Nuclear fuel rods fully exposed at Japan reactor

[FourScore]

Nuclear fuel rods fully exposed at Japan reactor: Jiji
Published: Monday, 14 Mar 2011 | 7:07 AM ET

TOKYO - Nuclear fuel rods at a quake-stricken Japanese nuclear reactor are now fully exposed, Jiji news agency said, quoting the plant's operator, Tokyo Eletcric Power Co.

The report referred to the Fukushima Daiichi complex's No.2 reactor, where levels of water coolant around the reactor core had been reported as falling earlier in the day.

The Jiji report said a meltdown of the fuel rods could not be ruled out. A meltdown raises the risk of damage to the reactor vessel and a possible radioactive leak, experts say.

http://www.cnbc.com/id/42068536

[drm604]

1. Damn!

The news just keeps getting worse.

[FourScore]

3. The disturbing part is that Unit 2 had been somewhat under control.

Units 1 and 3 were the problems before.

[Hannah Bell]

2. per news conference occuring right now, the exposure was due to running out of

fuel for the pumps. fuel has been restored & pumping resumed per the news live here:

http://yokosonews.com/live/

[FourScore]

4. Oh that is good news!

Let's hope it suffices.

[drm604]

6. That's good to know.

[eowyn_of_rohan]

11. Good. Because I read the rods had been TEMPORARILY exposed.

Hope still exists.

[MadHound]

5. That's not good,

Especially if they were exposed for any significant length of time. This means that the containment vessel is weakened even more.

[Atman]

7. They must be wrong...so many DU "experts" keep telling us it couldn't happen!

:banghead:

[Turbineguy]

8. Found this

(from ex-Navy nuke)

"Once the reactor is shut down, meaning the neutron population goes below self-sustaining, the reactor still retains that steady-state decay heat of ~7-8%
Immediately, the fast-decaying isotopes start to peter out, resulting in the decay heat dropping, as shown in the curve in the PDF.
After a day, the power is < 1%. After a week, around 0.1%. After a year, around 0.05%. After ten years, .0025%"

https://netfiles.uiuc.edu/mragheb/www/NPRE%20457%20CSE%20462%20Safety%20Analysis%20of%20Nuclear%20Reactor%20Systems/Decay%20Heat%20generation%20in%20Fission%20Reactors.pdf

My comment: I don't know how cooling flow interruptions play into this. One problem would be salt scale forming on hot surfaces building up an insulating layer where water levels dropped. Presumably this was already thought of before using salt water. Conventional steam engineers are always looking to increase their hoard of make-up feed.

[formercia]

10. They are also using Borates in the cooling water as a moderator.

When Borates dehydrate and are heated to the melting point (743 deg. C for Sodium Tetraborate), It form a glassy material that is very slow to dissolve. This will act to some degree as an insulating layer on the fuel assemblies.

[Turbineguy]

15. With fire pumps

for cooling putting out about 150 psi, the saturation temperature is around 180 deg C. Even at full plant operating pressure the temperature goes to 280 deg C.

[FourScore]

17. We have to remember that with each passing hour the risk is lessened. n/t

[thewiseguy]

9. The number 3 reactor is highly likely going through melting according to Edano

[gratuitous]

12. Let me reassure everyone

According to a report I saw, the owners of these plants will not be liable for any damage caused; that will be up to the Japanese government, funded by its citizens. So the owner (which goes by the initialism "GE" which could mean anything, and certainly does NOT automatically mean the owner of one of the major American broadcast networks, although it does in this particular case) will be free to build nuclear power plants on other fault lines, or in the shadow of a volcano, or in the path of typhoons and hurricanes, without penalty. Sure, running a nuclear power plant is no more risky than a really good professional juggler flipping balls of nitro glycerine. And because it's so safe, we'll have that juggler stand on a high wire. Over an enormous tank of gasoline. In the middle of a city. Safe, baby!

I hope you're all reassured.

[Junkdrawer]

13. Yes, but the cost of online disinfo operatives is borne by the industry....

that can't be cheap.

[DCKit]

14. Thankfully, though, only a couple have had the lack of sane judgment...

to show up here and try to defend/deflect on how bad this situation really is.

Folks, they just lost the war, and they damn well know it.

[FourScore]

16. Phew! Good to know!

I was particularly concerned about GE when I read this headline. Especially since the Supreme Court informed me that corporations are people, too -- Ever since then, I have been extremely concerned for their welfare.

BTW, love the juggler analogy!!