Illegal underwater salvage operations to get pre-1945 steel from sunken warships is so cyberpunk it's almost straight out of Neal Stephenson's Cryptonomicon.
Snap! - I thought of this book immediately when I started reading that article. The sheer engineering innovation to salvage those huge quantities of steel is not dissimilar to the ingenuity shown towards the end of the book. Different materials, similar challenges to bring to the surface...
I am personally with the salvagers. They are making good use of an economic resource for themselves and for others. They are also cleaning the ocean of old debris, not getting lost in some misplaced sense of sentimentality. If the home countries of these vessels want them so bad they should simply salvage them themselves. It's stupid that we have laws that protect stuff that sunk over a few decades ago. If you can't clean it up in 10-20 years, someone else should be entitled to it who can.
Most of the ships are final resting places for the crew that went down with them. You don't disturb them for personal economic gain. Just like you don't steal a 100 year old stone from a graveyard.
>The only difference is the amount of time that has passed.
To me, your wording makes it sound like you think that is a minor difference.
I think it's a major difference in the negative direction.
These maritime war graves that are being robbed are of men whose children or grandchildren are alive.
(How many souls were lost aboard the HMS Electra alone, over a hundred ?)
A question I'm not sure I want to know the answer to - what are these thieving scumbags doing with the remains of the sailors who died aboard these ships?
The ocean is quite a different place. Wrecks are often debris fields, and not simple plots of land.
It's not appropriate to wax indignant about remains that may have all but disintegrated into unrecognizable mud. These are not organized places, like the parks on land with paths that people walk.
I agree. I think it would be best to legalize this sort of salvage operation. It's kind of cool that anyone can make this sort of operation pay. More power to them.
One issue that does deserve some attention is what should be done to any human remains in the wrecks. But if the salvage operations themselves were legal, so the recovery operations didn't have to operate on the sly, it should be possible to get them to obey minimal standards of decency.
The governments that owns the vessels should also get a cut.
It should actually be the responsibility of a government/military to salvage. It may have sunk against their will, but they built it and put it in the water knowing that risk.
What's the difference between scrap metal and historically significant sites?
The Neolithic stone circle at Avebury, Wiltshire, had several stones removed by local villages who wanted stone to build cottages. https://en.wikipedia.org/wiki/Avebury
Historical sites are normally somewhat maintained and preserved. They are also quite often seen by tourists who are interested in those sites.
Most sunken ships, they just sit there and nobody wants to take responsibility and maintain them so that no oil and fuel gets into the ocean. Furthermore, there is little to see. Sure there is some historical information on them but we should save those otherwise the ocean destroys them (surely but slowly).
If those sunken ships were properly maintained, I would also call those scrapers thieves because they take something that belongs to someone else and it has value to them. But since most are just sitting there, waiting to slowly decay.
The only things those scrapers should be held responsible for, is when they damage a tank or something like that which pollutes the ocean (and there should be resources on how to do that safely). But then again, those fuel tanks will leak at some point anyway (they won't last forever) and it should be our responsibility (as humans) to make sure that does not happen.
>People taking this metal from sunken ships aren't just cleaning up a mess, they're destroying historical information.
Who cares? If you really cared about that historical information, you'd salvage it and put it on display in a museum. "Historical information" isn't doing anyone any good sitting on the ocean floor.
>And who knows what stuff is on the ships (oil, fuel) that isn't being properly cleaned up, just dumped into the ocean?
Again, who cares? If you cared, you'd clean it up properly yourself, instead of just leaving it there to leak out into the ocean. The USS Arizona is still visibly leaking diesel fuel out into the water, and no one's doing anything about that, so it's hypocritical for you to complain about this.
This whole subject is just fraught with silly, misplaced sentimentality. I do personally agree that oil and fuel should be properly cleaned up, but we don't do that now, so it obviously isn't a valid concern. I do agree that historical information should be preserved, but we don't do that now (by leaving it inaccessible to the general public on the ocean floor in a remote part of the Pacific), so it obviously isn't a valid concern.
I agree completely. Even worse is how some people (in the article) think that there should be regular patrols to prevent "illegal" diving at these sites. So we want to waste resources and fuel just patrolling some remote ocean site to keep people from messing with an old ship sunken decades ago, and also not let any non-salvagers just look at it? It's crazy.
I'm all for museums and saving history, but this isn't it. Museums are great: you take something that could otherwise be lost, and you preserve and protect it and put it on display so that people can see it and learn from it. Keeping people away from a sunken warship doesn't do that at all. And the concern for the feelings of relatives of these long-dead crew is nuts too. How much concern is there for the feelings of the descendants of King Tut with his body on display? With these old ships, there are no bodies in many cases: human remains don't last long in the sea, unless they're locked up in a watertight compartment.
The final paragraph of the article is the only place where they really got it right: if you want to preserve these things, then salvage them yourself and put them in a museum. If you're going to leave something abandoned in the middle of nowhere, you can't get mad when someone comes and takes it.
Long-dead? This was only 75 years ago. My nan could have gone to school with some of the men that were killed on these ships. My nan is alive and well.
These ships are maritime war graves. The remains were of men that weren't vikings or ancient Egyptians. They were our grandparents generation. That's pretty damned recent.
Can you find a concrete, non-emotionally biased reason that they should be left alone? They are dead, hey memories live on not in the ship, but in the people who's lives they impacted.
Is there any concrete non-emotionally biased reason we bother with gravestones? Or do anything ritualistic with our dead? Why we have tombs of the unknown soldier? We are emotional beings.
I mostly agree with you. After 50 years untouched it should be up for grabs for anyone who cares. However as the article explains these old ships are one of the only sources of radioactivity-free steel (newer steel is contaminated by radionuclides due to the atmospheric nuclear explosions that took place from 1945). We should keep better track of it.
In doing so, they also destroyed an artificial reef that was aggregating fish for the local fishing industry. We should at least have a plan to replace that.
I take your point. I grew up in a seaside community that was notorious for questionable activities in the 18th and 19th centuries[1],[2]. There is a blunt harsh practical opportunistic side to seagoing people that might surprise you.
How do we balance the opportunity afforded to the salvagers against the grazing rights of the local fisherfolk? Is there a replacement structure that can be sunk locally like a concrete wall or honeycomb? Is there research on the time scale needed to seed the coral colonies? Should we place all pre-1942 steel in a UN mandated market?
It's a really interesting story, but I don't get the general slant. Doesn't it make more sense for us to recover high quality steeel that's sitting there unused instead of carving up yet another mountain and burning tons of coal to make it from scratch?
Wouldn't the sailors have a grave elsewhere? I don't think place of death (or last known location since many would abandon ship prior to death) qualifies as a grave.
The first thought that came to my mind was that the scavengers are cleaning up a small part of the pollution in the oceans.
I'm certainly no expert on maritime disasters but I would think that if a ship goes down, particularly as a result of war, there may be significant numbers of the crew trapped inside.
As to cleaning up the oceans, I'd love it if someone could do some back of the napkin type calculations on how much pollution is caused by these sunken warships as opposed to commercial shipping or industrial runoff. I would assume this is negligible in the grand scheme of things.
So when westerners dig up mummies in Egypt, cart them to the Louvre and sell tickets for the privilege of visitation, that's historical research but when folks in poorer countries dig up metal from abandoned ships to sell, it's grave-robbing.
Do many of those mummies have living children? There are people alive today who survived the sinking of those ships.
Most Egyptian mummies come from a culture that was staggeringly remote and ancient - to Cleopatra, to later Byzantine culture, and certainly to Egypt after the Arab conquest... which was 1400 years ago!
Bronze age remains from Europe are not treated differently, you know. Those are also in museums around the world.
The passing of millennia blunt the emotional aspects.
Also, to assuage your cultural guilt, Egyptians, who feel no linkage to ancient people, are now digging up artifacts to hock to various wealthy collectors in the Middle East and Europe.
Cultural sensitivity has increased, especially in the last 30 years or so. In the example of Egyptian mummies, they would be covered under the 1983 law of Protection of Antiquities.
There's an ongoing controversy around the Elgin Marbles, which were removed to London between 1801 and 1805, and many people believe they should be returned.
I think there's an increasing recognition that the historic behaviour of archaeologists removing artifacts for display wasn't necessarily acceptable, but addressing past wrongs is much harder than preventing new ones.
It has not increased to any degree near adequate.
But remove antiquities foreign antiquities from European museums and see how barren the halls and storage become...
So I guess 'sensitivity' isn't going to increase any more than present levels.
So when westerners dig up mummies in Egypt, cart them to the Louvre and sell tickets for the privilege of visitation, that's historical research
No, that's grave robbing. When Westerners did that in the past, it was grave robbing. If they do it now, it's also grave robbing. I suspect a lot of Westerners agree.
I think it's generally well-understood that when your remains rest in the ocean, you become fish food. The vast expanse of water itself is your tomb, not some little square on the floor.
Argue over the vehicle wreckage, but don't misplace your sentimentality.
The bodies aboard these ships are there because people were often trapped in compartments and couldn't get out. It isn't a wreckage with bodies littering the floor around it. The bodies are literally inside the wreckage.
Your understanding is more-or-less irrelevant: war graves are legally protected by many nations, and you may not interfere with those nation's war graves them unless you have dispensation to do so.
The article also discusses the fact that sunken vessels are home to a lot of marine life - local fisheries get their catch there, as the wildlife thrives in those locations.
Thus salvaging the steel robs local folk of their income.
If you abandon a car it soon becomes home to wildlife but that doesn't make it 'nature enough' to be worthy of a David Attenborough documentary.
I think that another way of looking at this story is some 'god' miraculously tidying up the litter that humans have carelessly left at the bottom of the ocean for one reason or another. In this magic universe the mystery tidy-up persons should be thanked for doing such a thorough job, leaving not so much as a bolt behind.
It is all so much easier if the human remains part is conveniently ignored.
The entire reason I know sunken ships often wind up as artificial reefs is because of a documentary. So yeah, it really is David Attenborough level of nature. We just frame it differently with this because it involves humans.
Could it be that none of the current steel manufacturers want you pushing their prices down by doing the sensible thing of salvaging easily reused sources ? ;)
"there’s plenty of reason for scavengers to risk it: A single brass steering station can go for $5,000 or more on the internet. The thousands of pounds of bronze used to make a warship’s propeller can earn about $500,000 in the scrap market. Factor in the fact that a single ship might have two or more propellers, and you’re talking about a significant amount of cash."
I don't buy this either. It's $2/kg right now. a propeller for a destroyer might weigh what, 5 tons? at most... so that's 5000 * $2 = $10k - I have no idea where the author is getting $500k from.
I find it fascinating that there is enough human introduced radioactivity in our atmosphere that it's measurable in steel and even problematic for the creation of some medical devices et al.
I was wondering the same thing. If ambient levels of radiation have been raised so much since the dawn of nuclear testing, could that be partially to blame for the corresponding rise in cancer about that time?
The overall picture seems to be that thousands of people will get cancer as a result of fallout from nuclear testing, but millions of people get cancer for other reasons, so it's not a major effect.
There's only one long term solution to this problem if the countries involved want to assure that the remaining sunken ships aren't looted: salvage the ships themselves and put the wrecks in storage or museums.
I don't understand the arguments people are making that this is somehow grave robbing. Grave robbing you open up a grave and steal the personal artifacts and possibly the bones of the person interred there. Archaeologists have done a lot of this over the years and that activity is definitely grave robbing. It's a bit more restricted now in the US due to the NAGRA that restricts messing with human remains in some contexts.
In this case though the salvagers are not taking the bones out, nor the personal effects. They are taking huge amounts of steel, brass and copper, none of which were personal artifacts or property of a single one of the persons who died at the site.
To call this grave robbing, then removing a wrecked bus or truck from an accident site on the side of the freeway would have to be considered grave robbing as well. If the person removing the bus also took the body, wedding rings and gold teeth of the victims, that would be a crime. But the person removing the bus isn't doing that.
With a bus/truck they remove the bodies (usually). These ships went down with people in them and are graves. There is a difference.
It would be like you being buried in a coffin in a stone church and then one day someone decides they want the stones and they take the whole church ... including you :) As a relative i would be pretty pissed about that too.
If they were correctly identifying bodies and returning them to their families for proper burial etc... then it might be ok to reuse the steel.
Note that this is only about warships... not ships generally. Plenty of sailors went down, in war, on non-warships. Those are not afforded the same ethics and were long ago violently cut up for salvage. This boils down to odd laws, specifically that warships remain property of thier governments forever. Non-warships are free for the taking once "abandoned" by owners (oversimplification for space). Dead people are dead people. Why we get upset about the wargrave of someone in uniform, but dont think twice about the wargrave of someone not, eludes me.
Why we get upset about the wargrave of someone in uniform, but dont think twice about the wargrave of someone not, eludes me.
Because that's what the country is willing to pay you for willing to die for the country, i.e. being a soldier. The military has to uphold a much higher standard for honoring the dead, or it will face problems finding new recruits.
The fact that there was a 4000 ton warship on the sea bed, which then vanished leaving only the indentation, suggests that somebody is capable of it. I've had a look round for species that might be responsible, and so far humans do seem to be the most likely candidate.
I don't understand the author's confusion as to how a ship wreck could quietly be lifted without a trace, we were doing it in the Cold War. Granted back in 1974 [0] such a project was very expensive but GPS and ship stability has gotten cheaper/better and these war ships are not nearly as deep. The oil and gas industry uses GPS stabilized vessels during exploration and production. This shouldn't be that hard for a determined scavenger.
Incidentally, GPS stabilization is also used for SpaceX's ocean landing platforms. The barge is able to keep itself within a few meters of its target position. The rocket doesn't track the barge at all. It's just programmed to fly to the prearranged position where the barge will be.
Is this really stealing? I thought abandoned / destroyed ships in international waters were essentially fair game for salvage. What laws would even apply there?
If there are bodies inside, it is considered a war grave. What do the salvagers do with the human remains? I imagine they don't try to contact relatives or respectfully take care of them.
I thought abandoned / destroyed ships in international waters were essentially fair game for salvage. What laws would even apply there?
From the article: "Sunken warships remain the property of their country of origin regardless of where they are found. Laws regarding their stewardship vary a little from nation to nation, but in general, the ships—and everything on or in them—belong to that country’s navy."
So WWII steel is particularly good for making nuclear devices, and it would require nation state resources to steal an entire sunken ship without anyone noticing. Which nation state can we think of who would want to do that?
I don't buy that claim. The amount of nuclear contamination in steel is really small. It matters when you're building sensitive instruments, but I don't think nuclear weapons care very much. After all, they contain at least several pounds of radioactive material by necessity. A tiny amount of extra background radiation from the steel casing won't affect things.
Adding to my doubt is the article's mention of "pre-1942 vessels." Why would that be the date? The first nuclear weapon was detonated in summer 1945, and I'd wager that contamination remained sufficiently low until sometime in the 50s. According to this page, there were only 7 nuclear test explosions in the 40s, for a total of 9 nuclear explosions all together:
Back at the time, there was not very much requirement for nuclear safety/contamination prevention... so if you want steel definitely free from non-natural radiation you'll need 1942 or earlier steel.
That seems likely, although I strongly doubt the requirements are that stringent. The issue with bombs isn't just that they release (and create!) a lot of radioactive material, but that they pulverize that material and push it high into the atmosphere where a lot of it spreads around the world. Whatever radioactive material might have escaped from something like Chicago Pile 1 would have stayed local.
What actually prevents someone from constructing a metal stealing under water drone?
Ones fish farm is another ones scrap for the taking.
Do not enter the ocean, they are infected with Peer-2-Peeranhas
Not really. Even just putting a buoy in place has issues. It would turn a subsurface wreck into a new surface obstacle/hazard. Then you get into the tricky matter of detection and response. Sending out a tiny ship every time the buoy lost contact wouldn't be safe. You'd have to assume pirates each and every time. Local law enforcement/navies aren't going to be happy responding to possible pirates tampering with a buoy only to find none.
The USS Houston, for example, is property of the US Navy. They can task their satellites to image this and other sites regualarly. No need for a bouy. When a ship is there, they can get local or their own asserts to overfly or intercept. It's no big technical problem.
I'm thinking just about detection at this point. Knowing specifically what's going on and who is doing it would be an important first step towards any subsequent policing or political action.
Well, it most probably could be the work of some government in an attempt to steal the military tech that could be salvaged. The design of warships and submarines is invaluable. The only military with such resources to haul cargo in excess of 6440 tons in those waters is the Chinese army. Especially considering the secretiveness of the operation which would involve perhaps hundreds of individuals divers and crew both is no easy feat. This is not the work of an organized crime syndicate or burglars, nor do they have the resources to carry out an operation of this scale without getting noticed.
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[ 3.2 ms ] story [ 172 ms ] threadThe only difference is the amount of time that has passed.
To me, your wording makes it sound like you think that is a minor difference.
I think it's a major difference in the negative direction.
These maritime war graves that are being robbed are of men whose children or grandchildren are alive.
(How many souls were lost aboard the HMS Electra alone, over a hundred ?)
A question I'm not sure I want to know the answer to - what are these thieving scumbags doing with the remains of the sailors who died aboard these ships?
It's not appropriate to wax indignant about remains that may have all but disintegrated into unrecognizable mud. These are not organized places, like the parks on land with paths that people walk.
Consider the wreckage of the Titanic:
https://en.wikipedia.org/wiki/Wreck_of_the_RMS_Titanic
No one can simply swin to the bottom of the ocean to pay their respects.
One issue that does deserve some attention is what should be done to any human remains in the wrecks. But if the salvage operations themselves were legal, so the recovery operations didn't have to operate on the sly, it should be possible to get them to obey minimal standards of decency.
The governments that owns the vessels should also get a cut.
The Neolithic stone circle at Avebury, Wiltshire, had several stones removed by local villages who wanted stone to build cottages. https://en.wikipedia.org/wiki/Avebury
In the centre of this screen, just south of Tunnel House In, you can see a square outline in a field. https://www.google.co.uk/maps/place/Coates,+Cirencester/@51....
That's a Roman camp. It's been ploughed over (it's just a field) and unscrupulous metal detectorists have plundered the site: http://www.bgas.org.uk/tbgas_bg/v119/bg119083.pdf
People taking this metal from sunken ships aren't just cleaning up a mess, they're destroying historical information.
And who knows what stuff is on the ships (oil, fuel) that isn't being properly cleaned up, just dumped into the ocean?
Most sunken ships, they just sit there and nobody wants to take responsibility and maintain them so that no oil and fuel gets into the ocean. Furthermore, there is little to see. Sure there is some historical information on them but we should save those otherwise the ocean destroys them (surely but slowly).
If those sunken ships were properly maintained, I would also call those scrapers thieves because they take something that belongs to someone else and it has value to them. But since most are just sitting there, waiting to slowly decay.
The only things those scrapers should be held responsible for, is when they damage a tank or something like that which pollutes the ocean (and there should be resources on how to do that safely). But then again, those fuel tanks will leak at some point anyway (they won't last forever) and it should be our responsibility (as humans) to make sure that does not happen.
Who cares? If you really cared about that historical information, you'd salvage it and put it on display in a museum. "Historical information" isn't doing anyone any good sitting on the ocean floor.
>And who knows what stuff is on the ships (oil, fuel) that isn't being properly cleaned up, just dumped into the ocean?
Again, who cares? If you cared, you'd clean it up properly yourself, instead of just leaving it there to leak out into the ocean. The USS Arizona is still visibly leaking diesel fuel out into the water, and no one's doing anything about that, so it's hypocritical for you to complain about this.
This whole subject is just fraught with silly, misplaced sentimentality. I do personally agree that oil and fuel should be properly cleaned up, but we don't do that now, so it obviously isn't a valid concern. I do agree that historical information should be preserved, but we don't do that now (by leaving it inaccessible to the general public on the ocean floor in a remote part of the Pacific), so it obviously isn't a valid concern.
I'm all for museums and saving history, but this isn't it. Museums are great: you take something that could otherwise be lost, and you preserve and protect it and put it on display so that people can see it and learn from it. Keeping people away from a sunken warship doesn't do that at all. And the concern for the feelings of relatives of these long-dead crew is nuts too. How much concern is there for the feelings of the descendants of King Tut with his body on display? With these old ships, there are no bodies in many cases: human remains don't last long in the sea, unless they're locked up in a watertight compartment.
The final paragraph of the article is the only place where they really got it right: if you want to preserve these things, then salvage them yourself and put them in a museum. If you're going to leave something abandoned in the middle of nowhere, you can't get mad when someone comes and takes it.
These ships are maritime war graves. The remains were of men that weren't vikings or ancient Egyptians. They were our grandparents generation. That's pretty damned recent.
It's unsettling that a local population can not sink some steel to create a rich fishery anymore.
How do we balance the opportunity afforded to the salvagers against the grazing rights of the local fisherfolk? Is there a replacement structure that can be sunk locally like a concrete wall or honeycomb? Is there research on the time scale needed to seed the coral colonies? Should we place all pre-1942 steel in a UN mandated market?
[1] http://www.historyofwallasey.co.uk/wallasey/story_of_the_day...
[2] https://www.tutorhunt.com/resource/7035/
The first thought that came to my mind was that the scavengers are cleaning up a small part of the pollution in the oceans.
As to cleaning up the oceans, I'd love it if someone could do some back of the napkin type calculations on how much pollution is caused by these sunken warships as opposed to commercial shipping or industrial runoff. I would assume this is negligible in the grand scheme of things.
Our ability for self-deception is breath taking.
Most Egyptian mummies come from a culture that was staggeringly remote and ancient - to Cleopatra, to later Byzantine culture, and certainly to Egypt after the Arab conquest... which was 1400 years ago!
Bronze age remains from Europe are not treated differently, you know. Those are also in museums around the world.
Also, to assuage your cultural guilt, Egyptians, who feel no linkage to ancient people, are now digging up artifacts to hock to various wealthy collectors in the Middle East and Europe.
There's an ongoing controversy around the Elgin Marbles, which were removed to London between 1801 and 1805, and many people believe they should be returned.
I think there's an increasing recognition that the historic behaviour of archaeologists removing artifacts for display wasn't necessarily acceptable, but addressing past wrongs is much harder than preventing new ones.
It has not increased to any degree near adequate. But remove antiquities foreign antiquities from European museums and see how barren the halls and storage become... So I guess 'sensitivity' isn't going to increase any more than present levels.
https://en.wikipedia.org/wiki/Koh-i-Noor
No, that's grave robbing. When Westerners did that in the past, it was grave robbing. If they do it now, it's also grave robbing. I suspect a lot of Westerners agree.
I think it's generally well-understood that when your remains rest in the ocean, you become fish food. The vast expanse of water itself is your tomb, not some little square on the floor.
Argue over the vehicle wreckage, but don't misplace your sentimentality.
I am writing this right now in literally the exact spot where thousands died during the Battle of Brooklyn in the Revolutionary War.
We subsequently moved on, they built Brooklyn Heights and DUMBO and a rather notable bridge here. It happens.
Both the US and UK seem to protect sunken military vessels for this reason.
I think that another way of looking at this story is some 'god' miraculously tidying up the litter that humans have carelessly left at the bottom of the ocean for one reason or another. In this magic universe the mystery tidy-up persons should be thanked for doing such a thorough job, leaving not so much as a bolt behind.
It is all so much easier if the human remains part is conveniently ignored.
[0] http://physicsworld.com/cws/article/news/2008/jul/04/nuclear...
http://www.americanscientist.org/issues/pub/fallout-from-nuc...
The overall picture seems to be that thousands of people will get cancer as a result of fallout from nuclear testing, but millions of people get cancer for other reasons, so it's not a major effect.
That's very generous of the Danish government!
In this case though the salvagers are not taking the bones out, nor the personal effects. They are taking huge amounts of steel, brass and copper, none of which were personal artifacts or property of a single one of the persons who died at the site.
To call this grave robbing, then removing a wrecked bus or truck from an accident site on the side of the freeway would have to be considered grave robbing as well. If the person removing the bus also took the body, wedding rings and gold teeth of the victims, that would be a crime. But the person removing the bus isn't doing that.
It would be like you being buried in a coffin in a stone church and then one day someone decides they want the stones and they take the whole church ... including you :) As a relative i would be pretty pissed about that too.
If they were correctly identifying bodies and returning them to their families for proper burial etc... then it might be ok to reuse the steel.
Because that's what the country is willing to pay you for willing to die for the country, i.e. being a soldier. The military has to uphold a much higher standard for honoring the dead, or it will face problems finding new recruits.
0: https://en.m.wikipedia.org/wiki/Project_Azorian
From the article: "Sunken warships remain the property of their country of origin regardless of where they are found. Laws regarding their stewardship vary a little from nation to nation, but in general, the ships—and everything on or in them—belong to that country’s navy."
Adding to my doubt is the article's mention of "pre-1942 vessels." Why would that be the date? The first nuclear weapon was detonated in summer 1945, and I'd wager that contamination remained sufficiently low until sometime in the 50s. According to this page, there were only 7 nuclear test explosions in the 40s, for a total of 9 nuclear explosions all together:
https://www.armscontrol.org/factsheets/nucleartesttally
But even if a single bomb is too much, the date should be 1945.
Back at the time, there was not very much requirement for nuclear safety/contamination prevention... so if you want steel definitely free from non-natural radiation you'll need 1942 or earlier steel.
Supporting this idea, here's another article on salvaging Japanese wrecks which mentions low-background steel in the context of ships built in 1943 and 1944: https://www.theguardian.com/world/2017/feb/09/images-reveal-...
The Earth facing an environmental crisis...
Has anyone checked on the IJN Yamato lately?
[1] https://en.wikipedia.org/wiki/Kursk_submarine_disaster#Salva...
[2] https://en.wikipedia.org/wiki/Project_Azorian
[3] http://ardrubber.en.made-in-china.com/productimage/gSZmDMRbY...
and http://blueoceantackle.com/marine-supply-equipment/ship-salv...