New highly radioactive leak at Japan’s Fukushima plant

TOKYO (Reuters) – The operator of Japan’s Fukushima nuclear plant said on Thursday that 100 tonnes of highly contaminated water had leaked out of a tank, the worst incident since last August, when a series of radioactive water leaks sparked international alarm.

Initial measurements of the latest incident showed the leaked water had a reading of 230 million becquerels per litre of beta-emitting radioactive isotopes, including strontium 90.

The legal limit for releasing strontium 90 into the ocean is 30 becquerels per litre.

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Radiation doubles to new high in No. 1 plant water ditch

Tokyo Electric Power Co. said Thursday that radiation rose to a new record in water collected from a drainage ditch at its stricken Fukushima No. 1 nuclear plant.

Tepco said it detected a maximum of 140,000 becquerels per liter of beta ray-emitting substances, including strontium, from a water sample collected Wednesday from the ditch, which extends to the sea beyond the plant’s port.

The figure is 2.3 times higher than the previous record of 59,000 becquerels detected in water sampled at the same location Tuesday, and was more than 11 times the previous day’s reading.

The measurement location is about 600 meters from the open ocean and close to the storage tank that leaked some 300 tons of radioactive water in August.

Tepco said rainwater may have carried radioactive materials in surrounding areas into the drainage ditch.

Sandbags were placed downstream, but heavy rain may have caused the water in the ditch to overflow them and enter the ocean.

Also on Thursday, Tepco started transferring radioactive water that has built up inside the tanks’ flood enclosures to a covered reservoir ahead of heavy rain expected from fresh typhoons approaching Japan.


Fukushima: Tanks’ enclosures swamped by downpours; strontium level soars, radiation in rainwater overflow spikes

Kyodo, Jiji Reports

Rainwater that overflowed Sunday from the concrete-ringed enclosures around the water storage tanks at the Fukushima No. 1 nuclear plant had excessively high radiation readings, Tokyo Electric Power Co. disclosed Monday.

Strontium-90 in the rainwater, which had accumulated from recent downpours, was above the limit of 10 becquerels per liter near six tank clusters, with the reading in one area reaching 710 becquerels, Tepco said.

It said some of the radioactive water has seeped into the ground, but noted that most of the affected surface water probably didn’t flow to the Pacific Ocean because barrier mounds have been built outside the flood enclosures to prevent water from entering the drainage channels that lead to the sea.

Yet Tepco couldn’t totally rule out that surface water had reached the sea.

The concrete flood fences, about 30 cm high, were built to keep water from spreading if a tank leaks. There are 23 enclosed tank clusters. The tanks store highly radioactive water that was used to cool the melted cores of the three crippled reactors.

When rainwater accumulates in an enclosure, Tepco transfers it to other containers and checks the radiation level before discharging it. But Sunday’s rainfall was so heavy that it overflowed.

The rainwater that day overflowed the fences of 11 of the tank enclosures, Tepco said.

Simultaneous overflows had never taken place at so many clusters before.

Tepco also found water leaks from a concrete joint in a barrier at another tank cluster where excessively radioactive substances were found in the past. As a result, tainted water in such barriers has leaked from over half of the plant’s 23 tank enclosures.

In the past, radioactive materials in excess of the provisional limits set by Tepco have been detected in water in some of the tank cluster enclosures.

The overflows and leaks are the latest in a series of the Japanese government’s water problems at the plant.

On Sunday, the utility started draining water from inside the barriers at six tank areas, including five of the 11 overflowed areas, after confirming that radiation levels had fallen below the provisional limits.

At two other tank areas, Tepco transferred the enclosure water to sunken reservoirs. Although the utility stopped using the reservoirs to store the highly radioactive coolant after discovering in April that they were leaking, it took the emergency step this time because of the looming rainfall threat when Typhoon Wipha approached last week.

The total amount of water that overflowed and leaked Sunday is not known, the company said.

In one location among the 11 tank areas, a maximum of 29,000 becquerels per liter of strontium and other radioactive materials emitting beta-ray particles were detected in the past.

Tepco’s provisional limit on radiation is 10 becquerels per liter for strontium-90, a substance linked to bone cancer that is also believed to account for about half of beta ray-emitting radioactive materials. Airborne radioactive materials have fallen into the enclosures, while tainted tank water is thought to have leaked into some of the areas.

Water radiation soars at Fukushima No. 1

Strontium readings spike 6,500-fold in one day

FUKUSHIMA – Radiation levels in groundwater under Tokyo Electric Power Co.’s Fukushima No. 1 nuclear plant are soaring, Tepco said Friday after taking samples from an observation well.

Tepco said 400,000 becquerels per liter of beta ray-emitting substances such as strontium were detected in water sampled Thursday from the well located some 15 meters from a storage tank that leaked about 300 tons of highly radioactive water in August.

The level of becquerels, a record high for water in that well, was up 6,500-fold from the 61 becquerels found Wednesday.

Tepco was planning to pump groundwater up from different wells about 100 meters from the leaky tank for release into the Pacific before the water flows into the damaged reactor buildings and becomes heavily contaminated with radioactive materials.

But that plan appears in jeopardy because the sharp increase in the levels of radioactive materials in the observation well suggest the radioactive groundwater is spreading.

By law, water containing beta particle-emitting substances exceeding certain levels cannot be released into the sea. The upper limit is set at 30 becquerels per liter for strontium-90 and 60 becquerels for cesium-134.

Tepco also said water collected Thursday from a drainage ditch near the leaky tank contained 34,000 becquerels of beta particle-emitting substances per liter, compared with 2,300 becquerels the day before.

Water contaminated with radioactive materials flowed into the ditch when Typhoon Wipha hit the area this week, but then much of the water evaporated, leading to the surge in the density of beta particle-emitting materials there, Tepco officials explained.

It is believed some 400 tons of radioactive groundwater is flowing into the Pacific daily.

Officials said Thursday they will solicit proposals from both domestic and overseas nuclear experts and firms on how best to scrap the ruined reactors at Fukushima No. 1.

The International Research Institute for Nuclear Decommissioning will publicly seek ideas as early as this month, an institute official said.

While the body is not putting the entire decommissioning process out to tender, the move will be welcomed by the international community, which has long called for Japan to make better use of available expertise around the globe.

The institute, formed by nuclear-related firms and government-backed bodies in August to dismantle the crippled reactors, will screen decommissioning proposals and take the results to the government, the official said.

“We will set up a website in both Japanese and English to notify interested parties at home and abroad of our calls for decommissioning ideas so that we can offer more useful and practical proposals to the government,” the official said.