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[Contaminated water storage] 240,000 tones of tank is full, pipe runs for 10km, finding storage place getting harder
Nikkei reported the shortage of contaminated water storage in Fukushima plant, which is going worse.
10月中旬、報道陣への公開で原発の敷地内に事故後、初めて入った。バスで回ると、木が切り倒され青や白のタンクが並ぶ異様な光景が飛び込んできた。汚染水をためるタンクだ。
１～３号機から出る放射性物質の量は事故直後に比べ、約8000万分の１に減った。しかしメルトダウン（炉心溶融）で溶け落ちた、汚染源の燃料は手つかずのまま。再び炉が暴走しないよう毎時約17トンの水を炉内に流して冷やしている。
水は循環させて使っているが、炉が損傷しており漏れ出る。１日400トンもの地下水も原子炉周辺に流れ込む。増え続ける汚染水から、放射性物質をある程度除去してタンクにためている。
「来月はどこに水を入れるか。そんなことばかり考えている」。水処理対策を練る東電の福島第１対策プロジェクトチーム課長、新井知行（44）は頭を悩ませる。
既に約24万トン分のタンクがほぼ満杯で、東電は３年内に約70万トン分を追加する。東京ドームの半分を超える。地下水の流れを原子炉から遠ざける工事も始めたが、迂回させた水も当面はためておく。
循環水を流す配管は総延長10キロメートル近い。事故後しばらくは散乱するがれきやトラック、重機によって塩化ビニール管が傷つき水漏れが多発、対応に追われた。
昨秋までに一通り補修を終え安堵したのもつかの間、今年１月下旬には再び漏水が続出。多い日には10カ所以上で見つかった。原因は凍結だ。同じ過ちは繰り返せない。配管の大部分を耐久性が強いポリエチレン管に換え、２度目の冬を前に保温材も取り付けた。
冷却水を原子炉ごとに循環・浄化して配管を短くすれば不安は減るが、工事の余力もなく実施は遅れている。水との闘いは終わりが見えない。
The radiation level leaking from reactor1 ~ 3 reduced to be 1 in 80 million, but melted fuel remains there. Tepco keeps giving 17 tones of water every single hour so the cripple reactors don’t go out of control again.
They circulate the coolant water, but because the reactors are crippled, it keeps leaking. Even 400 tones of underground water flows to around the reactors. The contaminated water keeps increasing. They filter it out to an extent, and keep it in the tanks.
“Where to stock the water next month. It always gives me a headache.” Mr. Arai, the project team manager of water processing talks.
At this moment, the tank for 240,000 tones of contaminated water is already full. Tepco is going to add the storage facility of 700,000 tones of water in three years. It’s already more than a half of Tokyo dome. Tepco started the construction to bypass underground water to avoid flowing into the reactors but the bypassed water has to be stocked as well.
The pipe to circulate contaminated water runs for 10km. Scattered debris, trucks and heavy machinery damaged the vinyl chloride pipe to cause contaminated water leakage.
They were relieved to fix them by last Autumn in 2011, but water started leaking again in late January. It leaked at 10 locations in the same day at the most due to the frozen water in the pipe.
Tepco is supposed to have changed most of the pipe to polyethylene one and attached heat insulating material before the second winter.
They could shorten the pipe by making it circulate at each reactor, but they are postponing the construction due to the shortage of resource. Managing contaminated water is an endless process.
Related article..[Express] “Seismic stability of contaminated water storage tanks is questionable” [Link]
Iori Mochizuki
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