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August 19, 2018

Ukraine's recent nuclear reactor scare harkens back to ghosts of historic nuclear accidents

One of the reactors in Europe’s largest nuclear power plant in southern Ukraine suffered an accident that triggered an automatic shutdown this week. Reports suggest that damage occurred to a transformer in one of the 1000-megawatt reactors at the Zaporizhye plant, which provides over one-fifth of the country’s electricity.

Ukraine’s energy minister said that it was a “technical fault” and assured the public that there was “no threat” to the reactor’s safety, according to BBC News

With the country already suffering fuel shortage, Ukraine this winter will probably be forced to import electricity from Russia.

Accidents at nuclear rectors makes folks understandably nervous, and is also a reminder that despite all the climate change benefits we get from nuclear energy – like cutting greenhouse gas emissions – there are a lot of risks associated with it, too.

Three Mile Island, Chernobyl and Fukushima all grabbed the world’s attention over the past 30 years when the crises unfolded at those plants. But what happened after they left the headlines?

The worst-ever U.S. nuclear accident at Three Mile Island, near Middletown, Pennsylvania, was a partial meltdown that occurred on March 28, 1979

The facility was only 3 months old when a cooling problem caused one of the reactors to overheat and release radioactive gases and iodine into the environment, but it wasn’t enough to cause any confirmed health effects to local residents.

The reactor was shut down permanently, was decontaminated and put into what is known as “post-defueled monitored storage,” with plans for dismantling only after its neighbouring reactor on site is shut down sometime in 2034.

In April 1986, the world’s worst nuclear disaster occurred at Ukraine’s Chernobyl power plant. technicians lost control of nuclear fission reactions in the reactor core and heat rose quickly until pressure built up and explored the core, releasing radioactive steam into the atmosphere. After the initial explosion occurred, fire broke out that sent large clouds of radioactive particles high into the air, which was then swept over a large part of Western Europe. 

Thirty-one people – technicians and firefighters mostly – died from the accident itself, and untold thousands may have contracted cancer. Exact numbers are still being debated

If you want to see the devastation that this nuclear accident wrought in its immediate surroundings check out newly-released video footage obtained via a remote-controlled drone. This is the first time that the nearby ghost town Pripyat has been filmed from the air.

The power plant itself is entombed within an aging concrete structure that was hastily built back during the old Soviet era.

Currently, an internationally-funded project is underway to build a massive 32,000 ton metal arch that will contain the entire building. Hopes are that it will be ready by 2017, before the existing shelter collapses and releases more radioactive-laden dust into the atmosphere like a dirt bomb. It is expected that the arch should last anywhere from 100 to 300 years.

Finally, the March 2011 Japanese earthquake and tsunami showed us that there can be natural forces that have to be considered with nuclear power. The Fukushima Daiichi power plant, located 220 km northeast of Tokyo on Japan’s east coast, had three of its six reactors melt down when it got hit by tsunami waves triggered by a 9.0 earthquake. This knocked out its generators which caused its reactors to overheat, explode and release radioactivity into the environment – contaminating food, water and air.  

Over 300,000 people were evacuated from the surrounding villages. Nearly 16,000 residents are still unable to return to their homes because clean up efforts are being hindered by unsafe levels of radiation in the soil and water.

All this radiation from the disaster has definitely not been isolated to just Japan. Researchers monitoring the Pacific Ocean, in which much of the radiation spilled into, have detected radioactive isotopes this past November just 160 km off the coast of California.

So this story will continue to unfold for many years to come.

See the original article here – 

Ukraine's recent nuclear reactor scare harkens back to ghosts of historic nuclear accidents

Japan's nuclear cleanup stymied by water woes

OKUMA, Japan (AP) — More than three years into the massive cleanup of Japan’s tsunami-damaged nuclear power plant, only a tiny fraction of the workers are focused on key tasks such as preparing for the dismantling of the broken reactors and removing radioactive fuel rods.

Instead, nearly all the workers at the Fukushima Dai-ichi plant are devoted to an enormously distracting problem: a still-growing amount of contaminated water used to keep the damaged reactors from overheating. The amount has been swelled further by groundwater entering the reactor buildings.

Hundreds of huge blue and gray tanks to store the radioactive water, and buildings holding water treatment equipment are rapidly taking over the plant, where the cores of three reactors melted following a 2011 earthquake and tsunami. Workers were building more tanks during a visit to the complex Wednesday by foreign media, including The Associated Press.

“The contaminated water is a most pressing issue that we must tackle. There is no doubt about that,” said Akira Ono, head of the plant. “Our effort to mitigate the problem is at its peak now. Though I cannot say exactly when, I hope things start getting better when the measures start taking effect.”

The numbers tell the story.

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6,000 WORKERS

Every day, about 6,000 workers pass through the guarded gate of the Fukushima Dai-ichi plant on the Pacific coast — two to three times more than when it was actually producing electricity.

On a recent work day, about 100 workers were dismantling a makeshift roof over one of the reactor buildings, and about a dozen others were removing fuel rods from a cooling pool. Most of the rest were dealing with the contaminated water, said Tatsuhiro Yamagishi, a spokesman for Tokyo Electric Power Co., or TEPCO, the utility that owns the plant.

The work threatens to exhaust the supply of workers for other tasks, since employees must stop working when they reach annual radiation exposure limits. Experts say it is crucial to reduce the amount and radioactivity of the contaminated water to decrease the risk of exposure to workers and the environmental impact before the decommissioning work gets closer to the highly contaminated core areas.

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40 YEARS

The plant has six reactors, three of which were offline when disaster struck on March 11, 2011. A magnitude-9.0 earthquake triggered a huge tsunami which swept into the plant and knocked out its backup power and cooling systems, leading to meltdowns at the three active reactors.

Decommissioning and dismantling all six reactors is a delicate, time-consuming process that includes removing the melted fuel from a highly radioactive environment, as well as all the extra fuel rods, which sit in cooling pools at the top of the reactor buildings. Workers must determine the exact condition of the melted fuel debris and develop remote-controlled and radiation-resistant robotics to deal with it.

Troubles and delays in preparatory stages, including the water problem and additional measures needed to address environmental and health concerns in removing highly radioactive debris from atop reactor buildings that exploded during meltdowns, have pushed back schedules on the decommissioning roadmap. Recently, officials said the government and TEPCO plan to delay the planned start of fuel removal from Units 1 and 2 by about 5 years.

The process of decommissioning the four reactors is expected to take at least 40 years.

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500,000 TONS

The flow of underground water is doubling the amount of contaminated water and spreading it to vast areas of the compound.

Exposure to the radioactive fuel contaminates the water used to cool the melted fuel from inside, and much of it leaks and pours into the basements of the reactors and turbines, and into maintenance trenches that extend to the Pacific Ocean. Plans to freeze some of the most toxic water inside the trench near the reactors have been delayed for at least 8 months due to technical challenges.

The plant reuses some of the contaminated water for cooling after partially treating it, but the additional groundwater creates a huge excess that must be pumped out.

Currently, more than 500,000 tons of radioactive water is being stored in nearly 1,000 large tanks which now cover large areas of the sprawling plant. After a series of leaks last year, the tanks are being replaced with costlier welded ones.

That amount dwarfs the 9,000 tons of contaminated water produced during the 1979 partial meltdown of the Three Mile Island nuclear plant in the United States. At Three Mile Island, it took 14 years for the water to evaporate, said Lake Barrett, a retired U.S. nuclear regulatory official who was part of the early mitigation team there and has visited the Fukushima plant.

“This is a much more complex, much more difficult water management problem,” Barrett said.

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10 TRILLION YEN

An estimated 2 trillion yen ($18 billion) will be needed just for decontamination and other mitigation of the water problem. Altogether, the entire decommissioning process, including compensation for area residents, reportedly will cost about 10 trillion yen, or about $90 billion.

All this for a plant that will never produce a kilowatt of energy again.

About 500 workers are digging deep holes in preparation for a taxpayer-funded 32 billion yen ($290 million) underground “frozen wall” around four reactors and their turbine buildings to try to keep the contaminated water from seeping out.

TEPCO is developing systems to try to remove most radioactive elements from the water. One, known as ALPS, has been trouble-plagued, but utility officials hope to achieve its daily capacity of 2,000 tons when they enter full operation next month following a final inspection by regulators.

Officials hope to treat all contaminated water by the end of March, but that is far from certain.

This article:  

Japan's nuclear cleanup stymied by water woes

Report finds gaps in US nuclear disaster plans

Washington (AFP) – US nuclear plants must better prepare for the risk of natural disasters like earthquakes, tsunamis and floods, said a report Thursday on lessons learned from Japan’s Fukushima crisis in 2011.

Current approaches to regulating nuclear safety “are clearly inadequate for preventing core-melt accidents and mitigating their consequences,” the report said.

As of now, US safety regulations are based on making sure nuclear plants can withstand equipment failures, loss of power and other malfunctions related to the design of the plant, otherwise known as design-basis events.

But history has shown that the biggest nuclear accidents — including at Fukushima Daiichi, Three Mile Island and Chernobyl — “were all initiated by beyond-design-basis events,” said the report.

Things like natural disasters, human errors and power outages “have the potential to affect large geographical regions and multiple nuclear plants,” said John Garrick, a nuclear engineer and co-author of the report.

“These include earthquakes, tsunamis and other geographically extensive floods and such things as geomagnetic disturbances,” he told reporters.

Titled “Lessons Learned from the Fukushima Nuclear Accident for Improving the Safety of US Plants,” the report was commissioned by Congress from the National Academy of Sciences, a non-governmental group of experts that provides scientific and policy advice.

– Call to update plans –

The March 11, 2011 earthquake and tsunami knocked out power to the Fukushima Daiichi plant, causing severe core damage in three reactors, releases of radioactive material, widespread evacuations and the eventual shutdown of all nuclear power plants in Japan.

The report did not find fault with Japan’s actions before or after the incident.

Rather, it called for nuclear plants and US nuclear regulators to actively seek out the latest scientific data on risks and revise their plans accordingly.

The United States operates 100 nuclear power reactors, whose safety procedures are overseen by the Nuclear Regulatory Commission.

Nuclear plants should be ready to respond to a wide-spanning natural disaster that could damage infrastructure and disperse radioactive material beyond their 10-mile (16-kilometer) emergency planning zone, the report said.

It cited a number of off-site events that could interfere with electrical power to nuclear operations, from terrorism to human error to geomagnetic disturbances caused by solar storms that interrupt the electrical grid.

“There is some new evidence now that some of these events are not as rare as perhaps we thought,” said Garrick.

– Better understanding of risks –

The report did not include an in-depth examination of US preparedness for a nuclear accident, nor did it set a new safety threshold for whether US nuclear plants should be allowed to operate.

However, it said nuclear plants should examine emergency plans for backup sources of power as well as safety systems for monitoring reactors and spent-fuel pools.

It also recommended improved training for nuclear plant operators who may need to cope with unexpected disasters, and urged the US government to “incorporate modern risk concepts into its nuclear safety regulations.”

Risks of natural disaster are not necessarily greater than ever before, but experts now have a better understanding of their potential impacts, said the study authors.

Particular care should be given to treatment and evacuation of children, the elderly and the ill in case of a nuclear accident, the report added.

A number of changes have already been called for in the wake of the Fukushima Daiichi disaster, said study director Kevin Crowley.

“Since the accident, in the United States and in many other countries, there have been a great many efforts to understand the lessons and to implement changes,” Crowley told reporters.

“It is really too early to know just how they are going to turn out,” he said.

See original article:

Report finds gaps in US nuclear disaster plans

Fukushima study: Think about unthinkable disasters

WASHINGTON (AP) — A U.S. science advisory report says Japan’s Fukushima nuclear accident offers a key lesson to the nation’s nuclear industry: Focus more on the highly unlikely but worst case scenarios.

That means thinking about earthquakes, floods, tsunamis, solar storms, multiple failures and situations that seem freakishly unusual, according to Thursday’s National Academy of Sciences report. Those kinds of things triggered the world’s three major nuclear accidents.

“We need to do a soul searching when it comes to the assumptions” of how to deal with worst case events, said University of Southern California engineering professor Najmedin Meshkati, the panel’s technical adviser. Engineers should “think about something that could happen once every, perhaps 1,000 years” but that’s not really part of their training or nature, he said.

“You have to totally change your mode of thinking because complacency and hubris is the worst enemy to nuclear safety,” Meshkati said in an interview.

The report said the 2011 Japanese accident, caused by an earthquake and tsunami, should not have been a surprise. The report says another Japanese nuclear power plant also hit by the tsunami was closer to the quake’s fault. But the Onagawa plant wasn’t damaged because quakes and flooding were considered when it was built.

Onagawa had crucial backup electricity available for when the main power went down, as opposed to Fukushima which had emergency generators in a basement that flooded. Onagawa’s operators had “a different mindset” than the executives who ran Fukushima, Meshkati said.

The other two nuclear accidents — at Pennsylvania’s Three Mile Island and Ukraine’s Chernobyl— were caused by multiple system failures.

Lee Clarke, a Rutgers University risk expert and author of the book “Worst Cases,” criticized the academy’s report as too weak. He said the tone of the report made it seem like the accident was unpredictable and caught reasonable people by surprise “and it shouldn’t have.” But the report itself said the “the Fukushima accident was not a technical surprise.”

David Lochbaum of the activist group Union of Concerned Scientists said the problem is that federal law financially protects the U.S. nuclear industry from accidents gives utilities little incentive to spend money on low-probability, high-consequence problems.

But Nuclear Energy Institute senior vice president Anthony Pietrangelo said the American nuclear industry has already taken several steps to shore up backup power and deal with natural disasters.

“We cannot let such an accident happen here,” he said in a statement.

Another issue the report raised was about how far radiation may go in a worst case accident.

The U.S. Nuclear Regulatory Commission orders plants to have emergency plans for a zone of 10 miles around a nuclear plant. But the academy study said Fukushima showed that “may prove inadequate” if a similar accident happened in the U.S. People nearly 19 miles away in Japan needed protection from radiation. But the committee would not say what would be a good emergency zone.

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Online:

National Academy Report: http://bit.ly/1pMeTAX

Source:

Fukushima study: Think about unthinkable disasters