Beta or Alpha emitter nuclear fuel cycle?

Stanley514

Do exist some proposed nuclear fuel cycle in which uranium or thorium whoud be first converted in some beta or alpha emitting isotope and after energy whould be harnessed with direct energy conversion methods?Possibly, it could reduce size of power plant and make steam turbine unnecessary.

QuantumPion

There are various ways of harnessing nuclear energy without a steam cycle, e.g. betavoltaics, radioisotope thermoelectric generators, etc. But these are all very inefficient and limited to low power applications.

Stanley514

Could you explan,why betavoltaics is very inefficient?It suppose to be efficient because enrgy could be converted directly,with help of MHD generator.
Do you think that nuclear fusion based on aneutronic reactions is also going to be unefficient?