Tuesday, March 15, 2011

Fukushima Nuclear Accident

A simple and accurate explanation by Barry Brook.  This seems to be a well written and correct explanation of what has happened in Japan, sent to me by Phillip.  The article is long, but not as long as you might think from the web page size—most of the page consists of the follow up comments.

Note that I don't (necessarily) endorse the web site where the article is found.

Here's the most disheartening moment in the middle of the article—the point where the actual failure occured.

When the diesel generators were gone, the reactor operators switched to emergency battery power. The batteries were designed as one of the backups to the backups, to provide power for cooling the core for 8 hours. And they did.

Within the 8 hours, another power source had to be found and connected to the power plant. The power grid was down due to the earthquake. The diesel generators were destroyed by the tsunami. So mobile diesel generators were trucked in.

This is where things started to go seriously wrong. The external power generators could not be connected to the power plant (the plugs did not fit). So after the batteries ran out, the residual heat could not be carried away any more.

Here are the first three of the author's final conclusions.

  • The plant is safe now and will stay safe.
  • Japan is looking at an INES Level 4 Accident: Nuclear accident with local consequences. That is bad for the company that owns the plant, but not for anyone else. 
  • Some radiation was released when the pressure vessel was vented. All radioactive isotopes from the activated steam have gone (decayed). A very small amount of Cesium was released, as well as Iodine. If you were sitting on top of the plants’ chimney when they were venting, you should probably give up smoking to return to your former life expectancy. The Cesium and Iodine isotopes were carried out to the sea and will never be seen again.