(Seawater corrosion) fears for stricken nuke site

[jpak]

http://www.thesun.co.uk/sol/homepage/news/3480291/Corrode-fears-for-Japans-stricken-nuclear-site.html

OFFICIALS at Japan's worst-hit nuclear reactor were facing a new crisis last night after fears seawater being used to cool the generator is CORRODING it.

Experts at the stricken Fukushima power plant were considering opening a valve to release highly radioactive gas from reactor No3 in a bid to stop a full meltdown.

The alarm was raised after pressure rose unexpectedly in the reactor - the most volatile at the plant as it contains plutonium.

A government spokesman said: "At the moment, we are not so optimistic that there will be a breakthrough."

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[Old and In the Way]

1. Hi jpak.

The news has certainly been encouraging with power and water getting to the spent fuel pools. Has there been any talk about what the plan is with decommissioning these reactors? I assume all are now considered damaged beyond repair. Given the still delicate state of these plants and the possibility of near future earthquakes to set back progress in containing the damage, what's the plan to get these fuel rods out of there?

[jpak]

3. They need to get those cores cold and stable before they can even begin to plan for decommissioning

It took over a decade for Three Mile Island.

At this point no one has a clue how and when that will happen...

[Old and In the Way]

5. I suspect that's the case.

And that really scares the shit out of me. At least at TMI, the possibility of further quakes didn't complicate the recovery plan....this will be like the Sword of Damocles hanging over the heads of the Japanese for as long as it takes to get these fuel rods safely stored. I sure hope there's a plan that can make this a happen relatively quickly.

[Statistical]

13. There is no quickly. Time is your only ally.

Radioactive decay falls off based on time. It falls of very rapidly initially and the rate of decay slows continually.

The core won't be safe to open for at least 3 years. Most nuclear experts would probably want to wait 5-7 years. In normal refueling operations they can open the core only a few weeks after cold shutdown because they flood the entire reactor building so both the reactor and spent fuel pond are under 20 ft of water. The fuel handling machine then moves fuel from reactor to fuel pond and fuel continually remains under 20ft of water (radiation shielding).

With damaged reactor building damaged it is unlikely they can flood it with water. Even if they could if the fuel has melted removing it from the core remotely with use of fuel handling machine will also be impossible. It would need to be cut out of the reactor. At TMI they chose to wait a decade until activity levels were a tiny fraction of peak output.

The good news is that pretty soon (unless something else goes wrong) they will no longer need to keep the reactor pressurized (5 & 6 have already been pressurized). It can be brought to "cold shutdown" (1 atmosphere of pressure and <100 deg Celsius). Even then though it will require cooling water (much slower pumps but still pumped) o keep the temp and pressure from rising.

When it comes to radioactive decay time is your best maybe only ally.

[FBaggins]

7. They also have a great deal of debris to clear away

... before they even get AT the core.

Then there are the pools to consider. They can't leave fuel there in a damaged pool - too many things can go wrong. But getting the fuel OUT will be no easy task, especially if some of it is damaged.

[Throckmorton]

2. Yes, I do believe it will be a major factor going forward,

I suspect that the widespread use of seawater will shorten the time available to clean up the mess, Inter-granular Stress and all. But I also suspect that the time frame for this impact is years, not weeks or days.

Hey, but I am a just a lowly EE and a small wire Instrumentation guy to boot, so all I know is what my Materials co-workers tell me.

Should I have used "Too" instead of "To" in "To Boot"?

I also was not an english major, but my dear departed wife was, but she is not talking.

[aquart]

4. "To boot" is correct.

[BeFree]

6. jpak

Thanks for all you have done.
You've taken more shit over nukes than anyone yet you keep on plugging.

I know in your heart this devastates you, maybe more than I, and it don't look good.

But there is nothing more that could really have been done.
Once Pres. Carter got screwed over we became doomed.

Peace and good luck to us all.... we're gonna need it.

[PamW]

8. I've got news for you...

The alarm was raised after pressure rose unexpectedly in the reactor - the most volatile at the plant as it contains plutonium.
================================

I've go news for you, they ALL contain plutonium.

Plutonium is made inside commercial nuclear reactors. The fuel in
commercial reactors is about 3-4% U-235 and 96-97% U-238.

When neutrons hit the U-235, it fissions giving the energy desired.

When neutrons hit U-238, there is a small chance that the nucleus will
fission if the neutron has an energy greater than 1 MeV. However, the
most likely result will be that the U-238 captures the neutron and
transmutes into plutonium.

In the 3 years that the average fuel assembly spends in a reactor, about
40% to 45% of the energy you get out of that assembly comes from burning
plutonium.

Reactor #3 is the only one that had plutonium that had been in the reactor,
and was removed, and then "cleaned up" by removing the fission products and
then returned to the reactor. But they ALL have plutonium in them.

PamW

[madokie]

9. But not in the quantities that number 3 has

Nothing about this catastrophe is good in any way.
People will be dying for years to come because of this

[Name removed]

10. Deleted message

Message removed by moderator. Click here to review the message board rules.

[madokie]

12. The only thing you've shown conclusively so far is

well I won't spell it out but it starts with an a and ends with an s

You see lady I don't come here claiming to be anything except a concerned person who does not believe one word the nuclear boys tells me, girls either, and dang sure not the all knowing asses, you get my drift?

[FBaggins]

14. Sorry. Pam was right (again). I predicted this on the very first day of the crisis.

Before you ever read about it in the news, I pointed out that Fukushima was the first plant in Japan to start using MOX fuel and that this (non) issue would get lots of play in the coming days. (I had the wrong reactor from misreading "#1" as unit #1 when it was plant #1)

http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=115&topic_id=277612&mesg_id=277638

I'm not sure why her post was deleted, but I remember that she pointed out (correctly) that ALl spent reactor fuel has Plutonium in it (and yes, it's at similar levels).

But it doesn't matter because there IS NO MOX FUEL IN THAT POOL

I know you've read it half a dozen times in poor reporting from a number of sources. But it's simply wrong.

That unit first switched over to MOX fuel last September. It takes more than six months before a reactor needs refueling, so the first MOX fuel delivered to Fukushima is still sitting in the core of that reactor.

No. I don't have a single source for this apart from the report (linked below) announcing the new fuel... but I can add 2+2. It's only been in there for six months, so it would be "spent" yet. I think that we've also seen reported that the freshest fuel in pool #3 is nine months old.

http://nuclearstreet.com/nuclear_power_industry_news/b/nuclear_power_news/archive/2010/09/17/fukushima-to-restart-using-mox-fuel-for-first-time-091704.aspx

[AtheistCrusader]

11. "the most volatile at the plant as it contains plutonium"

I hope that's a mis-translation.

[Javaman]

15. I was waiting to hear this...

I said to my wife, when I first heard they were pumping sea water into the reactors, "this won't be good, expect a lot of corrosion".

and here we are.