If Thorium is so much better than Uranium, why don't we use it and why didn't we use it?

In the long term it is going to be all about thorium.  What that means is that we will have Thorium salt reactors acting as convenient heat engines world wide.  Why this is important is not production efficiency which the uranium cycle excels at, but the actual decay chain of Thorium.  That chain ends up producing safe decay products.

Even more important is that we can fold in uranium sourced radionucliedes which increases their neutron bombardment speeding their decay.

Thus the future of nuclear envisages absorbing all nuclear wastes into thorium salt reactors.  As time progresses all the waste can be hugely denatured while producing commercial heat...

A heat engine will always be valuable as we neded heat for all human housing and greenhouse  agriculture as well.

If Thorium is so much better than Uranium, why don't we use it and why didn't we use it?

quora

The only answer I know is a very simple one.

In the 1950’s when the British developed the first commercial nuclear generator there were 2 goals:

The abundance of electricity that comes from nuclear fission.

Let's get us some of that good old plutonium to put on some warheads to protect us from the Ruskies.

To them plutonium was not a problem waste product that needed to be dealt with somehow, it was a useful weapon in the fight against communism.

Now we have the problem that we highly developed fission generators built around the uranium fuel source which cost billions of dollars to develop, much of this funding came from governments who hate admitting they're wrong as their policies opponents throw it in there face even if it was 60 years ago.

So, to your question, why don't we invest in Thorium? The answer in my eyes is in many parts:

No one wants to admit they're wrong.

There are very large companies, often state owned, who would need to foot the bill to develop this and if they all decide it's not worth it they don't have to worry about anyone getting a commercial advantage by doing it, a sort of unofficial collusion. To get round this you need a maverick newbie (please random billionaire with a heart if you're reading this shake up the market).

Fukushima, this gave nuclear a bad name across the globe. Forget the fact that building a 1950s design of generator in an area know for tsunamis was a stupid idea, it still scared people enough to make politicians react by scaling back nuclear, no matter which type.

Renewables, we know we need to sort climate change out (well, most of us do). Renewables aren't run by hippies anymore, they're cold calculating businesses who have also sunk billions into developing their technology. They have large lobbying groups to make sure that when people talk low carbon economy the camera pans to shots of wind turbines and solar panels. If ever the idea of investing to develop Thorium was mentioned they'd be on the first morning TV slots to talk about how for that money they could “build 20,000 wind turbines which would power 2 cities the size of York” (old York not New York , it is renewables after all).

You may notice a common theme above. All the people who have the resources to develop Thorium as a viable fuel source don't want to for various reasons. The point they're missing is this, candle makers went bankrupt when the lightbulb came along, airlines destroyed the trans Atlantic passenger shipping lines, smartphones killed Nokia…all it takes is one nation to realise what Thorium could do and put money behind it. When they're done they'll have a world beating reactor they can peddle to every country at a huge profit.

Which is why I'm looking to China. They have motive (power hungry industry and smog filled streets), they have political cover (who needs to worry about getting re-elected when you don't have elections? FYI I'm not a fan of this system but in this case there is an upside), and they have the money ($3Tr in foreign reserves is just sitting there, put it to use guys).

EDIT

From New Scientist 25th Aug 2017: “now, NRG, a nuclear research facility in Petten, on the North Sea coast of the Netherlands, has launched the Salt Irradiation Experiment (SALIENT) in collaboration with the EU Commission. Thorium could power the next generation of nuclear reactors

Thanks to Roman Iwanczuk for the comment.