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Concentration of tritium in sea water soars

June 25, 2013



Higher seaborne tritium levels outside Fukushima plant suggest leaks not plugged





Tokyo Electric Power Co. said radioactive water may still be leaking into the sea from the crippled Fukushima No. 1 nuclear power plant after enhanced levels of radioactive tritium were detected in the port area in front of the facility.

The plant operator said June 24 it is investigating the matter with some urgency as the finding suggests that radioactive water, generated on the plant premises, may be leaking into the sea from the ground.

TEPCO said tritium levels of 1,100 becquerels per liter of seawater were recorded June 21 north of the water intakes for the No. 1, No. 2, No. 3 and No. 4 reactors in the port area.

The reading compares with 500 becquerels per liter measured on June 10. It was the highest concentration since the nuclear crisis began to unfurl in March 2011.

Officials said tritium levels of 910 becquerels per liter of seawater were detected at a different location near the water intakes for the No. 1 and No. 2 reactors and close to a well, up from the previous reading of 600 becquerels per liter on June 14.

The previous record for seawater in the port, 920 becquerels per liter, was taken in October 2011. Tritium levels in the port generally hovered 100 and 200 becquerels per liter during the past 12 months.

Tritium, a naturally existing radioisotope of hydrogen, is generated in coolant water for nuclear reactors. Unlike radioactive cesium, tritium, which exists in the form of water, is difficult to remove by way of absorption. Tritium, once ingested, flushes out of the human body relatively quickly.

Miniscule amounts of tritium are released into the environment during the normal course of operating a nuclear reactor.

The government has set an upper limit of 60,000 becquerels per liter for seaborne tritium concentrations outside a nuclear facility.

TEPCO had said June 19 that 500,000 becquerels of tritium was detected in late May per liter of water from a well on the sea side of the No. 1 and No. 2 reactors.

The utility said the radioactive water likely entered the ground immediately after the nuclear crisis began, and later mixed with groundwater and flowed into the well.

TEPCO also said it would inject a sealing agent into the ground between the well and the sea to prevent the radioactive water from spreading to the ocean and conduct drilling near the well to monitor radioactive concentrations more closely.

"We need more investigations to identify the cause," a TEPCO official said. "We will keep a close watch on the situation."

Tetsu Nozaki, who heads the Fukushima Prefectural Federation of Fisheries Cooperative Associations, expressed concern that fishing operations in local waters could be affected.

"I will be waiting for TEPCO to explain the cause and present its mitigation measures," Nozaki said. "Although I cannot yet gauge the magnitude of the latest development, I am afraid that a growing number of our members would feel anxious if similar incidences were to recur."

(Jin Nishikawa contributed to this article.)


Tritium samples in sea near No. 1 soar

Staff Writer

The density of radioactive tritium in samples of seawater from near the Fukushima No. 1 nuclear plant doubled over 10 days to hit a record 1,100 becquerels per liter, possibly indicating contaminated groundwater is seeping into the Pacific, Tokyo Electric Power Co. said.

The latest sample was taken June 21 from the sea near a water intake point east of the reactor 1 turbine building.

The legally permitted level of tritium is 60,000 becquerels per liter. Water taken from the same place June 10 had a reading of 500 becquerels per liter.

Tepco said late Monday it was still analyzing the water for strontium-90, which would pose a greater danger than tritium to human health if absorbed via the food chain. The level of cesium did not show any significant change between the two sample dates, according to the embattled utility.

On June 19, Tepco revealed that a groundwater sample taken from a nearby monitoring well was contaminated with both tritium and strontium-90.

At that time, seawater samples did not show any significant changes in the level of radioactive materials, and Tepco denied the dirty water was seeping into the sea.

But during a news conference Monday in Tokyo, Masayuki Ono, a Tepco executive and spokesman, this time did not deny the possibility of leakage into the sea, while he said Tepco is still trying to determine the cause of the spike.


Level of radioactive tritium rising in harbor at Fukushima plant




Tokyo Electric Power Co. has seen a rise in the level of radioactive tritium in seawater within the harbor at the crippled Fukushima No. 1 nuclear power plant.

A sample collected Friday contained around 1,100 becquerels of tritium per liter, the highest level detected in seawater since the nuclear crisis at the plant started in March 2011, the utility said Monday.

An official of the Nuclear Regulation Authority said groundwater containing radioactive substances may be seeping into the harbor from the plant site and there is a need to carry out a careful investigation because the data collected so far are limited.

According to Tepco, the sample with the highest tritium concentration was collected near a water intake on the east side of the reactor 1 turbine building. The level was more than double that of a sample taken on June 10 in the same area.

The latest announcement was made after Tepco detected high levels of radioactive tritium and strontium in groundwater from an observation well at the plant.

The government-set safety limit for tritium is 60,000 becquerels per liter of seawater.


See also :


Level of radioactive tritium rising in port at Fukushima plant



TOKYO (Kyodo) -- Tokyo Electric Power Co. said Monday it has seen a rise in the level of radioactive tritium in seawater within the port at the crippled Fukushima Daiichi nuclear power plant….


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