Please help me debunk this alarmist page re Fukushima

Factual Questions
21

Okay. I’m really busy right now. Maybe I can get to it later. But here is a hopefully corrrect method (don’t hold me to it though, doing this on the fly and will likely screw it up).

Watts are power. Power over a unit of time is a unit of energy. A thousand watts for an hour is a kilowatt hour. So, over 24 hours and 365 days for a year you get 24 times 365 kilowatt hours. Multiply that times say 1,000 for you reactors total production (reactors are on the order of megawatts which is a thousand kilowatts (or are reactors a 1000 megawatts? dangit)). Multiply that times the number of years the reactor has been in service.

Now, the bomb you want to compare it to. Its going to be in kilotons (of tnt). You need to find the conversion of that into kilowatts hours and you’ll have your very back of the envelope calculation.

You can do it! MacGyver could!
And oh yeah, the fact Chernobyl was basically a giant pile of charcoal with radioactive material in it that burned out in the open didn’t help things much.

22

Conditions at Chernobyl were far worse in part because of the nature of the accident. Due to a combination of terrible design and horribly unwise decisions on the part of the staff, the core was put into an unstable state which resulted in a brief power surge of around a hundred times the core’s normal maximum power output. That created a steam explosion that blew the core open and scattered core material across the landscape, followed by a fire. Chernobyl used graphite as a moderator, but technically it wasn’t a graphite fire. Nuclear-grade graphite won’t support combustion, but the remains of the core were by that time molten and heating the graphite to a high enough temperature to force it to burn.

What you had was a power output many times greater than the normal reactor maximum power that was acting to vaporize fuel material and lift it into a radioactive plume.

At Fukushima, you had a safe shutdown, followed by a loss of cooling. At the moment of shutdown the fuel rods were still producing about five percent of maximum power due to radioactive decay. With no cooling, that was enough to cause meltdowns in three units, and create enough hydrogen to fuel explosions in units 1, 3, and 4. Unit 4 did not actually have any fuel in the core at all - it had all been moved to the storage pond while the core was being repaired and upgraded. The cooling pond in unit 4 lost active power, but the water never boiled off to the point to expose any of the fuel.

The amount of energy generated by decay heat falls off with time. The fuel rods in the cooling pond of unit 4 ahd already been out of service for months, and didn’t have enough power to boil the pond dry. It appears now that the hydrogen which caused the explosion that blew off the roof of unit 4 was due to the fact that units 3 and 4 share common plumbing in their exhaust stacks. Hydrogen leaked from unit 3 into unit 4 and built up enough to cause an explosion.

Since then, all of the fuel in the cooling ponds, as well as the melted corium in units 1-3, has been cooling off, and today is only producing a fraction of the heat it did at the time of the meltdown. If there was going to be a big scary radiation-spewing event in the unit 4 spent fuel pond, it would have happened a year ago, not today when the entire site is being monitored carefully and cooling has been restored to all the ponds.

So even if the cooling pond in unit 4 collapses and all the fuel rods fall out into a pile, there’s just no mechanism to scatter them into the aerosolized plume that you’d need to cause widespread contamination. At worst, you’d contaminate the soil on site, and maybe have some radioactive runoff that gets diluted in the ocean.

23

You don’t need curly braces if you know the secret ninja trick to make [noparse][del]this[/del][/noparse] not look like [del]this[/del] that.

24

Ok this page does the conversion:

Tsar Bomba was 50 megatonnes = 50,000 kilotonnes = 58,111,111 MegaWatt Hours equivalent, so call it 60 million megawatt hours of energy released at once.

Fukushima Reactor 4 is 784 megawatts (is that per hour?) according to here:
http://af.reuters.com/article/commoditiesNews/idAFL3E8EQ09W20120507

So over 20 years it’s made 784 * 24 * 365 * 20 = 137,356,800 megawatt hours of energy. Thats just reactor number 4. So detonating all the spent fuel from reactor 4 20 years of use would be very very roughy equivalent to 2 Tsar Bomba’s in terms of total radioactive material released.

Does that make any sense at all?

25

Sounds good to me. BTW watts are just watts. You can have watt seconds, watt minutes, watt hours, watt days, watt years and so and so. I think you can see offhand how to convert between them. Watt hours is the most common ones though. IIRC the Tsar bomb ALONE released something like 25 (50?) percent the total radioactive stuff into the atmosphere due to above ground testing. And again, almost all the bomb shit went into the air. Almost all that reactor stuff is gonna stay put.

Ya done good. Keep it up kid and you’'ll get your own Stargate command position one day :slight_smile:

26

Gee, the Japanese reactor situation must be really dire if it gets Mike Adams, the “Health Ranger” of NaturalNews worried enough to stop obsessing about his usual targets:

“Worried about GMOs? Fluoride? Vaccines? Secret prisons? None of that even matters if we don’t solve the problem of Fukushima reactor No. 4, which is on the verge of a catastrophic failure that could unleash enough radiation to end human civilization on our planet.”

That list of “hot topics” should clue you in to the unfettered crazy that is the world of Mike Adams, and reassure you that whatever Adams is going bonkers about is extremely unlikely to be a valid concern.

Never take anything NaturalNews says at face value without getting the facts through reliable sources.

27

It’s not a useful instant debunking factoid I can quote back. All 6 reactors at Fukushima Daini are total 4,400 Megawatts per hour and they’ve been running for over 30 years not 20.
So the total fuel generated is 4400 * 24 * 365 * 30 = 11 Billion Megawatt hours which is very roughly equivalent to 20 Tsar Bomba’s… which to be honest would be pretty dire.

To debunk this properly we need more realistic figures based on the amount of decay thats already occurred on the spent fuel and realistic totals for radiation release in case of a 7.0 earthquake and resulting fire.

28

Busy here.

But think about this. If a large fraction of the radiactive material in Japan SOMEHOW (and thats one magical somehow at this point) managed to become airborn it would be on the same order as all of radioactive material released to to above ground atomic bomb testing…just how BAD could that be? Were people dieing in droves? Living underground? Mutants and zombies running amok? Sure, hippies and disco came to pass but come on. The decades during and shortly after all that above ground testing saw man’s typical lifespan increase greatly. Yeah, I guess you could argue (wrongly) that most of modern cancers were caused by those tests, but even then its not world stopping and no bigger a problem worldwide than car accidents, poverty, murder, starvation, and a host of other non radiation/cancer related deaths.

Heck, pick a release percentage of 1 percent. Thats only .2 Tsar bombs. Or ten percent, thats still only 2. Good enough.

29

I appreciate your efforts bill, but it’s a real question that deserves to be answered of what would be the worst case if all the material at Fukushima Daini caught fire after another major earthquake event. That’s pretty much what the alarmists are talking about and considering Japan’s tectonics position the chances of a major earthquake hitting the area again are pretty real.

The things is there has been cover ups, both TEPCO and the Japanese government are trying to cover their own asses, nowhere near to the degree that the CT websites say but to some degree.

Here at straight dope hand waving saying “it will be ok because we had 40 years of nuclear testing” is not going to cut it. And actually according to my figures 30 years of spent fuel from 6 reactors is probably actually MORE radioactive material than from all the above ground bombs ever detonated. it’s a lot of fuel.

30

I see. Youv’e got some rough worst case numbers now. And they still worry you. You are one of them. If you can’t wrap your mind around “its no worse than A because its literally no worse than A and A didn’t even cause anything anybody noticed” then I don’t know what else to say. My mistake. Good luck.

31

WTF does that mean? I realise there is no way to magically aerosolize all the radioactive material, and that most of it is going to stay in one place no matter what but I think we can do a better debunking thats what I’m trying to get.
And um the world did notice the effects of above ground testing, thats why it was banned.

32

To make my point clearer, the total amount of megatonnes detonated by all the above ground testing from Trinity to the CTBT was around 500 megatonnes in total as far as I can tell going off this page:
http://www.johnstonsarchive.net/nuclear/tests/multimegtests.html

That’s only 10 Tsar Bomba’s for all the above ground weapons ever detonated while we have a figure equivalent to 20 Tsar Bomba’s for all the radioactive fuel at Fukushima Daini. Now I might well have made a mistake and of course we are not going to detonate all the material as once even in the case of a earthquake / fire.

Wanting to get a grasp on the numbers does not make me “one of them”, but you’re telling me 20 Tsar Bombas equivalent of radiation release would be something you’d be happy with? it wouldn’t be an “extinction event” but it would make for a bad day for a large amount of people.

33

First you want us to show it would NOT make North American “uninhabitable” because of all your facebook idiot friends think it would. I think I showed that (or helped you to do so as it were). Hell, I think we showed it would at reasonable worst would be no worse than the 70’s or 80’s.

But now you want to move the goal posts to “bad day” for some small value of bad day.:dubious:

34

I want to try and come up with a clear simple debunking of the claims, and “well yeah actually if all the material burnt in a fire it would be twice as much radioactive material as all the above ground nuclear tests ever” is not a good debunking.

I think the straight dope can do better than that, but I’m not an expert so I’m trying to get some better answers, like what the actual equivalent of all that fuel is after taking into account how much of it has already decayed. We both know that its not an extinction event no matter what and that it’s not going to make north america unihabitable, the question I’m asking is “well how bad would it actually be?”

35

Well, no.
I’ve given up on such efforts, and advise you to not waste your time & thought on it.

Nothing (especially not facts & figures) will persuade the kind of idiots who credulously believe such sites. CTer’s and the like believe from emotional reasons (believing satisfies some emotional need in them) rather than logic. So logic, facts, etc. will not convince them not to believe such things.

So it’s a hopeless task. You’ll be happier, and more effective, putting your time into something else.

[Of course, some people have an emotional need to try to debunk such things, and to ‘fight ignorance’. Like a lot of us here on SMDB.] :slight_smile:

36

Sadly this is going to be a useless comparison. The physics of a power station versus a weapon are so wildly different that there is no useful way of comparing the reactions. As a specific point, note that many weapons have a yield setting (as simple a switch on the device), where for the same mass of fissile material you can get different yields. The efficiency of the device depends upon the time you can keep the fissile core contained and still critical. This depends upon totally different physics than is present in a power reactor, mostly being down to the compressing explosion, and the neutron flux that can be maintained whilst the bomb disassembles. A hydrogen bomb gets a large fraction of its additional yield from better fission, not from fusion, simply due to the additional neutron flux present due to the fusion reaction. There is probably a 100:1 variation in yield versus mass of fissile material in weapons, and again, it all comes down to the microseconds of time the reaction occurs in, rather than the sedate years upon years of steady fission. The Tsar and all the other megaton bombs are hydrogen bombs.

37

fine but “what would be the actual effects of a worse case disaster earthquake / fire on all the spent fuel at Fukushima Daini” is a question worth of GQ and thats what I am now asking.

38

Looking about, I think it isn’t too hard to estimate the amount of spent fuel, and its content. So, we know the reactors were boiling water, and one can find some typical design notes on these. Reactor 4 was rated at about 750 MW. A reactor that size would have had about 13 million fuel pellets in it. Fuel is turned over in these reactors in about a four year cycle, so in the time from 1978 to 2010 it would have had about 8 fuel turnovers (including the fuel still in it.) So roughly 100 million fuel pellets. A BWR pellet is 1cm in diameter by 1 cm long, and is made mostly of uranium dioxide, so weights about 8.6 grams. A spent pellet is about 1% plutonium, and 0.8% U235, plus 3% other nasty radioactive products (by mass). (Wikipedea) So we might say that the pellets are about 5% evil stuff, 1% of which is plutonium, which we generally consider the most evil. The older fuel rods won’t have so much of the 3% random nasties, but will have the plutonium, and newest ones in the reactor, will not be so bad, but still not good.

So we have: roughly 100 million pellets, containing about 5% nasty stuff (with 1% plutonium) weighing 8.6 grams each. That gets us 860 tones of fuel, with a total of over 8 tons of plutonium. That is just from Reactor 4. Add in the other reactors and it gets pretty big. Pretty close to 6 times.

The Fat Man bomb contained 6.2 kg of plutonium. So just Reactor 4 accounts for the equivalent of about 1200 Fat Man bombs.

In context one can see why there is such unease with reprocessing fuel and for any process that creates large amounts of plutonium.
As to the effects of earthquake/fire - the answer is essentially nothing. There is lot of evil stuff in those fuel pellets. But they are made mostly of uranium oxide. They won’t burn, they won’t melt, they won’t dissolve. After all they are designed to remain stable in the middle of a nuclear reactor immersed in superheated water.

39

Thanks Francis thats some great info and I believe you that Uranium Oxide (melting point 2400 C) and Plutonium (melting point 640 C or do) will pretty much just do nothing and sit there in case of a fire.
But specifically the CT websites are all talking about Caesium 137 produced in spent fuel, which has a very low melting point 28 C, boils at 670 C, has a 30 year half life and is by what I can tell is the nasty stuff which is still keeping certain areas of Chernobyl troublesome.

So are the CT sites wrong about how much Caesium 137 there is in the spent fuel, wrong about how dangerous it is, wrong about how easily it could get dispersed or something else?

Again, I am NOT trying to defend them, I am trying to understand a specific point, it certainly seems reasonable to me that in case of a fire a considerable amount of Caesium 137 would get dispersed as gaseous particles and yeah that would mess up the local environment in northern Japan pretty badly. Just how badly?

40

Looking at some of the information about fuel pellets we see a couple of things. The Caesium is held in microscopic voids in the pellet. The normal operating temperature of the pellet is 2600 C at the centre, down to 1700 C at its surface. During normal operations the Caesium does not escape from the pellet. So even when the pellet is held at close to its melting point for years, there is no risk of the Caesium escaping. If the pellet was melted, then it would be a problem. The graphite fire in Chernobyl, along with a real core meltdown got to this point. But short of deliberate action, you are not going to have any trouble with the spent fuel.

The pellets are themselves held in a rod made of Zirconium alloy, with a melting point of 1855 C.

There is a void in the rod to contain fission gases - Krypton and Xenon, and I would wonder if there isn’t some Caesium in here as well. But until you breach the rod, it isn’t going to get out.