Levels of iodine-131 were 3,355 times the legal safety limit, up from the previous high of 1,850 times the limit that was recorded Sunday, officials said. The water was sampled about 1,000 feet south of a wastewater outlet.
“Experts are trying to analyze the situation and looking at all possibilities,” Yukio Edano, Japan’s chief cabinet secretary, said. “We are considering the worst-case scenario. If the radiation goes up and it affects health of people in the area, we will advise people immediately.”
Hundreds of engineers are working to bring the nuclear plant under control, including many consultants from other countries. The chief executive of the French nuclear energy company Areva arrived in Tokyo Wednesday, following a team of French engineers.
Potential solutions for containing the hazardous materials include spraying a synthetic resin on the ground to slow or stop contamination from spreading to the sea, and dropping a cloth cover over the reactors. Hydrogen explosions blew off the roofs of two reactors and damaged a third; at least one reactor’s spent fuel pools are now exposed to the environment.
Hironobu Unesaki, professor of nuclear engineering at Kyoto University, said a cover, fit with a customized ventilation system, could be an effective way to control gaseous emissions from the reactors. But he said it would likely not have an impact on the water leaking from a pipe or a compression chamber at the base of the reactor, as the company suspects is happening.
Workers made limited progress Wednesday in eliminating radioactive water from the cavernous turbine rooms next to the first three nuclear reactors.
Water in two of the buildings has not yet been drained, because nearby condenser tanks needed to receive the water are already full. It could take several days to empty their contents safely into another tank on-site.
In the room adjacent to the first reactor, workers were able to reduce knee-deep water to a depth of about eight inches. But work stalled because the condenser tank there became full. Government officials Wednesday raised the possibility of using a tanker or large boat as a repository for the contaminated water.
Water-based radiation in the building outside the second reactor exceeds 1,000 millisieverts per hour, or 100,000 times the level that would be found if the plant were operating normally.
Also on Wednesday, Japan’s Emperor Akihito and Empress Michiko visited an evacuation center in Tokyo. The rare public visit followed the emperor’s first-ever televised address a week earlier, underscoring the gravity of the country’s situation.
Correspondent Andrew Higgins and special correspondents Tetsuya Kato and Akiko Yamamoto in Tokyo and staff writer Brian Vastag in Washington contributed to this report.