World Nuclear News published an article titled Consistency required for Fukushima return that mentions several topics worth increased discussion.
It mentions the report recently completed by the IAEA that complimented Japan on its efforts to decontaminate areas that were affected by the Fukushima Daiichi nuclear power station radioactive material releases. Then it went on to provide a gentle reminder to the government leaders that science does not provide any extra credit for excessive effort once decontamination has reduced annual exposure levels to 20 mSv. Any expense or effort spent getting any lower than that is wasted.
Of course, the diplomatic IAEA said it a little differently. Here is how World Nuclear News reported it.
The IAEA team encouraged Japanese institutions to “increase efforts to communicate that in remediation situations, any level of individual radiation dose in the range of 1 to 20 mSv per year is acceptable and in line with the international standards and with the recommendations from the relevant international organisations.” Here they refer to studies from the International Committee on Radiological Protection (ICRP), the United Nations Scientific Committee on the Effects of Atomic Radiation, the World Health Organisation (WHO) and the IAEA itself.
Once again, I will point out that if 20 mSv is acceptable, any resources expended to move dose rates any lower are wasted. Since many of the remediation efforts involve scraping valuable topsoil and treating it as a waste product, I submit that extra effort imposes the lasting harm of less productive farm land.
The World Nuclear News report includes the following statement.
In 22 towns across Fukushima prefecture a study of 77,400 people recorded individual doses some three to seven times less than those predicted by the generic formula.
“There needs to be a continued movement towards the use of individual doses, as measured by personal dosimeters,” said the IAEA. This would support planning for resettlement, and can also reassure people in the wider prefecture – particularly parents of small children.
I’d like to propose a utilitarian solution that would increase overall happiness and safety.
- Invest in a well designed communications effort to help people understand that an annual dose rate of 20 mSv is perfectly acceptable by even the most conservative professional radiation protection organizations in the world.
- Include information about the fact that the dose that matters is the one measured based on actual behavior, not the one predicted using overly conservative models. Since the models exaggerate actual dose rate by a factor of at least three, areas that have been calculated to have doses rates as high as 60 mSv should be considered safe enough to repopulate now.
- Evaluate areas with modeled dose rates up to 140 mSv per year to see if the actual dose to people might still be within the conservative standard of 20 mSv/year.
A higher limit is probably justifiable, but let’s take this step now to reassure people and reduce stresses associated with displacement, disruption and excessive fear of radiation. I suspect that most of the people who were evacuated would love to have their life back.
PS The formal title of the IAEA report is The Follow-up IAEA International Mission on Remediation of Large Contaminated Areas Off-Site the Fukushima Daiichi Nuclear Power Plant. The report documents observations from an IAEA visit to Japan from Oct 14-21, 2013. It was issued on January 23, 2014.