That's a pretty good article. I wish they had been a little more careful about absolute dose vs dose rate (per hour, year, etc). However, it is a LOT better than an AP article I found and decided not to post. They expressed erverything in rem, destroying any comparison with data we are seeing from Japan. They didn't even bother to relate the two.
--- On Thu, 3/17/11, James R. Frysinger <[email protected]> wrote: From: James R. Frysinger <[email protected]> Subject: [USMA:50066] Re: Increased dosage limits To: "U.S. Metric Association" <[email protected]> Cc: "U.S. Metric Association" <[email protected]> Date: Thursday, March 17, 2011, 11:25 AM Well, I suppose that one helpful thing this discussion does for members of the forum is to provide a "real feel" for some SI units that most people know very little about. It's one thing to say that 1 Gy stands for 1 J of absorbed energy by a kilogram of tissue but it's another matter to know some typical values and their implications. And it provides an opportunity to relate sieverts to grays. CNN today provided an interesting web page http://thechart.blogs.cnn.com/2011/03/15/what-you-should-know-about-radiation/ that linked to an FDA web page of interest: http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/MedicalImaging/MedicalX-Rays/ucm115329.htm The latter provides typical radiation dosages experienced in some common medical procedures. Those levels are comparable to values we've been discussing here. Even though I no longer go to sea on submarines or operate nuclear reactors, I reckon my Navy training on nuclear and radiological matters is still useful. Jim On 2011-03-17 0958, [email protected] wrote: > Jim (Frysinger), > > We recognize you as the most experienced authority on radiation reporting to > this forum. Please continue the good work. > > Gene. > --- Original message ---- >> Date: Wed, 16 Mar 2011 22:54:01 -0500 >> From: "James R. Frysinger"<[email protected]> >> Subject: [USMA:50063] Increased dosage limits >> To: "U.S. Metric Association"<[email protected]> >> >> I see in today's news that the "Fukushima 50" (50 workers at the site of >> reactor 4 at the Fukushima plant) have been authorized to exceed their >> normal annual dosage limit of 20 millisieverts (20 mSv). Their limits >> were raised to 100 mSv and then later to 250 mSv. >> >> Up to this "acute" dosage of 250 mSv, no significant radiological >> effects are expected (for 50 % of such exposed workers), by most >> radiological health personnel. Above that, workers might suffer >> radiation burns (akin to sunburns) and noticeable changes in their blood >> cell counts. As is the case in all fields, the dosage at which this is >> expected to set in is debatable, with some touting a lower dosage and >> some a higher dosage. And of course, people vary in their responses to >> challenges to their health. >> >> This higher dosage limit of 250 mSv is rarely authorized for >> occupational workers but this is not the first time that a national >> authority has done so. Susequently, these workers are likely to be >> reassigned away from radioactive fields, at least for several years, >> while their health is monitored closely. A few medical treatments (even >> beyond potassium iodide and chelating agents) are available, but I'm not >> knowledgeable enough to discuss those in depth. >> >> LD50 dosage (at which 50 % of such exposed people are expected to die) >> is usually considered to be 10 times this emergency dosage, that is, 2.5 >> Sv (2500 mSv). >> >> By the way, I am talking about whole-body radiation here. Ingestion of >> radioactive gas or particles is a different matter and there are too >> many variables to discuss it here. >> >> If there are any others here with experience working with nuclear power >> reactors or with comparable experience in radiological controls, feel >> free to jump in here! So far, I seem to be the only one who has run off >> at the mouth on this stuff. >> >> Jim >> >> -- >> James R. Frysinger >> 632 Stony Point Mountain Road >> Doyle, TN 38559-3030 >> >> (C) 931.212.0267 >> (H) 931.657.3107 >> (F) 931.657.3108 >> > > > > -- James R. Frysinger 632 Stony Point Mountain Road Doyle, TN 38559-3030 (C) 931.212.0267 (H) 931.657.3107 (F) 931.657.3108
