glowing fuel?

[innovine]

Hi all, sorry if this is the wrong subforum for this, but I am hoping to get a professional reply..

An acquaintance is claiming that he sees a glowing nuclear fuel rod lying around in a picture of the Fukushima disaster. Would you be able to comment on this? If the fuel is heated to near-melting, and then explosively ejected out of the reactor, how long would it take for the fuel to cool so it's no longer glowing?

Any other comments on the image would be greatly appreciated. Again, sorry if this isn't really the right place, but I can't find any information on this otherwise.
The image in question: http://oi57.tinypic.com/24pb21j.jpg

[Marlin]

Hi all, sorry if this is the wrong subforum for this, but I am hoping to get a professional reply..

An acquaintance is claiming that he sees a glowing nuclear fuel rod lying around in a picture of the Fukushima disaster. Would you be able to comment on this? If the fuel is heated to near-melting, and then explosively ejected out of the reactor, how long would it take for the fuel to cool so it's no longer glowing?

Any other comments on the image would be greatly appreciated. Again, sorry if this isn't really the right place, but I can't find any information on this otherwise.
The image in question: http://oi57.tinypic.com/24pb21j.jpg

The glow off of activated nuclear fuel is from Cherenkov radiation, it is electromagnetic radiation emitted when a charged particle (such as an electron) passes through a medium at a speed greater than the speed of light in that medium. The glow is a very pretty blue which I do not see in the image and would not see in air.

[innovine]

Yes, it is a pretty blue But in this case it's purported to be glowing red-orange due to very high temperature (ie near melting). The speculation is that the reactor loses all cooling, the pressure rises, the temperature rises, then something explodes and the fuel rod lands outside. In this scenario, would it self-heat (decay heat) so much as to glow, or would it lose thermal energy to the air and cool, and if so, how rapidly?

[Marlin]

Yes, it is a pretty blue But in this case it's purported to be glowing red-orange due to very high temperature (ie near melting). The speculation is that the reactor loses all cooling, the pressure rises, the temperature rises, then something explodes and the fuel rod lands outside. In this scenario, would it self-heat (decay heat) so much as to glow, or would it lose thermal energy to the air and cool, and if so, how rapidly?

I am not aware of any fuel outside of the spent fuel pools and reactor vessels. Decay heat from residual radioactivity can melt the fuel and rods enclosing them but this is a debris pile not a view of the spent fuel pool.

[innovine]

No, I'm not aware of it either  But for the sake of argument, how fast would such a thing cool down?
Are you guys able to calculate or guesstimate something like that? The only numbers I've seen show that the whole reactor would be down to under 1% of its thermal output after a day. Would that apply to individual rods too or is there some kind of cumulative effect when they are together?

[spentfuel]

The picture does not show burning fuel as there were no fuel ejections at Fukushima.  The picture shows some of the residual burning debris from the building materials post H2 explosion.

hope that helps

sf

[Marlin]

No, I'm not aware of it either  But for the sake of argument, how fast would such a thing cool down?
Are you guys able to calculate or guesstimate something like that? The only numbers I've seen show that the whole reactor would be down to under 1% of its thermal output after a day. Would that apply to individual rods too or is there some kind of cumulative effect when they are together?

Decay heat is ~7% of reactor power at shutdown, 2% of reactor power at one hour, and 1% at one day. Decay continues and after around 5 years fuel can be transferred to dry cask storage water cooling no longer needed if approved by NRC.

[btkeele]

No, I'm not aware of it either  But for the sake of argument, how fast would such a thing cool down?
Are you guys able to calculate or guesstimate something like that? The only numbers I've seen show that the whole reactor would be down to under 1% of its thermal output after a day. Would that apply to individual rods too or is there some kind of cumulative effect when they are together?

While I was working at TMI, post accident, we de-fueled the reactor using underwater tools and
would cut up bunches of damaged rods and stuff them into cannisters (all underwater, through a slot in a
shielded platform that sat where the Rx Head normally did).  Once in a while a section of fuel rod would
break the surface of the water, (awakening the tech due to alarms going off  )  While they were quickly
lowered (or kicked) back into the water, I never saw any glowing of any kind... although the soiling of underwear was another matter...
This was in 1988-89 timeframe, so approx 10 yrs after accident.

[spentfuel]

Might also be worth mentioning that the water in the pool is also used to adsorb neutrons and not just for cooling purposes.  Part of the waiting period prior to dry casks also has to do with neutron emission rates that are low enough so that stacking the fuel into a cask with other assemblies wont be and issue

sf

[Starkist]

While I was working at TMI, post accident, we de-fueled the reactor using underwater tools and
would cut up bunches of damaged rods and stuff them into cannisters (all underwater, through a slot in a
shielded platform that sat where the Rx Head normally did).  Once in a while a section of fuel rod would
break the surface of the water, (awakening the tech due to alarms going off  )  While they were quickly
lowered (or kicked) back into the water, I never saw any glowing of any kind... although the soiling of underwear was another matter...
This was in 1988-89 timeframe, so approx 10 yrs after accident.

This sounds like a book I would love to read honestly! Very interesting stuff.

[SloGlo]

The picture does not show burning fuel as there were no fuel ejections at Fukushima.  The picture shows some of the residual burning debris from the building materials post H2 explosion.

hope that helps

sf

yeah, watt he said. aye saw no fuel glowing.

[innovine]

yeah, watt he said. aye saw no fuel glowing.

No disrespect intended, but how is this supposed to be an answer to my question?

[innovine]

This sounds like a book I would love to read honestly! Very interesting stuff.

Me too!!
There's a great video on youtube: https://www.youtube.com/watch?v=VL7FB29zVZM

[Marlin]

No disrespect intended, but how is this supposed to be an answer to my question?

Confirmation???      I don't know if you have noticed but even though the forum rules require staying on topic they invariably drift a little (sometimes a lot ).


Draconian (Barney Fife) enforcement   is not wanted by anyone (well most   ) and most moderators would prefer to be a little tolerant (Sheriff Taylor).

[btkeele]

Me too!!
There's a great video on youtube: https://www.youtube.com/watch?v=VL7FB29zVZM

Brings back a lot of memories... at 4:10 you can see the platform (it was called the Westinghouse Platform cuz they built it) and the slot that was worked through.. even the walls on the sides of the slot were shielded.... then you can see the long handled tools used to grip and cut the fuel rods...
Then about 5:35 they show the core bore... that was crazy... I think that is where they got the idea
to drill on an asteroid in "Armegeddon".

[spentfuel]

No disrespect intended, but how is this supposed to be an answer to my question?

None taken, my initial comment was in response to your original post

An acquaintance is claiming that he sees a glowing nuclear fuel rod lying around in a picture of the Fukushima disaster. Would you be able to comment on this?

and

Any other comments on the image would be greatly appreciated. Again, sorry if this isn't really the right place, but I can't find any information on this otherwise.

My point being its not glowing fuel in the picture.  But to your other question if you have time read this perhaps it will provide answers to your questions.

http://www.nap.edu/catalog.php?record_id=11263

sf

[SloGlo]

No disrespect intended, but how is this supposed to be an answer to my question?

know disrespect taken. butt, they're plenty of responses to the time frame of the fuel glo guery, sew aye addressed the brite spot on the picture. coarse, eye did finger yew had red the rest.

[GoWest]

No, I'm not aware of it either  But for the sake of argument, how fast would such a thing cool down?
Are you guys able to calculate or guesstimate something like that? The only numbers I've seen show that the whole reactor would be down to under 1% of its thermal output after a day. Would that apply to individual rods too or is there some kind of cumulative effect when they are together?

This reminds me of heat equation PDEs in college. I don't know if there is an easy solution, but you would have to calculate the heat transfer do to conduction to the environment, the convection in air, and radiative losses to the environment based on the power of the fuel element. It would also likely be damaged or impacted, so this may impact the heat transfer rate (as well as the fact that if it heated up enough to deform, it would eventually make contact with the Earth and transfer heat that way). Then you would have to deal with oxidation, hydrogen reactions, and lots of other chemical reactions. You would probably need a supercomputer to do the calculations.

You could probably do an easy calculation for a rod (not an entire fuel assembly) on the ground or elevated and transferring with conduction at the ends and convection in the middle (as well as radiative heat transfer) with no chemical reactions occurring. But adding anything 'real' to the situation would make it infinitely more complex.

[GLW]

....(it was called the Westinghouse Platform cuz they built it)....

so,...

there is this unnamed Westinghouse guy, as big shots go, prob'ly analogous to a .45ACP, and about as vintage,...

in response to the quip "What do you think the NRC's take might be?",...

curt answer: "We were here before the NRC, they'll see it our way, we wrote their dam college books!",...

okee dokee then,....