Convert megatonne TNT to watt second

The watt (W) is a unit of power, the rate at which energy is used or produced. The watt-hour (Wh) is a unit of energy, one watt sustained for one hour, and is what this page converts: a 2 kW heater running for 3 hours uses 6 kWh, and an electricity bill counts kWh. 'Watts per hour' (W/h) would be a rate of change of power, is rarely needed, and is not the same thing as a watt-hour.

The tonne of TNT is defined as 4.184 GJ, about the energy released by detonating a tonne of the explosive, and is the unit of nuclear yields and of large explosions and impacts. The Hiroshima bomb was about 15 kt, the largest weapon ever tested (Tsar Bomba, 1961) 50 Mt, the 2020 Beirut explosion roughly 0.5 kt, and the Chicxulub impact that ended the dinosaurs on the order of 100 million Mt.