Tepco plays down decontamination failure
by Editore | 19 Giugno 2011 17:00
Decontamination efforts at the Fukushima No. 1 plant were halted Saturday after a filter expected to remove the radioactive element cesium for several weeks exceeded capacity in just five hours. Oil and sludge in the water contained much more radiation than expected, said Junichi Matsumoto, a spokesman for the utility.
Work on a self-contained cooling system has been suspended while the company seeks a solution, Matsumoto said at a media briefing in Tokyo Sunday. The setback won’t delay achievement of a stable cooling status by mid-July, he said.
“Decontamination is the key to solving the problems at the plant,” said Tadashi Narabayashi, a nuclear engineering professor at Hokkaido University.
Decontamination of about 105 million liters of water in basements and trenches at Fukushima No. 1 was halted after the level of cesium in a filtering unit reached 4.7 millisieverts of radiation, Matsumoto said Saturday. The units generally need replacement at a level of 4 millisieverts, and the company had expected the unit to last about a month, he said.
“Tepco should have had a very simple water decontamination system of its own,” Narabayashi said. “Then, it’s easy to fix or replace a troubled part by themselves.”
The utility, known as Tepco, on April 17 outlined plans to end within six to nine months the world’s worst nuclear crisis since Chernobyl in 1986. The first stage is to reduce radiation levels at the plant within three months and then achieve a so- called cold shutdown where reactor temperatures fall below 100 degrees.
The Fukushima plant suffered three reactor meltdowns after the March 11 earthquake and tsunami knocked out power and backup generators, crippling its cooling systems. Japan in April raised the severity rating of the crisis to 7, the highest on an international scale and the same as the Chernobyl disaster.
Tepco has been criticized for its slow response to the accident and for publishing erroneous radiation data, while the government-run Nuclear and Industrial Safety Agency has been blamed for not ensuring the utility heeded warnings that a tsunami could overwhelm the plant’s defenses.
The utility is now the subject of study by Yotaro Hatamura, appointed by Prime Minister Naoto Kan last month to head a 10-member team conducting an “impartial and multifaceted” investigation into what went wrong and how to prevent a repeat.
Hatamura told reporters in Tokyo last week that plant manager Masao Yoshida, said he couldn’t imagine such a huge tsunami.
“From our discussions, I gathered that no one at the plant could imagine that such a tsunami would occur,” Hatamura said.
While it struggles to shut down the reactors Tepco is also preparing to compensate victims of the disaster, including 50,000 households displaced because of radiation leaks.
The Cabinet on June 14 approved a disaster compensation bill to help the utility pay reparations.
The nation’s largest banks and insurers, including Sumitomo Mitsui Financial Group Inc. and Dai-ichi Life Insurance Co., will provide short-term operating funds to Tokyo Electric, according to local media reports.
Trade Minister Banri Kaieda on Saturday said he may let utilities restart nuclear generators that had been shut for routine maintenance. There are negatives to suspending all nuclear power, Kaieda said at a press briefing in Tokyo, citing an expected “gap” in power supply and demand in Japan’s coming summer months.
Source URL: https://www.dirittiglobali.it/2011/06/tepco-plays-down-decontamination-failure/