Why I am not worried about Japan’s nuclear reactors • Hacker News Board

Re: Why I am not worried about Japan’s nuclear reactors

#71

Post by ch0wn » Sun, Mar 13, 2011, 4:58 PM UTC

illumin8 wrote: post #44

lispm wrote: post #27

Wow, such a denial of reality. 'in control'? If anything I saw in the last hours, the thing is not in control. Diesel generators failed, a building exploded, core meltdowns going on, restoring of electricity failed, seawater used for cooling (how were they pumping it and are the pumps powerful enough to provide cooling over a longer period of time like days). Valves are not working, measurement of pressure is not pos…

The PhD from MIT failed to mention in his article, when he talks about the 3rd containment being concrete poured around the steel casing, that the reactor which caused an explosion was built prior to this 3rd containment layer being mandatory in BWR design. So, it would seem that his confidence in the 3rd containment layer preventing any melted radioactive materials from getting out should be taken with a huge grain…

This is the same impression I got from what I read so far. Unfortunately, it's pretty much impossible to get reliable information on that.

An announcement in Germany regarding the safety of our nuclear power plants stated that ours are supposed to be safer, because they would have at three to four safety layers instead of two used in Japan, which probably referred to the containment layers.

Re: Why I am not worried about Japan’s nuclear reactors

#72

Post by varjag » Sun, Mar 13, 2011, 4:59 PM UTC

ars wrote: post #17

weinzierl wrote: post #6

He says that even in the case of a total meltdown (which hopefully will not happen in Fukushima) we will be save because everything will be contained in the third containment. What I don't get is how cooling is supposed to happen in this case. I think they still would have to pump sea water into the containment which would then get contaminated not only by neutron activation but also with Uranium, Cesium, Iodine etc.…

You filter out the other elements, and release the water. Water pretty much can't get radioactive. (For more than a few minutes.) The longest radioactive oxygen you can make in a reactor has a half life of 26 seconds. For hydrogen, deuterium is not radioactive, and tritium can't be made in a light water reactor. So water effectively can't get radioactive.

Remember, they pump in salt water, without prior desalination. It will get radioactive, although to which extent I have no idea.

Re: Why I am not worried about Japan’s nuclear reactors

#73

Post by hammock » Sun, Mar 13, 2011, 4:59 PM UTC

Here's TLDR version: (1) the steam released has radioactivity lasting on the order of seconds, (2) if/when meltdown occurs, cesium/iodine radionuclides can exist in the steam but are apparently blown out to sea away from Japan, and (3) with the exception of controlled steam releases, a steel containment surrounding the core & related components will absolutely contain 100% of worst-case scenarios, meltdowns, etc.

At least that's how I understood it. Not an expert so I have no idea how much of it is true or not.

Re: Why I am not worried about Japan’s nuclear reactors

#74

Post by varjag » Sun, Mar 13, 2011, 5:02 PM UTC

waterlesscloud wrote: post #66

ars wrote: post #17

Earlier quoted context omitted.

You filter out the other elements, and release the water. Water pretty much can't get radioactive. (For more than a few minutes.) The longest radioactive oxygen you can make in a reactor has a half life of 26 seconds. For hydrogen, deuterium is not radioactive, and tritium can't be made in a light water reactor. So water effectively can't get radioactive.

And they have these filters right there, handy and ready to use just in case they started pumping in sea water?

They could probably hack up a particle filter together pretty quick, but unlikely do any desalination. Any reactor which got salt water in it is very much totaled.

Re: Why I am not worried about Japan’s nuclear reactors

#75

Post by ugh » Sun, Mar 13, 2011, 5:02 PM UTC

samlevine wrote: post #70

miles wrote: post #63

Grateful for the explanation, but the author's bias is questionable at best. He suggests, "If you want to stay informed, please forget the usual media outlets and consult the following websites" and goes on to list 3 nuclear lobbying websites. So, ignore the independent media and get all of your information from pro-nuclear lobbies? More: https://morgsatlarge.wordpress.com/2011/03/13/why-i-am-not-w...

>So, ignore the independent media and get all of your information from pro-nuclear lobbies? The msm usually doesn't have any idea what they're talking about when they report on computer related issues, why do you expect them to be any better when it comes to nuclear power?

You wouldn't trust Greenpeace, you shouldn't trust the nuclear lobby. There are other independent sources available.

Re: Why I am not worried about Japan’s nuclear reactors

#76

Post by lispm » Sun, Mar 13, 2011, 5:05 PM UTC

neutronicus wrote: post #59

lispm wrote: post #31

Earlier quoted context omitted.

The reactor 3 at the first Fukushima plant is not just using Uranium. It uses MOX fuel. So what the author ('expert???') wrote is already useless, he does not even know what the reactors are using as fuel. Japan Today: http://www.japantoday.com/category/technology/view/mox-fuel-... From August last year: MOX fuel loaded into Tokyo Electric's old Fukushima reactor Sunday 22nd August, 05:36 AM JST FUKUSHIMA — Tokyo Ele…

Honestly, whether the fuel is UOX or MOX is not particularly relevant at this point, since the primary differences between those fuels are neutronic, not thermal, and even there they are qualitatively very similar. I'm pretty sure the author is not an 'expert', exactly, because he seems unfamiliar with some of the nuances of BWR operation, but his summary is generally correct.

Sure it is relevant. It means that the level of Plutonium could be higher in reactor 3 of plant Fukushima 1. This could have relevance in case of a full meltdown. It is said that then there is a possibility that there is a different reaction.

Re: Why I am not worried about Japan’s nuclear reactors

#77

Post by kgarten » Sun, Mar 13, 2011, 5:06 PM UTC

samlevine wrote: post #70

miles wrote: post #63

Grateful for the explanation, but the author's bias is questionable at best. He suggests, "If you want to stay informed, please forget the usual media outlets and consult the following websites" and goes on to list 3 nuclear lobbying websites. So, ignore the independent media and get all of your information from pro-nuclear lobbies? More: https://morgsatlarge.wordpress.com/2011/03/13/why-i-am-not-w...

>So, ignore the independent media and get all of your information from pro-nuclear lobbies? The msm usually doesn't have any idea what they're talking about when they report on computer related issues, why do you expect them to be any better when it comes to nuclear power?

He is not talking about msm but independent media. Mentioning Lobby groups as good information source discredits in my opinion the complete write-up. Also does the mentioning of "phd. scientist" ...

So according to your analogy: Don't listen to independent tech news, just listen to what Gruber tells you about Apple ;)

Re: Why I am not worried about Japan’s nuclear reactors

#78

Post by daniel02216 » Sun, Mar 13, 2011, 5:28 PM UTC

ugh wrote: post #43

Kilimanjaro wrote: post #36

Earlier quoted context omitted.

Earthquake destroys nuclear plant: thousands killed. Tsunami destroys tidal power plant: none killed. You are the PM of Japan, you make the call.

As of yet, no one was killed during the nuclear incident.

Weren't some engineers already killed during the explosion?

Re: Why I am not worried about Japan’s nuclear reactors

#79

Post by pdenya » Sun, Mar 13, 2011, 5:28 PM UTC

neutronicus wrote: post #57

The article is mostly correct, but a few corrections from a nuclear engineer: 1. What he refers to as "moderator rods" are actually control rods. The term "moderator" refers to a material that is unlikely to absorb neutrons, but likely to scatter them. This helps lower the average neutron speed inside the reactor, which actually increases the fission rate. Since water serves this purpose just fine, most reactors do n…

Would you provide more detail on #4? I'm curious but not quite getting what the consequences of this are.

Re: Why I am not worried about Japan’s nuclear reactors

#80

Post by Wientje » Sun, Mar 13, 2011, 5:31 PM UTC

waterlesscloud wrote: post #66

ars wrote: post #17

Earlier quoted context omitted.

You filter out the other elements, and release the water. Water pretty much can't get radioactive. (For more than a few minutes.) The longest radioactive oxygen you can make in a reactor has a half life of 26 seconds. For hydrogen, deuterium is not radioactive, and tritium can't be made in a light water reactor. So water effectively can't get radioactive.

And they have these filters right there, handy and ready to use just in case they started pumping in sea water?

Since they asked the prime minister for permission to pump sea water, I'm guessing that it was an option all along i.e. they have the facilities to do just a thing. The whole defence in depth concept relies on having a bazilion emergency options.