Nuclear fusion results in a huge release of energy, yet it doesn't involve the use of dangerous radioactive elements. Why isn't it used to produce power?

Because extremely high energy is required for the process of nuclear fusion.

Explanation:

Although fusion is actually better than fission when it comes to the amount of energy released and also it does not release any dangerous radioactive element but still it is not used to generate power. The main reason behind this fact is the requirement of extremely high energy for the process of fusion to occur. It needs a temperature of at least 100,000,000 degrees Celsius which is more than 6 times as compared to temperature of core of the Sun. This huge amount of energy can't be generated in any practical conditions.