• Blog Stats

    • 79,937 hits
  • Archives

  • Enter your email address to subscribe to this blog and receive notifications of new posts by email.

    Join 157 other followers

  • Copyright notice

    This blog entry and all other text on this blog is copyrighted, you are free to read it, discuss it with friends, co-workers and anyone else who will pay attention.

    If you want to cite this blog article or quote from it in a not for profit website or blog then please feel free to do so as long as you provide a link back to this blog article.

    If as a school teacher or university teacher you wish to use content from my blog for the education of students then you may do so as long as the teaching materials produced from my blogged writings are not distributed for profit to others. Also at University level I ask that you provide a link to my blog to the students.

    If you want to quote from this blog in an academic paper published in an academic journal then please contact me before you submit your paper to enable us to discuss the matter.

    If you wish to reuse my text in a way where you will be making a profit (however small) please contact me before you do so, and we can discuss the licensing of the content.

    If you want to contact me then please do so by e-mailing me at Chalmers University of Technology, I am quite easy to find there as I am the only person with the surname “foreman” working at Chalmers. An alternative method of contacting me is to leave a comment on a blog article. If you do not know which one to comment on then just pick one at random, please include your email in the comment so I can contact you.

Fukushima water leak

Dear Reader,

It has come to my attention that a tank holding radioactive waste water at Fukushima has been leaking,

The story is that workers found leak from a tank and a puddle of water which was about 9 square meters (1 to 2 cm deep) which had leaked, this was found to be radioactive. This water was contained inside a dyke and had not started to flow into the sea. A second puddle was found outside the dyke (3 square meters and 1 cm deep). This was in the H4 area.

This water was found to be radioactive, it had 46 Bq of Cs-134 per cubic cm, 100 Bq of Cs-137 per cubic cm, 1.2 Bq Co-60 per cubic cm, 1.9 Bq of Mn-54 per cubic cm, 71 Bq of Sb-125 per cubic cm, 80 kBq of total beta activity per cubic cm and it contained 5200 ppm of chloride per litre.

In this area TEPCO workers measured dose rates of 6 mSv per hour in a drainage channel.

TEPCO workers also found a pair of leaks in the H3 area near a tank where the worst dose rate was 100 mSv per hour. Later radioactive water was found in drainage channel B (0.15 Bq of Cs-137 per cubic cm) this is near the H4 area. A set of diagrams of the tank farms and the drainage channels can be seen here.

The cesium level in the water leaking from the tank farms is much lower than the water which is flowing out of the reactor buildings, according to a recent report the water in the central radioactive waste treatment buildings is in the range of 55000 to 28000 Bq of Cs-137 per cubic cm. After the cesium removal plant the water only has 5 or fewer Bq of Cs-137 per cubic cm.

The radioactivity levels suggest one of two things is happening, either the leak is a very new leak which and the radioactivity has not had a chance to percolate out into the drainage channel which flows into the sea. Alternatively the soil is acting as a filter for the radioactivity, this could account for the much lower radioactivity level in the ditch water which is flowing to the sea.

What is needed in the long term are details of how well the soil on the site binds to cesium and also the cesium absorption capacity of the soil. When I know more I will provide you with my thoughts on what is happening. But always bear in mind that when radioactive cesium is a problem clay can often be your best friend.

On of the key parameters needed to understand how well the clay will trap radioactivity is the Kd value, to understand Kd please look at this post about plutonium in spanish soil. Also do bear in mind that not all clays are equally good at catching cesium for details of some different clays please see here.

Advertisements

Go on, Have your say !

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: