Flooding of Fukushima turbine halls ‘to drop a half metre by mid-September’

Tepco has forecast (26 August) that water levels in the flooded unit 2 and unit 3 turbine halls of stricken nuclear plant Fukushima Daiichi are estimated to fall by a half metre in about a month, assuming that there is no change in the water injection rate or the rainfall pattern. The system recently added a second train of caesium adsorption systems to increase throughput. The first desalination system is also up and running.

Seismic analysis of the seismic forces acting on units 2, and units 5&6, has found no structural damage as a result of the earthquake. Tepco said it assumes that there is no internal damage inside unit 2, although high radiation levels prohibit people from entering the building. A time transient response analysis using design basis earthquake ground motion (Ss) was used. Shear strain in unit 2 anti-earthquake walls was estimated at a maximum of 0.17×10^-3 (in east-west direction, on the fifth floor), only 1/24th of standard maximum value of 4×10^-3. A further study of the possible effect of the high temperatures in the primary containment vessel, and activity in the suppression chamber in the basement on the analysis showed that they did not change the figures significantly. In units 5&6, earthquake shear strain forces using the same analysis were found to be greater (0.19×10^-3 and 0.33×10^-3), but still not sufficient to challenge the building’s integrity.

Finally, Tepco has restarted pumping the unit 6 turbine building. Earlier reports mistakenly stated that pumping out this turbine building had finished.

Regular updates may be found on the website of our sister journal, Nuclear Engineering International, reachable on <www.neimagazine.com> or by clicking on the link in the navigation bar to the left of this page.

The following sites are also posting continuing updates:

<http://www.tepco.co.jp/en/index-e.html>

<http://www.iaea.org/>

<http://www.jaif.or.jp/english/>

<http://bravenewclimate.com/2011/03/15/tepco-reactor-status/>

<http://www.world-nuclear-news.org/>

<http://www.kantei.go.jp/foreign/index-e.html>

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