Quote:
From source: Richard Black Environment correspondent, BBC News
It appears that for the first time, the containment system around one of the Fukushima Daiichi reactors has been breached.
Officials have referred to a possible crack in the suppression chamber of reactor 2 - a large doughnut-shaped structure below the reactor housing. That would allow steam, containing radioactive substances, to escape continuously.
This is the most likely source of the high radioactivity readings seen near the site. Another possible source is the fire in reactor 4 building - believed to have started when a pool storing old fuel rods dried up.
The readings at the site rose beyond safe limits - 400 millisieverts per hour (mSv/hr), when the average person's exposure is 3mSv in a year.
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It seems to be growing a lot worse in Japan, The situation has been upgraded to a level 6 on the INES scale ( International Nuclear Event Scale ) --> Chernobyl was a 7 on the scale so we are getting close to the really bad situation. I have included a picture of the reactor building before and after the explosion we have seen on the news, it clearly shows that the building was severely damaged.
INES SCALE explained in detail:
Level 7: Major accident
Impact on People and Environment
Major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures
Level 6: Serious accident
Impact on People and Environment
Significant release of radioactive material likely to require implementation of planned countermeasures.
Level 5: Accident with wider consequences
Impact on People and Environment
Limited release of radioactive material likely to require implementation of some planned countermeasures.
Several deaths from radiation.
Impact on Radiological Barriers and Control
Severe damage to reactor core.
Release of large quantities of radioactive material within an installation with a high probability of significant public exposure. This could arise from a major criticality accident or fire
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.
Level 3-0 are largely non-threatening to humans - so I'll leave those alone - suffice it to say that the world has only had one level 7 INES - and that was Chernobyl that had 56 direct casualties and approximately 4000 died in later years of cancer related sickness. However a population close to 100.000 had to be rehabilitated in order to keep the safety zone clear of people, this is known as the Zone of Alienation in the former USSR.
The big problem is not so much the disaster itself, it is the aftermath of sickness, radiation of the surrounding areas and people, water, animals, basically everything. Japan is going to be hit EXTREMELY hard if this turns into a 7 - for one thing there is the current destruction already done from quake and water - but Fukushima Dai-Chi plant is also situated only 250 km from Tokyo - a city housing 35 mio people.
Quote:
From http://www.bbc.co.uk/news/world-asia-pacific-12732015
Could there be a Chernobyl-like disaster?
Experts say this is highly unlikely. The chain reaction at all Fukushima reactors has ceased. The explosions that have occurred have taken place outside the steel and concrete containment vessels enclosing the reactors. At Chernobyl an explosion exposed the core of the reactor to the air, and a fire raged for days sending its contents in a plume up into the atmosphere. At Fukushima the explosions - caused by hydrogen and oxygen vented from the reactor - have damaged only the roof and walls erected around the containment vessels.
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In regards to this from BBC, then it is reported that the explosions have created two giant holes in the containment casing, each about 8 meters in diameter and it has earlier been reported that the graphite casing of the rods themselves have been damaged by the heating.
