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   hoseobyoon (2013-08-06 03:00:15 )
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   후쿠시마 원전 방사능유출 "비상사태"


후쿠시마 원전 방사능유출 "비상사태"
(종합)(도쿄 로이터=뉴스1) 고현석 기자
2013.08.05 21:33:43  

일본 후쿠시마 원전의 방사능 유출이 통제불능의 "비상사태(emergency)"를 초래하고 있다고 일본 원자력당국 관계자가 5일 밝혔다.

일본원자력규제위원회(NRA) TF팀 긴조 신지 팀장은 5일 로이터에 "방사능 유출수가 지하장벽을 넘어 지표면을 향해 올라오고 있으며 도쿄전력(TEPCO)이 준비한 대책은 문제를 일시적으로 지연시키는데 그칠 것"이라고 밝혔다.

긴조 팀장은 "(도쿄전력의) 사태에 대한 위기위식은 너무 낮은 수위이며 현재 진행되고 있는 재앙은 도쿄전력 이 해결할 수 있는 수준을 넘어섰다"고 로이터통신에 말했다.

오염된 방사능 유출수가 어는 정도의 위협이 될지는 아직 확실하게 알려지지 않고 있다. 2011년 후쿠시마 원전 사고 이후 일본 정부는 긴급조치로 도쿄전력이 수천톤의 오염수를 인근 태평양 해역에 방출하는 것을 허용했다.

통신에 따르면 후쿠시마 원전은 방사능유출수의 태평양 유입을 막기위해 지하장벽을 설치했지만 이는 지표면에서 1.8m 정도만 고체화시키는데 효과를 지니고 있어 근본적인 해결책은 되지 못하고 있는 상황이다.

지하장벽이 무너지면 유출수는 지표면 바로 아래에서 바다로 흫러 들어갈 가능성이 매우 높다. 더 심각한 문제는 유출수가 지표면을 향해 접근하고 있어 일단 밖으로 분출되면 유출속도는 기하급수적으로 높아진다는데 있다.

도시바 엔지니어 출신인 고토 마사시는 "문제는 우리가 얼마나 버틸 수 있느냐에 있다"고 말했다.


radioactive water at Fukushima an 'emergency'

Exclusive: Japan nuclear body says radioactive water at Fukushima an 'emergency'
Mon Aug 5, 2013 8:24am EDT

TOKYO (Reuters) - Highly radioactive water seeping into the ocean from Japan's crippled Fukushima nuclear plant is creating an "emergency" that the operator is struggling to contain, an official from the country's nuclear watchdog said on Monday.

This contaminated groundwater has breached an underground barrier, is rising toward the surface and is exceeding legal limits of radioactive discharge, Shinji Kinjo, head of a Nuclear Regulatory Authority (NRA) task force, told Reuters.

Countermeasures planned by Tokyo Electric Power Co are only a temporary solution, he said.

Tepco's "sense of crisis is weak," Kinjo said. "This is why you can't just leave it up to Tepco alone" to grapple with the ongoing disaster.

"Right now, we have an emergency," he said.

Tepco has been widely castigated for its failure to prepare for the massive 2011 tsunami and earthquake that devastated its Fukushima plant and lambasted for its inept response to the reactor meltdowns. It has also been accused of covering up shortcomings.

It was not immediately clear how much of a threat the contaminated groundwater could pose. In the early weeks of the disaster, the Japanese government allowed Tepco to dump tens of thousands of metric tons of contaminated water into the Pacific in an emergency move.

The toxic water release was however heavily criticized by neighboring countries as well as local fishermen and the utility has since promised it would not dump irradiated water without the consent of local townships.

"Until we know the exact density and volume of the water that's flowing out, I honestly can't speculate on the impact on the sea," said Mitsuo Uematsu from the Center for International Collaboration, Atmosphere and Ocean Research Institute at the University of Tokyo.

"We also should check what the levels are like in the sea water. If it's only inside the port and it's not flowing out into the sea, it may not spread as widely as some fear."

NO OTHER OUTLET FOR WATER

Tepco said it is taking various measures to prevent contaminated water from leaking into the bay near the plant. In an e-mailed statement to Reuters, a company spokesman said Tepco deeply apologized to residents in Fukushima prefecture, the surrounding region and the larger public for causing inconveniences, worries and trouble.

The utility pumps out some 400 metric tons a day of groundwater flowing from the hills above the Fukushima Daiichi nuclear plant into the basements of the destroyed buildings, which mixes with highly irradiated water that is used to cool the reactors in a stable state below 100 degrees Celsius.

Tepco is trying to prevent groundwater from reaching the plant by building a "bypass" but recent spikes of radioactive elements in sea water has prompted the utility to reverse months of denials and finally admit that tainted water is reaching the sea.

In a bid to prevent more leaks into the bay of the Pacific Ocean, plant workers created the underground barrier by injecting chemicals to harden the ground along the shoreline of the No. 1 reactor building. But that barrier is only effective in solidifying the ground at least 1.8 meters below the surface.

By breaching the barrier, the water can seep through the shallow areas of earth into the nearby sea. More seriously, it is rising toward the surface - a break of which would accelerate the outflow.

"If you build a wall, of course the water is going to accumulate there. And there is no other way for the water to go but up or sideways and eventually lead to the ocean," said Masashi Goto, a retired Toshiba Corp nuclear engineer who worked on several Tepco plants. "So now, the question is how long do we have?"

Contaminated water could rise to the ground's surface within three weeks, the Asahi Shimbun said on Saturday. Kinjo said the three-week timeline was not based on NRA's calculations but acknowledged that if the water reaches the surface, "it would flow extremely fast."

A Tepco official said on Monday the company plans to start pumping out a further 100 metric tons of groundwater a day around the end of the week.

The regulatory task force overseeing accident measures of the Fukushima Daiichi nuclear power station, which met Friday, "concluded that new measures are needed to stop the water from flowing into the sea that way," Kinjo said.

Tepco said on Friday that a cumulative 20 trillion to 40 trillion becquerels of radioactive tritium had probably leaked into the sea since the disaster. The company said this was within legal limits.

Tritium is far less harmful than cesium and strontium, which have also been released from the plant. Tepco is scheduled to test strontium levels next.

The admission on the long-term tritium leaks, as well as renewed criticism from the regulator, show the precarious state of the $11 billion cleanup and Tepco's challenge to fix a fundamental problem: How to prevent water, tainted with radioactive elements like cesium, from flowing into the ocean.

(Additional reporting by Kentaro Hamada; Editing by Edmund Klamann and Raju Gopalakrishnan












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