thebulletin | Tepco and the Japanese government
have done a good job of containing most of the highly contaminated
water, which poses the highest risk to the public. They are, however,
having great difficulty in managing the overall contaminated-water
situation, especially from a public-confidence perspective. The
engineering challenge—control of a complex, ad hoc system of more than
1,000 temporary radioactive water tanks and tens of miles of pipes and
hoses throughout the severely damaged plant—is truly a herculean task.
Explaining what is going on and what has to be done to an emotional,
traumatized, and mistrusting public is an even larger challenge.
Approximately
340,000 tons (90 million gallons) of radioactive water is now stored in
large tanks at the site. A variety of water-processing systems have
been built fairly rapidly under very difficult circumstances. To
minimize the increases in water inventory growth, all cooling water now
being injected into the damaged reactor cores is recycled. It is
initially pumped from the building basements and processed through new
systems that remove most of the gamma emitting cesium 137 and cesium
134, oils, and salt contaminates, so that the water can be pumped back
into the three reactor cores to keep them cool. Because the cores are
mostly melted debris, the injected water picks up more radionuclides and
flows back into the basements. The water-processing systems now in use
are not capable of removing strontium 90, which is only a beta emitter
and not a major radiological hazard to trained workers who wear
protective clothing. But strontium 90 is an environmental concern and
will need to be removed from water before it can be returned to the
environment.
The reactor
and turbine buildings are not watertight up to the surface; the
basements are below the present groundwater elevation, and relatively
clean groundwater seeps into the buildings. Tepco is maintaining the
water levels in the basements slightly below the groundwater elevation
to prevent the leakage of highly contaminated water from the basements
into the general environment. But this in-leakage—estimated to be
approximately 400 tons (105,000 gallons) per day—mixes with the water
already in the basements, also becoming highly contaminated. So each
day, despite Tepco’s water-recycling efforts, the volume of contaminated
water at the plant increases; this is why 340,000 tons of water are
currently stored on site.
This
building-basement water is the highest-risk water associated with the
Fukushima situation. That water is being handled reasonably well at
present, but because of the constant in-leakage of groundwater, some
ultimate disposition will eventually be necessary. To further clean this
huge and increasing volume of medium-level radioactive water, the Tepco
team has built a major new water processing system called the Advanced
Liquid Waste Processing System. Built by Toshiba, this state-of-the-art
system is based on technology from a major US waste management company,
EnergySolutions.
Although this system is in a testing
phase, with startup design and operational issues being resolved, it
aims to remove more than 99.999 percent of radioactive contamination for
most radioisotopes. The radioactivity levels in the effluent of the
Advanced Liquid Waste Processing System are expected to be very low and
to meet international and Japanese discharge standards for the important
isotopes of cesium and strontium. This means that, from a radiological
risk point of view, the risk from water treated by this system and
released to the sea will be extremely low—a small fraction of the
natural variations in the environment’s background radiation. In fact, I
am writing this article while sitting on an airplane, and I am
receiving more ionizing radiation from cosmic rays at this higher
altitude than I would receive from drinking effluent water from the
Advanced Liquid Waste Processing System.
2 comments:
This writer is not a scientist, he's a technical bureaucrat, and he's lying on behalf of the industry that conferred him status.
http://enenews.com/law-professor-damage-from-fukushima-radiation-may-be-much-larger-than-we-expect
http://enenews.com/ban-on-japanese-seafood-in-full-effect-says-russia-includes-fukushima-and-7-other-prefectures-decision-is-based-on-monitoring
Do you think those were examples of the notorious "science trolls" in the comments attached to this article?
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