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Video of reactor 1 at Fukushima plant

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Re: Video of reactor 1 at Fukushima plant

#51

Post by jessedhillon »

JanezStupar wrote: post #43
wazoox wrote: post #34

Earlier quoted context omitted.

This is quite different from Chernobyl, which didn't even have a proper confinement wall. It's unlikely that it can get as bad as Chernobyl was.

It seems that proper containment is gone in this case...

It seems that what you saw was the building surrounding the reactor being blown up, not the containment vessel, according to news accounts.

The containment referred to in this case is a vessel made of a feet-thick layer of concrete surrounding the reactor. This is the final defense if a fuel meltdown occurs: its job is to contain the burning fuel and prevent it from being exposed to the environment. [1]

What the GP was referring to is that there was no such vessel at Chernobyl, which was a very old reactor design. Modern reactors are surrounded in such vessels. [2]

[1] http://en.wikipedia.org/wiki/Containment_building

[2] Here's some information about the reactor design at Chernobyl: http://en.wikipedia.org/wiki/RBMK#Containment

Another interesting read is the story of the Russian engineers who prevented an explosion at Chernobyl by diving into the pool of water beneath the reactor and opening the drainage valves: http://en.wikipedia.org/wiki/Chernobyl_disaster#Steam_explos...

Re: Video of reactor 1 at Fukushima plant

#52

Post by koski »

koski wrote: post #25

what I understand now is that the blast at the nuclear plant may have been caused by a hydrogen explosion (pressure) or If nuclear fuel rods overheat and then come into contact with water, this produces a large amount of highly-flammable hydrogen gas which can then ignite. Right? Can anyone with more knowledge and experience of this confirm?

An attempt to explain the risk to the Fukushima nuclear plants following the earthquake: The plants are designed to shut automatically, which halts the main nuclear fission reaction, but there is a residual amou ntense heat within the system. Back-up generators should kick in to power the coolin mechanisms needed to dissipate that heat - b they fail, as appears to have happened here, temperatures rise. If this isn't stopped, the reactor vessel itself could eventually melt an eak.

Right? Has anybody found any documents if Japan has been notified or warned about these backup systems of these plants? It sound like a design failure to me. (I know nothing about nuclear power plants)

Re: Video of reactor 1 at Fukushima plant

#53

Post by uvdiv »

nossralf wrote: post #49
uxp wrote: post #15

Earlier quoted context omitted.

This picture just appeared on Wikipedia, of which I am guessing is the building that may or may not be the one that possibly exploded. Maybe someone more knowledgable than myself can identify what the building is used for. The 2011 Sendai earthquake article says " the outer structure of reactor number 1's containment building had blown off, releasing a large cloud of dust and vapour." http://en.wikipedia.org/wiki/Fil…

http://www.ansn-jp.org/jneslibrary/npp2.pdf That PDF has a schematic of the containment building on page 4. The "MARK-I" image corresponds to the Fukushima I-1 building.

More detailed cutaways:

http://i.imgur.com/Oj4kg.png

http://i.imgur.com/CckjP.jpg

from, respectively,

Madgi Ragheb, UIUC https://netfiles.uiuc.edu/mragheb/www/NPRE%20457%20CSE%20462...

NRC http://www.nrc.gov/reading-rm/basic-ref/teachers/03.pdf

Re: Video of reactor 1 at Fukushima plant

#54

Post by gregholmberg »

brg wrote: post #36
brg wrote: post #26

Can someone provide background information on the type of reactor at Fukusima, it's age, and it's failsafe mechanism. I was under the impression that no modern reactor would sustain criticality in the event of a failure.

To answer my own question, Fukushima is a first generation bwr: http://en.wikipedia.org/wiki/Boiling_Water_Reactor It lacks the safety mechanisms of an abwr. Namely even after the control rods are deployed, heat can continue to build up. Hence the plant requires forced cooling, in this case provided by diesel and electric pumps. After the earthquake the diesel pumps failed and cooling was effected by battery power. W…

Japanese officials believe that the tops of the fuel rods are exposed.

Agency officials said a team of National Institute of Radiological Sciences detected cesium, a radioactive substance contained in nuclear fuel rods, near the No. 1 reactor of the No. 1 nuclear plant, leading them to suspect nuclear fuel rods in the reactor began melting amid the high temperatures.

The nuclear safety agency said in the afternoon that the level of cooling water in the No. 1 reactor likely had dropped to 1.7 meters below the top of nuclear fuel rods, leading officials to suspect that about half of the rods' length had been exposed.

Reactor meltdown feared / Quake disabled Fukushima N-plants' cooling systems

http://www.yomiuri.co.jp/dy/national/20110312dy01.htm

Re: Video of reactor 1 at Fukushima plant

#56

Post by JanezStupar »

jessedhillon wrote: post #51
JanezStupar wrote: post #43

Earlier quoted context omitted.

It seems that proper containment is gone in this case...

It seems that what you saw was the building surrounding the reactor being blown up, not the containment vessel, according to news accounts. The containment referred to in this case is a vessel made of a feet-thick layer of concrete surrounding the reactor. This is the final defense if a fuel meltdown occurs: its job is to contain the burning fuel and prevent it from being exposed to the environment. [1] What the GP w…

I know the general layout of various types of nuclear reactors.

But if the outer building which is supposed to contain everything else blows up - that's not exactly the best case is it?

Re: Video of reactor 1 at Fukushima plant

#57

Post by uvdiv »

gregholmberg wrote: post #54
brg wrote: post #36

Earlier quoted context omitted.

To answer my own question, Fukushima is a first generation bwr: http://en.wikipedia.org/wiki/Boiling_Water_Reactor It lacks the safety mechanisms of an abwr. Namely even after the control rods are deployed, heat can continue to build up. Hence the plant requires forced cooling, in this case provided by diesel and electric pumps. After the earthquake the diesel pumps failed and cooling was effected by battery power. W…

Japanese officials believe that the tops of the fuel rods are exposed. Agency officials said a team of National Institute of Radiological Sciences detected cesium, a radioactive substance contained in nuclear fuel rods, near the No. 1 reactor of the No. 1 nuclear plant, leading them to suspect nuclear fuel rods in the reactor began melting amid the high temperatures. The nuclear safety agency said in the afternoon th…

This was confirmed by Tokyo Electric Power (the operator):

"A portion of the reactor's fuel rods, which create heat through a nuclear reaction, had become exposed due to the cooling-system failure. The spokesman for Tepco said 1.5 meters of the 4.5 meter long fuel rods were exposed. It was unclear Saturday afternoon whether the water added by workers had re-covered the rods."

http://online.wsj.com/article/SB1000142405274870355540457619...

Re: Video of reactor 1 at Fukushima plant

#58

Post by [deleted] »

jessedhillon wrote: post #51
JanezStupar wrote: post #43

Earlier quoted context omitted.

It seems that proper containment is gone in this case...

It seems that what you saw was the building surrounding the reactor being blown up, not the containment vessel, according to news accounts. The containment referred to in this case is a vessel made of a feet-thick layer of concrete surrounding the reactor. This is the final defense if a fuel meltdown occurs: its job is to contain the burning fuel and prevent it from being exposed to the environment. [1] What the GP w…

[deleted]

Re: Video of reactor 1 at Fukushima plant

#59

Post by [deleted] »

jessedhillon wrote: post #51
JanezStupar wrote: post #43

Earlier quoted context omitted.

It seems that proper containment is gone in this case...

It seems that what you saw was the building surrounding the reactor being blown up, not the containment vessel, according to news accounts. The containment referred to in this case is a vessel made of a feet-thick layer of concrete surrounding the reactor. This is the final defense if a fuel meltdown occurs: its job is to contain the burning fuel and prevent it from being exposed to the environment. [1] What the GP w…

[deleted]

Re: Video of reactor 1 at Fukushima plant

#60

Post by vukk »

JanezStupar wrote: post #56
jessedhillon wrote: post #51

Earlier quoted context omitted.

It seems that what you saw was the building surrounding the reactor being blown up, not the containment vessel, according to news accounts. The containment referred to in this case is a vessel made of a feet-thick layer of concrete surrounding the reactor. This is the final defense if a fuel meltdown occurs: its job is to contain the burning fuel and prevent it from being exposed to the environment. [1] What the GP w…

I know the general layout of various types of nuclear reactors. But if the outer building which is supposed to contain everything else blows up - that's not exactly the best case is it?

"... that's not exactly the best case is it?"

You could think about the outer building as keeping the rain out, and possibly aeroplanes to some extent. It is not the critical last defence against stuff happening in the reactor, the containment building is. You can bet that the japanese army is keeping any possible threats out of there.

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