The Tokyo Electric Power Company (TEPCO) said on Wednesday that, as well as finding high levels of strontium, groundwater samples collected had also showed levels of the hydrogen isotope tritium at eight times the allowed level.

A TEPCO manager, Toshihiko Fukuda, told a press conference in Tokyo that the utility did not believe that strontium-90 had leaked via soils from the seaside facility into the ocean.

Groundwater samples taken outside reactor No. 2 had indicated a 100-fold jump in strontium-90 levels between December 2012 and May this year, he said. The elevated level was 30 times the legal limit.

Cooling systems failed

A huge tsunami unleashed meltdowns in three reactors in March 2011 when power and cooling systems failed. Workers flushed the rogue reactors with water, leaving TEPCO overwhelmed by contaminated liquids and looking for means of disposal.

Concrete foundations and steel sheets are supposed to restrain the spread of contaminants. But critics say the improvised fixes to storage pools and tanks have left Fukushima vulnerable to mishaps.

Fishermen anxious

TEPCO's admission is likely to complicate its request to discharge what it describes as waters with low-level radiation into the Pacific Ocean, despite objections from skeptical local fishermen.

At Nagoya University, nuclear chemical professor Michiaki Furukawa said the contaminated water should not be released into the ocean, because of potential effects on marine life and human consumers of seafoods.

"They have to keep it somewhere so that it can't escape outside the plant," Furukawa said.

Tens of thousands of people were forced to leave their homes and businesses during the meltdowns. Many remain displaced. No one was officially recorded as dying as a direct result of the meltdowns. The earthquake and subsequent tsunami that sparked the problems at Fukushima claimed more than 18,000 lives.

ipj/msh (AFP, Reuters)