> Initial work demonstrated the feasibility of building a 100-megawatt reactor measuring seven feet by 10 feet, which could fit on the back of a large truck, and is about 10 times smaller than current reactors, McGuire said.
So that would power 50k to 100k typical houses in the US... not bad!
Compact is good, because until you can fuse helium-3, the reactor is producing neutrons, which will transmute the reactor and its shielding into other, often radioactive elements. So the entire thing will have to be regularly replaced and disposed of (which we can do safely, but too many people believe otherwise).
I do not see how compact matters much here. As far as I understand, the basic reaction used is the same, so that compact design will produce the same number of neutrons per Watt produced as a large one.
Wouldn't the effect of its smaller mass be that the container will have to be replaced more often, more or less in the ratio of the masses of the machines?
We really don't know the practical consequences of this systematic transmutation (for all we know, neutron liberating fusion reactors will never be economic). It's entirely possible the device will have to be replaced more often, I'm just pointing out the less mass in it, the less that has to be disposed of when that happens.
So that would power 50k to 100k typical houses in the US... not bad!