In the third of our four-part series on the potential effect of nuclear weapons on selected targets around the world, we examine the possible destructive effect of the most powerful nuclear weapon ever created; the Soviet Union’s RDS-220 hydrogen bomb.

This weapon, which was detonated in a test explosion on 30th October 1961, remains the most powerful nuclear explosion ever. The weapon was nicknamed by the Soviet Union the Tsar Bomba or ‘King of Bombs’. Reflecting on the Tsar Bomba, an article in Pravda in September 2009 stated that the weapon was the most physically powerful single device ever invented. The RDS-220 was designed to have a theoretical explosive yield of 100 megatons (one megaton is equivalent to one million tonnes of conventional explosive). However, concerns regarding the radioactive fallout that such a device could trigger during an atmospheric test, plus the certainty that the resulting explosion would have destroyed the specially-modified Tupolev Tu-95V strategic bomber tasked to drop the weapon, limited the bomb’s yield to 57 megatons.

After being dropped from the Tu-95V, the weapon detonated at 07.32Z over the Cape of Sukhoy Nos on Severny Island, part of Russia’s Novaya Zemlaya archipelago in the Arctic Ocean. The bomb was believed to have experienced an airburst detonation at an altitude of 13779 feet (4200 metres), generating a yield of 50 megatons. The resulting mushroom cloud, open sources state, rose to an altitude of 64 kilometres/km (40 miles) with the top of the cloud reaching 95km (59 miles) in width. As if such superlatives were not impressive enough, the explosion’s shockwave circulated three times around the earth, and was sufficient to break windows in Finland and Sweden. Anecdotal evidence suggests that the quantity of parachute nylon required to construct the bomb’s parachute caused significant disruption to the Soviet hosiery industry.

What would be the effects of such a weapon on a populated target? We decided to simulate its effects using the Nukemap online nuclear weapons simulator. Choosing a suitable target was a challenge, but in the end, plumped for Charleroi in southern Belgium. The town has the sad accolade of being named Europe’s most depressing city in 2009, following this one year later by being branded the continent’s ugliest, following a poll in a Dutch newspaper.

Every attempt was made to simulate the original parameters of the 1961 test. A conveniently large aimpoint, in the form of the city’s Charleroi Sud (Charleroi South) railway station was chosen, and the bomb left to perform its deadly task. Unsurprisingly Charleroi, for all intents and purposes, ceased to exist. Over 601,600 of its inhabitants and those in a significant part of southern Belgium and northern France were killed instantly, with over 1.6 million suffering injuries. The explosion generated a fireball with a radius of 4.6 kilometres (2.9 miles). Those up to 59km (36.7 miles) from ground zero will suffer third degree burns. If the bomb had been detonated using its originally designed yield of 100 megatons, casualties increase to over 841,440 killed instantly, and over 2.8 million injured. The explosion would cause major damage in Brussels to the north, and a huge swathe of eastern Belgium would suffer catastrophic damage and become uninhabitable. While Charleroi has been voted as lacking aesthetic splendour, a detonation of the Tsar Bomba there would be unlikely to improve its appearance.