DHS radiological cleanup: 10rem/year for general public?

[rachmaninoff]

http://news.yahoo.com/s/ap/20060104/ap_on_he_me/dirty_bomb

WASHINGTON - The government issued cleanup standards Tuesday for a "dirty bomb" terrorist attack that would in some cases be far less rigorous than what is required for Superfund sites, nuclear power plants and nuclear waste dumps.
...
In some cases, the document suggested, long-term radiation exposures of as much as 10,000 millirems per year — a level equivalent to hundreds of chest X-rays a year or 30 times the annual exposure to radiation from natural "background" sources — could be allowed for areas that are returned to general use.

Not that this is an extremely probable scenario or anything - but are these journalists correct in getting excited over this? They're contending that the DHS response plan to a radiological incident is ridiculously lax in exposure limits, specifically for long-term exposure to the general public. I haven't been able to find the actual DHS guidelines (can anyone help?), so I'm not sure what to think of this - is this a total effecive dose (TEDE) or something else? I looked up the NRC's annual exposure limit, which is half of this (5 rem/yr TEDE), but I'm not a physician and I don't know how these things scale (not linearly I assume).

So is this another case of Katrina-like poor planning, or a case of overenthusiastic but confused journalism, or a bit of both? Maybe the wise Astronuc will clarify things?

edit: Also, any links to the methodology of radiation exposure limits?

 

[rachmaninoff]

I suspect I may need to justify this thread's existence. Radiological terrorism is far from the biggest threat to society - much smaller than all the chronic problems of poverty, obesity, lack of education, etc., as well as the high-visibility natural disasters such as hurricanes or earthquakes. The reason this subject is in discussion is - directly - because it receives high visibility in the media (correctly or not); and secondly - because it serves as a gauge of the efficiacy of the $36 billion/yr DHS, a relatively young bureaucracy whose capability and management have been strongly called into question over the past few months, and which has tremendous influence in many other, non-terrorist situations (hurricanes).

So I'm not trying to advocate a hype about this particular threat or anything.

 

[Pengwuino]

Well the day the government is able to regulate volcanic eruptions, force people to eat correctly, and pay attention in school... well that's one hell of a government.

I think the people who probably know about this aren't the type to hang around this part of the forum (ie people who don't have time to waste, unlike me!). I suspect Morbius would know however! Might want to drop him a line if he's around much anymore.

 

[Astronuc]

Here is some information on radiation protection and limits for radiation exposure.

http://www.nsc.org/issues/rad/protect.htm

and responsible agencies -
http://www.nsc.org/issues/rad/protect.htm#agencies

DHS is developing scenarios in the event of a radiological or nuclear (fissile weapon) attack. The radiological attack would be easier to deal with since in theory the radioactive material would be localized and could be cleaned. However, the 'clean-up' is hypothetical at this point.

The radiation limit of 10 rem/yr is rather high, and risk of cancer increases. The threat to infants and children is particularly significant, and basically infants and children should not be exposed to such levels of radiation.

See also - http://www.nsc.org/issues/radisafe.htm

http://www.icrp.org/

 

[daveb]

10 rem/year is very small (it's only twice the whole body occupational limit for adults). Although risk of cancer increases (assuming hormesis is not a reality), it's assumed to be such a small number that it makes little difference. Not to mention the fact that this equates to a rate of just over 1 mrem per hour, which is less than the limit for dose rate for a member of the public. I'd be more concerned if this was 10,000 mrem was an absorbed dose in one fell swoop.

 

[Pengwuino]

I wonder what "general use" means.

I also could see this being a realistic scenario if you toss in the economic implications of having a city abandoned...