The site in North Korea was a test site. It subsided and the airtightness of the detonation cavities was compromised. U-238 could have been a tamper component of some of the nuclear devices being tested. Or a residue from the enriched uranium used in the fission primary. (Enriched uranium is not 100% U-235.)
It is not at all likely that it was "rods from God." That concept was only an idea put forward by Jerry Pournelle. There are too many difficulties for its realization, and the assumed damage mechanism (total conversion of kinetic energy into thermal energy) has never been observed in the use of depleted uranium as tank-penetrating artillery rounds. Just good penetration. No developmental history. And the system would need to be a global constellation.
The site in North Korea was a test site. It subsided and the airtightness of the detonation cavities was compromised. U-238 could have been a tamper component of some of the nuclear devices being tested. Or a residue from the enriched uranium used in the fission primary. (Enriched uranium is not 100% U-235.)
It is not at all likely that it was "rods from God." That concept was only an idea put forward by Jerry Pournelle. There are too many difficulties for its realization, and the assumed damage mechanism (total conversion of kinetic energy into thermal energy) has never been observed in the use of depleted uranium as tank-penetrating artillery rounds. Just good penetration. No developmental history. And the system would need to be a global constellation.