There were only a handful of very tiny nuclear reactors before 1970. Almost all of the mined uranium went for nuclear weapons and not for generating power
The competition with the Soviet Union to build atomic arsenals spurred a uranium boom. In the late 1940s, there was a perceived need for a large and reliable domestic source of uranium to replace supplies predominantly from the Belgian Congo and, to a lesser degree, Canada. The AEC’s announcement in 1948 that it would purchase at a guaranteed price all the ore that was mined set off a stampede on the Colorado Plateau. Hundreds of mines, ranging from mines run by the prospectors themselves to larger corporate operations, were opened in the Four Corners area of Arizona, New Mexico, Utah, and Colorado, and several thousand miners, many of them Navajo, went to work.
Finally, in 1967, Secretary of Labor Willard Wirtz announced the first federally enforceable standard for radon and its daughters in uranium mines that supplied the federal government.
All before commercial nuclear reactors.
Yes, a tragedy but again not related to commercial nuclear power
There is far less of an issue now because there are far fewer uranium miners and the new leaching methods do not involve putting them to exposure to radon. There have been improvements to uranium pit mines to reduce exposure to radon. Russian uranium miners were also mostly mining uranium for nuclear weapons.
Uranium mining for commercial reactors was not significant until the 1970s, because there were almost no commercial nuclear reactors. There was 20,000+ nuclear bombs.
In regards to tallying deaths per terawatt hour, including deaths for mining uranium for nuclear weapons would be like adding in the deaths from falls from roofs even if they were not installing or maintaining solar panels against solar power.