High radiation levels have consistently stalled efforts to fix cooling systems at the plant, which was damaged in the massive March 11 earthquake and tsunami that killed at least 10,000 and displaced hundreds of thousands.
And while emergency workers for plant operator Tokyo Electric Power Co. (TEPCO) scramble to remove highly contaminated water that is preventing the repair of cooling systems, concerns are emerging about low levels of plutonium found in the soil nearby.
Plutonium, which is used in the manufacture of nuclear weapons, is said to be more dangerous than the uranium used in most of the plant's reactors, but chief government spokesman Yukio Edano said Tuesday that the levels found in the soil at five locations near the plant's reactors don't pose an immediate risk.
Indeed, the plutonium found does not appear to be an indicator that the crisis at the facility is worse than was previously thought.
“The presence of plutonium outside the reactor core confirms that there was at least a partial meltdown of the core from the reactor that used the MOX fuel rods,” says physics professor Kenneth N. Barish, from the University of California at Riverside. “This was already believed to be the case and does not necessarily mean that the situation is worse than thought or deteriorating. The levels reported are quite low and do not pose an immediate health risk.”
Scientists are also pointing out that because plutonium is an extremely heavy substance, the likelihood of it spreading across a wide area is less than that of uranium spreading.
Mr. Edano said that workers at the damaged reactors were struggling to balance the two missions of pumping in cooling water and removing the radioactive water that has leaked within the facility. If the fuel rods were allowed to dry out there would be a large-scale release of radiation into the atmosphere. However, the leaked radioactive water is also in danger of further contaminating the soil and sea around the plant.
Meanwhile, three workers who stood in radioactive water at the Fukushima Daiichi plant for two hours without adequate protective clothing, have been given a clean bill of health.
The workers were installing power cables at the No.3 reactor when they were unknowingly exposed to radiation levels of 3,000 millisieverts through water that was higher than the boots they were wearing. Two of the men were taken to the hospital.
The National Institute of Radiological Sciences in Chiba Prefecture released the men on Monday, saying they hadn’t needed the treatment for burns that had been expected, and that their internal organs had suffered minimal exposure. The men will be monitored again at the medical facility in a few days time.
“It appears in this case they had some minor burns like one can get sunburn from the sun’s radiation,” says Professor Barish.
Japan’s Meteorological Agency warned people along the Pacific coast to remain alert to the possibility of further tsunamis caused by powerful aftershocks. A magnitude 5 earthquake off the coast of Miyagi Prefecture on Monday led to a tsunami warning, though there were no reports of high waves reaching the shore.
The agency said that although aftershocks have been falling in frequency and intensity, the fact that the March 11 quake sunk the northeast coastline meant that the area was now more at risk of flooding. Those near the coast should take note of the nearest high ground they can evacuate to in the case of further tsunamis, said the agency.