Answer:
The financial problems associated with nuclear power are mostly related to the fact that we do not know a lot about the actually reaction of the process on a large skill. trying this means spending a lot of money on the building of a facility that is able to withstand the temperatures that come together with the environment in which the actual fusion takes place and the enlarged "Tokamak".
Basically all the required equipment and material costs a lot and if it turns out that there is some kind of problem which the scientists did not theorise or does not work somehow then they blew a lot of money.