core/homeassistant/components/aranet/icons.json

{
  "entity": {
    "sensor": {
      "radiation_total": {
        "default": "mdi:radioactive"
      },
      "radiation_rate": {
        "default": "mdi:radioactive"
      },
      "radon_concentration": {
        "default": "mdi:radioactive"
      }
    }
  }
}