Radiation leaks are never a good thing, no matter how small they may be.
It was the most serious release of radioactive material since Fukushima 2011, but the public took little notice of it: In September 2017, a slightly radioactive cloud moved across Europe. Now, a study has been published, analyzing more than 1300 measurements from all over Europe and other regions of the world to find out the cause of this incident.
For more, check out this Science Daily story.