Japan Does Not Face Another Chernobyl • Hacker News Board

Re: Japan Does Not Face Another Chernobyl

#71

Post by mpyne » Tue, Mar 15, 2011, 3:12 AM UTC

marshray wrote: post #60

mpyne wrote: post #56

Earlier quoted context omitted.

> Conflicting information keeps coming out about possible worst case scenarios (and their relative likelihoods) with the nuclear reactors. There is only one worst-case scenario, so although I very much agree that the information coming out of Tokyo Electric Power Co. and the Japanese national government is inconsistent, that doesn't mean new "worst-case" scenarios become possible. IMHO the worst-case scenario is fuel…

By "unimaginably bad" I meant the earthquake+tsunami disaster scenario. This is now the unfortunate baseline against which the nuclear issues are, perhaps, the most significant remaining unknowns. Reading again what I wrote I see it was ambiguous. There is only one worst-case scenario, so although I very much agree that the information coming out of Tokyo Electric Power Co. and the Japanese national government is inc…

> > There is only one worst-case scenario, so although I very much agree that the information coming out of Tokyo Electric Power Co. and the Japanese national government is inconsistent, that doesn't mean new "worst-case" scenarios become possible.

Well my opinion as to the worst-case scenario was wrong: http://www.nytimes.com/2011/03/15/world/asia/15fuel.html?_r=...

To be clear, the spent fuel facility at the shutdown and de-fueled Unit 4 reactor has ended up catching fire, and now they are measuring radiation levels on the site on the scale of 400 mSv/hr and 100 mSv/hr (yes, millisievert).

Re: Japan Does Not Face Another Chernobyl

#72

Post by bluedanieru » Tue, Mar 15, 2011, 8:38 AM UTC

bluedanieru wrote: post #69

I keep hearing that this is the second-worst nuclear disaster after Chernobyl. Folks, this isn't even the second-worst nuclear disaster on Japanese soil .

Gee, thanks for the downvote. Why don't you come on over to Tokyo and we can have a chat about it.

Re: Japan Does Not Face Another Chernobyl

#73

Post by marshray » Tue, Mar 15, 2011, 4:15 PM UTC

mpyne wrote: post #70

mpyne wrote: post #68

Earlier quoted context omitted.

Now these are better questions. :) As far as hydrogen goes, the building itself was not designed to be the containment (instead there's a hefty steel containment around the reactor and primary piping from what I understand), so I don't think they bothered trying to make the building resistant to explosion from the inside (since they didn't have to). It would still be better to have the building in place, but I think…

Man, wtf happened at Unit 2? I keep repeating the NHK broadcast and I'm not sure whether the suppression pool itself suffered damage and not the reactor vessel, or both, or what. They mentioned radiation going up right after the explosion, which could indicate a reactor vessel or other primary piping rupture, but could also just be from trapped radioactive contamination in the suppression pool being thrown out by the…

It's almost as if they're speaking in code. They don't want to spread panic, but they also can't hide the reality too much from those who understand engineering.

My theory is that the vessel pressure vented into the suppression pool which caused the drop in pressure. That could have made a loud noise, perhaps one they had never heard in testing. Since the pool is a metal torus containing water held up by concrete and tightly coupled to the other parts it's a rigid, massful, structure. It may have been damaged by the quake.

If the radiation is explained by the spent fuel fire at unit 4, the question remains whether or not the containment on unit 2 is still effective.

Re: Japan Does Not Face Another Chernobyl

#74

Post by Lazlo_Nibble » Tue, Mar 15, 2011, 9:02 PM UTC

knshaum wrote: post #67

Lazlo_Nibble wrote: post #59

Earlier quoted context omitted.

I've seen a lot of people latch on to this writeup as authoritative, and I'm not sure why. Oehmen may indeed be a "research scientist" at MIT but his specialty is supply-chain risk management, not reactor design ( http://web.mit.edu/oehmen/www/ ). Is there any reason to believe that he's anything more than an interested amateur on this topic?

The post has been moved, and updated by members of MIT's Nuclear Science and Engineering community: http://mitnse.com/2011/03/13/why-i-am-not-worried-about-japa...

Possibly relevant: http://geniusnow.com/2011/03/15/the-strange-case-of-josef-oe...