Posts Tagged ‘Fukushima Nuclear plant’

One year on from the Great Tohoku earthquake and tsunami

March 11, 2012

One year on and young hopes bloom eternal.

Illustration by Yuko Shimizu

Young hopes bloom eternal: Illustration by Yuko Shimizu: From The Japan Times

I was in Japan during the Great Hanshin Earthquake in 1995 when over 6,000 perished in Kobe and – inevitably – I try to relate events to my own experience. But the Graeat Tohuku earthquake and tsunami were something quite different and have claimed more than 20,000 lives.

The death toll was much greater after the Aceh earthquake and tsunami but was spread over many more countries and in that sense is more “diffuse”. Perceptions sometimes get diluted compared to the intensity of the reactions one year ago. The 2004 Indian Ocean earthquake and tsunami claimed over 230,000 lives in 14 countries.

The meltdowns at the Fukushima nuclear plant following the Tohoku earthquake and tsunami were pretty scary but sometimes the coverage (especially in Europe) becomes alarmist and tends to take away from the earthquake and tsunami. But it is worth remembering also that the incidents at Fukushima  – without trying to trivialise them – have caused no radiation related deaths.

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The Great Sendai Quake: Two reactors at Fukushima Dai-ichi nuclear plant have had partial meltdowns

March 13, 2011

0900 CET: Japanese SDF forces assigned for rescue operations doubled to 100,000. The focal zone for the quake was 500km long and 200km wide and the quake lasted 5 minutes. The highly unusual quake actually consisted of 3 massive quakes. Miyagi Police Dept Chief said the death toll in the prefecture will exceed 10,000. Fukushima Reactors 1 & 3 will probably not start again because of the ingress of sea water. Hydrogen has built up in Reactor no. 3 probably when the core was uncovered and could cause an explosion  as in Reactor No.1 but there is no risk of consequent radiation leakage. Cooling water levels have now increased . 210,000 people are being evacuated from the 20km exclusion zone . The hospital where 19 patients were found to have been exposed to some radiation is within the exclusion zone. A 63 old year man was rescued 15km out to sea on Sunday afternoon.

INES Level 4: Accident with local consequences

Impact on People and the Environment
Minor release of radioactive material unlikely to result in implementation of planned countermeasures other than local food controls.
At least one death from radiation.
Impact on Radiological Barriers and Control
Fuel melt or damage to fuel ­resulting in more than 0.1% release of core inventory.
Release of significant quantities of radioactive material within an installation with a high ­probability of significant public exposure.

Examples:

0800 CET: The 1999 event at the Tokai Uranium processing plant where 2 people died was also rated as a Level 4 incident. 19 patients at a hospital in Fukushima have been found to have been exposed to radiation and need to be decontaminated but are not in any danger.

Aftershocks of magnitude 7 or more have a probability of 70% and will continue for a week.  Magnitudes above 7 could generate tsunamis.

0730 CET: Chief cabinet secretary, Yukio Edano has just held a press conference.

Radiation measurements at Fukushima today rose from around 50 μSieverts to around 1557 μS for 1 hour between 1.44 and 2:42 pm and then came back to 184 μS. The spokesman stated on NHK that a deformation of part of the reactor cores has occurred but that we should be careful with terminology of a meltdown. Some part of some of the sheaths surrounding some of the fuel rods are thought to have melted. The level of 1557 μS should be compared with the 600 μS during a stomach X-Ray. There is no health risk he said.  Cooling and safety actions could still give small hydrogen accumulations and consequent explosions but these would not pose any danger or any radiation risks.

4 of the 6 reactors at Fukushima Dai-ichi may never operate again – partly because some of the measures being taken now for safety are irreversible.

Sunday 13th March: 0700 CET

The Quake magnitude has now been set at 9.0 and as more measurements come in it is likely that this probably will end up at 9.1 or 9.2. The number unaccounted for still remains very high.

TEPCO has declared a formal emergency around the Fukushima nuclear plants. Reactors No.1 and 3 at Fukushima Dai-ichi nuclear plant have probably had fuel rods exposed and with loss of cooling and have probably suffered core damage and melting – a partial if not a complete meltdown. However, so far it seems that the melted or partially melted cores have been confined within the containment. Temperatures are too high in 2 further reactors and radiation is still being released even if  at low but still unacceptable levels. Some deliberate venting of radioactive gases is still continuing.

The Japan Nuclear agency has (provisionally) rated the Fukushima nuclear plant incident at 4 on the 0 to 10 7 International Nuclear Event Scale developed by the IAEA. Three Mile Island was rated at 5 and Tjernobyl was rated at 7.

From CNN:

A meltdown may have occurred at at least one nuclear power reactor in Japan, the country’s chief cabinet secretary, Yukio Edano, said Sunday. He also said that authorities are concerned over the possibility of another meltdown at a second reactor.

“We do believe that there is a possibility that meltdown has occurred. It is inside the reactor. We can’t see. However, we are assuming that a meltdown has occurred,” he said of the No. 1 reactor at the Fukushima Daiichi nuclear facility. “And with reactor No. 3, we are also assuming that the possibility of a meltdown as we carry out measures.” Edano’s comments confirm an earlier report from an official with Japan’s Nuclear and Industrial Safety Agency, who said, “we see the possibility of a meltdown.”

A meltdown is a catastrophic failure of the reactor core, with a potential for widespread radiation release. However, Toshihiro Bannai, director of the agency’s international affairs office, expressed confidence that efforts to control the crisis would be successful.


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