Reports say the flooding has likely damaged some of North Korea's nuclear facilities.
This is according to the website 38 North, which monitors the regime.
It says satellite images show water from the Kuryong River has reached the two pump houses that service the reactors at the Yongbyon nuclear complex.
But, it says, the water has receded, so the flooding might not have affected key facilities such as the uranium enrichment plant.
In the first week of August, North Korea got more than 850 millimeters of rain, almost as much as the typical annual amount of of 960 millimeters.