Japan had a 9.1 earthquake (the measures have alternated between 9.0 and 9.1), which was followed by a 14 metre tsunami. As I have previously explained these are two unique events.
When the earthquake struck, the nuclear reactors at the Daiichi and Danii plants were automatically shut down. This is what they were designed to do when an earthquake struck, and it was like clockwork. After shutdown the emergency generators kicked in. However, the size of the tsunami caused the generators to fail. The emergency generators are necessary to keep the circulation of the cooling water flowing whilst the reactors are going through shut down. The battery operated generators kicked in but these only have a life of 8 hours.
When news of this disaster broke, it was hard to predict what else could go wrong. The shut down of the generators caused major problems, including several explosions in 4 reactors at the Daiichi plant. There was a fire at the nr 4 plant which had not been operating at the time. The explanation given by the Japanese authorities to the press was that the explosions were due to a build up of hydrogen which had caused pressure. Of the 4 reactors affected, only one of them has remained stable – the nr. 1 reactor.
There has been a race against time to try and reconnect the reactors to the electricity grid so that the cooling of the reactors and the spent fuel rods can continue.
Since the first earthquake there have been several more with some of them, the latest being this morning, being as much as 7.1 on the Richter scale, and these have been in the vicinity of Fukushima.
There has been some radiation spill from the plant. The first real signs of a much bigger problem than anticipated came with the announcement of contaminated milk as well as contaminated vegetables from farms close to Fukushima. The radiation is now being detected as far away as England and the USA. This is now quite serious.
Thus it should be no surprise to learn that that the authorities have now upgraded again the incident level to the highest which is 7, and that means that the Fukushima power plant incident is now listed as worse than Chernobyl. What it means is that contamination is now reaching a much wider population area than first anticipated.
To this news comes the further news that there had been another fire in the nr 4 reactor, although this is not related to the latest earthquake.
In the meantime the workers are struggling with contaminated water flowing into the ocean, as well as with contaminated water inside some of the reactors. There have been several reports of worker injuries due to contaminated water touching their skin.
From what I have been reading the biggest problem has been in the reactor where the rods were exposed for about 140 minutes. This had led to a partial core meltdown which the workers had hoped to avoid. This explains the escalating seriousness of the incident.
For those who are technically minded, you can read more on the subject at the following blog:
You can also read a good article from the UK Guardian here.