Video of reactor 1 at Fukushima plant • Hacker News Board

Re: Video of reactor 1 at Fukushima plant

#71

Post by A1kmm » Sat, Mar 12, 2011, 12:27 PM UTC

sliverstorm wrote: post #16

koski wrote: post #9

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 m…

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.

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%.

Re: Video of reactor 1 at Fukushima plant

#72

Post by jensnockert » Sat, Mar 12, 2011, 12:42 PM UTC

foobarbazetc wrote: post #69

http://twitter.com/#!/martyn_williams/status/465371589153914... The reactor DID NOT explode. HN is becoming a bit sensationalist today. Edit: http://en.wikipedia.org/wiki/Boiling_Water_Reactor_Safety_Sy... 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 (d…

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.

Re: Video of reactor 1 at Fukushima plant

#73

Post by uvdiv » Sat, Mar 12, 2011, 12:59 PM UTC

foobarbazetc wrote: post #69

http://twitter.com/#!/martyn_williams/status/465371589153914... The reactor DID NOT explode. HN is becoming a bit sensationalist today. Edit: http://en.wikipedia.org/wiki/Boiling_Water_Reactor_Safety_Sy... 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 (d…

"We've confirmed that the reactor container was not damaged. The explosion didn't occur inside the reactor container. As such there was no large amount of radiation leakage outside," [Japan Chief Cabinet Minister Yukio Edano] said.

"At this point, there has been no major change to the level of radiation leakage outside (from before and after the explosion), so we'd like everyone to respond calmly," Edano said."

http://www.reuters.com/article/2011/03/12/japan-quake-reacto...

Now they are going to flood the reactor container with seawater.

Re: Video of reactor 1 at Fukushima plant

#74

Post by uvdiv » Sat, Mar 12, 2011, 1:02 PM UTC

A1kmm wrote: post #71

sliverstorm wrote: post #16

Earlier quoted context omitted.

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.

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.…

That report is here (106.3 mSv measured):

http://www.tepco.co.jp/en/press/corp-com/release/11031219-e....

Re: Video of reactor 1 at Fukushima plant

#75

Post by adrianN » Sat, Mar 12, 2011, 1:10 PM UTC

oemera wrote: post #50

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

No. Even if shit gets real and the reactor goes Chernobyl, Japan is sufficiently far away from the western world that it doesn't matter at all. People weren't concerned about radiation from the nukes in Bikini either.

Re: Video of reactor 1 at Fukushima plant

#76

Post by foobarbazetc » Sat, Mar 12, 2011, 1:10 PM UTC

jensnockert wrote: post #72

foobarbazetc wrote: post #69

http://twitter.com/#!/martyn_williams/status/465371589153914... The reactor DID NOT explode. HN is becoming a bit sensationalist today. Edit: http://en.wikipedia.org/wiki/Boiling_Water_Reactor_Safety_Sy... 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 (d…

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.

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.

Re: Video of reactor 1 at Fukushima plant

#77

Post by JanezStupar » Sat, Mar 12, 2011, 1:11 PM UTC

vukk wrote: post #60

JanezStupar wrote: post #56

Earlier quoted context omitted.

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.

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.

Re: Video of reactor 1 at Fukushima plant

#78

Post by jensnockert » Sat, Mar 12, 2011, 1:15 PM UTC

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.

Re: Video of reactor 1 at Fukushima plant

#79

Post by foobarbazetc » Sat, Mar 12, 2011, 1:16 PM UTC

uvdiv wrote: post #73

foobarbazetc wrote: post #69

http://twitter.com/#!/martyn_williams/status/465371589153914... The reactor DID NOT explode. HN is becoming a bit sensationalist today. Edit: http://en.wikipedia.org/wiki/Boiling_Water_Reactor_Safety_Sy... 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 (d…

"We've confirmed that the reactor container was not damaged. The explosion didn't occur inside the reactor container. As such there was no large amount of radiation leakage outside," [Japan Chief Cabinet Minister Yukio Edano] said. "At this point, there has been no major change to the level of radiation leakage outside (from before and after the explosion), so we'd like everyone to respond calmly," Edano said." http:…

The reason for the building blowing out:

"Edano said due to the falling level of cooling water, hydrogen was generated and that leaked to the space between the building and the container and the explosion happened when the hydrogen mixed with oxygen there."

It looks like they're about to use this:

Low Pressure Coolant Injection System (LPCI)

Then this:

Standby Liquid Control System (SLCS)

http://en.wikipedia.org/wiki/Boiling_Water_Reactor_Safety_Sy...

Looks like they've given up saving the reactor.

Re: Video of reactor 1 at Fukushima plant

#80

Post by jensnockert » Sat, Mar 12, 2011, 1:24 PM UTC

foobarbazetc wrote: post #76

jensnockert wrote: post #72

Earlier quoted context omitted.

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.

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.

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