I always try to find a way to scale technology like this with known quantities. If we can assume it scales linearly the prospects are good.
Using the only real numbers we have from the Moscow Institute of Physics and Technology and some optimistic lithiumion numbers the NDB is 23.8 times more energydense for the same weight. So if we use the Tesla battery pack as our reference at 85kWh weighing 540kg, an NDB of the same weight would generate 2MWh. Given that the densities of materials only be slightly higher, it would be about the same size.
The only possible problems are around the thermals. All the materials talk about maintaining the optimum temperature for the battery stack. The radioactive decay is constantly heating the stack. There may be a limit on how dense the cells can be packed, making the battery larger.
