Professor Anthony Trewavas (“Thorium truly has the power to transform our energy supplies in a safe and green manner”, Friends of The Scotsman, 28 May) fails to mention any disadvantages of a thorium reactor.
While the Wikipedia article on such reactors lists 13 advantages, some of them mentioned by Prof Trewavas, it also lists 20 disadvantages, one of which is that there is a serious problem with the use of molten thorium salts.
It is not practicable to remove the heat directly from such a reactor by means of high-pressure water as the tube failure results in explosive reactions. This is why inert helium is used as the exchange medium. However, helium is not plentiful and widespread use of it would be problematic.