
Video of reactor 1 at Fukushima plant - maxharris
http://www.youtube.com/watch?v=pg4uogOEUrU
======
ck2
[http://news.google.com/news/more?ncl=d_LFixACgsQEvVMNHMag3MA...](http://news.google.com/news/more?ncl=d_LFixACgsQEvVMNHMag3MAIw9-fM)

There is almost guaranteed significant radiation release.

quote from slashdot:

    
    
      The outer walls of the Reactor 1 building have partially     
      blown off, leaving only what looks like a steel frame. 
    
      NHK is saying that a sensor within 5km of the plant is detecting 
      radiation levels approaching 1015 microsieverts 
      - that is apparently a year's worth of radiation exposure
       EACH HOUR
    
      People in the danger zones are being told to cover faces
      with wet towels, avoid eating vegetables and other fresh foods, 
      and refrain from drinking tap water.

~~~
koski
"This is starting to look a lot like Chernobyl" Walt Patterson, an associate
fellow with Chatham House, has told the BBC after seeing pictures of the
explosion at the Fukushima-Daiichi nuclear plant. "The nuclear agency says
that they have detected caesium and iodine outside the unit, which certainly
indicates fuel melting at the very least," he says. "Once you have melting
fuel coming into contact with water, that would almost certainly be the cause
of the explosion." (BBC)

(EDIT) More from Walt Patterson of Chatham House. He says the presence of the
radioactive caesium in the surrounding area does not pose a huge threat to
public health in the immediate aftermath of the explosion. "What would be
serious is if there was an explosion or fire that lifted this stuff high in
the air, meaning it could get carried over a wide area."

~~~
wazoox
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.

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

~~~
jessedhillon
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...](http://en.wikipedia.org/wiki/Chernobyl_disaster#Steam_explosion_risk)

~~~
JanezStupar
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?

~~~
vukk
"... 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.

~~~
JanezStupar
I read somewhere that this design does not have a containment dome. So
basically containment wise (in comparison to Chernobil) this reactor is a bit
better that it uses reactor containment vessel, but it does not use
containment dome.

I also read that on TMI a similar hydrogen explosion occurred but it was
contained by containment dome.

~~~
neutronicus
It doesn't have a concrete containment dome. It's got a steel containment
vessel surrounding the main reactor vessel, though.

------
foobarbazetc
[http://twitter.com/#!/martyn_williams/status/465371589153914...](http://twitter.com/#!/martyn_williams/status/46537158915391488)

The reactor DID NOT explode. HN is becoming a bit sensationalist today.

Edit:
[http://en.wikipedia.org/wiki/Boiling_Water_Reactor_Safety_Sy...](http://en.wikipedia.org/wiki/Boiling_Water_Reactor_Safety_Systems#Containment_system)

Basically, this bit:

The reactor building (the shield wall/missile shield) is also made of steel-
reinforced, pre-stressed concrete 0.3 m to 1 m (1–3 feet) thick.

The concrete surrounding the building is now gone (due to excess pressure).

Second edit:

[6:54 a.m. ET, 8:54 p.m. Tokyo] The explosion at Japan's Fukushima nuclear
plant was not caused by the nuclear reactor but by "water vapor that was part
of the cooling process," Chief Cabinet Secretary Yukio Edano said Saturday. He
said no harmful gases had been emitted by the explosion.

[6:44 a.m. ET, 8:44 p.m. Tokyo] Japanese Prime Minister Naoto Kan confirms
that the evacuation area around the Fukushima Daiichi nuclear plant has been
increased to 20 kilometers. But no one has been harmed by radiation, he says.

Third edit (from the BBC):

1218: It seems clear now from Mr Edano's comments that the nuclear plant
building that was blown apart earlier did house a reactor, but the reactor was
protected by its metal casing.

1216: Government spokesman Yukio Edano says the pressure as well as the
radiation at the Fukushima-Daiichi nuclear plant has fallen following this
afternoon's explosion.

So the "explosion" has actually helped the situation.

Fourth edit: Looking like Sendai just got hit with another earthquake. I hope
that hasn't caused any more damage to the reactor.
[http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/us...](http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/usc00020m9.php)

Fifth edit: From <http://twitter.com/#!/norishikata>

"Blast was caused by accumulated hydrogen combined with oxygen in the space
between container and outer structure. No damage to container."

"Trend of μ Sv/h of Unit 1 this afternoon. 1,015(at 15:29), blast (15:36),
860(15:40), 70.5 (18:58). After blast, radioactive level lowered."

"TEPCO's efforts to depressurize the container was successful. Additional
measures are now taken tonight using sea water and boric acid."

Things are looking up.

~~~
jensnockert
While damage to internal containment structures are possible, the building is
likely to be resistant to these kinds of explosions.

A (what I guess) is a similar explosion happened in the reactor building in
TMI, and the risk of an explosion such as this seems to be well known. The
reactor building was probably prepared to absorb the explosion away from the
containment structures, making it look much worse than it is.

~~~
foobarbazetc
I think you're right. I'm not sure on how PWR vs BWR plays out in this case
though, but it definitely seems like they knew this explosion would happen. It
looked very "controlled", even if it seemed like there was a lot of vapour and
debris on video.

~~~
jensnockert
Yes, PWR vs. BWR is definatly an issue when comparing the two events.

------
zach
Here's a link to the middle of the video where they replay the explosion:

<http://www.youtube.com/watch?v=pg4uogOEUrU#t=46s>

------
jensnockert
Got a mail from WANO relayed to me, below is the interesting part about the
explosion.

\-----

1\. Hydrogen explosion occurred at 15:36 between containment and reactor
building of Fukushima Daiichi unit 1. Walls of reactor building were blown out
or damaged.

2\. It was confirmed that unit 1 containment integrity was maintained.

Explosion was not inside the containment as it is inert.

3\. Radiation level at the Fukushima Daiichi site border once increased when
containment vent was conducted and reached 1,015 micro Sv per hour around the
time when explosion occurred; however, the radiation level turned to decrease
after the explosion down to 860 at 15:40 and 70.5 micro Sv per hour at 18:58.

4\. Government has agreed to TEPCO decision to fill the entire containment up
with sea water. The filling sea water will contain boron. TEPCO started the
work for filling up at 20:20.

~~~
sophacles
What is the significance of boron in the seawater?

(It just reads like one of those understated but extremely important bits you
find in these sorts of alerts :-| )

~~~
jensnockert
Boron has a high neutron cross-section, it therefore absorbs neutrons and
slows down the fission process.

In a PWR you add it into the water as a way to moderate the reaction, but in a
BWR (like the reactor 1 in Fukushima Daiichi) you only add it as a last
resort, since it is incredibly hard to clean out of the system.

------
koski
Kyodo News agency said radioactive caesium had been detected near the site,
quoting the Japanese nuclear safety commission. Radioactivity rose 20-fold
outside, reports said. (EDIT: this was before the explosion)

The plant "may be experiencing nuclear meltdown", Kyodo and Jiji reported
before the explosion, while public broadcaster NHK quoted the safety agency as
saying metal tubes that contain uranium fuel may have melted.(AFP)

~~~
sliverstorm
Is 20-fold increase in radioactivity actually hazardous? I was under the
impression dangerous levels of radiation are many, many times above normal
background radiation and typical 'acceptable' levels of exposure.

See <http://www.geigercounters.com/Danger.htm> for example. Occupational
acceptable exposure is 25x that of non-occupational.

~~~
A1kmm
According to <http://www3.nhk.or.jp/daily/english/12_51.html> the exposure
level measured outside the plant is 1.015 mSv / hr. Exposure to about 1000
times that hourly level in a short time period is needed for life-threatening
acute radiation poisoning.

Exposure to 1.015 mSv / hour for a year would give a dose equivalent of 8.9 Sv
- the excess relative risk of cancer for low dose chronic radiation exposure
is about 0.97 per Sv - so the exposure to that level for a year would
drastically increase cancer risk.

Obviously, people won't be allowed into the areas where radiation levels were
that high.

I saw a report of a worker acutely exposed to >100 mSv; that single event
would be enough to increase that worker's lifetime risk of cancer by about
10%.

~~~
uvdiv
That report is here (106.3 mSv measured):

[http://www.tepco.co.jp/en/press/corp-
com/release/11031219-e....](http://www.tepco.co.jp/en/press/corp-
com/release/11031219-e.html)

------
ajb
Any opinions on what the thing rising up very quickly during the explosion is?
I initially thought it was the roof, but I'm wondering now if it isn't
actually a flame from burning hydrogen. Ideas?

~~~
uvdiv
It looks like a hydrogen flame to me. The color is right (faint blue, barely
visible), and see how fast it rises straight up?

(I am not an engineer)

------
koski
If I understood correctly, there has been an explosion in Fukushiman Dai-
ichi's nuclear plant. And this is it.

~~~
angus77
That's correct.

------
brg
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.

~~~
brg
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.
While the government rushed in new diesel generators, they were not installed
in time to prevent the build up of pressure resulting in this explosion.

~~~
gregholmberg
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>

~~~
uvdiv
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...](http://online.wsj.com/article/SB10001424052748703555404576195700301455480.html)

------
famousactress
Can someone please build a user-css for youtube that makes it so I never
accidentally see the comments posted there?

~~~
mberning
Check out youtube comment snob.

------
anigbrowl
Evacuation zone was just doubled to 20km.

~~~
LogicHoleFlaw
Well, the _radius_ was doubled. The affected land area quadrupled.

~~~
buro9
Area of a 10km circle is 314 km2

Area of a 20km circle is 1257 km2

Assuming they go to 30km or 50km next:

Area of a 30km circle is 2827 km2

Area of a 50km circle is 7854 km2

~~~
mistermann
I have a feeling most people on HN know how to calculate the area of a circle.
;)

~~~
Retric
<pedantic> True, but calculating the land area by doing so is a mistake
because ~50% of that 20KM circle is over the ocean.</pedantic>
[http://maps.google.com/maps?hl=en&biw=864&bih=471...](http://maps.google.com/maps?hl=en&biw=864&bih=471&q=37%C2%B0+25%E2%80%B2+17%E2%80%B3+N,+141%C2%B0+1%E2%80%B2+57%E2%80%B3+E&um=1&ie=UTF-8&hq=&hnear=%2B37%C2%B0+25%27+17.28%22,+%2B141%C2%B0+1%27+57.28%22&gl=us&ei=F4d7Te_KNMaC0QG2w-DuAw&sa=X&oi=geocode_result&ct=title&resnum=1&ved=0CBgQ8gEwAA)

~~~
rphlx
Should we count lakes and other self-contained bodies of water on land?

------
brown9-2
Does anyone know what the flashing colors and lines separating regions on the
map of Japan in the lower right of the screen represent?

~~~
elliottcarlson
Areas under Tsunami watch (I believe)...

------
koski
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?

~~~
craigmccaskill
That's certainly possible, theoretically. However, I'm not sure if those
conditions can actually be met (rods should not ever come into contact with
water and nothing should be able to ignite the gas, especially not at higher
pressure levels).

~~~
uvdiv
No, actually the fuel pellets never need to come in contact with water; it is
their cladding, which is a zirconium alloy ("Zircaloy"), which can react with
steam under extreme conditions. It's a redox reaction: Zr + 2H2O --> ZrO2 +
2H2 or something similar.

This actually happened at Three Mile Island, and there was a hydrogen
explosion in the containment building there (which did not break).

(I am not an engineer)

~~~
craigmccaskill
That makes more sense, thanks.

------
cskau
Watching BBC, it seems mainly the walls and roof have been blown out.

The main steel structure is still standing, and the expert in the studio was
saying something like there still is a chance of the 3-Mile Island like
scenario. That is that the nuclear material is still contained within the core
structure.

------
anigbrowl
Some more information plus links to official press releases etc.
<http://news.ycombinator.com/item?id=2316371>

------
phreeza
skip to 0:46 for a closeup replay of the explosion

------
oemera
Real quick, what does that mean for the rest of the world? Do we have to fear
something?

~~~
by
The things we should fear are myocardial infarction [1] and cerebrovascular
accident [2]. These are what will probably kill us in developed countries [3].
The good news is that we know how to prevent many of these deaths: regular
exercise, not over-eating, not smoking and moderation in alcohol and drug
consumption. Other causes of death and ill-health are also reduced by these
actions.

[1] <http://en.wikipedia.org/wiki/Myocardial_infarction> [2]
<http://en.wikipedia.org/wiki/Stroke> [3]
[http://en.wikipedia.org/wiki/List_of_causes_of_death_by_rate...](http://en.wikipedia.org/wiki/List_of_causes_of_death_by_rate#Developed_vs._developing_economies)

~~~
mortenjorck
An excellent response to nearly any concern of disaster, terrorism, or other
highly-visible but highly-unlikely danger. Fear is only natural, but it's
amazing how quickly it can be allayed with a little perspective.

------
giberson
Is it exploding, or are they doing a pressure release?

~~~
cloudwalking
That doesn't look like a very controlled pressure release.

edit: BBC says it's an explosion but article is completely devoid of details:
<http://www.bbc.co.uk/news/world-asia-pacific-12720219>

~~~
david2777
CNN too,
[http://edition.cnn.com/2011/WORLD/asiapcf/03/12/japan.nuclea...](http://edition.cnn.com/2011/WORLD/asiapcf/03/12/japan.nuclear/index.html?hpt=T1)

------
dablue
Know why Japan is now clearing all this up now?

Cuz the USA offered to send emergency help.

Imagine the USA team going over and finding nothing really happened, an entire
hoax.

This bombing was crafted to short the stock markets.

It's pitiful what the rich do for their market gains.

~~~
dablue
Whoever downvotes this also believes that 9/11 incident was an accident. It
was cleverly crafted as well.

------
nazgulnarsil
fuck everything about shitty government monopolies on dangerous aging
infrastructure. not politically popular = not getting renovated this year! (ad
infinitum)

~~~
mousa
I don't think renovating a nuclear power is difficult to stir up popular
support for if the experts want it renovated badly. I doubt private industry
would have had any more foresight.

