Japan engineers use coloured dye to trace radiation leaks

Tokyo: Battling highly radioactive water from leaking into the sea, desperate Japanese engineers on Monday pumped coloured powder to trace leakage, as the operator TEPCO announced plans to dump 11,500 tons of contaminated water into the ocean to clear storage space at Fukushima nuclear plant.

Tokyo Electric Power Co. – the plant operator – poured 13 kilograms of milky white dye into an underground trench to find the source from where radioactive water is leaking into the Pacific Ocean, according to Kyodo news agency.

The move came after workers` effort to block the leakage from a cracked seaside pit connected to the No. 2 reactor turbine building showed no effect, it said.

The workers are struggling for more than three weeks to regain control after a powerful quake and tsunami knocked out cooling systems at the troubled nuclear plant.

Radioactive water has been filling up the basement of the No. 2 reactor turbine building and the tunnel-like trench connected to it. The coloured dye was injected into the trench shortly after 7 a.m. local time but did not come out from the crack as of 11 a.m., according to the company officials.

The TEPCO is also considering installing "silt fence" barriers in areas where radioactive water is suspected to be flowing into the sea, Hidehiko Nishiyama, a spokesman for the government`s nuclear safety agency told reporters.

"We would like to set up these fences as soon as possible," he was quoted as saying by the Kyodo. He said it would likely take "several days" to complete the work.

The barriers are comprised of curtains attached with weights, which the operator hopes will contain the radioactive water. One of the barriers would be placed in front of the No.

2 reactor`s water intake, close to the pit in question, and another barrier is expected to be set up around a damaged portion of the levee near the No. 4 reactor, the agency said.

Meanwhile, a spokesman for TEPCO said the company plans to dump 11,500 tons of radioactive water at sea to clear storage space at the plant for more highly contaminated water.

"Highly radioactive waste water has been accumulated at turbine buildings at Fukushima Daiichi, especially at the reactor unit 2," the official told reporters.

"There is a need to release already stored water in order to accept the additional waste water."

About 10,000 tons of radioactive waste water currently stored at a facility at quake-stricken plant will be released into the ocean along with 1,500 tons of water from pits under reactor units 5 and 6 in the six-reactor plant, he said.

Government spokesman Yukio Edano also confirmed the plan at a televised press conference, saying it was the only available option.

Meanwhile, Japan`s Chief Cabinet Secretary Yukio Edano said the leak must be stopped "as soon as possible".

"We must prevent radioactive water from spreading in the sea as soon as possible," Edano said, adding the longer the leakage continued, the larger the impact on the sea would be, even if radioactive materials were diluted.

Workers yesterday injected water absorbent known as "water gel bag", which contains polymeric materials used in diapers that can soak up 50 times its volume in their bid to block the leakage but the water flow remained unaffected.

They injected eight kgs of the absorbent along with 60 kgs of sawdust and three bags of shredded newspaper into pipes leading to a pit connected to the No. 2 reactor building.

The efforts were aimed at blocking the 20-centimetre crack that has been found in the containment pit through which highly radioactive water is seeping into the Pacific Ocean.

The injected materials were sent inside at a point 23 meters away from the seaside pit, but were not been sucked into the water flow.

A spokesman for the governmental Nuclear and Industrial Safety Agency had said the fact that the absorbent has not been sucked inside means there has been no impact on the rate of leakage.