Published: March 6th, 2012 at 2:33 pm ET
Follow-up to: All of Western US and most of East Coast, Midwest, Canada covered with airborne particles at various altitudes on March 20, Fukushima plume model shows -- Based solely on Reactor No. 1 explosion (PHOTO)
Japan’s Fukushima Daiichi ET Audio File
Nuclear Regulatory Commission
Thursday, March 17, 2011
BRIAN: Did we ever get the — I’m trying to think of what the best term is, the — everything everything (inaudible) scenario back from — I thought that was one we were going to ask NARAC to run once they had time.
MALE PARTICIPANT: Are you talking about the doses they saw all the way out in California?
MALE PARTICIPANT: Yeah. That is going to be run by Research in Sandia, but they are not going to be able to do it until later today.
BRIAN: Oh, okay.
MALE PARTICIPANT: Sounds like they had to modify the code first in order to do that run.
MALE PARTICIPANT: Had to modify the MAC code. They — NARAC did do their evaluation of — using our source term, and they — they were calculating doses, particularly for children — thyroid doses of (inaudible) after — that the one- year dose, assuming some very conservative assumptions about ingestion, and (inaudible) practices. So we had the group — the PMT look at some of the actual data from deposits from Chernobyl, which we had from DITTRA.
MALE PARTICIPANT: Historical data. And convert those to doses using the same update techniques. And they have some calculations — they hadn’t shown them to be (inaudible), but they are showing millirem range doses, like one to 10 millirem.
MALE PARTICIPANT: (Inaudible.)
MALE PARTICIPANT: For the actual deposits. So we think there is some extreme conservatism in the DITTRA numbers, and we will know more once Research does their (inaudible).
MR. LEWIS [Robert Lewis, Director of NRC's Division of Preparedness and Response]: Okay. Good morning. I will cover four things that occupied most of the protective measures team time last night. First, there was a flight by NARAC last night [...] We also are working — there was a request coming from last night — before last evening’s shift to develop projections for doses in California. And that is — has been in process. We will need to — in order to do that, we will need to engage with — we already have engaged with the Office of Research. We are looking to engage further with Sandia to make some modifications to the (inaudible) to effectuate those dose estimates in California. In conjunction with that, there was a DITTRA and NARAC dose estimate that was done for California that we obtained as part of the DOE briefing package. And those were estimating what we believe to be very high doses to children, and a thyroid (inaudible) dosage. We think that (inaudible) extremely conservative modeling related to those doses and assumptions. It’s a thyroid dose that involves deposition of material and (inaudible) integrated the dose over a year or two, for example, drinking milk from the same cow that’s grazing on the same contaminated field the entire time, things like that. But once we get the (inaudible), we will have something to compare (inaudible). Also, when we saw those dose estimates, we looked in the historical record for any kind of information related to Chernobyl actual deposits that were measured. We did find some and (inaudible) dose activity per area of deposits that were estimated — I think they were provided from DITTRA. We did the same dose calculations with those concentrations, and the doses were approximately 1,000 times lower. So we were in the one to 10 millirem range versus full rem range, which was — full rem thyroid dose range, which was being (inaudible) by DOE and DOE (inaudible). [...]
MIKE: Rob, this is (inaudible). I have a question for you. This request for doses in California projected with, I guess, worst-case assumptions, is that correct? (Inaudible.)
MR. LEWIS: I believe the doses that we saw from DITTRA represented a source term of 100 percent of the (inaudible).
MIKE: Okay. And where — is this information being considered for releasing publicly, like we do with the press release?
MR. LEWIS: Which information are you speaking about?
MIKE: I’m talking about these projected dose models, the models that you — the ones that you are doing and coordinating with other agencies, is there some thought about releasing that publicly?
MR. LEWIS: We have not had that discussion at this time.
MIKE: And don’t take that as a suggestion to (inaudible). I’m just curious as to how we came upon doing that with our press release, and then, are we advocating that for any future press releases here for doses in the U.S.?
MR. DORMAN: Mike, this is Dan. No. No, we’re not planning any press release with this information. This was a projection that we were requested to run. Separate from our being requested to run that, we got this DOE briefing package that had this other DITTRA run in it, and we’re not — I don’t know what prompted theirs or all of the assumptions that went into theirs, but it obviously caught our attention and we are looking to get what we think would be more realistic projections. Other questions?
MS. HOWE: Dan, just one comment, and Rob. This is Linda Howe in Region IV. Rob, I can talk with you offline about some background information for California. The DITTRA and DOE runs for California may have been prompted by queries from the state, because the state has been conducting interagency conference calls, and DOE, EPA, HHS, has been part of those calls. Our regional state liaison officer is also monitoring that, but there is some background that is politically sensitive that I can share with you offline.
MR. DORMAN: Okay. Thanks, Linda. That’s good.
MR. HICKSMAN: This is Tom Hicksman. Could you please repeat the DITTRA projection and our calculation for the thyroid dose rates in California, please?
MR. LEWIS: Well, our calculations are not done.
MR. HICKSMAN: But you thought that they might be 1,000 times less, or that they are –
MR. LEWIS: Yeah. The DITTRA result was four rem [40,000 microsieverts] to the thyroid of a one year-old child based on one year integration of uptake. They –
MR. HICKSMAN: I think it –
MR. LEWIS: What we did during the past shift was looked at the actual deposition rates in California from the Chernobyl accident in 1986 and extrapolated that out and came up with a comparable dose rate on the order of one to 10 millirem. So that kind of reinforced our disbelief of the DITTRA number when we saw it. But then, separately, Research is working with Sandia to do a separate run.
MALE PARTICIPANT: Just for clarity, we want to attribute the calculation for NARAC. Okay. It’s not (inaudible), it’s NARAC — the calculation.
MR. DORMAN: Any other questions?
MALE PARTICIPANT: And also, to clarify, we don’t have a run of it. We just have the output –
MALE PARTICIPANT: Right.
MALE PARTICIPANT: — that suggests the thyroid doses.
Published: March 6th, 2012 at 2:33 pm ET