Radioactivity fears at Japanese reactor in tsunami disaster

The fresh concerns over the Fukushima Dai-ichi nuclear facility came as a reactor in southern Japan was restarted and brought back online, marking a first since the March 11 disaster created an outcry over the safety of Japan’s nuclear power sites.

Utility officials said gas from inside the Fukushima plant’s No 2 reactor indicated the presence of radioactive xenon, which could be the by-product of unexpected nuclear fission. Boric acid was injected through a cooling pipe as a precaution because it can counteract nuclear reactions.

Tokyo Electric Power Co (Tepco) said there was no rise in the reactor’s temperature or pressure, and the radioactive materials had not reached the point when nuclear reactions are self-sustaining and the detection of the xenon would have no major impact on efforts to keep the reactor cool and stable.

Because the half-life of the isotopes detected is short, the xenon was probably created recently. But officials said the level was so low further tests would be required to confirm the measurements were not an error.

“We have confirmed the reactor is stable and we don’t believe this will have any impact on our future work,” said Tepco spokesman Osamu Yokokura. He said no radiation leaks outside the plant were detected.

Hiroyuki Imari, a spokesman with the Nuclear Industrial Safety Agency, said the detection of the gas was not believed to indicate a major problem.

The plant is the site of the worst nuclear disaster since Chernobyl in 1986. A 12-mile (20km) exclusion zone has been in effect since the earthquake and tsunami crippled the facility north-east of Tokyo, sending three of its reactors into meltdowns.

A Japanese government panel has said it will take at least 30 years to safely decommission the facility.