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Aaron Kinney writes in the San Jose Mercury News that scientists have captured the first clear images of the USS Independence, a radioactivity-polluted World War II aircraft carrier that rests on the ocean floor 30 miles off the coast of Half Moon Bay. The Independence saw combat at Wake Island and other decisive battles against Japan in 1944 and 1945 and was later blasted with radiation in two South Pacific nuclear tests. Assigned as a target vessel for the Operation Crossroads atomic bomb tests, she was placed within one-half-mile of ground zero and was engulfed in a fireball and heavily damaged during the 1946 nuclear weapons tests at Bikini Atoll. The veteran ship did not sink, however (though her funnels and island were crumpled by the blast), and after taking part in another explosion on 25 July, the highly radioactive hull was later taken to Pearl Harbor and San Francisco for further tests and was finally scuttled off the coast of San Francisco, California, on 29 January 1951. "This ship is an evocative artifact of the dawn of the atomic age, when we began to learn the nature of the genie we'd uncorked from the bottle," says James Delgado. "It speaks to the 'Greatest Generation' -- people's fathers, grandfathers, uncles and brothers who served on these ships, who flew off those decks and what they did to turn the tide in the Pacific war."
Delgado says he doesn't know how many drums of radioactive material are buried within the ship -- perhaps a few hundred. But he is doubtful that they pose any health or environmental risk. The barrels were filled with concrete and sealed in the ship's engine and boiler rooms, which were protected by thick walls of steel. The carrier itself was clearly "hot" when it went down and and it was packed full of fresh fission products and other radiological waste at the time it sank. The Independence was scuttled in what is now the Gulf of the Farallones sanctuary, a haven for wildlife, from white sharks to elephant seals and whales. Despite its history as a dumping ground Richard Charter says the radioactive waste is a relic of a dark age before the environmental movement took hold. "It's just one of those things that humans rather stupidly did in the past that we can't retroactively fix."
(Score: 2) by Magic Oddball on Sunday April 19 2015, @09:44AM
Steel lasts a lot longer time in salt water
Longer in salt water compared to what? Though even without an answer, I can say that it contradicts what (little) I was taught growing up on a tidal slough attached to San Francisco Bay and being fascinated with our poppy-colored bridge growing up. :-)
Here's a bit from the official FAQ [goldengatebridge.org] for the Golden Gate Bridge, which opened in 1937:
Painting the Golden Gate Bridge is an ongoing task [that] protects the Bridge from the high salt content in the air which rusts and corrodes the steel components.
...
In 1965, advancing corrosion sparked a program to [replace] the original lead-based paint...with an inorganic zinc silicate primer and acrylic emulsion topcoat. In the 1980s, this paint system was replaced by a water-borne inorganic zinc primer and an acrylic topcoat. The Bridge will continue to require routine touch up painting on an on-going basis.
...
Currently, a revered and rugged group of of 13 ironworkers and 3 pusher ironworkers along with 28 painters, 5 painter laborers, and a chief bridge painter battle wind, sea air and fog, often suspended high above the Gate, to repair corroding steel. Ironworkers replace corroding steel and rivets with high-strength steel [galvanized ASTM A-325] bolts, make small fabrications for use on the Bridge, and assist painters with their rigging. ... Painters prepare all Bridge surfaces and repaint all corroded areas.
Based on what various websites on the matter say, it looks like a generic corrosion rate for "seawater" upon steel that has a protective coating is approximately 0.4mm/year, though certain bacteria can boost that as high as 10-25mm/year.
(Score: 2) by frojack on Sunday April 19 2015, @06:41PM
Longer than what? Longer in salt water compared to the GP's expectations.
Had you bothered to quote the next 4 additional words, your question would have answered.
Again, I point out that Titanic (as well as many much older wrecks) still lie on the seafloor relatively intact. Rust has not caused much in the way of structural collapse.
Below the water line Titanic used at least 1 inch thick steel plate, thicker in some places. Above the water line it was mostly half inch plate. Above deck super structure was thinner yet. The steel used in constructing the Titanic was probably the best plain carbon ship plate available in the period of 1909 to 1911, but it would not be acceptable at the present time for any construction purposes and particularly not for ship construction.
Independence was a warship, designed to endure heavy damage. It used much better steel than Titanic. She was built on Cleveland Class lite Cruiser hulls, starting in 1941, and as such they were pretty fast durable ships, (31 knots). Its hull and deck were both thicker than Titanic's thickest plate.
It survived not one, but two nuclear blasts. Its still largely intact where it sits.
If it was rusting away at your highest proposed rate the upper decks (51mm thick) would be totally gone by now. At your lowest rate, the superstructure should last 127 years. This assumes there were no zinks on the ship.
No, you are mistaken. I've always had this sig.