Decontamination: Why so slow? - FUKUSHIMA MAIS MORTÍFERA QUE HIROSHIMA, NAGAZAKI E CHERNOBYL JUNTAS 17

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Decontamination: Why so slow?

November 17, 2013

News Navigator: Why has decontamination work in Fukushima been slow?

The Mainichi answers common questions readers may have about decontamination work carried out in areas near the stricken Fukushima nuclear plant.

Question: Has the decontamination work been successful?

Answer: Not entirely. The national government has designated 11 municipalities in Fukushima Prefecture into three zones depending on the

level of radioactive contamination: zones where the yearly dosage tops 50 millisieverts and returning to live there is deemed difficult; zones where living restrictions are in place (a yearly radiation level exceeding 20 millisieverts but no more than 50 millisieverts); and zones preparing for the lifting of evacuation orders (a yearly radiation level up to 20 millisieverts).

In June this year, the government completed the decontamination process in the Miyakoji district in the city of Tamura, which is designated as a zone preparing for the lifting of evacuation orders. However, average radiation levels in residential areas didn't drop to the annual permissible dosage of 1 millisievert, or 0.23 microsievert per hour -- the government-set long-term goal for the annual maximum dosage.

Q: How come it's not working?

A: Radioactive contaminated objects such as soil and leaves travel with the wind and rain from places where decontamination work hasn't been completed to decontaminated areas, raising radiation levels.

Since 70 percent of the prefecture is covered by forests, even if decontamination work is completed in one area, radioactive substances can move from the surrounding forests.

Q: When will we see radiation levels drop in those areas?

A: Even taking radioactive decay into account and also considering that rain washes away radioactive materials, annual radiation levels in the difficult-to-return zone are predicted to top 20 millisieverts even some six years after the nuclear plant accident. To reduce the level in the same zone to below 10 millisieverts per year, it is predicted to take...LINK

Leia (em português) uma introdução à esta série de posts aqui.