Fukushima Threat Down?

The Los Angeles Times reports that the crisis at Fukushima appears to be ebbing, and that at least some US experts believe that the fuel has not melted in any of the reactors.

The most telling evidence about the condition of the reactors is the absence of heavy radionuclide contamination around the plant, which would indicate that uranium fuel became so overheated that it vaporized heavy fission products such as strontium and technetium, experts said.

Instead, the main contaminants have been isotopes of iodine and cesium, which are water soluble and are not held in the uranium fuel itself.

It's those radionuclides associated with fuel breakdown that I've been looking for in the monitoring reports and not seeing. It's important to remember that this evaluation is not final and is based on very limited data. But earlier, breathless reports in the New York Times for example, were based on even less data.

The LA Times article mentions the disarray at the NRC, where Chairman Gregory Jaczko early on recommended a much wider evacuation than did the Japanese government, apparently without consulting them. I suspect that Jaczko's recommendation was based on the modeling represented by the map published shortly after his statement in the New York Times showing deadly contamination out to 50 miles from the reactors. At the Carnegie Conference last week, when asked specifically about this recommendation, NRC Commissioner George Apostolakis said that the recommendation was made "in consultation with staff," decisions were made "in extreme ignorance," based on "extremely conservative calculations." It's been clear for some time that NRC has been trying to walk Jaczko's too-early comments back, and today's LA Times article indicates that questions continue to be asked on this subject.

With every day that passes, the heat load and radioactivity of the reactors decreases. The three biggest cement-pumping trucks in the world are arriving at Fukushima to keep water in the spent fuel pools. I still don't have a full answer to my question on whether water is being recirculated or added open-loop, but the amounts of water suggest that it is open-loop with significant evaporation.

And yeah, this is an I-told-you-so post. I'm not convinced that the scenario quoted in the LA Times is accurate, but the fact that modeling can now come up with a scenario in which the fuel is not all melted and the spent fuel pools did not catch fire suggests that the doomsayers haven't had the full picture and may have been driven by other motives than technical accuracy.

If it's an I-told-you-so post, it's incomplete. I'm headed out in a little while and will try to provide links later. I'm not sure I put as much of my thinking on the blog as I shared with others via email and discussions. But at least some of it is here at Phronesisaical.