Fukushima update


Japan has at last admitted the actual severity of the Fukushima nuclear accident. It needs to be made clear that in all probability no one had any real way of knowing the full extent of what happened until the nuclear reactor buildings were stabilized.  The actual severity of the accident is much worse than Chernobyl, which is probably what most of us were fearing in the first place.  The latest from the LSM is the following:

Molten nuclear fuel in three reactors at the Fukushima Daiichi power plant is likely to have burned through pressure vessels, not just the cores, Japan has said in a report in which it also acknowledges it was unprepared for an accident of the severity of Fukushima.

It is the first time Japanese authorities have admitted the possibility that the fuel suffered “melt-through” – a more serious scenario than a core meltdown.

The report, which is to be submitted to the International Atomic Energy Agency (IAEA), said fuel rods in reactors No 1, 2 and 3 had probably not only melted, but also breached their inner containment vessels and accumulated in the outer steel containment vessels.

The plant’s operator, Tokyo Electric Power (Tepco), says it believes the molten fuel is being cooled by water that has built up in the bottom of the three reactor buildings.

The report comes a day after Japan’s nuclear safety agency said the amount of radiation that leaked from Fukushima Daiichi in the first week of the accident may have been more than double that initially estimated by Tepco.

The 750-page report, compiled by Japan’s emergency nuclear task force, concedes that the country was wrongfooted by the severity of the accident, which occurred after the plant was struck by waves more than 14 metres high following the earthquake on 11 March.

The nuclear task force’s head, Goshi Hosono, said Tepco had failed to adequately protect plant workers early on in the crisis, and had provided inadequate information about radiation leaks.

About 7,800 workers had been involved in the battle to stabilise the plant as of late May, the report said. While their average exposure dose was well within safe limits, “a certain number” may have been exposed to more than 250 millisieverts per year, the maximum allowable dose under revised government guidelines for Fukushima workers.

The report acknowledged that bureaucratic red tape, and the division of responsibilities across several government agencies, had hampered the response to the accident.

It said the government would separate the country’s nuclear safety watchdog from the trade and industry ministry, a recommendation made earlier this month by a team of experts from the IAEA.

The reality of this situation is that it was much more severe for Japan and the Japanese population than it was for the rest of the world. Whilst there was some fallout that reached Europe and the USA, the amount of the fallout was minimal and there was no real threat. However, in Japan, it is a very different story. Despite the severity of the accident, a severity that is only now being revealed, there are lessons to be learned regarding the safety of nuclear reactors in particular circumstances – severe earthquake and tsunami. Most of the damage was done because of the tsunami and not the earthquake, which means that the siting of a nuclear reactor is very important. The Daiichi plant was too close to the ocean, but we must keep in mind the height of the tsunami wave was also extraordinarily high, and when the plant was planned in the first place, the possibility of this high a wave was not taken into account. 

It is worth noting that at this point, the Japanese are maintaining that the spent fuel rods are cooling in the water that remains in the plant. The fact that there was a complete molten melt down would logically explain the high levels of radiation that were being experienced when workers first tried to re-enter the plant.

It is important to keep in mind the exact sequence of events:

1. 9.1 earthquake led to the commencement of the shut down of the plants that were in operation i.e. reactors 1, 2 and 3. The other three reactors were shutdown due to maintenance.

2. 14 metre high tsunami wave knocked out the diesel powered generators, which had been placed at a height of about 10 metres.  The sea-wall that had been built was also not adequate.

3. the back-up battery generators had a life of about 8 hours. The failure of these generators led to a sequence of events that has led to the final admission of the level of the melt-down involved.

4. the rods in each of the operating reactors at the time that the earthquake hit were exposed for more than 2 hours. This exposure led to the melt-down.

5. the loss of power due to the extraordinary situation, and the inability to get power hooked up in as fast a time as possible, led to further exposure of the rods because of the inability to keep the water circulating, which was a necessary part of the cooling process during the shut down.  This in turn has led to what has now been revealed.

The real point to consider, without the hysteria from the watermelons and anti-nuclear types, is that there are lessons to be learned from this nuclear accident. As well as these lessons, it is noteworthy that there were no reported deaths as a direct result of the accident. However, we do not know what the future situation will be for those workers who received high levels of exposure to the radiation.

 

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