Larry, I continue to be amazed at your calm attitude.
I spent 14 years working in emergency management. During that time I tested repaired and calibrated radiological monitoring equipment and was one of the primary trainers for radiological emergency response operations. I also participated in writing emergency response plans for radiological facilities and conducting and evaluating emergency response exercises. I also served as the assistant communications officer so was immersed in the communication streams of several emergencies.
I also helped create one of the Urban Heavy Rescue teams that FEMA sponsors, and spent 5 years on a mountain rescue team.
Lessons learned:
1. The media seldom has a clue what is going on -- we spent more time fixing bad information from the media than we did dealing with actual situations. Therefor take media accounts with a very large bag of salt.
2. You seldom know all the facts even if you are on scene, -- getting excited does not help anyone.
3. The reporting process regarding radiological monitoring is historically a huge problem, it is VERY difficult to get good monitoring data even from trained emergency response personal, and radiological data from untrained sources is 99.99% crap.
It took us years of training to get Phd and masters degree health department responders to report useful radiological data, and even then it was about 30% useless. Under the stress of the moment (just the stress from a simple evaluation exercise) they never could get their head around gathering all the data needed. They also frequently mis-reported actual readings, due to having the equipment set on the wrong range multiplier setting, they reported 100's of mr/h when actual readings were 10's or 1's mr/hr. They could not remember to tell us the actual location or time the readings were taken. They could not remember to write down their measurements and mis-spoke when reporting by radio. They reported readings taken at location A as readings taken at location B. They forgot to include units in their measurements they would report rates of exposure as absorbed dose exposures. (rates would be units/hr, absorbed dose would be units --- they would forget or jumble those units)
As a result it took some detective work to throw out the bad reports and infer the real situation from a body of reports that gave a consistent picture.
4. The public perception of radiation risk is many times higher than the actual risk.
5. Protective actions can cause more harm than good. We considered and rejected the idea of issuing Potassium Iodide tablets to the public for radiological protection because there was a very real risk of killing people due to serious allergic reactions to Potassium Iodide that a small percentage of the population will experience to protect against low levels of radiation exposure that have absolutely zero biological risk.
We are talking about extremely low radiation exposures off site in the context of biological injury. Radiation exposure from a brief whole body dose of gamma radiation is asymptomatic (not reliably detectable even by evaluation of blood tests) at levels of 12-15 RAD, with in modern measuring units would be total exposure of:
120,000 - 500,000 microsieverts -- the media are reporting exposure rates of anything from fractional microsievert rates per hour to 10's of microsieverts per hour in areas off site. In short the actual radiological risk in those areas is essentially zero.
Normal background radiation in most of the world is around 10 microsieverts per day with some areas like here in Denver Colorado having normal background radiation of 20-30 microsieverts. The levels of radiation they are reporting off site are in the first place trivial biologically, second the levels will rapidly drop as decay of the radioactive isotopes occurs.
In the U.S. Annual allowed Occupational exposure rates for non-radiation workers are set at 0.1 rem/year (1000 microsieverts) on top of the normal annual exposure of 0.3 rem/year (3000 microsieverts) from normal background radiation, and incidental exposure of 0.05 rem/year (500 microsieverts) we receive from medical x-rays, high altitude air plane flights etc.
Annual allowed Occupational exposure to radiation workers (which the plant staff is) is much higher at 5 rem/year or (50000 microsieverts) These are considered safe and allowed exposure rates on a continuing basis.
Emergency responders one time acute exposures would be much higher. An employer can allow an individual who works in a restricted area to receive up to 3 Rem / quarter (30,000 microsieverts) ie any 3 month period or total accumulated whole body dose cannot exceed 5(N-18) rems where N is the persons age in years at their last birthday. That means a 40 year old emergency responder could be allowed to receive 5(50-18) REM or an accute dose of 160 Rem (160000 microsieverts).
That said the ALARA guideline is to keep radiation exposure As Low As Reasonably Achievable -- that is why they are doing all the evacuations. It is simply good practice, and probably required by their protective action guidelines, but those levels of radiation exposure are in real terms trivial. They are about as serious as going out in mid day sun without sun screen.
Larry
