Fukushima air to stay radioactive in 2022

[xchrom]

http://www.japantimes.co.jp/text/nn20120423x2.html

FUKUSHIMA — A decade from now, airborne radiation levels in some parts of Fukushima Prefecture are still expected to be dangerous at above 50 millisieverts a year, a government report says.

The report, which contains projections through March 2032, was presented by trade minister Yukio Edano Sunday to leaders of Futaba, one of the towns that host the crippled Fukushima No. 1 power plant.

The report includes radiation forecasts for 2012 to 2014, and for 2017, 2022 and 2032, based on the results of monitoring in November last year. It was compiled to help municipalities draw up recovery and repopulation programs for the nuclear disaster.

The forecasts do not take into account experimental decontamination efforts.

[TheWraith]

1. "50 millisieverts a year" is not "dangerous."

50 millisieverts per year is the standard background dose found in most of India and Europe.

What's really killing us is scientific illiteracy, particularly in the media. And that includes blogs.

[TalkingDog]

2. Your argument is weak. Standard background radiation found in X

does not necessarily imply lack of danger.

What does indicate a lack of danger is saying: When exposed, on a regular basis, to 50 millisieverts per year of radiation, the human body is affected in X ways.


No noticeable effect implies no danger.

What are the effects on the human body of being exposed to 50 millisieverts per year of radiation?

Do us all a favor, Liter-ate me with some science. Provide links please, because, I'm a skeptic and your say-so is not adequate.

[FBaggins]

5. Safety levels are normally set below that.

But that's a normal excess of caution. It's also important to note that it's almost certain that the 50mSv/yr level is a part of the area that will remain closed.

There has been no scientific correlation between an increased risk and an annual dose below double that amount.

http://www.google.com/url?sa=t&rct=j&q=radiation%20benefits%20and%20risk%20assessment&source=web&cd=1&ved=0CDcQFjAA&url=http%3A%2F%2Fhps.org%2Fphysicians%2Fdocuments%2FRadiation_Benefit_and_Risk_Assessment.ppt&ei=dK6VT7jsEvP06AHa8pCxBA&usg=AFQjCNF1iqsrJpbK_oA5n9HDg4EZcNvcqA

[TalkingDog]

12. Thank you. That is much more instructive than suggesting people lack scientific literacy.

n/t

[bananas]

6. Natural background radiation in Europe

[Demeter]

11. Well, that explains my Ex from Finland

Sigh. I married a mutant.

[bananas]

7. US NRC: Radiation Dose Limits for Individual Members of the Public: 1mSv/year

http://www.nrc.gov/reading-rm/doc-collections/cfr/part020/full-text.html#part020-1301

Subpart D--Radiation Dose Limits for Individual Members of the Public

Source: 56 FR 23398, May 21, 1991, unless otherwise noted.

§ 20.1301 Dose limits for individual members of the public.

(a) Each licensee shall conduct operations so that -

(1) The total effective dose equivalent to individual members of the public from the licensed operation does not exceed 0.1 rem (1 mSv) in a year, exclusive of the dose contributions from background radiation, from any administration the individual has received, from exposure to individuals administered radioactive material and released under § 35.75, from voluntary participation in medical research programs, and from the licensee's disposal of radioactive material into sanitary sewerage in accordance with § 20.2003, and

(2) The dose in any unrestricted area from external sources, exclusive of the dose contributions from patients administered radioactive material and released in accordance with § 35.75, does not exceed 0.002 rem (0.02 millisievert) in any one hour.

(b) If the licensee permits members of the public to have access to controlled areas, the limits for members of the public continue to apply to those individuals.

(c) Notwithstanding paragraph (a)(1) of this section, a licensee may permit visitors to an individual who cannot be released, under § 35.75, to receive a radiation dose greater than 0.1 rem (1 mSv) if-

(1) The radiation dose received does not exceed 0.5 rem (5 mSv); and

(2) The authorized user, as defined in 10 CFR Part 35, has determined before the visit that it is appropriate.

(d) A licensee or license applicant may apply for prior NRC authorization to operate up to an annual dose limit for an individual member of the public of 0.5 rem (5 mSv). The licensee or license applicant shall include the following information in this application:

(1) Demonstration of the need for and the expected duration of operations in excess of the limit in paragraph (a) of this section;

(2) The licensee's program to assess and control dose within the 0.5 rem (5 mSv) annual limit; and

(3) The procedures to be followed to maintain the dose as low as is reasonably achievable.

(e) In addition to the requirements of this part, a licensee subject to the provisions of EPA's generally applicable environmental radiation standards in 40 CFR part 190 shall comply with those standards.

(f) The Commission may impose additional restrictions on radiation levels in unrestricted areas and on the total quantity of radionuclides that a licensee may release in effluents in order to restrict the collective dose.

(56 FR 23398, May 21, 1991, as amended at 60 FR 48625, Sept. 20, 1995; 62 FR 4133, Jan. 29, 1997; 67 FR 20370, Apr. 24, 2002; 67 FR 62872, Oct. 9, 2002)

[caraher]

9. Are you thinking of 50 mrem/year?

If so, there's a factor of 100 missing

[FBaggins]

10. Are you saying that the article got it wrong?

Or are you saying that the danger threshold is actually much lower than the stated amount?

[caraher]

13. I'm replying to TheWraith

The article said 50 mSv/year and I have no basis for questioning the figure. TheWraith said,

50 millisieverts per year is the standard background dose found in most of India and Europe.

That would be 5000 mrem/year, which is about ten times the correct figure for background radiation (which would be a few hundred mrem/year; see post #6 by bananas, for instance). So I'm wondering whether TheWraith misread mSv as mrem.

I'm also making no assertions regarding the safety of such a dose. 50 mSv is the annual exposure limit for radiation workers in the US, so that gives some sense of where health physics professionals think one should start exercising caution.

[FBaggins]

14. I see, thanks!

I was reading the amount and didn't pay much attention to the claim that it's a common background figure. I agree that it's high (though not 100-times too high).

The underlying point is accurate, however. There are areas of the world where background radiation levels exceed 50 mSv/year, and no negative health impacts have been identified.

[caraher]

15. The factor of 100

I was referring to the difference between a mSv and a mrem, which is a factor of 100. It's closer to a factor of 10 in terms of overstating common background levels.

[bananas]

3. Bad link - need a space between ".hml" and "FUKUSHIMA"

Here's the correct link: http://www.japantimes.co.jp/text/nn20120423x2.html

and I'll add this paragraph from the article:

Earlier this month, the government designated areas where annual radiation dosage exceeds 50 millisieverts as those likely to remain off-limits to evacuees in the near term.

[xchrom]

4. thanks! nt

[caraher]

8. It is certainly written (translated?) badly

If I understand what they're reporting, they just mean that the external dose one would receive in those regions over the course of a year would be above 50 mSv/year. They are not describing the radioactivity of the air itself; rather, they're reporting a dose rate one would measure with a detector "in the air" above those regions.

The relative safety of a 50 mSv/year additional radiation dose is, of course, open to debate (both in terms of modeling risks from low dose radiation and the philosophical question of what should be declared "safe" given risks, with or without uncertainties in the risk estimates), but it's at least a benchmark value one can use to assess the amount of exposure.