The 50 workers struggling to contain the fallout at the crippled Fukushima Daiichi nuclear plant faced two significant setbacks Wednesday both of which appeared to increase the risk of a significant release of radiation into the atmosphere. As thick plumes of steam rose from the stricken Fukushima plant, Japan's Chief Cabinet Secretary, Yukio Edano, said Wednesday morning local time that the containment vessel for reactor unit No. 3 one of the three reactors that had been active when the earthquake and tsunami struck last Friday may have been damaged, apparently in the explosion Monday that destroyed a portion of the building that houses it. The extent of the damage to containment vessels the steel-and-concrete vaults that are the last line of defense against a major radiation leak was unclear as of late afternoon. The government and Tokyo Electric Power Co. (TEPCO), Fukushima Daiichi's operator, now acknowledge that two of the three reactors that were operating at the time of last Friday's magnitude-9.0 earthquake and tsunami have since sustained damage to their containment vessels.
The widespread feeling of dread surrounding the nuclear crisis intensified further Wednesday when, for the second consecutive day, a fire broke out at reactor unit No. 4, where 15 highly radioactive spent fuel rods are being stored in a pool of water 45 ft. (14 m) deep. The 50 remaining TEPCO workers at the Daiichi plant, who are tasked with trying to cool the reactors down with seawater, were hustled into a protective room as radiation levels spiked higher. They remained there for 90 minutes, but were able to resume work when radiation levels fell.
For now, neither the outbreak of fire nor the fear that the containment unit at reactor No. 3 has been damaged has prompted a widening of the 12-mile (19 km) evacuation zone around the plant. However, nuclear scientists say that the sequence of events at unit No. 4 is a reason for intense concern. Once the cooling pumps stop as they did when the tsunami struck on Friday the water in the spent fuel rods' pools will begin to heat up and slowly start to boil off. David Wright, of the Union of Concerned Scientists (UCS) in the U.S., says the fuel rods at reactor No. 4 are stored in the lower 15 ft. (4.5 m) of the pool, "so 30 ft. [9 m] of water would have to boil off before exposing the rods. That could take several days, so this issue may only be appearing now."
The exposure of those rods is particularly serious because TEPCO officials have said the rods were removed relatively recently from the reactor core during a refueling cycle. Thus, they still have "a very high level of radiation and are generating more heat than the spent fuel at the other reactors at the Daiichi site," Wright says.
Under normal circumstances, that wouldn't necessarily be a source of concern, because of the existence of a secondary containment unit and a ventilation system housed in the reactor's building. But on Monday morning, a huge hydrogen explosion at reactor No. 3 blew a 26-ft. (8 m) hole in the side of the building containing reactor No. 4. The hydrogen, nuclear scientists say, almost certainly came from the spent fuel "There is no other source for it,'' says UCS' Wright and that in turn means the water level in the pool has sunk low enough to expose a "significant fraction of the fuel rods." The upshot is that the gaping hole in the secondary containment unit at reactor No. 4 means that radioactive gases iodine-131 and cesium from the spent fuel "will be vented directly to the outside," Wright says.
TEPCO has considered trying to refill the levels in the pool by dumping water from helicopters, but discarded the idea when officials decided that the hole in the building was not big enough. By late Wednesday afternoon, flames were no longer visible at reactor No. 4, but smoke and steam were still billowing skyward, prompting fears that the authorities were stumbling in the face of the crisis and reacting haphazardly to events as they unfolded. Yukiya Amano, the Japanese director general of the International Atomic Energy Agency, himself complained of not having sufficient information from the Japanese authorities to enable the IAEA to help. "I am trying to further improve the communication," he told a press conference in Vienna on Tuesday. "It is difficult to see whether future developments will be a worsening or improving of the situation."
Many Japanese share his unease. For the first time, there has been a whiff of panic as far south as Tokyo. Convenience stores are running out of ready-to-eat foods like instant noodles. A pharmacy manager in the Nihonbashi business district says that by Monday he sold out of stable-iodine tablets, which protect against the carcinogenic effects of iodine-131 emissions.
Airlines reported that there were few seats remaining for flights out of Tokyo on Wednesday and Thursday, and hotels normally full of business executives and tourists have emptied. At Tokyo Station Wednesday, one of the city's main rail hubs, there were long lines of passengers waiting to buy tickets for bullet trains heading south. One Yuki Ito said this morning that she was heading to stay with relatives in Shikoku, about 390 miles (630 km) from Tokyo. "Once I heard the reports about the wind blowing toward Tokyo, I just thought it would be safer to get out of here. It's not clear that they have the nuclear situation under control, and until they do, I'm going to go somewhere safer."