Altogether, those features are enough to qualify Kairos’ designs as “Generation IV” reactors, a classification system created by an international organization backed by national nuclear agencies. The classification system is both vague and broad, so it’s hard to tell exactly how Hermes 2 might score on the rubric.
Kairos has been inching toward approval for the reactor design for the last year and a half. Hermes 2 passed its safety review with the NRC in July and its environmental assessment in August. All told, it took 18 months for the NRC to issue the construction permit, a relatively swift timeline compared with previous reactor permits.