③At 100 meters away it (the helicopter) was reading 4 sieverts per hour. That is an astronomical number and it told me, what that number means to me, a trained person, is there is no water on the reactor cores and they are just melting down, there is nothing containing the release of radioactivity. It is an unmitigated, unshielded number. (Confidential communication, September 17, 2012).11
In transcribed telephone conversations between U.S. based federal government officials, nuclear authorities, U.S. embassy officials in Tokyo and military staff in the Pacific Command (PACOM) made available through the Freedom of Information Act (FOIA), the U.S. government response to the nuclear crisis can be seen in real-time as it played out over the course of the first month of the crisis:
ADMIRAL DONALD: (...) Earlier this evening, as the USS Ronald Reagan was operating off the coast of Japan, we - the ship just arrived. We had given the ship some guidance as far as positioning was concerned to stay clear of the area of the potential plume, basically told her to stay 50 miles outside of the radius of the -- 100 miles -- excuse me -- 50 miles radius outside of the plant and then 100 miles along the plume with a vector of 45 degrees. The ship was adhering to that requirement and detected some activity about two and a half times above normal airborne activity using on-board sensors on the aircraft carriers. So that indicated that they had found the plume and it was probably more significant than what we had originally thought. The second thing that has happened is we have had some helicopters conducting operations from the aircraft carrier and one of the helicopters came back from having stopped on board the Japanese command ship in the area, and people who had been on -- were on the helicopter who had walked on the deck of the ship, were monitored and had elevated counts on their feet, 2500 counts per minute. But I wanted to get you guys on the line and my expert on the line so we can get the data and then the proper people notified.
MR. PONEMAN: Okay, I have a couple of questions. Number one, in terms of the level of radiation that you are picking up, what's the delta between that and any information we have from the Japanese or other sources of what the level of radiation would be, given the venting and so forth that we know has occurred?
MR. MUELLER: So -- this is Mueller -- the sample that was taken and then what we detected, we were 100 nautical miles away and it's -- in our terms it's -- ①compared to just normal background it's about 30 times what you would detect just on a normal air sample out at sea. And so we thought -- we thought based on what we had heard on the reactors that we wouldn't detect that level even at 25 miles. So it's much greater than what we had thought. We didn't think we would detect anything at 100 miles.
MR.. PONEMAN: You didn't think you'd detect anything at 100 miles. Okay, and then in terms of the regulations and so forth of people operating in these kinds of areas, I forget some you know, acronym for it, PAG (Protective Action Guidelines) or something, how do the levels detected compare with what is permissible?
MR. MUELLER: If it were a member of the general public, it would take -- well, it would take about 10 hours to reach a limit, a PAG limit.
MUELLER: Right. For a member of the public.
PONEMAN: Right. You mean, at the level you detected?
MR. MUELLER: Yes sir. ④But 10 hours, it's a thyroid dose issue.
MR. PONEMAN: Okay, but the net of all this is that the amount of release that is detected by these two episodes whatever you would call them, is significantly higher than anything you would have expected what you have been reading from all sources?
MR. MUELLER: Yes sir. The number specific number we detected was 2.5 the times 10 to the 88 minus nine microcuries per milliliter, airborne, and that's particulate airborne. It is -- we did not take radioiodide samples so I don't know that value, but this is particulate airborne...
MR. PONEMAN: Tell me again exactly how you picked up these two forms of samples.
MR. MUELLER: We have automatic detectors in the plant that picked up -- picked up the airborne, ②and all of our continuous monitors alarmed at the same level, at this value. And then we took portable air samples on the flight desk and got the same value.
ADMIRAL DONALD: These are normally running continuous detectors, continuous monitors that run in the engine room all the time, monitoring our equipment.
MR. PONEMAN: These are detectors on the Reagan?
ADMIRAL DONALD: On the Ronald Reagan, correct.
MR. MUELLER: Yes sir.
MR. PONEMAN: On the Ronald Reagan. They are there because you have got equipment there that you know, it could emit stuff and while you were there, you picked up stuff that was ambient which indicated that you actually were in the plume?
MR. MUELLER: That's correct.
MR. PONEMAN: And this was -- this was 30 times higher than what you would have expected?