Expanding a wee bit on what the other guy said, that's typically 20Gy *one Gray at a time*.

A whole body exposure of 5Gy would kill you, although it would happen over two weeks.

10kGy? Spectacularly fatal.

1 Megarad (10 Kilogray)

In comparison radtherapy patients get 20 gray in 1-2 weeks so it's the 20/10000 = 0.02% of what these designs target