Not all thorium reactors. A good example for an industrial grade thorium reactor is the thtr-300 a high temperature thorium pebble bed reactor (http://en.wikipedia.org/wiki/THTR-300)
> Thorium reactors are inherently stable, so “nuclear meltdowns” can’t happen.
This was also one reason for the design of the AVR in Jülich and it's successor the THTR-300. Although there wasn't any "nuclear meltdown", there were various other problems:
- Small amounts of water leaking into the primary cooling circuit. Bigger amounts could have lead to a buildup of hydrogen and oxygen which can cause explosions. This is very comparable to a meltdown
- The pebbles proved to be not very stable. This lead to a bigger amount of radioactive matter being released into the surrounding environment by the THTR-300
- The AVR leaked a big amount of radioactive matter into the ground water
- various other problems
Newer thorium reactor types won't have these problems because they will be considered in their designs, but there's still the problem with the timeframe. Estimates are that 2030 is the time when Gen IV reactors will get rolled out (http://en.wikipedia.org/wiki/Generation_IV_reactor). Meanwhile Germany replaced 3.5% of it's electric power sources from 2010 to 2011 with renewable ones.