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 >
