If that bag is about the same size as her head, which for girls averages ~50 cm circumference, then there’s about 2 litres of uranium there. Uranium’s density is 19g / cm3, so that’s about a 40 kg bag she’s lifting in one hand. Strong girl!

We can also determine that that’s a bag of U-235, because the critical mass of U-233 is only 15 kg, and she’d be in the middle of a mushroom cloud otherwise.