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+--- Thread: Update: Two Japanese Nuclear Reactors in Meltdown... Maybe. Probably. Can't tell because nobody can go in to see...-gcti (/showthread.php?tid=113656)
Re: Update: Two Japanese Nuclear Reactors in Meltdown... Maybe. Probably. Can't tell because nobody can go in to see... - Article Accelerator - 03-13-2011
freeradical wrote:
An interesting site about Chernobyl.
http://www.kiddofspeed.com/default.htm
An oldie but a goodie. Probably apocryphal:
http://articles.latimes.com/2004/jul/06/world/fg-chernobyl6
Re: Update: Two Japanese Nuclear Reactors in Meltdown... Maybe. Probably. Can't tell because nobody can go in to see... - Chakravartin - 03-13-2011
Paul F. wrote: it's a once in a thousand year event..Maybe even once in SEVERAL thousand years.
Maybe a 9.0.
But massive earthquakes generally devastate Japan every 75-100 years. A few have been estimated to be around 8.4-8.5 even though they pre-date modern measuring devices.
One in the 1850s was followed by a tsunami that made it quite a ways inland.
Check out the Ansei Great Earthquakes. Preparing for nothing stronger than a 7.9 does not seem wise with that regional history.
Re: Update: Two Japanese Nuclear Reactors in Meltdown... Maybe. Probably. Can't tell because nobody can go in to see... - Paul F. - 03-13-2011
I can agree with you there...
By the way, the Japanese nuclear industry must agree, since I just read that unit 1 was scheduled for decommissioning THIS MONTH.
Re: Update: Two Japanese Nuclear Reactors in Meltdown... Maybe. Probably. Can't tell because nobody can go in to see... - M A V I C - 03-13-2011
Meltdown confirmed. They believe the explosion was caused by the meltdown.
Japanese Government Confirms Meltdown
Japan’s Nuclear and Industrial Safety Agency (NISA) said March 12 that the explosion at the Fukushima Daiichi No. 1 nuclear plant could only have been caused by a meltdown of the reactor core, Japanese daily Nikkei reported.
http://www.stratfor.com/analysis/20110312-japanese-government-confirms-meltdown?utm_source=redalert&utm_medium=email&utm_campaign=110312%286%29&utm_content=readmore&elq=32703dd2f60b451f90ede888a8700aa4
Re: Update: Two Japanese Nuclear Reactors in Meltdown... Maybe. Probably. Can't tell because nobody can go in to see... - Lux Interior - 03-13-2011
billb wrote:
In a sense, yes it is.
Only in the sense that they were both nuclear reactors.
From there the designs, the physics, the construction and the accidents they have suffered are different.
Chernobyl did not undergo a slow, gradual, predictable meltdown. It exploded. Violently. And not an explosion near the reactor, but in the core itself. The graphite moderator continued to do its job in the absence of coolant and the nuclear reactions continued. This is why people died trying to smother it. They had to stop the fission.
This is not possible with a light water moderated reactor, which is what all the Japanese (and French & Swiss & US & German, etc.) reactors are.
If these cores do meltdown, melt through the containment and get released to the environment, then it will be bad. But "first responders" are not going to die.
Paul F. wrote:
filled with neutron absorbing, reaction killing, chemicals (halfnium and boron, I think... but I admit my nuclear physics is barely above layman level, and more than a little rusty).
This is another misconception - that the reactor is out of control. The reactor(s) are shutdown. They have been since the quake hit. The problem isn't fission. It's decay heat. Even after you stop the fission chain reaction, the core continues to produce heat from the decay of the fission products. This is about 7% of the operating power before shutdown and then it decays from there.
About 40 MW of heat to remove from unit one assuming it was going at full power. Not a lot, but enough heat to melt the fuel unless adequate cooling is provided.
Re: Update: Two Japanese Nuclear Reactors in Meltdown... Maybe. Probably. Can't tell because nobody can go in to see... - OWC Jamie - 03-13-2011
Lux Interior wrote:
[quote=billb]
In a sense, yes it is.
Only in the sense that they were both nuclear reactors. The International Nuclear Event Scale doesn't discriminate generator types.
It's one hell of a lot closer to a 7 than it was a week ago.
No one said anything about it possibly becoming a 7. Isn't a 4 bad enough for you ?
There's already a dead first responder.
Unless you're not counting engineers.
Re: Update: Two Japanese Nuclear Reactors in Meltdown... Maybe. Probably. Can't tell because nobody can go in to see... - OWC Jamie - 03-13-2011
Lux Interior wrote:
This is another misconception - that the reactor is out of control. The reactor(s) are shutdown. They have been since the quake hit. .
Most people consider the release of radio active components "out of control".
The misconception is the belief that a "shut off " generator is "safe.
Recent events would seem to indicate otherwise.
Re: Update: Two Japanese Nuclear Reactors in Meltdown... Maybe. Probably. Can't tell because nobody can go in to see... - Chakravartin - 03-13-2011
Interesting POV here:
http://www.businessinsider.com/japan-reactors-pose-no-risk-2011-3
If correct then we're past the worst of it.
Re: Update: Two Japanese Nuclear Reactors in Meltdown... Maybe. Probably. Can't tell because nobody can go in to see... - mpau0516 - 03-13-2011
It seems the BBC in the UK is doing an outstanding job on covering this event.
2044: Professor Regan said when they vented the first reactor at Fukushima on Saturday - triggering the explosion at the plant - "that vapour would almost certainly have had a little bit of radioactive material called nitrogen 16 - which is in all reactors. That decays away very quickly, in 5 to 10 seconds, but if some of the fuel rods - which appears to have been the case - were compromised, some of the radioactive material from the fuel would have got into the steam and that would also have been taken out." So a key question seems to be to what extent the fuel rods had begun to melt down.
2042: Professor Patrick Regan, radiation and environmental protection expert from Surrey University, has told the BBC that it appears none of the secure vessels holding radioactive material at the reactors in Japan has broken, and "it looks like the worst is over".
You can follow this here:
http://www.bbc.co.uk/news/world-middle-east-12307698
There have been reports that the reactor is being cooled by sea water, but so far the instruments have not detected the water rising. I wonder where all that water is going? (China Syndrome).
Re: Update: Two Japanese Nuclear Reactors in Meltdown... Maybe. Probably. Can't tell because nobody can go in to see... - Paul F. - 03-13-2011
Lux Interior wrote:
[quote=Paul F.]
filled with neutron absorbing, reaction killing, chemicals (halfnium and boron, I think... but I admit my nuclear physics is barely above layman level, and more than a little rusty).
This is another misconception - that the reactor is out of control. The reactor(s) are shutdown. They have been since the quake hit. The problem isn't fission. It's decay heat. Even after you stop the fission chain reaction, the core continues to produce heat from the decay of the fission products. This is about 7% of the operating power before shutdown and then it decays from there.
About 40 MW of heat to remove from unit one assuming it was going at full power. Not a lot, but enough heat to melt the fuel unless adequate cooling is provided.
I appreciate the correction..
It's my understanding that IF the fuel rods melt completely, that the resulting "puddle" could begin fissioning again, at a reduced rate.
So whatever is below the reactor vessel is another step to keep it from fissioning under that sort of "worst case" - which neither of these reactors seems to be close to.
If the residual heat and decay heat are removed, that's no longer a possibility (if it ever was with this type of fuel design...)
From what I've read about this design.. there is an outer building (where the hydrogen collected and exploded), an outer containment shell of reinforced concrete and steel, which is INTACT, and inside THAT, the 6" thick stainless steel reactor pressure vessel, which is also intact.