The half-life of thorium-232 is about 14.05 billion years.

Here are some facts on Thorium.

The half-life of thorium-232 is about 14.05 billion years.

Can someone please explain to me how thorium can be a safe alternative to Uranium in the production of nuclear energy?

Twenty-seven radioisotopes have been characterized, with a range in atomic weight from 210 u (²¹⁰Th) to 236 u (²³⁶Th).^[8] The most stableisotopes are:

• ²³²Th with a half-life of 14.05 billion years, it represents all but a trace of naturally occurring thorium.
• ²³⁰Th with a half-life of 75,380 years. Occurs as the daughter product of ²³⁸U decay.
• ²²⁹Th with a half-life of 7340 years. It has a nuclear isomer (or metastable state) with a remarkably low excitation energy of 7.6 eV.^[9]
• ²²⁸Th with a half-life of 1.92 years.

All of the remaining radioactive isotopes have half-lives that are less than thirty days and the majority of these have half-lives that are less than ten minutes.

Above facts taken from Wikipedia.