Daunting tasks await Japan after cold shutdown of Fukushima plant

Kyodo News, Mainichi Shimbun, December 17, 2011

TOKYO (Kyodo) — Japan on Friday finally declared a state of cold shutdown at the crisis-hit Fukushima Daiichi nuclear power plant, only to find itself facing a long and thorny road toward the goal of scrapping the stricken reactors and restoring shattered public confidence in the government’s nuclear policies.

The country plans to draw on the experience of the 1979 Three Mile Island accident in taking out the nuclear fuel from the plant’s Nos. 1 to 3 reactors, but the task will be more challenging than in the U.S. case because the fuel is believed to have melted through the base of the reactor pressure vessels.

“A prolonged and enduring effort will be necessary for the decommissioning, along with work that requires an extremely flexible mind. The government will act responsibly in such medium- to long-term measures,” nuclear disaster minister Goshi Hosono told a press conference.

Hosono also said he expects the decommission work to take 30 years or more, which experts think may require top-level technology that would be used for the first time in the world.

It took about 11 years to defuel the Three Mile Island Unit 2, which suffered severe damage to the reactor core. In the case of the Fukushima Daiichi plant disaster, a panel of experts set up under Japan’s Atomic Energy Commission said in a recent report the plant operator Tokyo Electric Power Co. should aim to start taking out the fuel within 10 years after the shutdown.

But many uncertainties remain regarding how the next decade will unfold, let alone the next 30 years. Panel head Hajimu Yamana, a Kyoto University professor, said in drafting the report that the panel has decided to propose the goal of commencing within 10 years the work of removing fuel from the damaged reactors, but added it “would not be possible to make a firm commitment to do so.”

“At this moment, we cannot say anything for sure until we take a look inside the reactor core,” Yamana told reporters in late October.

Before taking the fuel out of the reactors, workers are expected to start within two years removing spent nuclear fuel stored in pools inside the Nos. 1 to 4 reactor buildings. They also must repair the damaged primary containment vessels of the Nos. 1 to 3 reactors so the vessels can be filled with water to block radiation.

But doubts remain over the method of flooding the vessels because the utility known as TEPCO once tried in the past to create a system to cool the reactors and later gave up, while the report said there is currently no alternative method to take out the fuel.

The report, which highlights the tasks TEPCO will have to deal with in the medium to long term, also said no existing technology is capable of recovering fuel which has melted through a reactor pressure vessel and is accumulating at the outer primary container.

Tadahiro Katsuta, an associate professor at Meiji University specializing in nuclear engineering and nuclear policy, warns that the government and TEPCO should not rush toward actual decommissioning work without grasping more accurately the conditions of the melted fuel.

“I feel there is a view within the government to ’put a lid on stinky things’ (by moving ahead with the process of scrapping)…But much time is needed for preparation, possibly more than 10 years, to get to know where the fuel is located and think about how work can proceed with minimum radiation exposure,” he said.

Hiroshi Tasaka, who served as a special adviser to the prime minister for about five months after the nuclear crisis erupted on March 11, has said that a cold shutdown is “just the beginning” of further problems created by the Fukushima accident.

“It is fine that the facility to clean radioactive water (created by cooling the melted fuel) is moving smoothly. But I must mention that the water treatment process is creating massive amounts of highly radioactive waste, left in places such as filters. It is just moving a problem from one place to another,” he said.

He also said that there is a more important task than the reinforcement of nuclear safety for the government now, which is to restore public trust in its handling of nuclear issues.

“No matter how much a government spokesman talks about safety now, it will mean nothing to the public if the government is not trusted,” said the Tama University professor of nuclear safety and radioactive waste.

The government has decided to separate the nuclear regulatory body from the Ministry of Economy, Trade and Industry, which has also played a role in promoting nuclear power. It is creating a new nuclear safety agency as a step toward enhanced nuclear safety regulation.

But a mere organizational change is not enough, experts say.

“The government must carry out reforms that can ensure the highest level of safety in terms of personnel, organization, system and culture” to help restore public trust, Tasaka said.

He noted the need, for example, to increase the number of personnel of the new regulatory agency to a level closer to the U.S. Nuclear Regulatory Commission, which employs about 4,000 people, and to strictly train regulators to avoid cozy relationships with related organizations.

But Tasaka added that there is still a long list of questions the government should respond to, including how to dispose of high-level radioactive waste, what would be the long-term impact of radioactive substances released into the environment, and whether nuclear power generation is truly as cheap an energy source as thought earlier.

“Responding to public questions in a sincere manner is where the government should start,” Tasaka said.

Kyodo Press, December 17, 2011
http://mdn.mainichi.jp/mdnnews/nati…

Condition of Fukushima Daiichi plant declared to be in cold shutdown

TOKYO (Kyodo) — The following is the current condition of the Fukushima Daiichi nuclear power plant, which paved the way for the government to announce Friday that the complex has achieved a stable state of cold shutdown.

— The temperature at the bottom of the reactor pressure vessels of the crippled Nos. 1 to 3 units is being kept below 100 C, while that of the water in the spent fuel pools of the Nos. 1 to 4 units is being kept below 25 C.

— The amount of radioactive substances currently being released from the reactors equals the radiation level at the boundary of the plant below the government-set target limit of 1 millisievert per year.

— The water circulation system to keep reactors cool has multiple backups. Even if all the equipment fails, water injection can be resumed in about three hours by using fire trucks.

— The radiation level of below 1 millisievert per year can be maintained even in the event water injection into the Nos. 1 to 3 reactors stops for 12 hours.

— A nuclear chain reaction called “recriticality” is unlikely but can be prevented by injecting water containing boric acid.

— A system to cool spent fuel pools has multiple backups. Even if the system fails, it would take at least around 16 days until the water in the No. 4 unit’s spent fuel pool, which holds a larger amount of fuel than the other three, drops below the necessary level.

— A system to process highly radioactive water accumulating at the plant is capable of reducing radioactive cesium to below one ten-thousandth of the original level.

Kyodo Press, December 17, 2011
http://mdn.mainichi.jp/mdnnews/nati…

On this matter, see on ESSF (article 23829): Few believe assertion that Fukushima crisis is over
Decommissioning Fukushima plant to take max. 40 years

It will take 30 to 40 years for Tokyo Electric Power Co. (TEPCO) and the government to decommission the No. 1-4 reactors at the crippled Fukushima No. 1 nuclear plant, according to a road map made available to the Mainichi Shimbun on Dec. 15.

The road map was drawn up by the utility and the Ministry of Economy, Trade and Industry (METI), and will be released after a joint government-TEPCO declaration set for Dec. 16 stating the Fukushima plant has achieved a stable “cold shutdown.”

With the nuclear crisis triggered by the March 11 earthquake and tsunami under control, the government and TEPCO are prepared to decommission the four reactors in three phases. During the first phase set to run from next year to 2014, a common pool south of the four reactors will be emptied, the spent nuclear fuel in pools at each reactor building will be removed and shifted to the common pool, starting with the fuel at the No. 4 reactor. Repair work on the containment vessels and work to fill the vessels with water to block radiation will run from 2015 to 2021, and extraction of the melted fuel in the reactors will be started by 2022.

A Japan Atomic Energy Commission expert panel had initially proposed starting the work to remove fuel from pools after 2015, but that date was moved up one year at nuclear disaster minister Goshi Hosono’s instructions.

In the second phase, the damaged containment vessels will be repaired before being filled with water. In the third phase, TEPCO and the government will deploy remote-controlled cranes to collect the melted fuel rods — a process which will take at least 30 years and a maximum of 40 years.

There are 3,108 fuel rods in the pools of the four reactor buildings, and another 1,496 fuel rods inside reactors No. 1-3. TEPCO and the government must extract them to decommission the four reactors.

Mainichi Shimbun, December 16, 2011
http://mdn.mainichi.jp/mdnnews/nati…

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