That's commercial achievement, not scientific. The Obninsk power plant has been connected to a grid in 1954. It is useless to assess commercial achievements of the country which didn't have commerce at all. And in general, the question "who was the first" is unproductive, as science doesn't have nationality.

Well, I'm from the UK and I've heard it repeated often enough that Calder Hall was the first nuclear plant to generate power - so I did a search to confirm it and found that wiki page.

It's actually quite interesting that the Soviets had an earlier one - I guess the page should be updated?

> The Obninsk power plant has been connected to a grid in 1954

Are you aware that Obninsk was a "closed" city and wasn't marked on the Soviet maps initially?

So whole town was classified, among the power plant.

Why is that relevant at all to the discussion?

This is factually false. Obninsk was not a "closed" town. As soon as it got town status, it wasn't closed.