It has come to my attention that some time ago the Ford motor company had the idea of a nuclear powered car, I have a few things to say regarding this car.
A 10 cm cube of lead weighs 10 kilos, if the reactor in this car has a reactor which is the size of a football then as the volume of a sphere is given by V = 1.3333 x pi x r x r x r, then as a foot ball has a radius of 10 cm we can estimate the volume of lead needed.
A 20 cm radius sphere has a volume of 33.5 litres, the 10 cm radius sphere has a volume of 4.2 litres, so a total of 29.3 litres of lead is needed. This will have a mass of 293 kilos.
Now this 10 cm layer is just the primary shield, in most reactor designs we need some additional shielding to deal with the fact that radiation will leak out through the holes in the primary shield which are needed for things like steam to come out of the reactor. I think that we also need to consider the shielding of other key parts.
Now to avoid the xenon hole we will need to use some form of vented fuel such as liquid in a homogenous aqueous reactor or a molten salt reactor. We will need to purge the xenon out of the fuel and trap this on an activated carbon pad. If we make the pad 10 cm in diameter and 20 cm long then it will need a lead shield of 10 cm. This will have a volume of 1570 cc. The shield will be a cylinder which will have a radius of 15 cm and be 40 cm long. This means it will have a volume of 28.3 litres, if we deduct the volume of the pad this leaves us with a need for 26.7 litres (267 kilos) of lead.
Now already before we consider the secondary shield and the shielding around the turbine and the pumps we have a lot of lead (560 kilos), I am sure that my readers will be aware that the engine weight of this car is getting larger. As the UK car (class B) license only covers up to 3.5 tons, I think it is possible that the nuclear powered car may be too heavy for a normal car driver to legally drive.