-->I'd like to suggest adding module slots so that we can put modules in it to increase productivity(make it a little more efficient). 3000 smelts/fuel is 8GJ/3000 = 2.67MJ per smelt. That's more than half a piece of coal per item.
-->Perhaps it could be fueled by heat instead of nuclear fuel. You'd still need a reactor to make enough heat for it to work, but this way you could still get neighbor bonus at least while using up your nuclear fuel.
-->Plutonium Energy mod adds MOX fuel. It'd be nice to be able to use that with the nuclear furnace. Is there any possibility to add it to the accepted fuels?

1. This furnace must be pretty ineffective, but compact, fast and cheap(?). So, more than one coal per smelting is a good price.
   Here can be added new furnace: bigger, slower and more effective version, are you think that such furnace will be better alternative for you?

2. Heat furnace mod: Heat furnace, may be also with
   Heat Processing.

3. Plutonium Energy must be compatible, not tested in 0.18. See dependencies