Depleted Uranium used as ballast in 747

[limpitakis]

Is it true?
A National Geographic docymentary tried to light up a 747 Corean cargo plane that crashed just outside Stansted airport a few minutes after take off.
The reason I am reporting this is that NTSB restricted the area not for the usual reasons only but additionally to another one.
That reason had to do with the depleted uranium used to rudder and wings as ballast.
Even though there was no leakage then I have to ask ...
Why do they use depleted uranium in public transportation? What is the purpose?
Is it safe from the point of radioactivity even though it is depleted uranium?
What about the safety of the crue which fly the planes around the clock?

[matkat]

Extensively used as elavator balance weights, certainly nothing new.

[Daysleeper]

Why do they use depleted uranium in public transportation? What is the purpose?

Various components need to have weights to balance other bits. The smaller the size of a given weight the better, you can have better aerodynamics or more fuel or whatever. Depleted Uranium (DU) is very very dense (so very heavy for a given area). More recently other materials that are nearly as heavy but not so risky are used.

Is it safe from the point of radioactivity even though it is depleted uranium?

Yes, the material is depleted as in not as radioactive as natural uranium. That said there is a reasonable argument that any radiation is bad but in normal use it is a long way from people.
However...it is highly toxic so, in the simplest terms, if it breaks up or burns you don't want to be near it.

What about the safety of the crue which fly the planes around the clock?

The DU is safely locked away in the structure of the plane and as long as they don't crash they have nothing to worry about. If they do crash and it's bad enough to liberate the DU, then they are probably beyond caring anyway.

More interestingly is what happens to the fire crews and others who respond to the accident.

[Al Murdoch]

As long as the DU is not allowed into the environment (i.e. in a fire or crash) it is perfectly safe. Even if it is allowed into the environment, the effects of it are controversial as it is only very weakly radioactive. I think the emissions are mostly alpha particles and very, very low gamma rays, so you would need to ingest it for it to be dangerous.
It is used because its density is much, much higher than lead (by about 70% I think).

[mustafagander]

When did the B747 Classic first fly RPT? Early 1970 I think. Not really a new discovery.

Spent uranium - properly protected, meaning kept away from the environment and intact rather than dust - is quite benign. It is very useful in the area of flight control mass balance due to its high density.

[limpitakis]

Thank you all for your replies,
As for the 747 being a very old plane yes it is true but the corean 747 that crashed was a very modern 747 which means that DU is still being used today as it used to.
I had no idea about its density but it is clear now.
Thank you again all for your input.

[oggers]

I wouldn't be surprised of it was lurking near the bottom of the list of things to worry about in the case of a 747 going up in flames.

[gas path]

We had a visit from the NRPB, CAA and the AAIB (mob handed!) following the loss of PA103 asking how much DU could possibly be fitted. The answer being no idea! It was used to mass balance the elevators, outb'd ailerons IIRC upper rudder and could also be found bolted inside the outb'd nacelles to stop or rather damp out 'pod nod'. The latter depending on the mod state because the other option, would be to do away with the nacelle weights and fit a damn great block of Ti at the back of the exhaust plug.
I don't think it was ever recovered, more than likely scattered over several thousand square miles of Scotland.

[stepwilk]

An acquaintance of mine (Bob Lutz of GM/Chrysler fame) landed his L-39 Albatros gear-up several years ago. It was a particularly expensive gear-up because the L-39 has somewhere on its underside an ice-detection mechanism that uses strontium 90 as an active element. The strontium was spread for 1,500 feet down the runway, which required the involvement of a major hazmat team from the EPA.

[911slf]

Wot me worry?

In 1966 I was working on a laboratory scale process using Uranium Oxide as a catalyst. It came in small lumps which I cheerfully broke up into smaller lumps using a hammer, and generating dust. I never thought much about it, still don't to be honest. On the other hand the glass jars in which it was delivered were contained in metal cans and packed with cotton wool to reduce risk of breakage. No ill effects so far.

[zondaracer]

During my time in the USAF I was based at Davis-Monthan. Every now and then, the local anti-war protesters would protest outside the main gate, particularly our use of depleted uranium rounds in the GAU-8. When the depleted uranium rounds are used against tanks and other armored vehicles, it would leave a dust cloud of depleted uranium, and soldiers who go looking for war trophies in the vehicles shortly after they are neutralized end up with long term /permanent illnesses.

[frontlefthamster]

The reason I am reporting this is that NTSB restricted the area not for the usual reasons only but additionally to another one.

Mes amis on the other side of la Manche wouldn't be very pleased to read that!

[Flash131]

It is not just those looking for war trophies. Someone has to clear up the mess. We had to clear the road to Basra of burnt out armour holding up our advance. As you might imagine, it is not easy to shift dead MBTs out of the way without stirring up a fair amount of dust.

[JammedStab]

https://aviation.stackexchange.com/q...hts-in-the-747

Provides some pictures.

[megan]

Widely used, C-130, Jetstar, S-3, C-141, 747, 1011, DC-10, helicopter rotor blades. Since 1981 Boeing has supplied tungsten weights as replacements. Rescued the crews of two Wessex helos that clipped blades during formation flight, and finding the DU weights which had been spread about the countryside was of some concern to management. Wessex was a licence built H-34 which came into production in 1954, presumably they used DU since that time.

[riff_raff]

I believe the use of DU was discontinued for new commercial aircraft designs by Boeing back in the 1980's. Tungsten works just as well. But probably costs more.

[lomapaseo]

I've worked around Boron, DU and composite structures all my life and the medical profession has yet to find a link within me.

I use to be nervous and jerky.

but
I'm not nervous anymore

[vapilot2004]

Boeing switched to tungsten counterweights in 1981. They also provided updated tungsten weights for aircraft manufactured prior to 1981, although replacement of the DU weights was up to the aircraft owners and operators.

According to the NRC, a fire burning in excess of 600C is required to cause the DU weights to become a serious danger to firefighters.

[TURIN]

As a very young apprentice I found some very heavy weights lieing around the hangar many years ago. The upholsterers used them to hold down glued joints on the furniture.
We used them as blocker bars when riveting.

[Gilmorrie]

Depleted uranium is not "spent" uranium. Depleted uranium is what's left of natural uranium when much of the fissile isotope, U-235 is removed while producing enriched uranium. Uranium is a natural element that appears in the earth's crust. Relax.