Asahi May 13
As if Tokyo Electric Power Co., the embattled operator of the crippled Fukushima No. 1 nuclear power plant, didn’t have enough problems, another daunting task is what to do with an estimated 90,000 tons of radioactive water.
This vast amount remains from the pumping of water to cool reactors after the plant’s regular cooling systems were disabled in the March 11 Great East Japan Earthquake and seawater from the tsunami.
The problem is growing by the day, as the volume of contaminated water keeps increasing.
TEPCO needs to treat and recycle contaminated water escaping from the facilities to maintain the cooling of the reactors without increasing the volume of contaminated water.
It signed a deal with France’s Areva SA, a nuclear engineering company, to start treating the radioactive water in June. But Areva’s equipment is capable of treating only 1,200 tons a day, and it is not clear if it can handle a total of 90,000 tons.
In dealing with this volume of contaminated water, the plant’s No. 2 reactor presents the most serious challenge of its four stricken reactors.
Workers discovered on April 2 that highly radioactive water gushed into the sea through cracks close to a pit near an intake of the No. 2 reactor. Technicians spent a total of 93 hours before successfully plugging the leaks on April 6.
The contaminated water came from buildings housing the No. 2 reactor and turbine as well as a trench.
TEPCO is transferring the contaminated water to a disposal-and-treatment facility in the compound to prevent further overflow.
The total amount of contaminated water at the No. 2 reactor was estimated at 25,000 tons before the transfer work got under way, equivalent to about 400,000 terabecquerels of radioactivity.
When Japan’s nuclear industry regulator, the Nuclear and Industrial Safety Agency (NISA), upgraded the severity level of the accident at the plant to a maximum 7 on the International Nuclear and Radiological Event Scale (INES) on April 12, it cited an estimate for the radiation emitted into the atmosphere at 370,000 terabecquerels as the basis for the raise.
That means that radioactive water at the No. 2 reactor alone suffices to be classified as a level-7 accident.
In another ongoing problem, TEPCO is trying to deal with about 300,000 tons of contaminated water that has already leaked into the sea and has been contained inside the port.
Following the accident, some of the contaminated water found its way into the ocean. Other amounts, which were less radioactive, were discharged by TEPCO as it needed to free up storage space to hold more highly toxic water.
The utility installed plastic curtain-like partitions, called silt fences, that hang from floats to near the sea bottom at six locations to help stop radioactive water from spreading farther in the ocean.
But NISA said on May 11 that it was highly likely that almost all the radioactivity in the water had escaped into the sea by the time the utility installed the fences April 11-14.
Sources within NISA said that installing the fences–five to eight days after the leak was stopped–came too late.
The radioactivity level in the water contained by the fences is 100 terabecquerels at most, according to NISA calculations.
TEPCO estimated that a total of 520 tons of contaminated water leaked into the sea containing 4,700 terabecquerels of radioactivity.
That is 20,000 times the annual radiation level permitted by the government for release.
Still, the utility plans to install filtration equipment to remove radioactive substances with the usage of zeolite, a mineral, this month.
However, it is not known how effective the filter is and how much capacity the equipment has.
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MARCH 12: Timing on decision to use seawater at Fukushima under scrutiny
In the hours after the March 11 Great East Japan Earthquake, the most important challenge at the Fukushima No. 1 nuclear power plant was to cool down the fuel rods in the reactor pressure vessels to prevent the reactor cores from being damaged.
This required a continued and massive injection of water. At the No. 1 reactor, where the situation was tense on March 12, the decision was made to pump in seawater. In the Upper House of the Diet, deliberations are focused on whether that decision came too late.
At the No. 1 reactor, at around 2:50 p.m., all the available fresh water had been pumped into the reactor pressure vessel to cool down the reactor core.
At that stage, according to Tokyo Electric Power Co., the plant operator, it hastily began preparing to switch to seawater.
“I instructed them to begin injecting seawater at 2:50 p.m. when the injection of fresh water stopped,” TEPCO President Masataka Shimizu told the budget committee of the Upper House as an unsworn witness.
But before the pumping of seawater could begin, a hydrogen explosion occurred at the No. 1 reactor at 3:36 p.m.
Industry minister Banri Kaieda told the Upper House Budget Committee that he, too, had been talking about pumping in seawater.
“I spoke about it continually (after all the fresh water had been used) and I issued multiple instructions,” he said.
At around 6 p.m., about two and a half hours after the explosion, Kaieda ordered TEPCO, by way of the Nuclear and Industrial Safety Agency, to inject seawater into the No. 1 reactor. However, problems at the facility resulting from the explosion delayed the immediate startup of pumping, which did not begin until 7:04 p.m.
First, a 20-minute pumping test was conducted, Kaieda said. At 8:05 p.m., the prime minister issued a new order to pump in seawater and operations resumed at 8:20 p.m, after being interrupted for about one hour.
Keiji Miyazaki, professor emeritus of nuclear reactor engineering at Osaka University, said the interruption may not have had much effect on the situation.
“Water would have had to be injected proactively and uninterruptedly to prevent the fuel rods from being damaged,” he said.
“If fresh water is unavailable, you have to use seawater. Still, given that a hydrogen explosion had already occurred, the interruption of about an hour may not have had a large impact on what happened afterward.”
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APRIL 4: Contaminated water discharge into sea angered other countries
When Tokyo Electric Power Co. discharged about 10,000 tons of low-level radioactive water from its Fukushima No. 1 nuclear power plant into the sea in early April, it made waves with its neighbors across the Sea of Japan.
The release, from April 4-10, was deemed necessary when TEPCO had to make room for highly radioactive water transferred to an on-site wastewater treatment plant and had the blessing of the Japanese government.
After the leak of highly radioactive water from the damaged pit at the No. 2 reactor was found April 2, Goshi Hosono, a special adviser to Prime Minister Naoto Kan– who had opposed the water release at the end of March–reported to Kan on the handling of contaminated water at the plant. The Kan government then decided to allow the release of the water into the sea, saying it contained low levels of radiation.
The planned release, however, was not fully conveyed to other countries.
At 3:30 p.m. on April 4, TEPCO announced its plan to discharge the water into the sea, of which the Foreign Ministry was immediately notified. Thirty minutes later, the ministry held a regular briefing for all embassies in Japan, which diplomatic officials from 51 countries attended, regarding updates on the Great East Japan Earthquake.
The Foreign Ministry, in a brief mention, informed these attendees of TEPCO’s planned release. However, officials from neighboring countries across the Sea of Japan–China, South Korea and Russia–were not in attendance.
The briefing ended around 6 p.m. Shortly afterward, TEPCO notified the Foreign Ministry of its renewed plan for the water release later that day. The ministry added to a report on the meeting a statement that the release of low-level radioactive water into the sea would begin that night.
At 7:03 p.m., the release into the sea began. At 7:05 p.m., the Foreign Ministry sent the report to all embassies in Japan by fax and e-mail.
It wasn’t until April 6 that the ministry provided detailed information on the release to the Russian Embassy. The Russian foreign ministry considers this to be the date when its government was officially notified, saying the Japanese government handled the matter inappropriately.
The South Korean government, which was given a detailed explanation on the release by the Foreign Ministry on April 6, was also upset at the delay. Major South Korean newspapers gave extensive coverage to the contaminated water release, while questions flew in the South Korean parliament regarding the way the Japanese government treated the issue.
In China, the water release was also severely criticized by the media, saying the Japanese government did not thoroughly weigh possible consequences to the global community as a result of the contaminated water release.