
Low-Background Steel - confeit
https://en.wikipedia.org/wiki/Low-background_steel
======
goatsi
Low-background lead is also sought after in shipwrecks [0]. With lead it isn't
contamination from nuclear tests that's the issue, but natural radioactivity
that needs hundreds of years to decay.

[0]
[https://www.theatlantic.com/science/archive/2019/10/search-d...](https://www.theatlantic.com/science/archive/2019/10/search-
dark-matter-depends-ancient-shipwrecks/600718/)

~~~
Natsu
It's always confused me how mined lead somehow has more radioactivity.
Shouldn't the lead in the ground also have decayed over time?

Also, it makes me wonder why someone enterprising hasn't stockpiled a few tons
of the stuff somewhere to let it become low background lead for the future.
You'd think that some government or another would be able to drop a million
dollars on putting a lead stockpile somewhere safe for the future.

~~~
toast0
> It's always confused me how mined lead somehow has more radioactivity.
> Shouldn't the lead in the ground also have decayed over time?

Looking into this a bit, it seems that the radiation in refined lead isn't
coming from the lead ore, but from the other materials used in the smelting
process. Old lead would have had time for all those things to decay.

~~~
oh_sigh
I wonder why manufacturers don't just use filtered atmospheric air in the
process to create low-background steel, if it is infact valuable.

~~~
garmaine
How do you suggest filtering by isotope?

~~~
gruturo
As others said, simply separating the CO2 away would mostly get rid of the
problem - all non-stable isotopes of Oxygen have a max half life of 122
seconds, but, for the record, isotopic separation is easy when there is a very
large difference in atomic weight.

In Uranium's case it's difficult because it's 235/238 = 1.28% (actually way
worse - Uranium hexafluoride is used, which adds 114 units, bringing the ratio
down to 0.86%)

In Oxygen's case the ratio would be at least 6.6% (15 vs 16).

Most importantly in Uranium you are interested in the tiny amount of U235,
while in Oxygen you'd be interested in the huge bulk of O16, O17, O18, which
are the stable isotopes. O16 alone is 99.762% of all Oxygen, and you can
afford to lose half in your centrifuge if it spares you a few cycles, it's not
exactly hard to come by.

~~~
awalton
Great. None of these do anything for the real problem: Cobalt-60.

------
Cerium
This comes up on HN every now and then, it is how I learned about low
background steel. If this is new to you, you may also enjoy reading about the
cesium content of wine:
[https://www.technologyreview.com/2018/07/19/141390/fukushima...](https://www.technologyreview.com/2018/07/19/141390/fukushimas-
nuclear-signature-found-in-california-wine/)

~~~
xattt
Is there a particular trigger for this post?

Is this a case of someone stumbling into the concept and wanting to share it
with the world? Is there some trend in SV around low-background steel right
now?

Genuinely curious about the phenomenon of posts around topics that have a
great deal of understanding and aren’t necessarily trending in the general
news cycle.

~~~
confeit
I saw it linked from the comments on a Tweet by Karpathy and found it
intellectually curious.

> By posting GPT generated text we’re polluting the data for its future
> versions

[https://twitter.com/karpathy/status/1284660899198820352](https://twitter.com/karpathy/status/1284660899198820352)

~~~
Gaelan
You seem to have gotten your replies mixed up. This looks like it's for the
GPT "Bitcoin" thread?

~~~
ad404b8a372f2b9
No, low-background steel is mentioned in the replies. It's similar in the
sense that GPT-3 generated text is going to contaminate the data we collect
from now on.

~~~
Gaelan
Ah, yeah, that makes sense. My bad.

------
est31
I'm not sure about some of the the claims of the Wikipedia article.

* First, the article implies that air continues to be the main reason for contamination of steel. It might have been the case, back when atmospheric levels for radioactive elements were higher. However now there is less contamination in the air [0], and the main source for contamination is recycled steel. Either because it itself is non-low-background steel or because e.g. medical radioactive sources were put into the scrap metal supply. See also this IAEA report on scrap metal [1].

* The article also says that the _primary_ source for low background steel are shipwrecks, but I think that's an exaggeration. Especially, the topic came up on hn a few weeks ago and someone in the know debunked it [2].

[0]:
[https://upload.wikimedia.org/wikipedia/commons/e/e2/Radiocar...](https://upload.wikimedia.org/wikipedia/commons/e/e2/Radiocarbon_bomb_spike.svg)

[1]:
[http://web.archive.org/web/20111016193221/http://www.iaea.or...](http://web.archive.org/web/20111016193221/http://www.iaea.org/Publications/Booklets/SealedRadioactiveSources/pdfs/handout_scrap.pdf)

[2]:
[https://news.ycombinator.com/item?id=23666436](https://news.ycombinator.com/item?id=23666436)

~~~
rossdavidh
You should update the Wikipedia article. I mean, you've already got the
references.

------
tshoaib
These isotopes are also used to help spot fake art

[https://physicsworld.com/a/nuclear-fallout-used-to-spot-
fake...](https://physicsworld.com/a/nuclear-fallout-used-to-spot-fake-art/)

------
TwoBit
If I understand it right, it's possible to produce non-radioactive steel but
doing do is just a lot more expensive for the time being than just getting it
from old sources.

------
dang
If curious see also

2016
[https://news.ycombinator.com/item?id=11931747](https://news.ycombinator.com/item?id=11931747)

2013
[https://news.ycombinator.com/item?id=6609114](https://news.ycombinator.com/item?id=6609114)

~~~
anamexis
Related: 2017
[https://news.ycombinator.com/item?id=13973322](https://news.ycombinator.com/item?id=13973322)

------
w0mbat
The scene of the battle of Midway would also hold a hoard of nice steel (the
Japanese lost a lot of ships including aircraft carriers). I understand that
Scapa Flow has been heavily salvaged with only 7 out of 52 ships still down
there.

~~~
nwallin
The Battle of Midway was fought in spectacularly deep water, on the order of
17,000-18,000 feet deep. This would make salvaging difficult, if not
impossible. Scapa Flow is shallow enough for divers.

Once we run out of cheaply salvageable steel, we'll likely turn to steel
smelting processes that do not introduce air into the steel. These processes
require dramatically more energy and are thus more expensive, but will still
be way less expensive than attempting to salvage at deep ocean depths.

~~~
awalton
> Once we run out of cheaply salvageable steel, we'll likely turn to steel
> smelting processes that do not introduce air into the steel.

This would be exceptionally difficult, as oxygen is a basic requirement for
steel making as we have ever known it. Steel is made from iron mixed with
carbon and then heated to melt. Then oxygen is added which burns the excess
carbon into carbon dioxide and reacts with all of the other reactive
contaminants and brings them to the surface where they can be cupped off as
slag. The melt is poured and cooled and you have steel. Early steel processes
used air, blast into the furnace with high powered pumps. Modern steel is made
with purified oxygen from cryogenic processes (and there are even designs
floating around for steel mills which use the turboexpander from the oxygen
processing to help generate electricity to drive the mill).

Without oxygen, you'd have to start with very, very clean iron ore (containing
nothing but iron and whatever you wanted to alloy with the final steel), and
add _exactly_ the right amount of carbon (which is also exceptionally
difficult, since carbon is light and the heat will want to make it sublime
anyway). Odds are such a steel would still contain so much impurity as to
require a second melt in a vacuum arc furnace, which also would dramatically
drive up the cost.

While there might be a future making steel like this in space, I'm not
counting it as very likely in the slightest to happen in this century.

It's much easier to use exceptionally clean oxygen - the mill could use an
oxygen generation process (like a hydrogen peroxide chemical process plant
being added to the mill), or by ultrafiltration of the process oxygen (which
seems more realistic all told).

~~~
burfog
Start with iron pentacarbonyl, which is conveniently a liquid that can be
distilled. That gets rid of nearly all impurities.

------
dsun179
Since tabacco gets its cancer making polonium from the air, I wonder if
smoking got riskier because of the nuklear testing.

~~~
albntomat0
Do you have more information on this? Seems interesting!

~~~
grkvlt
Just search for the paper on the topic, written by the Phillip Morris Unbiased
Research Group. it explains how frogs breathing air got more cancer then frogs
trapped in airtight boxes and only allowed to breathe exhaled tobacco smoke,
who mostly died for other reasons. seems legit...

------
superjan
A few years ago it was in the news that several militairy shipwrecks vanished
in indonesia waters[0], presumably plundered for the steel.

[0] [https://www.bbc.com/news/world-
asia-37997640](https://www.bbc.com/news/world-asia-37997640)

------
whoisjuan
Can it be recycled without contamination of existing radiation in other
elements used to melt it and such?

I mean how do they create the instruments in the first place and keep the
radiation low?

------
crispyporkbites
Im always curious how we will send messages to future civilizations. How will
we ensure we’ll be remembered or even noted in 10,000, 100,000, 1 million
years? How can we prevent the same disaster(s) that eventually wipes our
civilisation out from repeating again in future intelligent generations (human
or otherwise)

Could environmental markers like these be the way? After all, it’s how we look
at the past today

~~~
Razengan
We already know what can last for literally millions of years: Life.

Maybe we could encode some information in birdsong, tree rings, or the matting
patterns drawn by fish in the seafloor. :)

[https://www.youtube.com/watch?v=hpdlQae5wP8](https://www.youtube.com/watch?v=hpdlQae5wP8)

~~~
philipswood
A SF short story about a biologically encoded message from ancient aliens
(written by one of the Autodesk founders): We'll Return, After This Message by
John Walker

[https://www.fourmilab.ch/documents/sftriple/gpic](https://www.fourmilab.ch/documents/sftriple/gpic).

~~~
vmilner
It's fascinating that in 1983 it was thought that a 768-bit RSA number would
take 40 million years to factor. (It actually took 26 - RSA-768 was factored
in 2009.)

------
amacbride
It occurred to me as they were taking down the cantilever (eastern) section of
the Bay Bridge that lots of it would have been low-background, based on its
construction in the 1930s.

------
melvyn2
[https://xkcd.com/2321/](https://xkcd.com/2321/)

~~~
fuball63
That's how I first heard about this concept, which was fairly recently.

------
gnufx
It's been pointed out it's wrong but, as a sometime nuclear spectroscopist,
I'm curious: why are people insisting that β-decay, i.e. ¹⁴C, is the issue?

------
shmerl
Can you make such steel by using clean air? Or it's not possible to purify it
from radionuclides?

------
Havoc
I seem to recall some of those shipwreckers getting nicked too?

------
fnord77
no way to make steel without forced air?

~~~
Taek
Presumably no way that's cheaper than just getting it from shipwrecks. Doesn't
seem like there's a huge demand, so old shipwrecks for the time being have
enough supply.

~~~
xwdv
What about using trapped air in shipwrecks, or glaciers.

------
jeffrallen
War is stupid.

------
batt4good
I need to find the source, but this has actually been a significant issue
sourcing steel and titanium from China.

