system
Given the following post, respond as if you're commenting on Reddit:
human
Why do nuclear power plants produce unique isotopes?

After the Fukushima disaster scientists were able to trace radiation detected in fish off the west coast of the US as originating from the Fukushima plant. I think there was a similar occurrence with Chernobyl

If they are using the same fuel and the same process shouldn't the byproducts be the same?
gpt
All nuclear power plants produce the same isotopes. Not in exactly the same ratio, but that's not relevant here. Many of these isotopes have no natural source, and by default reactors keep these isotopes inside the reactor. Fukushima was the only relevant source of these isotopes in the environment in the last 30 years. What Chernobyl released 35 years ago has decayed, is somewhere in the ground, or has been diluted beyond measurement thresholds, depending on the isotope. There are certainly measurements where you get contributions from both accidents, but also measurements where you can be sure the source was Fukushima.