sent 20110428 To: contact@fairewinds.com From: xxxxxxxxxxxxxxxxxxxxxxxxxxx Subject: Fukushima Unit 3 explosion Dear Mr Gunderson, I have been following your informative videos on Fukushima, and greatly appreciate them. Thank you for all your effort. I'm writing about your recent video, http://vimeo.com/22865967 , in which you discuss the probability that the Unit 3 event was a prompt criticality in the SFP. I agree with you. Though I have relatively little knowledge of nuclear matters - I'm a retired electronics engineer, who only follows nuclear fission issues out of strong personal interest related to Humankind's urgent need to get fusion working, in particular a variant of the Farnsworth Fusor. (Personal hobby, don't want to bore you with that.) In any case I have a few observations regarding Fukushima unit 3 that might interest you. And a question for you. My initial impression at the time was based solely on the highly directed nature of the main blast. It did not fit with a hydrogen-air mix explosion, given the structural makeup of the building. Initially when I saw the video of the Unit 3 explosion I assumed that the reactor pressure vessel must have blown its lid, resulting in a kind of shotgun blast effect. But on seeing the high-res shots of the wreckage, I realised that wasn't right. Because the roof girder framework is intact over the central area of the building. So the pressure vessel lid and contents can't have blown upwards through it. Then there's the very odd detail that there are three distinct 'bangs' audible in the video, closely spaced. Also there's a visible initial sideways orange blast, THEN a separate vertical jet-like blast. The roof girder structure is completely blown away over on the south side of the building, and judging by the steam emitting from under the rubble in that area, that's where the SFP is. A hydrogen explosion exerts overpressure on walls and roof, able to blow concrete panels out, and concrete roof slab completely off (as with #3 & 4) or upwards only to fall back down like a crumbling blanket (as with #1.) But the roof girder grid has insignificant surface area, so the overpressure just blows past it, leaving the girders relatively intact. As we see with #4. With #1 the concrete roof material crushed the roof girders downwards as it fell back. But with #3, _something_ completely obliterated the girders on the south side. If it wasn't the lid of the pressure vessel and containment structure, that only leaves the SFP as a contender for 'shotgun barrel' effect. If it was a simple H-air explosion in the SFP that was almost empty of water, I suppose it's possible the H-air explosion could have been sufficiently 'below' enough fuel rod structures to blast them upwards like shot in a barrel, taking out the roof girders. But there's still the detail of the audible 'three bangs'. They are very distinct. I can't see how the effect could be one explosion and two echos. Echos from what? Maybe atmosphere temperature inversion layers, but then the equal spacing and apparently identical amplitudes is a problem. Here's my guess at events: The water in the SFP of #3 boiled off enough to expose some of the tops of the rods. The exposed rod sections overheated and the zirconium burnt in steam, releasing H gas. The building filled with H gas. Something, perhaps the overheating fuel rods, ignited the H-air mix, resulting in an initial H explosion. This shock caused a rapid redistribution of the loose fuel pellets among the decomposing fuel rods. A prompt criticality occured, resulting in a massive sudden heat output, vaporizing rods and fuel in the area of criticality, and flash boiling water just below the area of criticality. This would blast steam and fuel materials upwards, with sufficient force to cut through the roof girders. The time delay between H-air explosion, and criticality could have been very small, on the order of milliseconds, so wouldn't be noticed in the video of the event. So the 'orange explosion' fireball seen could be from the criticality. The orange-hot dust and gasses are bursting sideways due to deflection caused by roof slab material still not far above its original rest location, after the H-air explosion gave it a relatively weak initial kick. But that was just the _first_ criticality, because... As a result of the (first) criticality, water from further down in the fuel rod pool has flash boiled. It blows upwards as steam, as the rods in that area are being crushed downwards by shock waves from the criticality explosion further up the assembly. Suddenly this area of the rods is 'denser', and also the shielding/moderating water is leaving as steam. So... a second prompt criticality occurs. The second 'bang' heard. The result is much the same as with the first. More material is vaporized and blasted upwards, joining the upwards debris jet. More water flash boils, and departs upwards as steam. More of the rods structure is crushed downwards, compressing, and also now without shielding/moderating water. The third prompt criticality occurs.... The third 'bang' heard. Same effect. Except by now there's not enough rod structure left below the explosion point to support a fourth cycle, so the process stops. Or... did it just stop because the water lower down was cooler, or the crush effect wasn't quite right? Apart from the initial visible orange fireball, there are no visual indicators of the 'three blasts' because the second two result only in a continuation of the same effect - an upward jet of dark grey-brown fuel/ concrete dust/ steam mix, with its base obscured by general dust from the overall event. Results- The roof girders over the SFP are visibly absent. Probably so is a lot of the fuel material from the pool. The pool structure has suffered extreme overpressure, so is very likely cracked (at a minimum.) The building suffered a distributed overpressure from a H-air explosion that blew out the side walls and concrete roof slab. Closely followed by a separate and much more powerful highly directed upwards blast from the SFP, that actually consists of three sequenced pressure pulses, obliterates an area of the roof girders and carries debris upwards in a distinct jet-like vertical blast cloud. Large solid ojects (probably bits of roof slab) are carried upwards on the apex of this jet, then fall back out with little sideways vector. In the weeks afterwards, highly irradiated pieces of concrete are found around the site, and fuel pellets found kilometers away. Worries: That kind of event hasn't happened in the SFPs of units 1, 2 and 4. Could it still? Incidentally, my understanding of the term 'prompt criticality' derives only from reading accounts of the SL-1 accident. In which removal (by boiling) of the moderating water terminated the criticality. Which I can see is a problem for my scenario above, since I'm assuming that removal of the water further down in the SFP causes another area of the fuel rod assemblies to go prompt-critical. Opposite effect... So a question for you - in a SFP, isn't the inter-rod spacing arranged to be large enough such that the water has a neutron shielding effect? While without the water, neutrons are not being slowed down enough to support criticality? I'm unclear on this. But if that's right, is there an intermediate state (mix of flash boiling water and steam) in which criticality is possible? I'm really trying to see how events in the SFP could produce a sequence of three distinct, equally spaced 'bangs'. You have heard that in the video, I hope? Some of the videos of unit 3 exploding have no sound, but one does. That one is very clear, you can even hear the general background crashing as stuff falls down. Of course there's a sound delay, due to distance. The video is here: Fukushima unit #3 explosion. http://youtu.be/T_N-wNFSGyQ Has sound of three distinct explosions. Onscreen titles: "oztvwatcher", TCN 9 "Footage recorded off Sky News UK via Nine Network Australia" A few random points- I'm pretty certain a volume H-air mix explosion _can_ go supersonic. You noticed that in the videos of unit 1 blowing, there's a spherical atmospheric shock wave expanding from the building in the very early stages of the blast? It only lasts a few frames, and is easily missed. But it's there. Fwiw, I've been keeping some notes of news/info URLs re Fukushima. In case there's anything there of interest: http://everist.org/archives/links/!_Fukushima_nuclear_disaster_info.txt I also produced these images: (copy freely) http://everist.org/pics/Fukushima/Fukushima_fuel_tanks.jpg Before/after washed away fuel tanks (190KB) http://everist.org/pics/Fukushima/Fukushima_pyramids_sm.jpg Fukushima vs Pyramids of Giza (109KB) http://everist.org/pics/Fukushima/Fukushima_pyramids.png Ditto, medium (762KB) http://everist.org/pics/Fukushima/Fukushima_pyramids_large.png Ditto, large version (1.5MB) http://everist.org/pics/Fukushima/Fukushima_water_diag.jpg Watercourses at Fukushima (360KB) Well, I hope you haven't found this a waste of your time. Once again, thanks for the excellent and informative videos. Best regards, Guy (aka TerraHertz) PS. Oh, one other thing. How frustrating is this! Here's an email exchange I had recently with a friend. David: Years ago ('70s) I had a good friend who spoke fluent Japanese and worked on those reactors as a tech writer and translator. He was a physicist by trade, but found the best money in translating etc. I have been trying to find him again but can't. I remember he kept copies of all the service manuals etc, (Getting Started with your new fission reactor. Pressurised reactors for dummies etc). It would be interesting to browse through them. ---- Me: 'Interesting'! My god, if you can find him and he still has them!!! Please keep trying. Anything I can do to help find him? Seriously! What was his name, and where was he living at the time? How old then? Would even be worth hiring private detectives. Those manuals really need to be PDF'd and put online. However, I BET even if you can find him, he'll have long ago tossed them. ---- His name is Dr Steve Shama BPhys Phd. and an old acquaintance of mine thought he had been offered a teaching job at a Japanese uni, He'd be my age now Quite an honour if true. He is of the jewish persuasion, but not a believer. (Yeah......well.....maybe). He is an academic type who probably _did_ keep the manuals. I doubt if we can find him though. If this was a movie he would have died in a mysterious car smash last week! BTW according to an old diary it was 1978 I shared a flat with him. Long time...... He was a great fan of Jap art and culture and a mighty smart dude. He could even write old style Japanese characters and read them too of course. It would be good to see him again. Oh well, not likely. ---- Did you try google? There are many hits for "Dr Steve Shama" (in quotes) but looks like all the 1st page ones are for one who is a biologist. "Dr Steve Shama BPhys Phd" zero hits, but that's not surprising. There's also a 'Dr Steven Shama'. You could also try phoning the Japanese embassy, ask them if they can tell you whether an old Australian friend you lost contact with is still in Japan. ---- It may be BSc. I'd expect an MSc as well as that's a prelude to a doctorate. It was a long time ago. He is american. ---- Ha. Maybe you can find him?