2027: Japan's Nuclear and Industrial Safety Agency has said it is also concerned about the spent fuel storage pool inside the building housing reactor 3 at Fukushima Daiichi. The pools at both reactors 3 and 4 are reportedly boiling - there may not even be any water left in reactor 4's pool - and unless the spent fuel rods are cooled down, they could emit large quantities radiation. Radioactive steam was earlier said to be coming from reactor 3's pool. If cooling operations did not proceed well, the situation would "reach a critical stage in a couple of days", an agency official told the Kyodo news agency.