A colleague sent this to me; it's from a Japanese colleague of his.
I can vouch for its legitimacy.
His note to me:
This message is from a wonderful Japanese colleague,
who has a heartfelt concern for his countrymen and friends,
as is evident in this unedited text concerning the aftermath of the
earthquake and tsunami nearly two years ago. He talks about
some issues that many of us might not think of immediately with
regard to the disastrous consequences of the fallout.
**********************************************************************
Dear my friends,
Toward the end of the year 2012, I remind the recent situation
of the terrible accidents of nuclear power plants in Fukushima.
I believe we have the responsibility to inform what kind of
extraordinary events happened and how we are coping with
that phenomena regarding urban drainage issues.
1. Infiltration of radioactive stormwater
I found at the bottom of four infiltration pits, that is soakaways,
around my house a high dosage of radioactive materials,
which came down from the accumulated ashes on the roof.
It counted 0.3 micro-sievert per hour. That means soakaway
could collect the radioactive materials from the roof. It cleaned
up the surface of the roof.
On the surface of the ground of my property, the
dosage was 0.05 micro-sievert per hour, that is almost no problem.
Japanese Government announced that the radioactive materials
could be acceptable for the people if it is under 0.23 micro-sievert
per hour.
However, there are many ‘hot spots’ over the value
in our neighborhood.
2. Spread all over the ground
After the accidents of the melt-down of the nuclear
power plants in Fukushima, the radioactive ashes,
dusts, powders, and particles have been spreading
over large areas.
They fell down with rainfalls onto the grounds; roads,
roofs, gardens, agricultural fields, forests, and water
bodies all over.
They are gradually flowing down into the rivers, lakes,
and the sea.
Radioactive materials do not infiltrate into the ground
since they are absorbed on the small dusts and ashes
as a shape of particles.
Radioactive materials are accumulated at the bottom
of the water courses, especially at the river mouths, and
semi-closed bay such as Tokyo Bay. - - - -
I am afraid it would be included in the food chain.
3. Continuous sweeping of the contamination
We can sweep those of roofs and roads.
However it is very difficult to remove the accumulated
radioactive materials in the forests and agricultural fields.
The trees and plants have been retaining the fallen materials
for a long time.
The radioactive materials gradually flow down to other
places; the neighboring grounds and water bodies.
For example, at a city near Fukushima, the dosage
was decreased successfully from 10 micro-sievert to
1.8 micro-sievert after the cleaning of the area. However
six months later, it returned to 8 micro-sievert, because
the radioactive materials continuously came from
the neighboring contaminated zones, especially that
of trees and plants around there.
4. Concentration into sewage sludge
The sludge collected at the wastewater treatment plants
(WWTP) was full of radioactive materials in the
eastern part of Japan. They are gradually decreasing.
The dewatered sludge, referred as to sludge cake,
had various ways to be disposed or utilized; landfill,
reclamation, gasification, fertilizer, solid resources for
cement industry, and so on.
Japanese Government decided to dispose the sludge
over 8,000 Bq/kg could be treated by the Government.
Sludge less than that value should be disposed under
the responsibility of each municipal government.
However, for example, cement companies do not
accept the sludge if they are more than 100 Bq/kg.
People do not agree to move the sludge including
radioactive substances out of WWTP.
At the other point of view, drainage system worked
well to collect the spread radioactive substances from
the non-point sources to a WWTP.
5. Piled up sludge in WWTPs
As a results, the sludge is reserved at the site of WWTP
enveloped in large plastic bags and piled up on site.
The total volume of reserved sludge in the WWTP
is more than 120,000 tons in Japan at the end of this July.
We are exploring how to remove them and how to treat them.
6. Our tasks
1) To find the places where the contaminated sludge could
be accepted.
2) To clean up the contaminated rivers, forests, agricultural
fields. But how?
3) To treat the highly contaminated sludge. But how?
4) To establish the comprehensive strategy against
the spread of radioactives.
7. What we learned
In a country which has many strong earthquakes, it is
almost impossible to have nuclear power plants.
As the memory of the day, I tried to talk about recent
situation of our fields after one year and nine months.
I hope I could report much detail regarding ‘the radioactives
and urban drainage' some day in the near future.
I hope it does not come to ‘a good information' for the
similar accident.
The next one should never be happened.Japanese experiences
should be the final in the globe.
I expect nobody would utilize the information of Japanese
experiences.
December 5, 2012.
Shoichi FUJITA TOKYO JAPAN
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