“Fallout” is episode fourteen of season seven of Stargate SG-1.
Jonas Quinn, who had returned to his homeworld, Kelowna, in “Homecoming” returns to the SGC (with an odd new hairstyle). He explains that the naquadria found on his planet is created from naquahdah by a process started by the Goa’uld who used to rule the planet.
The, highly unstable, naquadria is still being created, deeper and deeper into the planet’s core, and Jonas believes that it will eventually explode, destroying Kelowna. So, he wants help with this. Not destroying a planet? Sam returns with him.
Another option given is the abandonment of the planet. The other two civilisations think that this is mostly a Kelownan problem, but it is explained to them that, when the deposit explodes, it will devastate an entire planet.
Despite the planet supposedly being at peace, the three countries are not exactly on the best terms.
Sam discovers that what caused this to happen was the naquadria bomb test that Kelowna did a few years ago. O’Neill gets annoyed with the diplomatic representatives of the governments. Admittedly, it doesn’t take much for him to get annoyed with politicians. And, of course, there’s something else going on.