Where is fukushima reactor

After a magnitude 9. About tons of melted nuclear fuel remain inside the three damaged reactors, and its removal is a daunting task that officials say will take years. Separate efforts to remove spent fuel from cooling pools inside the reactor buildings were hampered by high radiation and debris and have been delayed for up to five years. The melted cores in Units 1, 2 and 3 mostly fell to the bottom of their primary containment vessels, some penetrating and mixing with the concrete foundation, making removal extremely difficult.

Remote-controlled robots with cameras have provided only a limited view of the melted fuel in areas still too dangerous for humans to go. Since the disaster, contaminated cooling water has constantly escaped from the damaged primary containment vessels into the reactor building basements, where it mixes with groundwater that seeps in. The water is pumped up and treated. Part is recycled as cooling water, with the remainder stored in 1, huge tanks crowding the plant.

Units 3 and 5 were supplied by Toshiba and Unit 4 by Hitachi. The earthquake measured 8. The remaining two units 5 and 6 were also shut down for regular inspection.

The emergency onsite generation had failed to provide the necessary backup power needed to support the critical instruments and control systems. Even the special cooling system known as the reactor core isolation cooling system that uses waste heat to run the critical systems could not provide the power needed to operate the control systems. Unit 1 exploded on 12 March knocking down the external concrete building. However, the reactor and the steel containment structure remained intact.

The radiation levels rose to microsievert, which is equivalent to the maximum permissible level for a year in a single day. This scale measures from deviation-no safety significance — major accident and is used to communicate the safety significance of events associated with radiation sources. Unit 3 exploded due to hydrogen ignition on 14 March In November the NRA decided to change the way radiation exposure was estimated. Instead of airborne surveys being the basis, personal dosimeters would be used, giving very much more accurate figures, often much less than airborne estimates.

Measurement was by personal dosimeters over August-September Disaster-related deaths are in addition to the over 19, that died in the actual earthquake and tsunami. The premature disaster-related deaths were mainly related to i physical and mental illness brought about by having to reside in shelters and the trauma of being forced to move from care settings and homes; and ii delays in obtaining needed medical support because of the enormous destruction caused by the earthquake and tsunami.

However, the radiation levels in most of the evacuated areas were not greater than the natural radiation levels in high background areas elsewhere in the world where no adverse health effect is evident. The figure is greater than for Iwate and Miyagi prefectures, with and respectively, though they had much higher loss of life in the earthquake and tsunami — over 14, Causes of indirect deaths include physical and mental stress stemming from long stays at shelters, a lack of initial care as a result of hospitals being disabled by the disaster, and suicides.

As of July , over 41, people from Fukushima were still living as evacuees. The money was tax-exempt and paid unconditionally. In October , about 84, evacuees received the payments.

The Fukushima prefecture had 17, government-financed temporary housing units for some 29, evacuees from the accident. The number compared with very few built in Miyagi, Iwate and Aomori prefectures for the , tsunami survivor refugees there. In April , the first residents of Okuma, the closest town to the plant, were allowed to return home. According to a survey released by the prefectural government in April , the majority of people who voluntarily evacuated their homes after the accident and who are now living outside of Fukushima prefecture do not intend to return.

A Mainichi report said that Of the voluntary evacuees still living in Fukushima prefecture, An August Reconstruction Agency report also considered workers at Fukushima power plant. The death toll directly due to the nuclear accident or radiation exposure remained zero, but stress and disruption due to the continuing evacuation remains high.

Summary : Many evacuated people remain unable to fully return home due to government-mandated restrictions based on conservative radiation exposure criteria. Decontamination work is proceeding while radiation levels decline naturally. Removing contaminated water from the reactor and turbine buildings had become the main challenge by week 3, along with contaminated water in trenches carrying cabling and pipework. This was both from the tsunami inundation and leakage from reactors.

Run-off from the site into the sea was also carrying radionuclides well in excess of allowable levels. By the end of March all storages around the four units — basically the main condenser units and condensate tanks — were largely full of contaminated water pumped from the buildings. Some storage tanks were set up progressively, including initially steel tanks with rubber seams, each holding m 3.

A few of these developed leaks in Accordingly, with government approval, Tepco over April released to the sea about 10, cubic metres of slightly contaminated water 0.

Unit 2 is the main source of contaminated water, though some of it comes from drainage pits. NISA confirmed that there was no significant change in radioactivity levels in the sea as a result of the 0. By the end of June , Tepco had installed concrete panels to seal the water intakes of units , preventing contaminated water leaking to the harbour. From October, a steel water shield wall was built on the sea frontage of units It extends about one kilometre, and down to an impermeable layer beneath two permeable strata which potentially leak contaminated groundwater to the sea.

The inner harbour area which has some contamination is about 30 ha in area. In July-August only 0. Tepco built a new wastewater treatment facility to treat contaminated water. A supplementary and simpler SARRY simplified active water retrieve and recovery system plant to remove caesium using Japanese technology and made by Toshiba and The Shaw Group was installed and commissioned in August The NRA approved the extra capacity in August ALPS is a chemical system which will remove radionuclides to below legal limits for release.

However, because tritium is contained in water molecules, ALPS cannot remove it, which gives rise to questions about the discharge of treated water to the sea. Collected water from them, with high radioactivity levels, was being treated for caesium removal and re-used.

Apart from this recirculating loop, the cumulative treated volume was then 1. Almost m 3 of sludge from the water treatment was stored in shielded containers.

ALPS-treated water is currently stored in tanks onsite which will reach full capacity by the summer of As of February , more than 1. Some of the ALPS treated water will require secondary processing to further reduce concentrations of radionuclides in line with government requirements.

Disposal will be either into the atmosphere or the sea. In November the trade and industry ministry stated that annual radiation levels from the release of the tritium-tainted water are estimated at between 0.

The clean tritiated water was the focus of attention in A September report from the Atomic Energy Society of Japan recommended diluting the ALPS-treated water with seawater and releasing it to the sea at the legal discharge concentration of 0. The WHO drinking water guideline is 0. The government had an expert task force considering the options.

In April the Japanese government confirmed that the water would be released into the sea in This is fed through a catalytic exchange column with a little water which preferentially takes up the tritium. It can be incorporated into concrete and disposed as low-level waste. The tritium is concentrated to 20, times. The MDS is the first system to be able economically to treat large volumes of water with low tritium concentrations, and builds on existing heavy water tritium removal systems.

Each module treats up to litres per day. Earlier in a new Kurion strontium removal system was commissioned. This is mobile and can be moved around the tank groups to further clean up water which has been treated by ALPS. Apart from the above-ground water treatment activity, there is now a groundwater bypass to reduce the groundwater level above the reactors by about 1.

This prevents some of it flowing into the reactor basements and becoming contaminated. In addition, an impermeable wall was constructed on the sea-side of the reactors, and inside this a frozen soil wall was created to further block water flow into the reactor buildings. In October guidelines for rainwater release from the site allowed Tepco to release water to the sea without specific NRA approval as long as it conformed to activity limits.

Summary: A large amount of contaminated water has accumulated onsite and has been treated to remove radioactive elements, apart from tritium. In April , the Japanese government confirmed that the water would be released into the sea. Some radioactivity has already been released to the sea, but this has mostly been low-level and it has not had any significant impact beyond the immediate plant structures.

Concentrations outside these structures have been below regulatory levels since April In particular, proposals were sought for dealing with: the accumulation of contaminated water in storage tanks, etc ; the treatment of contaminated water including tritium removal; the removal of radioactive materials from the seawater in the plant's 30 ha harbour; the management of contaminated water inside the buildings; measures to block groundwater from flowing into the site; and, understanding the flow of groundwater.

Responses were submitted to the government in November. In December IRID called for innovative proposals for removing fuel debris from units about It works with IRID, whose focus now is on developing mid- and long-term decommissioning technologies. They were in 'cold shutdown' at the time, but still requiring pumped cooling. They were restored to cold shutdown by the normal recirculating system on 20 March, and mains power was restored on March.

In September Tepco commenced work to remove the fuel from unit 6. Prime minister Abe then called for Tepco to decommission both units. Tepco announced in December that it would decommission both units from the end of January They entered commercial operation in and respectively.

It is proposed that they will be used for training. Tepco published a six- to nine-month plan in April for dealing with the disabled Fukushima reactors, and updated this several times subsequently. Remediation over the first couple of years proceeded approximately as planned.

In August Tepco announced its general plan for proceeding with removing fuel from the four units, initially from the spent fuel ponds and then from the actual reactors. At the end of Tepco announced the establishment of an internal entity to focus on measures for decommissioning units and dealing with contaminated water. In June the government revised the decommissioning plan for the second time, though without major change. It clarified milestones to accomplish preventive and multi-layered measures, involving the three principles of removing the source of the contamination, isolating groundwater from the contamination source, and preventing leakage of the contaminated water.

It included a new goal of cutting the amount of groundwater flowing into the buildings to less than m 3 per day by April The schedule for fuel removal from the pond at unit 1 was postponed from late FY17 to FY20, while that for unit 2 was delayed from early FY20 to later the same fiscal year, and that at unit 3 from early FY15 to FY Fuel debris removal was to begin in , as before. In September the government updated the June decommissioning roadmap, with no changes to the framework, and confirming first removal of fuel debris from unit 1 in Treatment of all contaminated water accumulated in the reactor buildings was to be completed by For unit 3, fuel removal was completed in February Fuel debris removal remains scheduled to begin in FY Tepco has a website giving updates on decommissioning work and environmental monitoring.

Storage ponds : Debris has been removed from the upper parts of the reactor buildings using large cranes and heavy machinery. Casks to transfer the removed fuel to the central spent fuel facility have been designed and manufactured using existing cask technology.

In July two unused fuel assemblies were removed from unit 4 pond, and were found to be in good shape, with no deformation or corrosion.

Tepco started removal of both fresh and used fuel from the pond in November , 22 assemblies at a time in each cask, with used and new ones to be moved. This was uneventful, and the task continued through By 22 December , all used as well as all new fuel assemblies had been moved in 71 cask shuttles without incident.

All of the radioactive used fuel was removed by early November, eliminating a significant radiological hazard on the site. The used fuel went to the central storage pond, from which older assemblies were transferred to dry cask storage.

The fresh fuel assemblies are stored in the pool of the undamaged unit 6. Tepco completed moving fuel from unit 3 in February It will now focus on used fuel assemblies and new ones from unit 1, and then used assemblies and 28 new ones from unit 2 will be transferred. The NRA has expressed concern about the unit 1 used fuel. Reactors order of work : The locations of leaks from the primary containment vessels PCVs and reactor buildings should first be identified using manual and remotely controlled dosimeters, cameras, etc.

Any leakage points will be repaired and both reactor vessels RPVs and PCVs filled with water sufficient to achieve shielding. Then the vessel heads will be removed. The location of melted fuel and corium will then be established. In particular, the distribution of damaged fuel believed to have flowed out from the RPVs into PCVs will be ascertained, and it will be sampled and analysed. After examination of the inside of the reactors, states of the damaged fuel rods and reactor core internals, sampling will be done and the damaged core material will be removed from the RPVs as well as from the PCVs.

Updated plans are on the IRID website. The four reactors will be completely demolished in years — much the same timeframe as for any nuclear plant. Earlier, consortia led by both Hitachi-GE and Toshiba submitted proposals to Tepco for decommissioning units This would generally involve removing the fuel and then sealing the units for a further decade or two while the activation products in the steel of the reactor pressure vessels decay. They can then be demolished. Removal of the very degraded fuel will be a long process in units , but will draw on experience at Three Mile Island in the USA.

A member international expert team assembled by the IAEA at the request of the Japanese government carried out a fact-finding mission in October on remediation strategies for contaminated land.

Its report focused on the remediation of the affected areas outside of the 20 km restricted area. The team said that it agreed with the prioritization and the general strategy being implemented, but advised the government to focus on actual dose reduction.

They should "avoid over-conservatism" which "could not effectively contribute to the reduction of exposure doses" to people. It warned the government against being preoccupied with "contamination concentrations The four units at Fukushima Daini were shut down automatically due to the earthquake. The tsunami — here only 9 m high — affected the generators and there was major interruption to cooling due to damaged heat exchangers, so the reactors were almost completely isolated from their ultimate heat sink.

At the Fukushima nuclear power plant, the gigantic wave surged over defences and flooded the reactors, sparking a major disaster. Authorities set up an exclusion zone which grew larger and larger as radiation leaked from the plant, forcing more than , people to evacuate from the area.

A decade later, that zone remains in place and many residents have not returned. Authorities believe it will take up to 40 years to finish the work, which has already cost Japan trillions of yen. It sits on the country's east coast, about km miles north-east of the capital Tokyo.

On 11 March at local time GMT the earthquake - known as the Great East Japan Earthquake, or the Tohoku earthquake - struck east of the city of Sendai, 97km north of the plant.

Residents had just 10 minutes warning before the tsunami hit the coast. Overall almost half-a-million people were forced to leave their homes as a result of the earthquake, tsunami and nuclear accident. Systems at the nuclear plant detected the earthquake and automatically shut down the nuclear reactors.

Emergency diesel generators turned on to keep coolant pumping around the cores, which remain incredibly hot even after reactions stop. But soon after a wave over 14 metres 46ft high hit Fukushima. The water overwhelmed the defensive sea wall, flooding the plant and knocking out the emergency generators.

Workers rushed to restore power, but in the days that followed the nuclear fuel in three of the reactors overheated and partly melted the cores - something known as a nuclear meltdown. The plant also suffered a number of chemical explosions which badly damaged the buildings. Radioactive material began leaking into the atmosphere and the Pacific Ocean, prompting the evacuations and an ever-widening exclusion zone.

There were no deaths immediately during the nuclear disaster. At least 16 workers were injured in the explosions, while dozens more were exposed to radiation as they worked to cool the reactors and stabilise the plant. Three people were reportedly taken to hospital after high-level exposure. Long-term effects of the radiation are a matter of debate.