Operator Tepco has undertaken the spraying of a green polymer resin over the Fukushima Daiichi site to prevent radioactive dust from blowing away. The utility has now announced a similar plan to bind contaminated sand and soil in the intake canals of units 1-4 and 5&6.
Concerned that contaminated soil might be spread outside by wave action, the utility has been working since January on a survey of the seabed inside the port, and since December on a suitable covering material.
It now proposes to cover the seabed with two layers of bentonite clay/concrete mixes. These materials have the advantage of not affecting the coastal environment coupled with a uniform make-up. A lighter-coloured lower layer will consist of a lightweight mix to cover the highly-mobile floating mud on the seafloor. On top of it will be a second, more durable layer.
The materials will be provided, mixed and poured on site on several barges. A special mixing barge has arrived at site, and will feed a crane barge mounting a tremie pipe, which is designed to pump concrete under water. A test pour was due to start on 25 February.
Tepco plans to monitor radionuclide content before, after and during construction to understand if the construction work tends to contaminate the area. As part of the work, it will also install a silt fence across the unit 5&6 intake canal to reduce the spread of radioactive material.
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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