Electrical power = (voltage) x (current)
Electrical energy = (power) x (time)
Combine those definitions:
Energy = (voltage) x (current) x (time)
Divide each side by (voltage x time), and we have
Current = Energy / (voltage x time)
You told us that
Energy = 1.8 x 10⁷ joules
Time = 1 hour = 3,600 seconds
so we have
Current = (1.8 x 10⁷) / (voltage x 3,600).
If you live in the US, Canada, or Mexico, your voltage is 120 volts.
Current = (1.8 x 10⁷) / (120 x 3,600) = 41-2/3 Amperes
If you live practically anywhere else in the world, your voltage is 240 volts.
Current = (1.8 x 10⁷) / (240 x 3,600) = 20-5/6 Amperes.
