They were never built, but during that period people had absolutely wild ideas. Great Britain was considering building 10 kton nuclear mines, to be buried along the borders of Germany and to be detonated in case of a Soviet invasion.

Even if buried, those mines would just end up freezing, so some bright mind came up with the idea of putting live chicken inside them, to keep the temperature up.

https://en.wikipedia.org/wiki/Blue_Peacock