What methods were used to clean up the Chernobyl and three mile island accidents?

Electric evaporator has been used to clean up the Chernobyl and 3 mile island accident.

Explanation:

About 14 years back, there was a puff of radioactive steam from the evaporator used in the "Three-mile island" nuclear plant. It took two years for the electric evaporator to clean up the 2.2 million gallons of water that have been destroyed because of the nuclear power plant accident.

The steam that came out of the electric evaporator carried a radioactive form of hydrogen and tritium with itself. Cost of clean up was $1 billion.