APR: your source for nuclear news and analysis since April 16, 2010

Saturday, April 9, 2011

Saturday morning update

A few different details from Fukushima Daiichi..

TEPCO is reporting that the level of water in No. 2 plant pipe tunnel is now up a total of 10 cm, leaving about 90 cm roughly to the top of the trench. No overflow has occurred.

TEPCO is beginning to install the barriers that had been mentioned by NISA at one or two briefings. This entails sealing the southern end of the intake water breakwater enclosure with steel sheets, and placing fiter type silt screens across the seawater inlet of No. 2 plant and at the north end of the inlet area for all four plants. This should contain all particulate matter in this local area.

TEPCO will attempt to increase the purity of the nitrogen being injected to No. 1 plant. The motivations for this are not known; perhaps there is some oxygen content in the nitrogen gas.

Finally, from another totally unrelated site...

There is now information that during the most recent earthquake, Higashidori nuclear station experienced inoperability of all three of its diesel generators. NISA has commented that one diesel on standby isn't enough. Whether or not Higashidori actually entered a full SBO is not clear yet, but this will surely come out somewhere at some point and we'll keep an eye out for it. I myself am beginning to suspect that the Japanese industry's standby power requirements and SBO awareness are a leading contributor to the Fukushima Daiichi accident.

6:18 AM Eastern 4/9


  1. Station blackout is a serious requirement to cater for and remain continuously capable of handling. If there is a generally lax attitude towards this important capability in Japan, that is a serious regulatory failure. Of course it can also be ascribed to the operators but if widespread and unchecked then the regulators should be carrying most of that can.

    PS: Nice tags, thanks, but you don't need the quotes, even for multiword phrases.

  2. I don't think I even need the tags any more, now that I've put the Google search box on the site. They're more trouble than they're worth; if you try to use a comma between them without quotes it auto-fills the tag box because of some peculiarity with the way Blogger's tag software is running. No big deal though; a Google search box is easy enough to use!

  3. Actually Will, I think I should withdraw my remark above, or at least temper it a little. It would not be true to say that station blackout was neglected at Fukushima, since the emergency generators started and ran when the earthquake knocked out off-site power. They only failed when immersed and deprived of fuel by the tsunami.

    The fact that this was possible is perhaps a testament to poor design selection, but not to operator or regulatory neglect of SBO facilities. I have heard that (ironically) the positioning of the diesel generators was selected for maximum earthquake safety - do you have any knowledge of that?

  4. I have understood that the diesels at these plants were indeed earthquake-proofed, but exactly what that entails is more mysterious. It looks as if little could have been expected though considering the height of the tsunami that hit the plant. We do seem to have enough supporting data now to say that the overall approach in Japan to EDGs needs to be addressed. Some of the problems are just simply because of the nature of the natural disaster, and could not have been predicted or expected but there are other nagging details (as pointed out on this blog) that seem to indicate that a thorough review of the overall approach to EDGs needs to be done.