«According to estimates by the US Oak Ridge National Laboratory, the world’s coal-fired power stations currently generate waste containing around 5,000 tonnes of uranium and 15,000 tonnes of thorium. Collectively, that’s over 100 times more radiation dumped into the environment than that released by nuclear power stations.»
About 1% of it is leaked into air, so about 500 tonnes of uranium and 1500 tonnes of thorium are leaked into air every year.
However, uranium and thorium are much less dangerous than radioactive iodine, strontium, and cesium.
For Chornobyl, I found estimate at Wikipedia:
«An early estimate for total nuclear fuel material released to the environment was 3±1.5%; this was later revised to 3.5±0.5%. This corresponds to the atmospheric emission of 6 tonnes (5.9 long tons; 6.6 short tons) of fragmented fuel.[127]»
