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Wednesday, March 21, 2012

News photo
Beyond repair: The reactor 4 building at the Fukushima No. 1 power plant, heavily damaged in a hydrogen explosion, is seen in an aerial photo taken on March 11, the first anniversary of the Great East Japan Earthquake. KYODO

No. 1 long way from being out of the woods

Kyodo

A year after the Fukushima No. 1 nuclear power plant was ravaged by an earthquake and tsunami, the challenge of keeping the facility under control continues, and does so without a clear picture of what is actually happening inside the three crippled reactors.

The country is also groping for ways to clean the vast radiation-contaminated areas outside the plant, located about 220 km northeast of Tokyo, but securing places to store even topsoil after removal is not easy, given the opposition of communities beyond the fallout areas.

The nuclear crisis started shortly after the March 11 natural disasters led to the loss of nearly all of Fukushima No. 1's power sources, and consequently the ability to cool the reactors and spent fuel pools.

Reactors 1, 2 and 3 suffered core meltdowns and the buildings housing reactors 1, 3 and 4 were ripped apart by explosions presumably caused by hydrogen released from the cores of units 1 through 3.

Following a painstaking process to contain the world's worst nuclear crisis since the 1986 Chernobyl disaster, the government announced in December that the plant had achieved a stable state of cold shutdown.

But the fact that no one knows precisely what has happened inside the reactors and where the melted nuclear fuel is located means there is still great uncertainty over the complex's status.

Most recently, tensions grew in February over the status of reactor 2 after readings on one of its thermometers showed a notable rise, in a possible sign that there may be some trouble in cooling the fuel.

While Tokyo Electric Power Co. determined that the thermometer, a thermal-couple device, was broken, the incident highlighted the need for the utility to enhance the credibility of its system for monitoring the reactors.

"We should take this problem in the measuring equipment seriously," nuclear disaster minister Goshi Hosono told a news conference on Feb. 14. "Given that work toward scrapping the reactors is expected to take 30 to 40 years, it is extremely unfavorable to see a situation in which the utility cannot obtain data."

According to a step-by-step plan for decommissioning the reactors, Tepco will start removing the fuel stored in the spent fuel pools of reactors 1 through 4 within two years and the fuel from the cores of reactors 1, 2 and 3 within 10 years.

Tadashi Narabayashi, a Hokkaido University professor, called on the utility to swiftly create "criteria and a monitoring system to judge whether the cold shutdown condition has been maintained," using the readings of properly functioning thermometers and the amount of radioactive substances released from the reactor buildings.

He also pointed to the need to develop robots within five years that can operate inside the reactors, where radiation levels could be high enough to quickly destroy integrated circuits, so that they can carry out work such as installing new temperature-monitoring equipment.

In addition to the melted fuel, due attention is needed in handling the massive amounts of contaminated water created as a result of constant water injection into the stricken reactors.

After being used to cool the reactors, the water goes through a processing facility so that radioactive substances are removed to a certain extent. Some of the water is then recycled as a coolant and the remaining portion is placed in tanks at the site.

The makeshift water circulation systems have suffered various problems, including weather-related glitches. The shoreline plant is also still vulnerable to further quakes and tsunami.

But the storage capacity is eventually expected to run short, raising the possibility that Tepco may resort to dumping low-level radioactive water in the Pacific Ocean, a plan the utility said it was considering in December but gave up on due to opposition from the fishing industry.

Outside the plant's premises, work to reduce the contamination level of land detected to have an annual exposure dose of 1 millisievert or more, excluding from natural sources, is scheduled to accelerate in eight prefectures in the Tohoku region.

Talks are also under way between the central government and municipalities located near the stricken plant to build a facility in Fukushima Prefecture to store the removed soil for an undetermined period of time.

The government aims to select the location for the interim storage facility in fiscal 2012, but the eight municipalities under consideration have not yet reached a consensus and it remains to be seen if the plan will move forward.

Reflecting the sensitivity of the matter, a gathering between the central government and the municipalities planned for Feb. 26 was abruptly canceled, with the mayor of one of the two towns that host the Fukushima plant expressing "strong mistrust" due to media reports that described in advance what the central government planned to discuss at the meeting.

Swift establishment of the facility is necessary to move the decontamination process forward and help people in Fukushima Prefecture restore their shattered lives.



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