Japan nuclear - How safe are we?

[strawberry]

Haha, I love this. Japan has its largest disaster since World War 2. It lies decimated in the wake of a truly horrendous earthquake and tsunami and our reaction is...how does all this affect me personally? Forget the Japanese I want to know about me! Haha, humans.

wow... harsh much?? :(

[rhafrika]

I studied engineering and know a little bit about nuclear reactors and my dad actually worked on a similar reactor to the ones in Japan. Just a few thoughts from him and some of my friends who are studying nuclear engineering. Currently the radiation levels as a result of the explosions are at the same level as the radiation we would be exposed to from flying on a plane a few times (therefore we have all been exposed to this level of radiation). Even though two of the plants have had a partial meltdown the entire reactor is still enclosed in a building. Here is an e-mail I received from my friend who is getting her PhD in Nuclear Engineering at MIT (long but has some good info):

Background info:
Immediately after the earthquake, the reactors’ safety systems worked as they were designed. For an external event such as earthquake, hurricane, plane crash, etc., the plant immediately “scrams” (shuts down) the reactor. This was the case for the reactors in Japan, and it shut down the reactors successfully. In a nuclear reactor, there is always residual heat being produced even after reactor shutdown due to the fission product buildup that occurs during power production (these fission products are radioactive and continue to decay over time, which produces heat in the fuel, i.e. core, of the reactor). There are redundant safety cooling systems that keeps water flowing through the core to continue cooling so that a meltdown does not occur (the primary concern after emergency shutdown is to keep the reactor VESSEL intact, to prevent a large radioactive release into the environment), that are in this case, run on electricity. The tsunami waves swept away the power lines to the reactor buildings, so all external electricity was lost. Since the power lines were lost, the diesel generators were run to keep water flowing, but in the case of reactors #1 and #3 at the Fukushima Daiichi power station, their generators were too badly damaged by the earthquake and/or lost their fuel supply from the tsunami to run.
 
As the fuel temperature increased, the water began to boil off, increasing the pressure in the reactor vessel (which is housed in the containment building that is made of thick concrete). Battery-powered cooling pumps were able to run for about 8 hours until all their power was consumed. At this point, the reactors now had no electricity to run the coolant pumps. As the water continued to boil off, the water level decreased, exposing the fuel rods to air. The emergency water supply then flooded the core to cover the fuel again. But after time, this water was again boiled off. Once the fuel rods (made of Zirconium) are exposed to air, they begin to heat up very quickly and can crack and release fission products into the reactor VESSEL. Exposure of extremely hot Zirconium to steam also causes an oxidation reaction that produces hydrogen gas. As the pressure of the vessel continued to rise, the emergency pressure relief valves functioned as designed to release some of the pressure in the vessel to prevent a vessel breach from occurring. This released the steam and hydrogen gas into the containment building. Filters are attached to these vents that filter out fission products from being released (although minute amounts of radioactivity are released, the levels are generally so extremely low, it is not much different from the extra radiation exposure received from a few airplane trips). Both reactors #1 and #3 have since had explosions occur in the containment buildings due to this buildup of hydrogen gas. Both reactor VESSELS remain intact even though the containment buildings are damaged.
 
The last emergency cooling safety system was started, which flooded the vessels with sea water. Now it is unsure if the water levels in the vessels are high enough to cover the entirety of the fuel. If any of the fuel is exposed to air, it will continue to heat up until it melts- thus a “meltdown” (or “partial meltdown” if only a portion of the fuel melts).
 
A meltdown does NOT mean that radioactivity will be released into the environment. There are additional safety systems in the design to prevent this. As the fuel melts and falls to the bottom of the vessel, if they can keep it covered with water, it should not breech the vessel. If it does not remain covered with water, and it reaches the melting point of the materials of the vessel, then it would melt through the bottom of the vessel, and this substance is now called the “corium” (basically a mixture of melted metal, fuel, and fission products). Underneath the vessel is a “corium catcher”. This is a large pool of water that allows the corium to spread out thinly over a large area. This creates a large surface area that allows for faster and easier cooling and can thus contain the corium from moving any further and thus preventing its release into the environment. This is a worst case scenario.

We are safe in Korea. I am not a full supporter of nuclear power because of the potential effects of these once in a lifetime natural disasters but at the moment I don't think we need to panic. Hopefully Japanese engineers will be able to get the situation under control. The sad thing is Japan depended on power from these reactors and therefore will be forced to resort to non clean energy sources such as fossil fuels which will also have long term effects on the environment. Here is a new york times article that also describes the situation quite well:http://www.nytimes.com/interactive/2011/03/12/world/asia/the-explosion-at-the-japanese-reactor.html?nl=todaysheadlines&emc=tha2

[sbelleball]

... From the International Atomic Energy Agency:

http://iaea.org/newscenter/news/tsunamiupdate01.html

[rhafrika]

I should add to my above post. When the news uses the words "meltdown" and Chernobyl there is one more thing to consider. The design of these reactors are much better and so even in the absolute worst situation the seriousness of radiation will not be at the level of Chernobyl or Three Mile Island.

[rhafrika]

OK, so at your request I won't mock the question...but can I mock the fact that you are asking a bunch of English teachers a question about nuclear disasters and radiation?
 ::)

Haha! no not everyone on this site studied humanities type subjects. My only qualification in teaching English is the fact that I learned it as a kid. I think I know more about nuclear reactors than I do English grammer.

[DMZ]

I think people are also freaking out because of stories of explosions and images of steam coming from the plants. Of course, these are hydrogen blasts and very small amounts of radioactive steam.

Basically, a whole image is being built of a giant explosion and all safety measures failing and a huge plume of radioactive stuff spreading at break neck speed and killing us all or giving us 6 extra eyes and the urge to kill and eat other people that take a "wrong turn" or wander through our hills.

[honeynutloops]

I think people are also freaking out because of stories of explosions and images of steam coming from the plants. Of course, these are hydrogen blasts and very small amounts of radioactive steam.

Basically, a whole image is being built of a giant explosion and all safety measures failing and a huge plume of radioactive stuff spreading at break neck speed and killing us all or giving us 6 extra eyes and the urge to kill and eat other people that take a "wrong turn" or wander through our hills.

Yeah.  My knowledge of Nuclear power mainly comes directly from the Simpsons.  Homer was frequently causing meltdowns and he was always ok!

[grandfromage]

The media enjoys words like explosion and meltdown because they're scary and people have no idea what they mean.  Fukushima is going to be a mess to clean up but it's barely going to affect anyone in Japan, let alone Korea.  Three Mile Island is a good comparison--it's a radiation leak, evacuating those nearby is a good idea, but in the end nothing serious is going to happen.

A Chernobyl-like disaster (or anything affecting more than the immediate surroundings) is literally impossible because of the design differences between the reactors.  No need to be concerned.

[dmhr25]

OK, so at your request I won't mock the question...but can I mock the fact that you are asking a bunch of English teachers a question about nuclear disasters and radiation?
 ::)

My PhD minor is in Nuclear Engineering.  Ask away!

[derbear86]

It also seems silly to me that you would ask this question on Waygook. The vast majority of the responses you are going to get will be from people who really know nothing about the matter. Remember you don't need a brain to respond in these forums, you just need an internet connection. Why not check out a News website and read a few articles there. They may have some answers for you and actually know a little more about nuclear reactors than those of us who have only seen them on The Simpsons. I go to this site quite a bit for news in Korea...

http://joongangdaily.joins.com/

[techteacher]

My school just issued a notice saying stay inside for the next 24 hours beacuse of the Fukushima explosion and close the windows and do not expose your skin as much as possible...it ended with "Have a nice day!" ...in Ulsan

[grandfromage]

I'm totally willing to believe in the magical Fukushima if it gets me a day off.  Unfortunately I am in Ulsan too and no such luck at my school.

[be the ball]

It also seems silly to me that you would ask this question on Waygook. The vast majority of the responses you are going to get will be from people who really know nothing about the matter. Remember you don't need a brain to respond in these forums, you just need an internet connection. Why not check out a News website and read a few articles there. They may have some answers for you and actually know a little more about nuclear reactors than those of us who have only seen them on The Simpsons. I go to this site quite a bit for news in Korea...

http://joongangdaily.joins.com/

amen to that

and to the guy with a PHd in Nuclear Engineering, how's all that studying workin' out for ya? ???

[kcjohn7]

Thought I'd throw in that Chernobyl spread damaging radiation a ways into eastern Europe - even though the jet stream there is generally out of the east (blowing to the west).  So in a large scale disaster it's possible for the radiation to carry the distance to Korea - we're not that far.  Also radiation levels are currently rising in Tokyo, which is southeast of the power plants location - but these are said to be from low level winds and can't carry this far.

Having said that - it's very unlikely the winds would shift this direction.  Also the "experts" I've read are saying this virtually has no possibility of being like Chernobyl because of design differences.  The bigger worry here is large scale environmental disaster because if the radiation breaks from it's containment it will go into the soil and water supply.  Which in turn would hurt humans through food and water supply issues... but not direct radiation contamination.

[grandfromage]

Just because you guys don't know anything about nuclear reactors doesn't mean none of us do.  :p

[Busanveggie]

amen to that

and to the guy with a PHd in Nuclear Engineering, how's all that studying workin' out for ya? ???

Why do some people have to turn posts into a fight?If the OP felt the need to ask on Waygook then who cares. Sometimes news reports are full of technical language and here the guy was in luck and a few people were able to explain the situation to him in laymans terms.

[Epistemology]

http://www.bbc.co.uk/news/world-12740843

Apparently the containment chamber at one of the reactors is now damaged and leaking, which is responsible for the whopping dose equivalent of 8 Sieverts per hour in the atmosphere around the plant. That’s the level used to kill cancer cells, except when that is done, the radiation is targeted on a tiny area of the body

[adamwatch]

When it comes to nuclear power there are no experts.

Adam

PS We were told in the UK by the "experts" in the past that nuclear power would be so cheap it would be free!

[adamwatch]

"My school just issued a notice saying stay inside for the next 24 hours beacuse of the Fukushima explosion and close the windows and do not expose your skin as much as possible."

There is a civil defense drilll on today, I think maybe your school are a bit "confused":)

Adam

[emwsu]

OK, so at your request I won't mock the question...but can I mock the fact that you are asking a bunch of English teachers a question about nuclear disasters and radiation?
 ::)

Seems to me some people, like Gilbert.a.h. knows more about the stuff than I do... so probably wasn't a too crappy place to ask a question...?  :)

I thought this was a site we can share things about living overseas in addition to teaching. Most of us are not english majors and very well may know a thing or two about what is going on. Or they may have had the time to read more news sources than someone who has an easier teaching schedule and knows what every news channel is saying.  We also all provide a different base of information and this is a place we can share. My father used to work with IAEA regarding saftey, he has yet to issue me any concerns or reasons to be worried.

After Chernobyl there have been a lot more saftey things inforced and maintained regularly. Japan has been doing their best to control the situation and that is all we can hope for. For ourselves, Japan and everyone else.