Btu (I.T.)
The British Thermal Unit (International Table) is a unit of energy commonly used in the United States defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit at a constant pressure of one atmosphere.
Kilotons (explosive energy)
A kiloton is a unit of measurement that quantifies the energy released in an explosion. It is the energy released by detonating 1,000 tons of TNT (trinitrotoluene). One kiloton is approximately equal to 4.184 × 1012 joules.