The shale oil factory at Sillamae, Estonia was founded in 1928 by the "Estonian Oil Consortium", belonging to Swedish capital. It is the only factory that has processed both the brown (kukersite) oil shale and the black (dictyonema) shale that are both abundant in Estonia. The much older black shale contains, besides the oil-bearing organic material, significant amounts of various heavy metals, including uranium, and is therefore radioactive. Uranium-based nuclear technology has dominated the second half of the last century, but now faces potential competition from the emerging hydrogen-based energy technologies. It is little known that the Sillamae Oil Shale Plant has played a significant role in the development of the gas cooled very high temperature pebble bed reactor for direct production of either hydrogen or electricity. We analyze here the timeline of this development effort.