Fukushima Daiichi reactors internal estimates by Tepco



In dismantling the Fukushima Daiichi nuclear power plant, it is essential to grasp the state of nuclear fuel melted its nuclear reactors, but the radiation is very high and it is difficult to see inside. Under these circumstances, TEPCO announced a new estimate chart for the interior of the three nuclear reactors.

TEPCO announced the estimate inside the nuclear reactors at the International Forum on Waste Plant on the July 3rd, 2017. In the inside of the nuclear reactor of Unit 3, a part of the nuclear fuel collapsed to the bottom of the pressure vessel and is stacked like a garbage while keeping its shape. Meanwhile, it seems that molten nuclear fuel has fallen to the bottom of the storage container beneath, but when analyzing the data at the time of the accident again, it is said that there is a possibility that it is eroding the concrete on the floor of the containment vessel .

Estimates were obtained reflecting computer simulations and recent internal surveys, etc. Based on these estimates, the government decided how to remove “fuel debris”.




Where to put all the radioactive waste is now the burning issue

decommission 5 reactors 20 04 2017.jpg


The call might have been made to decommission five over-the-hill nuclear reactors, but the problem remains of where to dispose of their total 26,820 tons of radioactive waste.

The plant operators have yet to find disposal sites, and few local governments are expected to volunteer to store the waste on their properties.

The decommissioning plans for the five reactors that first went into service more than 40 years ago was green-lighted by the Nuclear Regulation Authority on April 19.

It is the first NRA approval for decommissioning since the 2011 Fukushima nuclear disaster triggered by the Great East Japan earthquake and tsunami.

That disaster led to a new regulation putting a 40-year cap, in principle, on the operating life span of reactors.

The reactors to be decommissioned are the No. 1 reactor at Japan Atomic Power Co.’s Tsuruga plant in Fukui Prefecture; the No. 1 reactor at Kyushu Electric Power Co.’s Genkai plant in Saga Prefecture; the No. 1 and No. 2 reactors at Kansai Electric Power Co.’s Mihama plant in Fukui Prefecture; and the No. 1 reactor at Chugoku Electric Power Co.’s Shimane plant in Shimane Prefecture.

The decommissioning will be completed between fiscal 2039 and fiscal 2045 at a total cost of 178.9 billion yen ($1.64 billion), according to the utilities.

In the process, the projects are expected to produce 26,820 tons of radioactive waste–reactors and pipes included.

An additional 40,300 tons of waste, such as scrap construction material, will be handled as nonradioactive waste due to radiation doses deemed lower than the government safety limit.

Securing disposal sites for radioactive waste has proved a big headache for utilities.

About 110 tons of relatively high-level in potency radioactive waste, including control rods, are projected to pile up from the decommissioning of the No. 1 reactor at the Mihama plant.

Such waste needs to be buried underground deeper than 70 meters from the surface and managed for 100,000 years, according to the NRA’s guidelines.

In addition, the decommissioning of the same reactor will generate 2,230 tons of less toxic waste as well, including pipes and steam generators.

Under the current setup, utilities must secure disposal sites on their own.

Kansai Electric, the operator of the Mihama plant, has pledged to find a disposal site “by the time the decommissioning is completed.”

But Fukui Prefecture, which hosts that plant and others, is demanding the waste from the Mihama facility be disposed of outside its borders.

The project to dismantle the reactor and other facilities has been postponed at Japan Atomic Power’s Tokai plant in Ibaraki Prefecture because the company could not find a disposal site for the relatively high-level waste.

The decommissioning of the reactor had been under way there since before the Fukushima disaster.

The expected difficulty of securing disposal sites could jeopardize the decommissioning timetable, experts say.

Even finding a disposal site for waste that will be handled as nonradioactive has made little headway.

What is more daunting is the hunt for a place to store high-level radioactive waste that will be generated during the reprocessing of spent fuel, they said.


Japan to scrap 5 more nuclear reactors

String of facilities approaching maximum life span

0420N-Decommissioning-Business_article_main_image.jpgWorkers take apart a pump at Chubu Electric Power’s Hamaoka nuclear plant.

TOKYO — Five nuclear reactors in Japan were approved for decommissioning on Wednesday, pushing utilities and other companies to join hands to tackle both the great business opportunities and daunting technical problems involved with the process.

Two reactors at Kansai Electric Power‘s Mihama plant, as well as one each at Japan Atomic Power’s Tsuruga plant, Chugoku Electric Power‘s Shimane plant and Kyushu Electric Power‘s Genkai facility received the green light from Japan’s Nuclear Regulation Authority. The safety updates needed to keep them running beyond their mandated 40-year life span were deemed too costly.

Japan had 54 nuclear reactors before the 2011 meltdown at the Fukushima Daiichi nuclear plant. A total of 15, including the six at Fukushima Daiichi, are now set to be taken out of service. Another one or two will be brushing up against the 40-year limit every year, unless one-time, 20-year extensions are sought and granted.

Companies now face a pressing need to acquire expertise on dismantling reactors and disposing of radioactive materials. No commercial nuclear reactor has ever been decommissioned in Japan before, and utilities are looking for partners with the necessary capabilities.

Kansai Electric is seeking help from France’s Areva and Japan’s Mitsubishi Heavy Industries in decommissioning the Nos. 1 and 2 reactors at Mihama, particularly in decontaminating pipes and equipment. Japan Atomic Power and U.S.-based EnergySolutions signed an agreement last spring to cooperate on the former’s Tsuruga plant.

Japanese utilities are also beginning to work with each other. Kansai Electric entered a partnership last year with Kyushu Electric, Chugoku Electric and Shikoku Electric Power. The four plan to cut decommissioning costs by jointly procuring materials and sharing technology and staffers. 

Other players are also angling for a piece of the pie. Two years ago, Mitsubishi Heavy set up a department specializing in dismantling nuclear reactors. The company was a key player in building the Mihama and Genkai reactors, and wants a lead role in taking them apart. Japanese general contractor Shimizu also signed a technical cooperation agreement with U.K.-based Cavendish Nuclear.

Utilities have increased their rates in order to raise the necessary funds to decommission the five newly approved reactors. They have already come up with about 160 billion yen ($1.47 billion) of the estimated 180 billion yen total. But the process will likely take two or three decades, and costs could easily grow.

The utilities may also face significant challenges to disposing of the roughly 27,000 tons of contaminated waste the five reactors are expected to generate. For example, Japan Atomic Power wants to bury less radioactive materials at the site of the Tokai nuclear plant, one of the earlier plants approved for decommissioning, but faces strong local opposition.

Relevant legislation has not been finalized either. Highly contaminated materials are supposed to be buried more than 70 meters below ground. But the Nuclear Regulation Authority has only just begun debating exactly how they should be buried.


5 Reactors Decommissioning Approved


Decommissioning plans for 5 reactors approved

Japan’s nuclear regulator has approved plans submitted by operators of 4 power plants to decommission 5 aging nuclear reactors. The reactors are to be scrapped in a process lasting up to nearly 30 years.

The Nuclear Regulation Authority approved the plans at a meeting on Wednesday.

Under a government policy introduced after the 2011 nuclear accident at the Fukushima Daiichi plant, reactor lifespan was limited to 40 years in principle.

In 2015, utility companies decided to dismantle the 5 reactors. The 5 include 2 reactors at the Mihama plant and one at the Tsuruga plant, both in Fukui Prefecture, one at the Shimane plant in Shimane Prefecture and one at the Genkai plant in Saga Prefecture.

The plans call for first decontaminating pipes and dismantling facilities that are free of radioactive contamination.

The operators assume that the reactors and their buildings will be taken down and removed by fiscal 2045 at the latest.

At issue is where to put control rods, reactor parts and other radioactive waste. No site for a final disposal facility has been designated.

The regulator is checking another decommissioning plan for a reactor at the Ikata plant in Ehime Prefecture. The facility’s operator decided last year to dismantle it.



Nuclear authority approves decommissioning plans for 5 aging reactors

TOKYO (Kyodo) — Japan’s nuclear authority approved decommissioning plans for five aging reactors at four power plants on Wednesday, the first such approvals since a government regulation was implemented after the 2011 Fukushima disaster to stop the operation of reactors beyond 40 years.

The five reactors are the Nos. 1 and 2 units at Kansai Electric Power Co.’s Mihama plant in Fukui Prefecture, the No. 1 unit at Japan Atomic Power Co.’s Tsuruga plant in Fukui Prefecture, the No. 1 unit at Chugoku Electric Power Co.’s Shimane plant in Shimane Prefecture and the No. 1 unit at Kyushu Electric Power Co.’s Genkai plant in Saga Prefecture.

While the utilities indicated it will take about 30 years to complete the decommissioning of each reactor, the disposal sites for the radioactive waste from the facilities have yet to be determined.

The decommissioning work will involve removing spent fuel from pools, dismantling reactors and demolishing surrounding facilities.

The regulation brought in following the 2011 disaster at Tokyo Electric Power Co.’s Fukushima Daiichi plant prohibits nuclear reactors from operating for over 40 years in principle, but the Nuclear Regulation Authority can approve the operation of a unit for up to 20 more years if the operator makes safety upgrades and the unit passes screening.

It was decided in March 2015 to scrap the five reactors, mainly due to profitability, as huge amounts of additional investment would be needed to meet the new safety requirements to keep the reactors operating beyond 40 years.

Meanwhile, the authority has given approval for the extended operation of the No. 3 unit at Kansai Electric’s Mihama plant as well as the Nos. 1 and 2 units at its Takahama plant in Fukui Prefecture, which are also around 40 years old.

The authority is currently examining Shikoku Electric Power Co.’s decommissioning plan for the No. 1 unit at the Ikata plant in Ehime Prefecture, after the utility decided in March 2016 to scrap the reactor.

In Wednesday’s meeting, the authority also decided that Japan Nuclear Fuel Ltd.’s uranium enrichment facility in the village of Rokkasho, Aomori Prefecture, satisfies regulatory requirements, virtually giving a green light for its operation. The decision will become official after consultation with the industry minister.

It will become the second fuel plant to clear new regulatory requirements after Global Nuclear Fuel-Japan Co.’s plant in Kanagawa Prefecture.


Nuclear Reactor Design Chosen – Not Because It Was Safe – But Because It Worked On Navy Submarines

From June 20, 2011

Virtually all of the nuclear reactors in the U.S. are of the same archaic design as those at Fukushima (Indeed, MSNBC notes that there are 23 U.S. reactors which are more or less identical to those at Fukushima.)

Called “light-water reactors”, this design was not chosen for safety reasons. Rather, it was chosen because it worked in Navy submarines.

Specifically, as the Atlantic reported in March:

In the early years of atomic power, as recounted by Alvin Weinberg, head of Oak Ridge National Laboratory in his book The First Nuclear Era, there was intense competition to come up with the cheapest, safest, best nuclear reactor design.

Every variable in building an immensely complex industrial plant was up for grabs: the nature of the radioactive fuel and other substances that form the reactor’s core, the safety systems, the containment buildings, the construction substances, and everything else that might go into building an immensely complex industrial plant. The light water reactor became the technological victor, but no one is quite sure whether that was a good idea.

Few of these alternatives were seriously investigated after light water reactors were selected for Navy submarines by Admiral Hyman Rickover. Once light water reactors gained government backing and the many advantages that conferred, other designs could not break into the market, even though commercial nuclear power wouldn’t explode for years after Rickover’s decision. “There were lots and lots of ideas floating around, and they essentially lost when light water came to dominate,” University of Strasbourg professor Robin Cowan told the Boston Globe in an excellent article on “technological lock-in” in the nuclear industry.

As it turned out, there were real political and corporate imperatives to commercialize nuclear power with whatever designs were already to hand. It was geopolitically useful for the United States to show they could offer civilian nuclear facilities to its allies and the companies who built the plants (mainly GE and Westinghouse) did not want to lose the competitive advantage they’d gained as the contractors on the Manhattan Project. Those companies stood to make much more money on nuclear plants than traditional fossil fuel-based plants, and they had less competitors. The invention and use of the atomic bomb weighed heavily on the minds of nuclear scientists. Widespread nuclear power was about the only thing that could redeem their role in the creation of the first weapon with which it was possible to destroy life on earth. In other words, the most powerful interest groups surrounding the nuclear question all wanted to settle on a power plant design and start building.


President Lyndon Johnson and his administration sent the message that we were going to use nuclear power, and it would be largely through the reactor designs that already existed, regardless of whether they had the best safety characteristics that could be imagined. [Nixon also fired the main government scientist developing safer types of reactors, because he was focused on safety instead of sticking with Nixon’s favored reactors.] We learned in later years that boiling water reactors like Fukushima are subject to certain types of failure under very unusual circumstances, but we probably would have discovered such problems if we’d explored the technical designs for longer before trying to start building large numbers of nuclear plants.

The Atomic Energy Commission’s first general manager – MIT professor Carroll Wilson – confirmed in 1979:

The pressurized water reactor was peculiarly suitable and necessary for a submarine power plant where limitations of space and wieght were extreme. So as interest in the civilian use of nuclear power began to grow, it was natural to consider a system that had already proven reliable in submarines. This was further encouraged by the fact that the Atomic Energy Commission provided funds to build the first civilian nuclear power plant … using essentially the same system as the submarine power plant. Thus it was that a pressurized light water system became the standard model for the world. Although other kinds of reactors were under development in different countries, there was a rapid scale-up of of the pressurized water reactor and a variant called the boiling water reactor developed by General Electric. These became the standard types for civilian power plants. in the United States and were licensed to be built in France, Germany, Japan and elsewhere.

If one had started to design a civilian electric power plant without the constraints of weight and space as required by the submarine, quite different criteria would apply.

(Wilson also notes that the engineers who built the original reactors didn’t really think about the waste or other basic parts of the plants’ life cycle.)

Ambrose Evans-Pritchard argues that there was another reason why all safer alternative designs – including thorium reactors – were abandoned:

The plans were shelved because thorium does not produce plutonium for bombs.

As Boing Boing notes:

Reactors like this [are] flawed in some ways that would be almost comical, were it not for the risk those flaws impart. Maybe you’ve wondered over the past couple of weeks why anyone would design a nuclear reactor that relied on external generators to power the pumps for it’s emergency cooling system. In a real emergency, isn’t there a decent chance that the backup generators would be compromised, as well?

It’s a good question. In fact, modern reactor designs have solved that very problem, by feeding water through the emergency cooling system using gravity, rather than powered pumps. Newer designs are much safer, and more reliable. But we haven’t built any of them in the United States …

Not the Navy’s Fault

This is in no way a criticism of the U.S. Navy or its submarine reactors. As a reader comments:

There are some things to know about Navy reactors:

  1. They don’t store thirty years worth of used, spent fuel rods next to the reactor.

  2. They don’t continue to operate a reactor that had a design life of 25 years for 60 years.

  3. The spent fuel pool is back on land on a base somewhere.

(In addition, the reactors on subs are much smaller than commercial reactors, and so have almost no consequences for the civilian population if they meltdown. And if an accident were to happen on a nuclear sub, the sub would likely sink or at least flood, presumably keeping the reactor from melting down in the first place.)

There Are No Independent Regulators and No Real Safety Standards

But at least the government compensates for the inherently unsafe design of these reactors by requiring high safety and maintenance standards.

Unfortunately, no …

As AP notes today:

Federal regulators have been working closely with the nuclear power industry to keep the nation’s aging reactors operating within safety standards by repeatedly weakening those standards or simply failing to enforce them.


Examples abound. When valves leaked, more leakage was allowed — up to 20 times the original limit. When rampant cracking caused radioactive leaks from steam generator tubing, an easier test of the tubes was devised so plants could meet standards.


Records show a recurring pattern: reactor parts or systems fall out of compliance with the rules; studies are conducted by the industry and government; and all agree that existing standards are “unnecessarily conservative.’’

Regulations are loosened, and the reactors are back in compliance.

Of course, the Nuclear Regulatory Commission – like all nuclear “agencies” worldwide – is 100% captured and not an independent agency, and the NRC has never denied a request for relicensing old, unsafe nuclear plants.

Indeed, Senator Sanders says that the NRC pressured the Department of Justice to sue the state of Vermont after the state and its people rejected relicensing of the Vermont Yankee plant, siding with the nuclear operator instead. The Nation notes:

Aileen Mioko Smith, director of Green Action Kyoto, met Fukushima plant and government officials in August 2010. “At the plant they seemed to dismiss our concerns about spent fuel pools,” said Mioko Smith. “At the prefecture, they were very worried but had no plan for how to deal with it.”

Remarkably, that is the norm—both in Japan and in the United States. Spent fuel pools at Fukushima are not equipped with backup water-circulation systems or backup generators for the water-circulation system they do have.

The exact same design flaw is in place at Vermont Yankee, a nuclear plant of the same GE design as the Fukushima reactors. At Fukushima each reactor has between 60 and 83 tons of spent fuel rods stored next to them. Vermont Yankee has a staggering 690 tons of spent fuel rods on site.

Nuclear safety activists in the United States have long known of these problems and have sought repeatedly to have them addressed. At least get backup generators for the pools, they implored. But at every turn the industry has pushed back, and the Nuclear Regulatory Commission (NRC) has consistently ruled in favor of plant owners over local communities.

After 9/11 the issue of spent fuel rods again had momentary traction. Numerous citizen groups petitioned and pressured the NRC for enhanced protections of the pools. But the NRC deemed “the possibility of a terrorist attack…speculative and simply too far removed from the natural or expected consequences of agency action.” So nothing was done—not even the provision of backup water-circulation systems or emergency power-generation systems.

As an example of how dangerous American nuclear reactors are, AP noted in a report Friday that 75 percent of all U.S. nuclear sites have leaked radioactive tritium.

Indeed, because of poor design, horrible safety practices, and no real regulation, a U.S. nuclear accident could be a lot worse than Fukushima.



Lethal radiation levels but no melted fuel found in Fukushima reactor water


The Unit 2 reactor building at Tokyo Electric Power Co.’s Fukushima Daiichi nuclear power plant.

The level of radiation was measured by a special robot on Sunday at a point about 30cm (one foot) from the bottom of the containment vessel of Reactor 1, the Japan Times reported on Tuesday.

The current radiation level is 11 sieverts per hour, the highest detected in water inside the containment vessel. A person exposed to this amount of radiation would likely die in about 40 minutes, the Japan Times reports.

Sunday’s probe also revealed sandy substances building up at the bottom of the vessel. Tokyo Electric Power Company Holdings (TEPCO) officials, however, dismissed the idea that it might be melted nuclear fuel.

Experts have been looking for the melted fuel, which they believe has been accumulating in tainted water.

In March 2011, a 9.1 earthquake and the 15-meter tsunami that followed disabled the cooling system of Fukushima’s three reactors, causing the worst nuclear incident since the 1986 Chernobyl incident in Ukraine.

TEPCO, which operates the crippled power plant, has been obliged to deal with the consequences of the incident.

In February, a robot sent to explore Reactor 2 broke down because of the “unimaginable” levels of radiation, close to 650 sieverts per hour. This was the first time a robot entered this reactor since the plant’s meltdown in 2011.

Previously, the highest radiation level was recorded one year after the disaster and went up to 73 sieverts per hour.

TEPCO has promised extract the hazardous material stuck in the plant’s second reactor, its president Naohiro Masuda said, according to the Japan Times.

In December, TEPCO nearly doubled the estimated cost for the Fukushima clean-up to $188 billion.

A zone of more than 300 square miles around the plant is currently uninhabitable due to the continuing radiation.



Plan to tunnel under the reactor buildings to remove melted fuel

Buried in technical reports was this interesting plan. Researchers have developed a method to tunnel under the reactor buildings to remove melted fuel.

The plan itself bases itself in existing concepts for sealed underground tunnel systems similar to the BART train system in the US or the Channel in the UK. Japan has a similar tunnel system used for rail lines that run between the main island of Honshu and Hokkaido.

TEPCO has attempted to continue presenting a narrative that the melted fuel remained in the reactor vessels or at least remained in the containment vessels, making it more straightforward to remove. This new plan assumes fuel to have melted deeply down into the reactor building basement concrete or potentially through the ground below.

The plan doesn’t clarify how much human entry to the underground base unit would be allowed or required. Seeing broader planning for potential scenarios would seem a wise move after early work found unexpected surprises causing designers to go back and rework plans. For such a plan to be under development means there is some thought among the decommissioning research teams that a worst case scenario could exist. These would include further inspections inside the containment structures and horizontal drilling below the reactor buildings to obtain soil samples.

The divergence between the work of the parties that have to actually plan the decommissioning work vs. the parties that have a stake in comforting public relations is quite clear. The very notion of such a plan raises questions about the true nature of the meltdowns.

A complex system of drilling equipment, debris retrieval, and nuclear waste casks would be included in the system. Additional inspection work will be required to determine if this new method will be needed.

The same report also includes the controversial sarcophagus plan.