign group. Both have have been arrested many times for their demonstrations.
Miss Zelter, 69, said: “After decades of nuclear resisters sitting on cold wet roads, swimming freezing lochs, being dragged through courts and thrown into police cells and prisons, today we are welcoming the arrival of the nuclear weapons ban treaty.
“We have argued many times in court that nuclear weapons are immoral and illegal because any use of these terrible weapons would cause a humanitarian and environmental catastrophe.”
“The entry into force of the ban treaty signals a massive change globally. Recognising that nuclear weapons are one of the greatest threats to humanity - the countries of the United Nations have outlawed them. Countries which everyday threaten to launch nuclear weapons are outside the norm of civilized society.
“The UK must now take heed. It should immediately take Trident off patrol, sign up to the treaty, disarm the warheads and put the freed up resources into tackling the other existential crisis – climate change.”
She said Trident Ploughshares had recently written to the Queen, Prime Minister Boris Johnson and the armed forces about the matter.