# What would hap­pen

Popular Mechanics (South Africa) - - HOW YOUR WORLD WORKS -

mil­lions of de­grees. “If you’re within that, you’re dead,” Sch­legelmilch says. Ac­cord­ing to an on­line sim­u­la­tion cre­ated by Alex Weller­stein at the Stevens In­sti­tute of Tech­nol­ogy (it’s in­ter­ac­tive, scary and fun; go to nu­cle­ar­secrecy.com/nukemap/), a 10-kilo­ton bomb would pro­duce a fire­ball with a ra­dius of 150 to 200 me­tres.

SHOCK WAVE

Af­ter the fire­ball comes the shock wave or air blast. If det­o­nated in the air, that same 10-kilo­ton bomb would de­stroy most build­ings and kill nearly ev­ery­one within 600 m of ground zero. The ef­fect is re­duced by 23 per cent if the det­o­na­tion oc­curs on the ground. The shock wave weak­ens from there but can still take out res­i­den­tial build­ings and cause mass ca­su­al­ties two to two-and-a-half times the ini­tial spread of the shock wave, ac­cord­ing to Weller­stein’s pro­jec­tions.

RA­DI­A­TION

If you sur­vive the fire­ball and shock wave, now you have to avoid the ra­di­a­tion. Ex­po­sure within 1 200 m of that 10-kilo­ton bomb, Weller­stein shows, will kill up to 90 per cent of peo­ple with­out med­i­cal treat­ment. For 400 m past that, your chances of sur­vival in­crease but you’ll get third-de­gree burns, which you probably won’t feel, be­cause the ra­di­a­tion also kills your pain re­cep­tors.

FALL­OUT

If the at­tack comes from the ground, dirt and de­bris are ir­ra­di­ated and shot into the air by the ex­plo­sion, form­ing the classic mush­room cloud. Winds can carry the ra­di­a­tion, called nu­clear fall­out, from that cloud tens or hun­dreds of miles away, de­pend­ing on the size of the bomb and the strength of the wind. As it falls back to Earth, it sick­ens more peo­ple.

A nu­clear ex­plo­sion that oc­curs on the ground cre­ates a smaller shock wave than an air­burst, but also sends a mush­room cloud of ra­dioac­tive ma­te­rial into the air, where it is car­ried for miles by the wind. 1 Fire­ball 2 Ini­tial shock wave 3 Weak­ened shock wave 4 Ra­di­a­tion ra­dius 5 Ther­mal ra­di­a­tion ra­dius 6 Fall­out di­rec­tion