An excellent article to complement the one James referred to. This arrived unbidden in my inbox from an existing feed - I didn't seek it out. It's good. Even James will like most of it :-). The writer is extremely well qualified to comment and is also "pro-nuclear" as one would hope he would be. That being the case, his comments as reporte= d by his daughter in her blog add some perspective to his measured words. < http://www.cfact.org/a/1912/A-nuclear-engineers-briefing-on-the-emergency-i= n-Japan?utm_source=3DCFACT+Updates&utm_campaign=3Dd600964d1a-Nuclear_engine= er_on_Japan_emergency3_14_2011&utm_medium=3Demail > Blog of same plus audio transcript plus more. < http://skepchick.org/2011/03/a-conversation-with-my-dad-a-nuclear-engineer-= about-the-fukushima-daiichi-nuclear-power-plant-disaster-in-japan/ > Note that the man in the article that James referred to lied badly by omission. He talked about primary and secondary radiation products, and the= n spoke entirely only about the admittedly very very short half lives of the secondary products. Reading the attached reader comments to the article it is clear that many people were mislead by what he was saying or appearing t= o say. His lies may have been accidental in the heat of the moment but they constitute enough misinformation in the context and in an article which is claimed to combat press disinformation to not be excusable as an honest error. The half lives of the primary released products are what is of concern and significant radiation persistence is long enough (weeks to months) to justify far more extreme evacuation action than he implies. Japanese evacuation numbers, issuing of iodine tablets to local population, and as of today formal request for help on the nuclear issues from the US, would all seem to be massive overkill if the scenario was remotely close to being under control as that article suggests. Maybe so. Maybe not. The ongoing severe injury and deaths of small numbers of brave and self sacrificing military and civilian personnel at the reactor sites (5 more reported today) would also seem an unfortunate price to pay for such a now well controlled situation as is described. note that the number 3 plant now being wrestled wit uses a Uranium/Plutonium fuel mix, unlike the two initially being dealt with. Plutonium is NOT anywhere near as toxic as is widely held, but it would be nicer if it manages to stay where it belongs. Interesting note: Second article notes that addition of water alone to a fully moderated reactor may result in regaining criticality due to thermal layering of water with neutron deflection and thus 'amplification'. Addition of Boron as was, of course, done is a necessary part of adding water and not risking reactivation. Adding seawater is, of course, only something happens when all formal systems have failed and there is no other sensible on non-sensible solution left. . _________ Note that comments in several places about the force of quake that the plan= t was designed to withstand are approximately meaningless without vastly greater context. An M8.9 "up the bay and well out to sea" as opposed the M8.2 at whatever location and depth was specified in the original design ar= e unable to be mutually compared without more information. eg a say M6.5+ a= t say 1 km under the plant would about certainly rupture one some or all of the 6 operating containment vessels. An M9.5 in London / SF / Moscow certainly wouldn't. The comments re "... survived the earthquake; but then the Tsunami came ... " are true, but irrelevant as any form of defence. Elsewhere they had beautifully designed and built* 10 metre Tsunami defence walls, built afte= r a prior very very very bad experience. These were overtopped by several metres by the latest Tsunami, with immense loss of life and property behind them BUT they held, and appear to have averted a much greater tragedy than if they had not been there. (* Beautiful - really. From the sea side a rising curve with a "re entrant" top designed to transition the flow from horizontal to vertical and throw it back and create a "hydraulic jump" if needs be. From the back a slow sloping buttressed honeycomb support system that told you that the designers understood the challenge they were facing= .. The Tsunami ran over the top by several metres. Understandable, as a Tsunam= i is effectively a step function wave and what needs to be (impossibly) absorbed is not mere height but the energy of a vast column of following water. Diversion of all possible incoming water rather than deflection, seems to me to be all that would "work". ie -choose your preferred local path for a Tsunami and channel it there. Allow it to back fill a local rive= r valley for 10 or 15 km if needed rather than he immediate coastal plain for 1 or 2 km. Had protection of even something like the 10 metre Tsunami defence wall been available at the reactor site the present situation may have been far better. Or not. With Japan's history, building a reactor cluster at a site where a Tsunami of any magnitude or of any conceivable improbability, when safer sites are available with suitable will seems "unwise". More so with hindsight :-(. Much good has been accomplished, and many brave people have contributed to things not being far worse than they could easily have been. As events are still "in progress" it's arguably not an overly good time to note how safe nonpolluting and desirable the systems all are/were. Russell --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .