Friday, July 10, 2020
Home Japan Fukushima Well on It’s Way to “Cold Shutdown”

Fukushima Well on It’s Way to “Cold Shutdown”

The news from Fukushima has largely been good recently, since the temperature of the nuclear reactors at the Fukushima #1 power plant have been steadily reduced. The government has redefined cold shutdown to include the state of the power plant releasing only up to 1 millisievert per year. This is hoped to be achieved by the end of the year, and this is a very good sign. But is it too early to celebrate, or can we relax a little knowing that things are much safer than before?

From the Japan Times (bolds are mine):

Tokyo Electric Power Co. reported Wednesday that the bottom of all three crippled reactors’ pressure vessels at its Fukushima No. 1 nuclear plant were now below 100 degrees — a collective first since the crisis erupted after the March 11 temblor-tsunami catastrophe.

The temperature of reactor 2, which had remained over 100 degrees, had fallen to 99.40 as of 5 p.m. Wednesday. The temperature for reactor 1 has been under 100 degrees since late July, and the same condition was reached for reactor 3 on Sept. 5.

Lowering the temperature of the bottom of the pressure vessels below 100 degrees is a key condition for achieving their cold shutdown, which the government and Tepco seek to establish by year’s end.

“Although the temperature (of reactor 2) has been showing a falling tendency overall, the temperature of the bottom of the pressure vessel has gone up and down, so it is still too early to (make a definitive conclusion),” Tepco spokesman Junichi Matsumoto told an evening press conference at the utility’s headquarters.

Tepco has been employing a sprinkler system approach, using pipes to spread an increasing amount of coolant water over the melted core of reactor 2. As of 5 p.m. Wednesday, the temperatures for reactors 1 to 3 were hovering between 78 and 79 degrees.

In regular reactor operations, a cold shutdown means the reactor-core coolant temperatures are under 100 degrees.
But because reactors 1, 2 and 3 are damaged and their fuel rod cores melted down, the government redefined the concept of their cold shutdown. One condition is to cool the temperature of the bottom of the pressure vessel below 100 and another is to keep the radiation leakage from the three reactors under 1 millisievert per year around the plant.

Reuters notes that nuclear crisis officials are optimistic about a cold shutdown by the end of this year.

The government and the Tokyo Electric Power Co (Tepco) utility that operated the plant had earlier said they planned to achieve cold shutdown by January.

“We will move up the existing target period and endeavour to achieve this cold shutdown by the end of this year,” Nuclear Disaster Minister Goshi Hosono said at the annual member state gathering of the International Atomic Energy Agency (IAEA)in Vienna.

IAEA head Yukiya Amano had said last week that the reactors at Fukushima were “essentially stable” six months after the world’s worst nuclear disaster in a quarter of a century.

Fuel rods in three reactors at the complex started melting down when power and cooling functions failed after it was hit by the earthquake and tsunami.

Tepco this month edged a step closer to its goal of bringing the reactors to a state of cold shutdown as the temperature at the second of three damaged units fell below boiling point.

Cold shutdown occurs when water used to cool nuclear fuel rods remains below 100 degrees Celsius, preventing the fuel from reheating.

But Business Week suggests that the damage has already been done, both directly and indirectly affecting the farming and tourism industries.

Takako Harada, 80, returned to an evacuated area of Iitate village to retrieve her car. Beside her house is an empty cattle pen, the 100 cows slaughtered on government order after radiation from the March 11 atomic disaster saturated the area, forcing 160,000 people to move away and leaving some places uninhabitable for two decades or more.

“Older folks want to return, but the young worry about radiation,” said Harada, whose family ran the farm for 40 years. “I want to farm, but will we be able to sell anything?”

What’s emerging in Japan six months since the nuclear meltdown at the Tokyo Electric Power Co. plant is a radioactive zone bigger than that left by the 1945 atomic bombings at Hiroshima and Nagasaki. While nature reclaims the 20 kilometer (12 mile) no-go zone, Fukushima’s $3.2 billion-a-year farm industry is being devastated and tourists that hiked the prefecture’s mountains and surfed off its beaches have all but vanished.

The March earthquake and tsunami that caused the nuclear crisis and left almost 20,000 people dead or missing may cost 17 trillion yen ($223 billion), hindering recovery of the world’s third-largest economy from two decades of stagnation.

And the Japan Times also reports that celebrating may be premature.

On Sept. 20, Tepco estimated the annual radiation level around the plant at 0.4 millisievert, although it said measurements were needed at more locations.

This means Tepco may have achieved its cold shutdown goal, but Matsumoto admitted further monitoring is needed because the Nuclear and Industrial Safety Agency is expected to take more time to evaluate whether this status can be declared.
Even if a cold shutdown is achieved, the government and Tepco are still unsure of the extent of the melted fuel cores and of the reactor damage.

Thus experts say there is still a long way to go before an end to the nuclear crisis can be declared, even if the cold shutdown is achieved.

It’s a shame that it has taken six months to make such progress, but at least it seems like the situation is more under control than it has been since the beginning of the crisis. And curiously, I haven’t seen a great deal of press about this outside Japan.

Regardless, you can expect to hear more good news from Japan in the coming months, which is always something I’m happy to see.

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