Muons suggest location of fuel in unit 3 — World Nuclear News

” Some of the fuel in the damaged unit 3 of the Fukushima Daiichi plant has melted and dropped into the primary containment vessel, initial results from using a muon detection system indicate. Part of the fuel, however, is believed to remain in the reactor pressure vessel.

Muons are high-energy subatomic particles that are created when cosmic rays enter Earth’s upper atmosphere. These particles naturally and harmlessly strike the Earth’s surface at a rate of some 10,000 muons per square meter per minute. Muon tracking devices detect and track these particles as they pass through objects. Subtle changes in the trajectory of the muons as they penetrate materials and change in direction correlate with material density. Nuclear materials such as uranium and plutonium are very dense and are therefore relatively easy to identify. The muon detection system uses the so-called permeation method to measure the muon data.

Tokyo Electric Power Company (Tepco) installed a muon detection system on the first floor of unit 3’s turbine building. Measurements were taken between May and September this year.

Tepco said analysis of muon examinations of the fuel debris shows that most of the fuel has melted and dropped from its original position within the core.

Prior to the 2011 accident, some 160 tonnes of fuel rods and about 15 tonnes of control rods were located within the reactor core of unit 3. The upper and lower parts of the reactor vessel contains about 35 tonnes and 80 tonnes of structures, respectively.

The muon examination indicates that most of the debris – some 160 tonnes – had fallen to the bottom of the reactor pressure vessel and resolidified, with only about 30 tonnes remaining in the reactor core. Tepco said another 90 tonnes of debris remains in the upper part of the vessel.

The bulk of the fuel and structures in the core area dropped to the bottom of the reactor pressure vessel (RPV), Tepco believes. While part of the molten fuel is understood to have then fallen into the primary containment vessel (PCV), “there is a possibility that some fuel debris remains in the bottom of the RPV, though this is uncertain”, the company noted.

Similar muon measurements have already been conducted at units 1 and 2 at Fukushima Daiichi. Measurements taken at unit 1 between February and September 2015 indicated most of the fuel was no longer in the reactor’s core area. Measurements taken between March and July 2016 at unit 2 showed high-density materials, considered to be fuel debris, in the lower area of the RPV. Tepco said that more fuel debris may have fallen into the PCV in unit 3 than in unit 2.

Tepco said the results obtained from the muon measurements together with knowledge obtained from internal investigations of the primary containment vessels using remote-controlled robots will help it plan the future removal of fuel debris from the damaged units. ”

by World Nuclear News

source with illustration of Unit 1-3

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Tepco to delay emptying fuel storage pools at Fukushima plant — The Asahi Shimbun

” Plans to remove fuel rods from two spent fuel pools at the Fukushima No. 1 nuclear plant will be delayed by up to three years because of difficulties in clearing debris and reducing radiation levels.

The government and plant operator Tokyo Electric Power Co. originally expected to start emptying the storage pools at the No. 1 and No. 2 reactor buildings in fiscal 2020.

But they plan to move the starting time to fiscal 2023 in their first review in two years of the roadmap for decommissioning the stricken nuclear plant, sources said Sept. 20.

They are expected to announce the revised roadmap later this month.

A survey of the upper levels of the two reactor buildings, where the storage pools are located, found debris piled up in a much more complicated way than initially envisaged.

That will lengthen the time needed to clear the debris, thus delaying the removal of the fuel rods, the sources said.

In addition, radiation levels remain extremely high inside the buildings.

The No. 1 reactor’s storage pool holds 392 nuclear fuel assemblies, while the No. 2 reactor’s pool has 615 assemblies.

Work to remove the 566 assemblies from the No. 3 reactor’s pool is scheduled to begin in the middle of fiscal 2018 as originally planned.

The three reactors melted down in the 2011 disaster, triggered by the magnitude-9.0 Great East Japan Earthquake and tsunami.

The review of the decommissioning roadmap is also expected to revise the target of “starting the removal” of melted nuclear fuel and debris in the three reactors in 2021 to “aiming to start the removal” in 2021.

But the government and TEPCO will maintain the goal of completing the decommissioning in “30 to 40 years,” the sources said. ”

by Chikako Kawahara, The Asahi Shimbun

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The Fukushima nuclear meltdown continues unabated — Helen Caldicott, Independent Australia

Helen Caldicott sums up the situation here:

” Recent reporting of a huge radiation measurement at Unit 2 in the Fukushima Daichi reactor complex does not signify that there is a peak in radiation in the reactor building.

All that it indicates is that, for the first time, the Japanese have been able to measure the intense radiation given off by the molten fuel, as each previous attempt has led to failure because the radiation is so intense the robotic parts were functionally destroyed.

The radiation measurement was 530 sieverts, or 53,000 rems (Roentgen Equivalent for Man). The dose at which half an exposed population would die is 250 to 500 rems, so this is a massive measurement. It is quite likely had the robot been able to penetrate deeper into the inner cavern containing the molten corium, the measurement would have been much greater.

These facts illustrate why it will be almost impossible to “decommission” units 1, 2 and 3 as no human could ever be exposed to such extreme radiation. This fact means that Fukushima Daichi will remain a diabolical blot upon Japan and the world for the rest of time, sitting as it does on active earthquake zones.

What the photos taken by the robot did reveal was that some of the structural supports of Unit 2 have been damaged. It is also true that all four buildings were structurally damaged by the original earthquake some five years ago and by the subsequent hydrogen explosions so, should there be an earthquake greater than seven on the Richter scale, it is very possible that one or more of these structures could collapse, leading to a massive release of radiation as the building fell on the molten core beneath. But units 1, 2 and 3 also contain cooling pools with very radioactive fuel rods — numbering 392 in Unit 1, 615 in Unit 2, and 566 in Unit 3; if an earthquake were to breach a pool, the gamma rays would be so intense that the site would have to be permanently evacuated. The fuel from Unit 4 and its cooling pool has been removed.

But there is more to fear.

The reactor complex was built adjacent to a mountain range and millions of gallons of water emanate from the mountains daily beneath the reactor complex, causing some of the earth below the reactor buildings to partially liquefy. As the water flows beneath the damaged reactors, it immerses the three molten cores and becomes extremely radioactive as it continues its journey into the adjacent Pacific Ocean.

Every day since the accident began, 300 to 400 tons of water has poured into the Pacific where numerous isotopes – including cesium 137, 134, strontium 90, tritium, plutonium, americium and up to 100 more – enter the ocean and bio-concentrate by orders of magnitude at each step of the food chain — algae, crustaceans, little fish, big fish then us.

Fish swim thousands of miles and tuna, salmon and other species found on the American west coast now contain some of these radioactive elements, which are tasteless, odourless and invisible. Entering the human body by ingestion they concentrate in various organs, irradiating adjacent cells for many years. The cancer cycle is initiated by a single mutation in a single regulatory gene in a single cell and the incubation time for cancer is any time from 2 to 90 years. And no cancer defines its origin.

We could be catching radioactive fish in Australia or the fish that are imported could contain radioactive isotopes, but unless they are consistently tested we will never know.

As well as the mountain water reaching the Pacific Ocean, since the accident, TEPCO has daily pumped over 300 tons of sea water into the damaged reactors to keep them cool. It becomes intensely radioactive and is pumped out again and stored in over 1,200 huge storage tanks scattered over the Daichi site. These tanks could not withstand a large earthquake and could rupture releasing their contents into the ocean.

But even if that does not happen, TEPCO is rapidly running out of storage space and is trying to convince the local fishermen that it would be okay to empty the tanks into the sea. The Bremsstrahlung radiation like x-rays given off by these tanks is quite high – measuring 10 milirems – presenting a danger to the workers. There are over 4,000 workers on site each day, many recruited by the Yakuza (the Japanese Mafia) and include men who are homeless, drug addicts and those who are mentally unstable.

There’s another problem. Because the molten cores are continuously generating hydrogen, which is explosive, TEPCO has been pumping nitrogen into the reactors to dilute the hydrogen dangers.

Vast areas of Japan are now contaminated, including some areas of Tokyo, which are so radioactive that roadside soil measuring 7,000 becquerels (bc) per kilo would qualify to be buried in a radioactive waste facility in the U.S..

As previously explained, these radioactive elements concentrate in the food chain. The Fukushima Prefecture has always been a food bowl for Japan and, although much of the rice, vegetables and fruit now grown here is radioactive, there is a big push to sell this food both in the Japanese market and overseas. Taiwan has banned the sale of Japanese food, but Australia and the U.S. have not.

Prime Minister Abe recently passed a law that any reporter who told the truth about the situation could be [jail]ed for ten years. In addition, doctors who tell their patients their disease could be radiation related will not be paid, so there is an immense cover-up in Japan as well as the global media.

The Prefectural Oversite Committee for Fukushima Health is only looking at thyroid cancer among the population and by June 2016, 172 people who were under the age of 18 at the time of the accident have developed, or have suspected, thyroid cancer; the normal incidence in this population is 1 to 2 per million.

However, other cancers and leukemia that are caused by radiation are not being routinely documented, nor are congenital malformations, which were, and are, still rife among the exposed Chernobyl population.

Bottom line, these reactors will never be cleaned up nor decommissioned because such a task is not humanly possible. Hence, they will continue to pour water into the Pacific for the rest of time and threaten Japan and the northern hemisphere with massive releases of radiation should there be another large earthquake. ”

by Helen Caldicott

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Kansai Electric begins fuel loading for nuclear restart — Kyodo News

” Kansai Electric Power Co. said Friday that it has started loading nuclear fuel into a reactor on the Sea of Japan following a court decision to lift an injunction against the move, paving the way for its restart in late January as the country’s third reactor to operate.

After the restart earlier this year of two reactors in southwestern Japan, while others remain offline in the aftermath of the 2011 Fukushima nuclear disaster, the No. 3 reactor at the utility’s Takahama plant in Fukui Prefecture would be the first to run on uranium-plutonium mixed oxide, or MOX fuel, if it begins operations as scheduled.

The utility is scheduled to insert a total of 157 fuel rod assemblies by next Tuesday, including 24 of MOX fuel, according to Kansai Electric.

The reactor along with the No. 4 at the same plant was allowed to resume operation by the Fukui District Court on Thursday.

The power company envisions reactivating the No. 3 unit sometime between January 28 and 30 and having it start power generation and transmission around Feb. 1, followed by the restart of the No. 4 unit in late February.

“We will put top priority on the safety of the work” for the restart, Kansai Electric President Makoto Yagi said at a press conference Friday.

Japan returned to nuclear power generation when Kyushu Electric Power Co. brought the two reactors at its Sendai plant in Kagoshima Prefecture back online in August and October respectively.

The government is seeking to make up at least 20 percent of the country’s electricity using nuclear power plants by 2030.

The restart of Takahama’s two reactors will be “a step forward” toward the goal, Motoo Hayashi, the industry minister who is in charge of the energy policy, said at a separate press conference the same day.

Prior to the court decision, both reactors gained approval for resumption in February from the state’s Nuclear Regulation Authority under new safety regulations introduced after the nuclear meltdowns at Tokyo Electric Power Co.’s Fukushima Daiichi plant.

The injunction issued by the court in April, however, banned the utility from restarting the units until it was lifted Thursday.

The Fukui governor on Tuesday gave the go-ahead for the company to restart the two units following approval by the local prefectural assembly and the mayor of Takahama.

The court’s Presiding Judge Jun Hayashi said in Thursday’s decision that he recognizes the rationality of the post-Fukushima safety regulations set by the nuclear regulator.

Hideaki Higuchi, presiding judge when the same court issued the injunction in April, said then the court could not see any credible evidence in the utility’s assumptions regarding earthquake risk and restarting the two reactors posed “imminent danger” to residents around the plant, about 380 kilometers west of Tokyo.

==Kyodo ”

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**Declassified U.S. government report prepared a week after Fukushima accident: “100 percent of the total spent fuel was released to the atmosphere from Unit 4” — GlobalResearch; RT

GlobalResearch:

” We reported in 2011 that the International Atomic Energy Agency knew within weeks that Fukushima had melted down … but failed and refused to tell the public.

The same year, we reported in 2011 that the U.S. knew within days of the Fukushima accident that Fukushima had melted down … but failed to tell the public.

We noted in 2012:

The fuel pools and rods at Fukushima appear to have “boiled”, caught fire and/or exploded soon after the earthquake knocked out power systems. See this, this, this, this and this.

Now, a declassified report written by the U.S. Nuclear Regulatory Commission on March 18, 2011 – one week after the tidal wave hit Fukushima – states:

The source term provided to NARAC was: (1) 25% of the total fuel in unit 2 released to the atmosphere, (2) 50% of the total spent fuel from unit 3 was released to the atmosphere, and (3) 100% of the total spent fuel was released to the atmosphere from unit 4.

FukushimaNARAC is the the U.S. National Atmospheric Release Advisory Center, located at the University of California’s Lawrence Livermore National Laboratory. NARAC “provides tools and services that map the probable spread of hazardous material accidentally or intentionally released into the atmosphere“.

The fuel pools at Units 3 and 4 contained enormous amounts of radiation.

For example, there was “more cesium in that [Unit 4] fuel pool than in all 800 nuclear bombs exploded above ground.”

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* * *

RT:

” Fukushima nuclear power plant is still experiencing major contamination issues nearly five years after the earthquake, tsunami, and subsequent meltdown.

A new declassified report from the US Nuclear Regulatory Commission, written on March 18, 2011 just days after the disaster, sheds light on just how bad it was.

We now know that “100% of the total spent fuel was released to the atmosphere from unit 4.”

According to nuclear expert and whistleblower Arnie Gundersen in an interview with WBAI in New York, unit four contained more cesium “than in all 800 nuclear bombs exploded above ground”.

Cesium has been linked to thyroid cancer, which is on the increase in the Fukushima area since the tsunami, according to the US National Library of Medicine.

The chemical is highly soluble in water and can find its way into foodstuffs that have been prepared in contaminated areas.

Another report this week revealed there are more than nine million bags of nuclear material piling up in Japan, according to the Fukushima Prefecture and the Environment Ministry.

Anti-nuclear activist Dr Helen Caldicott said during the crisis that if unit four collapsed, she was going to move her family from Boston to the southern hemisphere.

The declassified report from the US Nuclear Regulatory Commission said the 2011 thyroid dose estimates ‘downstream’ from Japan in the US were within guidelines “except for Alaska”.

Engineers at Fukushima are still dealing with fallout from four years ago. Last week, the radioactivity at Reactor 1 was measured at 482,000 becquerels per liter of radioactive cesium, Tokyo Electric Power Company (TEPCO) said.

This is 4,000 times higher than last year and the company believes the contaminated water stored at a nearby building may have leaked into the duct, according to The Asahi Shimbun.

Increases in other areas have not been registered, the company said.

400 to 500 tons of radioactive seawater that washed ashore in the 2011 tsunami is pooled in the tunnels, which lie next to a temporary storage facility for radioactive water being used to cool nuclear fuel inside the damaged reactors.

TEPCO said they plan to investigate the spike in radiation. ”

source with videos

The nuclear disaster at Fukushima didn’t have to happen — The Washington Post

” After a devastating tsunami left 18,000 people dead in 2011, Japan was about to face a potentially more significant disaster as several reactors at the Fukushima Daiichi nuclear power plant started to melt down. More than 300,000 people were evacuated.

Since then, the Japanese government has tried to defend the Tokyo Electric Power Co. (TEPCO), which operated the plant, and offer reassurances that the country’s nuclear reactors are secure. A study released Monday in the science journal Philosophical Transactions reaches a different conclusion, however: “The Fukushima accident was preventable, if international best practices and standards had been followed, if there had been international reviews, and had common sense prevailed in the interpretation of preexisting geological and hydrodynamic findings.”

The study’s authors paint a bleak picture of TEPCO’s failures before the disaster, as well as the company’s handling of the crisis. Using documents provided by the U.S. National Research Council, the U.S. Nuclear Regulatory Commission, Japan’s bicameral legislature and TEPCO itself, they conclude: “Had the TEPCO modellers had any experience with tsunamis, they would have had immediately recognized that their ‘high’ resolution predictions were underestimating the hazard.”

Researchers Costas Synolakis and Utku Kanoglu allege that the accident revealed striking inaccuracies in TEPCO’s internal risk analysis, as well as a “cascade of engineering and regulatory failures.”

“The entire experience with TEPCO’s pre-event internal studies not to mention the entire methodology that has been used in Japan to assess tsunami hazards points to the perils of insularity,” the study’s authors wrote.

According to Synolakis and Kanoglu, TEPCO researchers had long known that earthquakes could threaten power plants in the region. Despite that, necessary safety measures were not implemented.

The researchers also question the designs of some Japanese nuclear power plants, which could leave certain structures more vulnerable than others. “Interestingly, while the Onagawa [nuclear power plant] was also hit by a tsunami of approximately the same height as Dai-ichi, it survived the event ‘remarkably undamaged.’” The differences in vulnerability could partially be due to methodological mistakes “which almost nobody experienced in tsunami engineering would have made,” according to Synolakis and Kanoglu, who warn that similar flaws could lead to more accidents in the future.

“When it comes to studying hazards or designing structures whose catastrophic failure will transcend national boundaries, even countries with sophisticated technologies need to take note of Godel’s incompleteness theorem,” they wrote, referring to a mathematical concept most commonly interpreted as signifying the limits of provability.

Regulatory measures could have prevented the 2011 accident, but the researchers found “substantial inadequacies” there, as well.

The allegations are among the most extensive — but they are far from being the first. The Japanese government under the leadership of Shinzo Abe has refuted allegations of structural failures in the past and said that its response to the disaster had been adequate. Shortly afterward, the government decided to restart many of the country’s nuclear power plants, despite protests and safety concerns.

Meanwhile in Fukushima, the nuclear power plant is far from being secured: Hundreds of fuel rods stored nearby have not been removed. ”

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