Apparently, a nuclear reactor type unlike any others we are utilising today, was developed in the 1960s. It is called the Molten salt reactor (MSR) and the project was cancelled in the US much due to its non-existent alignment with the nuclear weapon’s programme. The MSR fuelled with thorium, denoted TMSR, possesses various safety advantages, much better fuel efficiency, less and not as long-lived nuclear waste such as a larger proliferation resistance.
The UK newspaper BusinessInsider have written a comprehensive description of the TMSR: http://uk.businessinsider.com/thorium-molten-salt-reactors-sorensen-lftr-2017-2?r=US&IR=T
The SciShow introduces the perhaps most promising TMSR desgin:
The rather old idea attracts several start-up companies and nations, such as China and India, and this video makes a summary of the progress of the TMSR in the world: http://www.thoriumenergyworld.com/news/tmsr-progress-summary