2 Japanese nuclear reactors may be in meltdown

DavidU (Dave) · #1 13-03-2011, 04:46 PM

This is not good at all.
http://edition.cnn.com/2011/WORLD/as...uclear/?hpt=T1

gary · #2 13-03-2011, 05:13 PM

Hi David,

Thanks for the link to the story.

The links in this post here have additional information -
http://www.iceinspace.com.au/forum/s...2&postcount=51

The detection of the cesium 137 as a "smoking gun" is of a concern and let's
hope if melting has occurred that it is limited and contained.

As I mentioned, as we all relax here on a Sunday afternoon, spare a thought for the workers
who at this very moment will be in there trying to stabilize the reactors. One is reported dead,
two missing and several others injured. Tomorrow morning, when the alarm clock sounds,
many of us will groan about having to get up and go to work. But how many of us would be
willing to take on the jobs that these guys must be battling with right now?

renormalised (Carl) · #3 13-03-2011, 05:16 PM

They believe it maybe contained....let's hope so, otherwise having 2 breached reactors will be the icing on top of a very bitter tasting cake.

toc (Tim) · #4 14-03-2011, 04:08 PM

I came back from a bike ride with my daughter, and ABC24 host announced 'there has been a nuclear explosion in Japan'.

I nearly fainted. Thankfully it was just an poor turn of phrase, but its still a tragic situation.

Steffen · #5 14-03-2011, 04:51 PM

Amongst the hysteria and misinformation spread by the mainstream press I found this quite informative:

http://bravenewclimate.com/2011/03/1...e-explanation/

Cheers
Steffen.

CraigS · #6 14-03-2011, 05:12 PM

Quote:

Originally Posted by Steffen

Amongst the hysteria and misinformation spread by the mainstream press I found this quite informative:

http://bravenewclimate.com/2011/03/1...e-explanation/

Cheers
Steffen.

Good rational article, there Steffen.

Thanks kindly for that.

There seems to be one bullet point missing from the end.
If I can believe the newspapers, it doesn't seem to have worked out too well for a few of the workers at one of the plants .. I read somewhere that they are receiving treatment for radiation burns … (maybe).

Cheers

steve000 (Steve) · #7 14-03-2011, 05:22 PM

May i suggest reading
http://morgsatlarge.wordpress.com/20...clear-reactors

scroll down a little and read the HUGH story

casstony · #8 14-03-2011, 05:23 PM

Governments regularly demonstrate that we can't trust them so is it any wonder that the populace gets a little worried at times like this.

CarlJoseph (Carl) · #9 14-03-2011, 07:21 PM

Another article to throw into the mix. This one describes how nuclear power plants work.

http://www.boingboing.net/2011/03/12...rgy-insid.html

Ric · #10 15-03-2011, 12:57 AM

Very interesting links guys.

Thanks

ballaratdragons (Ken) · #11 15-03-2011, 02:08 AM

Quote:

Originally Posted by renormalised

They believe it maybe contained....let's hope so, otherwise having 2 breached reactors will be the icing on top of a very bitter tasting cake.

New announcement states 3 reactors now possibly at meltdown danger.

bartman (Bart) · #12 15-03-2011, 04:59 AM

Thanks Steffen,
Thats great reading!
Bartman

CraigS · #13 15-03-2011, 07:44 AM

Ok … so is this latest report in the newspapers (SMH) accurate or not ?

Quote:

Fears of a meltdown at one of the troubled nuclear reactors in Japan have grown after officials said its fuel rods were "fully exposed", as the country grappled with a growing humanitarian and economic crisis after Friday's devastating earthquake and tsunami.

Air pressure inside the No.2 reactor at the Fukushima Daiichi plant, located 250 kilometres north of Tokyo, rose suddenly when the air flow gauge was accidentally turned off, its operator Tokyo Electric Power Company (TEPCO) said.

Cooling water was blocked from flowing into the reactor, leading to full exposure of the rods at about 11.00pm on Monday (1.00am AEDT on Tuesday). When the rods are exposed and temperatures rise within the containment vessel, the rods could lose their vertical shape and melt down.

"We are not optimistic but I think we can inject water once we can reopen the valve and lower air pressure," a TEPCO official told reporters.

Full exposure of the rods is a major issue … something to be very worried about.

Cheers

xelasnave · #14 15-03-2011, 09:21 AM

Why not build your own reactor?
http://www.youtube-nocookie.com/watc...eature=related

Certainly a melt down is serious but modern reactors have a "drip tray" to make them absolutely safe

alex

CraigS · #15 15-03-2011, 09:24 AM

Quote:

Originally Posted by xelasnave

Why not build your own reactor?
http://www.youtube-nocookie.com/watc...eature=related

Certainly a melt down is serious but modern reactors have a "drip tray" to make them absolutely safe

alex

He's baaack ! (Hi Alex).

Steffan's paper described this aspect ..

Cheers

xelasnave · #16 15-03-2011, 09:48 AM

Yes indeed Craig and I must say I found it all most comforting. I have been anti NP in the past only because I feel humans sometimes make mistakes and things dont always go according to the plan however with each new disaster we learn more as to how to avoid the disaster we find ourselves in and the drip tray is yet another advance for the industry.

I think all the reactors have been shut down and it is only residual heat they need to dissipate and although they suspect a rod or two may have suffered a little melting it is not all that bad, it could have been much worse....certainly I am hopeful that atmospheric contamination does not become a concern and that the casualties of plant workers is minimal.

I can not imagine how it must be for those poor souls in Japan or Christchurch having to come to grips with the devastation all around them and yet somehow plan for a future where all is normal.

alex

CraigS · #17 15-03-2011, 10:48 AM

Quote:

An explosion has been heard at No. 2 reactor at the Japanese nuclear facility where scientists are battling to prevent a fuel rod meltdown after two earlier explosions at neighbouring reactors.

A spokesman for Japan's nuclear safety agency, speaking on Tuesday on national television, said the explosion was heard at 6.10am (8.10am AEDT).

.. and then ..

Quote:

Air pressure inside the No.2 reactor at the Fukushima Daiichi plant, located 250 kilometres north of Tokyo, rose suddenly when the air flow gauge was accidentally turned off, its operator Tokyo Electric Power Company (TEPCO) said.

Cooling water was blocked from flowing into the reactor, leading to full exposure of the rods about 11pm on Monday (1am AEDT on Tuesday).

The government's nuclear safety agency said the rods were fully exposed for about 140 minutes, Kyodo news agency reported.

What a mess …. its all just terrible ..

xelasnave · #18 15-03-2011, 11:35 AM

140 minutes

That would suggest major melting of the containment jackets as I think 50 minutes is their time limit...

The day before the quake I was arguing with a chap about NP and he said it was a good idea for Australia and I said yes maybe but when things go wrong they go wrong in a big way ...but I did not think a real life example of my fears would present in such a horrible way...

All of this is so very sad.

I thought I was personally having a bad time of it..flood problems, car smashed, car near stolen and trashed, health issues etc but looking around I cant complain my difficulties are nothing in comparison.

alex

gary · #19 15-03-2011, 11:50 AM

As Alex mentioned, all reactors reportedly successfully SCRAM'd when the
earthquake was detected.

A 'SCRAM' involves the rapid insertion of the reactors control rods which
absorb neutrons and moderate the fission reaction.

Immediately after the control rods are inserted, the core is still at high temperatures for some time
due to the natural decay of fission products. It is then vital to cool the core by continually pumping cool
water through it.

Unfortunately the emergency coolant systems failed undoubtedly due to the earthquake.
However, workers have been pumping sea water through the core.

The temperatures though are sufficiently high that the water's hydrogen becomes
disassociated with the oxygen. The explosions have come from the hydrogen
igniting.

When a running reactor has been shutdown due to a SCRAM, the fission
reaction is largely stopped but some heating sttill occurs due to natural
radioactive decay of the fission products. If the coolant system has been kept operational,
then after the first 72 hours the core will have cooled to a point to
become more manageable.

However, if the core is not kept surrounded by fresh coolant during that
first 72 hours for an extended period of time, then the rods will be sufficiently
hot that a meltdown can occur.

When a meltdown occurs, the steel containment vessel is designed to try and
prevent the molten mass from burning its way through the bottom.

NHK report one of the reactors apparently had the rods exposed for half of
their length for 148 minutes, so a partial meltdown might have taken place.
However, 72 hours have passed for the reactors that have been flooded with
seawater cooling, so hopefully the risk of a full meltdown has passed.

NHK just now report that after the most recent explosion that the radiation levels
were 10,000 times higher than background and that the operators have been evacuated.
There is a concern as to whether the containment vessel has been damaged.

Trixie (Carey) · #20 15-03-2011, 12:13 PM

Quote:

Originally Posted by xelasnave

Why not build your own reactor?
http://www.youtube-nocookie.com/watc...eature=related

Certainly a melt down is serious but modern reactors have a "drip tray" to make them absolutely safe

alex

well I hope these ones have a "drip tray"... and its not cracked...