It was never cheap. Nuclear energy got a lot of subventions which limited the prices as seen by end users, but not cheap in general. You can read a writeup of the parliamentary scientific service about that at https://www.bundestag.de/resource/blob/877586/4e4dce913c3d88...
A striking example is the German state having to pay for storing the nuclear waste (temporary and final, see https://www.bafa.de/DE/Wirtschaft/Handwerk_Industrie/Rueckba..., though Germany has no final storage). Also when tearing down the old plants it can happen that the state is paying for that, as in https://www.handelsblatt.com/politik/deutschland/atomkraft-n.... Those costs were not part of the calculated energy costs, and in the past there were further subventions for the companies that lowered the price. Those are also listed at my first link.
>Nuclear energy got a lot of subventions which limited the prices as seen by end users
You think that isn't happening even more now?
And yes it was a lot cheaper than it is now. One reason being that a lot more were built around that time in europe and our reactors actually went up in about 5 years.
A striking example is the German state having to pay for storing the nuclear waste (temporary and final, see https://www.bafa.de/DE/Wirtschaft/Handwerk_Industrie/Rueckba..., though Germany has no final storage). Also when tearing down the old plants it can happen that the state is paying for that, as in https://www.handelsblatt.com/politik/deutschland/atomkraft-n.... Those costs were not part of the calculated energy costs, and in the past there were further subventions for the companies that lowered the price. Those are also listed at my first link.