Fukushima. Part 1 – A Man-Made Disaster Due To A Natural Event.

The Natural Event

On Friday 11th March 2011 at 14:46 JST a magnitude 9.0 undersea mega-thrust earthquake struck approximately 70 kilometers (43 miles) off the coast of Oshika Peninsula of Tohuku, Japan. The earthquake triggered tsunami waves up to 40 meters (133 feet) high that traveled inland in some areas as much as 10 kilometers (6 miles).

 

Map

 

The earthquake was so powerful that it moved Honshu Island 2.4 m (8 ft) east and shifted the Earth on its axis by estimates of between 10 cm (4 in) and 25 cm (10 in). It generated sound waves detected by the low orbiting GOCE satellite. (Gravity Field and Steady-State Ocean Circulation Explorer)

Although the earthquake itself was huge most of the damage along the Japanese coastline was caused by the tsunami waves it generated.

  •  The official death toll from the event stands at 15,884 with a further 2,615 people still unaccounted for.
  • 127,290 buildings totally collapsed, with a further 272,788 buildings ‘half collapsed’, and another 747,989 buildings partially damaged.
  • An estimated 230,000 automobiles and trucks were damaged or destroyed.
  • Around 4.4 million households in northeastern Japan were left without electricity and 1.5 million without water due to extensive and severe structural damage including heavy damage to roads and railways, a dam collapse and fires in many areas.
  • Fukushima 1 Daiichi Nuclear Power Plant was severely damaged by level 7 meltdowns at three nuclear reactors.

The World Bank’s estimated economic cost was US$235 billion, making it the costliest natural disaster in world history.

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What Happened Inside The Reactors

There are 6 reactors at the Fukushima 1 Daiichi Nuclear Plant. Reactor 4 had been de-fueled and 5 and 6 were shutdown. When the earthquake struck reactors 1,2 and 3 automatically SCRAMmed and the control rods shutdown sustained fission reaction.

Even though fission had stopped, decay heat continued to be released so reactor cooling was needed to keep the fuel rods below their melting point. Emergency generators automatically activated to power the electronics and keep the cooling systems running.

 All for units after event

Fukushima #1 Daiichi Nuclear Plant AFTER events of March 2011 earthquake/tsunami disaster.

 

50 minutes later the 14 meter (46 foot) high tsunami struck, overwhelming the plants 10 meter (33 foot) seawall. Water flooded the low-lying rooms in which the emergency generators were housed. When the generator batteries ran out, less than 24 hrs after the event, the cooling system stopped and the reactor cores began to heat up.

A hydrogen gas build-up was created when the zirconium cladding used inside the units, reacted with water steam at high temperature created by the rapidly heating fuel rods in the reactor core.

Unit 4 also filled with hydrogen gas thought to have been piped in via a connection to Unit 3. Explosions occurred in the upper secondary containment building in all three reactors.

 12 March, an explosion in Unit 1 destroyed the upper part of the building.  It was later discovered that the core had meltdown

12 March, an explosion in Unit 1 destroyed the upper part of the building. It was later discovered that the core had meltdown

 

 No 3 Explosion

Smoke rises from Fukushima #1 Daiichi Nuclear Power Plant after a hydrogen explosion at the No.3 reactor.

 

 Fukushima Unit 3

14 March, a similar explosion occurred in the Unit 3 building, blowing off the roof and injuring eleven people.

 

 Fukushima #1 Unit 4

Fukushima #1 Daiichi Nuclear Plant, Unit 4 damage after explosion 15 March 2011

 

 Helicopter with water bucket

Japanese military helicopters were were used to dump seawater on stricken nuclear reactor 3 to cool overheated fuel rods inside its core.

 

Power was restored to cooling systems on 24 March and by 28 March temperatures were reported down to 35 °C.

After inspections of the damaged unit were able to be carried out it was determined that Unit 1 reactor core had suffered significant damage and the molten fuel had meltdown into the bottom of the Primary Containment Vessel.

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A month later the Japanese government’s nuclear safety agency rated The Fukushima disaster at level 7 on the INES.

Major damage to the backup power and containment systems was caused by the earthquake and tsunami.  This resulted in overheating and leaking from 4 of the 6 reactors at the Fukushima Daiichi Nuclear Plant.

Each reactor accident was rated separately; out of the six reactors, three were rated level 5, one was rated at a level 3, and the situation as a whole was rated level 7.

Level 7

 Major accident

 Major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures.

 Level 5

 Accident with wider consequences

 Limited release of radioactive material likely to require implementation of some planned countermeasures.

 Several deaths from radiation.

 Level 3

 Serious Incident

 Exposure in excess of ten times the statutory annual limit for workers. Non-lethal deterministic health effect (e.g., burns) from radiation.

 

NIES – The International Nuclear and Radiological Event Scale

 

The Fukushima Nuclear Accident Independent Investigation Commission (NAIIC) found the nuclear disaster was “man made” and that its direct causes were all foreseeable.

The report also found that the plant was incapable of withstanding the earthquake and tsunami.

TEPCO, regulators Nuclear and Industrial Safety Agency (NISA) and NSC and the government body promoting the nuclear power industry (METI), all failed to meet the most basic safety requirements, such as assessing the probability of damage, preparing for containing collateral damage from such a disaster, and developing evacuation plans.

A separate study by Stanford researchers found that Japanese plants operated by the largest utility companies were particularly unprotected against potential tsunamis.

 

Following the 2011 Fukushima nuclear disaster, Japanese authorities shut down the nation’s 54 nuclear power plants. As of 2014, the Fukushima site remains highly radioactive, with some 160,000 evacuees still living in temporary housing, and some land will be unfarmable for centuries. The difficult cleanup job will take 40 or more years, and cost many tens of billions of dollars, with total economic costs estimated at $250–$500 billion.

 

I will add more to this series as time permits.  I have got you started.  Now go out there and find the real interesting stuff !

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References:

Wikipedia – 2011 Japan earthquake and Tsunami https://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquake_and_tsunami