The route of action at the crossroads.

1946 65438+1On October 24th, Brandy publicly chose Bikini Atoll as the nuclear test site, and it is expected that three nuclear tests will be conducted. The first nuclear test code can, nuclear bombs explode in the air; The second nuclear test, code-named Baker, was detonated underwater; The third nuclear test, code-named Charlie, detonated in deep water. The main consideration for choosing bikini is that it is far away from residential areas, with few aborigines, vast lagoons, few storms, stable wind direction and current, and controlled by the United States. On February 6, the navy sent a ship to bomb the bikini atoll waterway, but concealed its intention from the aborigines. 10 In February, the Governor of Marshall Islands of the United States arrived in Bikini Island, using the Bible Exodus as a metaphor, saying that the United States would lead the residents of Bikini Island to the "promised land" and successfully induced all 167 residents on the island to agree to move.

In the choice of nuclear bomb, both nuclear tests used the plutonium element of Fat Man's atomic bomb. The nuclear bomb used by Able is code-named "Gilda". Baker's nuclear bomb is Helen in bikini. The plutonium core of Gilda's nuclear bomb accidentally exceeded the critical point twice in Los Alamos, resulting in the deaths of two scientists, Harry K. Daghlian Jr. and louis slotin, which earned them the nickname "Devil's Nuclear".

In terms of target ships, the navy has selected 95 warships of various types, including 2 aircraft carriers, 5 battleships, 4 cruisers, 12 destroyers, 8 submarines, 60 landing vehicles and transport ships, and 3 barges. In order to measure how the destructive power of nuclear explosion decreases with distance, the navy arranges warships intensively without reconstructing the actual anchorage. All warships are equipped with measuring instruments to monitor air pressure, ship movement and radiation. In the whole nuclear test, the United States used a total of 200 pigs, 60 guinea pigs, 204 goats, 5,000 mice, 200 mice, and grains containing different kinds of insects to test the genetic variation of organisms under high radiation.

As for the observation troops, the navy has dispatched 150 support ships to provide accommodation, experimental stations or workshops for 42,000 people, of whom more than 37,000 belong to the navy, plus 37 female nurses. The flagship of the observation fleet is located on the aircraft carrier Shangri-La, and other personnel are scattered in different ships and locations, including Eniwetok Atoll and Kwajalein Atoll. Navy personnel can also apply for a one-year extension of service and stay on the atoll to watch the nuclear explosion.

In aerial photography, the US military modified eight B- 17 bombers, including automatic cameras, radiation detectors and air sample collectors. These bombers can fly remotely by ground radio, flying into the high radiation environment that the human body can't bear, and even the top of the mushroom cloud produced by nuclear explosion. The photographic equipment on the ground is also remotely operated by the tower outside the atoll. Generally speaking, the lens in the atoll can shoot more than 50,000 still pictures and 65,438+0,500,000 feet of animated films. One of the cameras can take 1 second with 1 000 images. Before the nuclear test, all personnel were evacuated from the atoll, and the fleet was observed on the sea surface at a distance of 18.5km. Even so, people who directly observed the nuclear test at first still had to wear sunglasses to protect their eyes from the strong light of the nuclear explosion, but before the Able nuclear test, the relevant regulations were cancelled. The military pointed out that sunglasses have almost no protective effect, and everyone is required to turn their backs to the nuclear explosion area, close their eyes and cover their faces with their hands to ensure safety. However, some observers did not follow the instructions, and most of the observation reports on board were "disappointing": the crew often felt only a slight vibration and heard a weak explosion.

1 946 At 9: 00 am on July1July, a B-29 bomber dropped a 23,000-equivalent Gilda nuclear bomb over the target ship. The nuclear bomb was originally scheduled to explode 520 feet (65,438+060 meters) above the battleship Nevada, but unexpectedly missed the target at 765,438+00 yards (650 meters) and finally detonated over the USS Gilliam (APA-57). The explosion immediately sank the American warships Csorian and Carlisle (APA-69); Two American destroyers, Anderson and Linsen, sank within an hour, while the light cruiser Jiugou sank the next day. Some media were deeply disappointed because the losses caused by the nuclear explosion were far less than expected. On the 2nd, Forrest said that heavy warships would only suffer great damage if they were tested at close range underwater, but slightly mentioned that the nuclear bomb deviated from the target. Able nuclear explosion array sunken ship (from the sea level of the explosion center) Serial number Name and distance of the ship: Type 5 Gilian transport ship 50 yards (46 meters) 9 light cruisers 420 yards (380 meters) 4 Carlyle transport ship 430 yards (390 meters) 1 destroyer Anderson 600 yards (550 meters). The destroyer 6 Linsen was badly damaged at 760 yards (690 meters). The number of ships is 40. The distance between ships is 40. Aircraft carrier Scott, SS-305 submarine 400 yards (370 meters) 12 YO- 160 oil barge 520 yards (480 meters) 28 Independent light aircraft carrier 560 yards (5 10 meters) 22 Crittenden aircraft carrier, APA-. 5 yards (562 meters) 3 Battleship Arkansas 620 yards floating dry dock 825 yards (754 meters) 23 Dawson USS, APA-79 transport ship 855 yards (782 meters) 38 Salt Lake City Cruiser 895 yards (8 18 meters) 27 Hughes destroyer 920 yards (840 meters). 49 LST-52 landing tank 1, 530 yards (1 For example, destroyer Tomlinson, No.6 in the array diagram, sank within an hour because its starboard side was facing the explosion center, causing the hull to bear shock waves laterally, thus increasing the damaged area. On the contrary, the ship in the southeast of the explosion center faces the explosion center with the stern and the nuclear explosion shock wave longitudinally, and the damaged area is small; Coupled with the dense array of warships and the scattered shock wave force, the warships in this area are relatively slightly damaged and will not sink even if they are hit hard.

The battleship Changmen is the only large ship within the explosion center 1 0,000 yards (9 10 meters), but it has not been seriously damaged. Because Nagato participated in the attack on Pearl Harbor, the US military specially arranged Nagato near the Nevada (No.32), and it was scheduled to explode, with the ship's side facing the Nevada. However, due to the airdrop error, the shock wave borne by the long gate is greatly reduced; In addition, the hull of the Changmen is relatively strong, but the US military overestimated the damage of the Changmen in wartime air strikes, which made the calculation of nuclear test damage variable, so that the expected heavy damage did not appear. Nagato will eventually sink in the second nuclear test.

In contrast, although Saratoga was more than 2,000 yards (1 1,800 meters) away from the explosion center, it was severely damaged. The heavy damage of Saratoga was not caused by shock wave, but by the fire and explosion of hull fuel and armed forces caused by nuclear explosion. Before the nuclear test, the U.S. military filled all warships with fuel and ammunition needed in reality, even carrier-based aircraft distributed in version A and hangar, while the aircraft carrier was loaded with a large amount of flammable flight fuel, which was distributed throughout the hull, making the fire extremely fierce. What's more, battleships such as Nagato have heavy armor, while the hull of the aircraft carrier is extremely fragile. Finally, the fire in Saratoga was put out by the navy participating in the underwater nuclear test code-named Baker.

According to the experience of Hiroshima's original explosion, if the force exerted by the shock wave generated by the nuclear explosion exceeds 5 pounds per square inch (that is, 5psi, pound force per square inch), the substances in this range will spontaneously ignite. The spontaneous combustion area caused by Able nuclear test is about 3.2 kilometers in diameter, including Saratoga and most peripheral warships. However, because seawater does not burn, most warships can withstand explosions and fires except aircraft carriers, so there is no spontaneous combustion of the original explosion on land.

In order to reduce radioactive dust, the Able nuclear bomb is detonated in the same way as the nuclear bombs in Hiroshima and Nagasaki, and its detonation height is set at 520 feet (160m). When detonated in the air, less ground materials will be sucked into the fireball of the nuclear explosion, and most of the radioactive materials will be brought into the stratosphere, so the radioactive dust produced by the nuclear test site is quite limited. Because the radioactive dust of nuclear test will eventually be diluted into the global environment instead of staying in local areas, it is called "self-cleaning" nuclear test method by the military. In fact, none of the target ships on the atoll are radioactive because of the less radioactive dust. The day after the nuclear test, naval personnel were able to board most target ships and collect nuclear test data.

However, at the moment of nuclear explosion, the ships near the explosion center are still irradiated by a large number of neutrons and intense gamma radiation; Experiments and outer materials on board may also be activated by neutrons with deadly radiation. These radiation combined with the shock wave of nuclear explosion killed a large number of creatures. The US military placed 57 guinea pigs, 109 mice, 146 pigs, 176 goats and 3030 mice in the activity spaces of 22 target ships to simulate the officers and men of warships. Results 10% of the creatures were immediately killed by the shock wave. In addition, 15% creatures were injured by fireballs with radiation and died within a few days; Finally, in the follow-up study, 10% of organisms died of radiation. Because the nuclear explosion only produces one-off radiation, and a large number of mice are deliberately placed outside the lethal range to study whether radiation will cause variation in animal offspring, the overall survival rate is raised.

Some creatures survived unexpectedly after the nuclear explosion, the most famous of which was a pig numbered 3 1 1, which was placed on nine buildings before the nuclear test. After the nuclear test, it was found swimming in the atoll and was rescued by the US military. The pig was finally sent to the National Zoo in Washington with another surviving goat. However, if animals are treated as adults, nuclear explosions will still cause a large number of warship officers and soldiers to die. Although the Nevada was protected by heavy armor, the goats inside and outside the ship died four days and two days after the nuclear test. According to the calculation, the Nevada, which was unexpectedly far away from the explosion center, will still have casualties. Baker's underwater nuclear test used 2 1000 equivalent nuclear bomb (23,000 equivalent). The nuclear bomb was placed 90 feet (27 meters) below the landing ship (LSM-60) (seabed depth 180 feet (55 meters)), right in the center of the target ship array. At 8: 35 am on July 25, the nuclear bomb detonated. After the nuclear explosion, the LSM-60 landing ship did not leave any identifiable wreckage and was judged to have been gasified by nuclear explosion; Eight other warships sank after the nuclear explosion, including the battleships Arkansas and Changmen; Saratoga aircraft carrier; Submarine? First, bonito and octopus; And YO- 160 barge. The heavy cruiser "Prince Eugen" was seriously damaged after the nuclear explosion and sank during towing in June+February, 5438. The destructive power of this nuclear test mainly comes from the water pressure shock wave, and its radioactive dust pollutes almost all the target ships, making them radioactive.

Baker nuclear explosion array sunken ship (from the explosion center sea level, in yards) Name, ship type, 50 LSM-60 landing ship, 0 yards (0 meters), 3 battleship Arkansas, 170 yards (160 meters), 8 boats? Submarine 363 yards (332 meters) 10 Saratoga 450 yards (4 10 meters) 12 YO- 160 oil barge 520 yards (480 meters) 7 Long Gate Battleship 770 yards (700 meters) 4/. 730m) 2 submarine Tianzhu 850m (780m)113 floating dry dock1.150m) 36 heavy cruiser prinz eugen 6550. After the nuclear explosion, the Arkansas turned to sink almost instantly, but according to the shots taken during the nuclear explosion, a huge shadow appeared on the water wall above the Arkansas, so it is likely that the Arkansas was sucked up by the water wall after the explosion, and then the bow might hit the bottom of the sea, and finally the bow fell backwards, causing the hull to sink into the lagoon. However, some observers hold the opposite opinion: Brandi at the scene thinks that the shadow is just smoke; In the later period, some writers refer to the cracks in the water wall. In any case, when the navy sent divers to the wreck of the Arkansas, it was found that the Arkansas was capsized at the bottom of the sea, and the stern was facing the explosion center, which was in line with the theory of first sucking and then capsizing; The main gun and superstructure of the hull are invisible and covered with a layer of radioactive sludge. Divers from the National Park Service revisited their old places at 1989 and 1990 respectively. The sea sand still covers the hull, but the silt has disappeared. Divers also saw the front 12 inch main gun of the battleship. Before 1990 returned to Arkansas again, the diver went to the museum ship Texas for a preview to understand the environment of the air defense turret on the Arkansas side and facilitate its return to the scene.

As for the aircraft carrier, the huge chimney of Saratoga collapsed on the flight deck after the nuclear explosion; However, the bow and the bow were pulled by different currents, which caused the center of the ship to break and greatly flooded. Brandy ordered a tugboat to rescue, but it was abandoned because of radiation problems. Saratoga finally sank eight hours after the nuclear test. With the radiation level decreasing year by year, Saratoga has become one of its diving hotspots. As for Independence, which was hit hard as early as Able nuclear test, it was not hit hard because of its long distance, but it was seriously polluted by radiation. Due to years of fruitless radiation cleaning, Independence finally sank in the Faralon Islands in 195 1.

The German heavy cruiser "Prince Eugen" successfully escaped two nuclear explosions, but the serious nuclear pollution prevented sailors from boarding to repair the water surface. In September of the same year, the prinz eugen was towed to Kwajalein Atoll and capsized in shallow water on the way on February 22nd, 65438. Today, its starboard propeller can still be seen on the water; The port propeller was salvaged in 1978, and now it is hidden in the Leiber Naval Memorial Hall in Kiel, Germany.

The submarine bonito is the only sunken ship, which can be successfully salvaged and surfaced afterwards. Later, the ship was towed to the sea near California and sank as a target ship two years later. As for the three seriously damaged warships: the navy transport ship Fallon (APA-8 1 25), Hughes (DD-4127) and Dentuda (USS Dentuda, SS-335, 24), all nearly sank after the nuclear test, while the navy Because all three ships are outside the explosion center of 1000 yards (9 10 meters), the damage is relatively small; Long sharks are underwater, less polluted by radiation, and finally re-serve for a short time.

You are the first underwater nuclear test in human history, and the process of Baker's nuclear test has been widely concerned. At the moment when the nuclear bomb detonated, a fireball expanded at high speed appeared at the explosion point, and a supersonic hydraulic shock wave was generated underwater, tearing the keel of a nearby ship; Underwater shock waves are also clearly recorded by aerial cameras: when underwater shock waves spread outward, the color of seawater darkens, just like oil pollution at sea; The sea level turned white immediately after the shock wave. Because the sound transmission speed of water is five times faster than that of air, when the shock wave propagates underwater at high speed, the rear sea surface is quickly dyed white, just like a thin white surface extending outward at high speed at sea.

After the nuclear explosion 1 millisecond, the bubbles produced by the fireball reached the seabed and sea level at the same time. Bubbles burst a hole with a diameter of 30 feet (9. 1 m) by 2,000 feet (6 10/m) on the seabed, atomizing seawater and spraying it into the air in a dome shape. One second after the nuclear explosion, the bubble sprayed 2 million tons of seawater and sea sand with a diameter of 500 feet (1 1,800 meters) into the air, forming bubbles with a height of 6,000 feet (1 1,800 meters) and a width of 2,000 feet (665,438). Finally, when the bubble rises into the air, it triggers an air shock wave. As the air pressure behind the shock wave suddenly drops, the water vapor immediately condenses into clouds. This kind of condensation cloud (also known as "Wilson Cloud", named after Wilson Cloud Room) rises rapidly from the sea surface, covering the whole water wall, and spreads outward in a disc shape, and finally disappears after the air pressure rises gradually.

With the disappearance of condensation clouds, the top of the water wall began to turn into cauliflower-like, and all the sea water, sea sand and water mist exhausted their strength and were about to fall back to the sea surface under the action of gravity. The nuclear explosion did not produce mushroom clouds. At the same time, the bubbles absorbed a lot of seawater and formed a vacuum under water. When the seawater on both sides pours into the filling space, it will push the seawater outside, thus triggering tsunami-like waves. After the nuclear explosion 1 1 s, the first wave has surged at a distance of 1 1,000 feet (300 meters) from the explosion center, with a wave height of 94 feet (29 meters). When the waves rushed to the beach 3.5 miles (5,600 meters) away, they were still 15 feet (4.6 meters) high, and they repeatedly hit 9 times. Several landing tanks on the beach were washed ashore and covered with a thick layer of sand.

12 seconds after the nuclear explosion, the water wall began to fall under the action of gravity, forming a giant waterfall as high as 900 feet (270 meters). The waterfall fell from the sky, which aroused the once high radiation tide and flooded most of the target ships on the sea. This eventually caused the target ship to suffer from extremely serious radiation pollution.

Baker's nuclear test has a lot of experimental data, many of which are unheard of by the military and the scientific community. Two months after the nuclear test, the military will even hold another meeting to standardize the terminology of research projects and redefine the description and calculation of each report.

The main analysis data after the nuclear test is radioactive materials. Baker is the first nuclear explosion in the world that produced a large amount of radioactive dust and fission products at the explosion point. The previous explosions in New Mexico, Hiroshima and Nagasaki were all at high altitudes, so there were relatively few radioactive materials. But at that time, the military underestimated the problems and harm caused by radiation.

Baker's nuclear test produced about 3 pounds (1.4 kg) of nuclear fission products. These pollutants are mixed with water mist, water walls and clouds, and most of them eventually return to the lagoon and are taken to other places with tides and ocean currents. However, when the water wall collapsed, part of the polluted water mist was stirred up again, and spread outward at a high speed with the radiation tide, and finally floated out of the test site with the wind. More dangerously, when the water vapor of these water mist evaporates, these fission products will become transparent and invisible to the naked eye, and continue to spread with the wind, threatening personal safety.

In addition to nuclear fission products, nuclear explosions also make seawater itself radioactive. The nuclear fission caused by Baker's nuclear explosion ejected more than twice as many free neutrons into the surrounding environment. In the air explosion environment, these neutrons will be absorbed by high heat and brought to the stratosphere together with nuclear fission products and undivided plutonium. However, the key point is that Baker is conducting an underwater nuclear test, and environmental neutrons are absorbed by lagoon seawater: if an extra neutron is pumped into the nucleus of sodium in seawater, sodium will become radioactive. Generally speaking, sodium -23 becomes radioactive sodium -24, and its half-life will be 15 hours. However, sodium will not sink to the bottom of the sea like other heavy elements, but will remain liquid and can continue to pollute other warships with seawater. In the first six days after the nuclear test, the radiation intensity of sodium will be reduced by 1000 times, but it is still enough to damage the human health entering the atoll.

Finally, the plutonium -239 used in the nuclear bomb also caused a serious crisis. After the nuclear explosion, a total of 1 1.6 pounds (5.3 kilograms) of plutonium did not fission, and it was mixed with 3 pounds (1.4 kilograms) of nuclear fission products. Although the alpha particle radiation of plutonium cannot penetrate human skin, it will be enriched in bone marrow and become highly toxic if ingested by human body. More importantly, the film dosimeter and Geiger counter of the staff could not detect plutonium; The half-life of plutonium -239 is nearly 24200 years. In other words, once the human body accidentally eats plutonium -239, it will be unable to detoxify for life.

After Baker's nuclear test, the US military first sent remote control boat into the lagoon to detect radiation. Subsequently, the US military began to try to clean the radiation of the target ship, including using shipboard fire hydrants, fire fighting bubbles, mops, soap and even alkaline water, but only the first round of gas injection had a slight effect. In addition, the sodium in seawater is radioactive, so that the seawater used to clean the hull of the US military support ship is radioactive, which not only has no cleaning effect, but also causes the sailors to be contaminated by radiation when the water mist splashes on them. At first, according to the experience of Manhattan Project, the US military limited the maximum intake of roentgen per person per day to 0. 1 roentgen (0. 1 r). However, due to the large amount of radiation, the US military could only board the five target ships farthest from the explosion center on the first day. During the first six-day half-life of sodium, a total of 4900 people boarded the seriously polluted target ship. After 10 days of nuclear test, the US military approved personnel to board all ships.

The US military soon discovered the effects of radiation on organisms. In Able nuclear test, the radiation source mainly comes from the moment of nuclear explosion and will not cause environmental radiation. However, Baker's nuclear test caused most warships to be polluted by radiation, which made organisms absorb and accumulate radiation in their living environment. In the first few days after Baker's nuclear test, most warships were not suitable for human boarding, while almost all the pigs and mice scattered around the ships died of radiation, and only a few mice survived.

Biological experiments were the focus of American media at that time. In September, Brandi pointed out to the media that "the suffering of animals used in experiments is almost negligible. They either become weak and recover, or die painlessly. " However, the death process of two scientists who died because of the unexpected criticality of the "devil core" was extremely painful; However, because the military still classified the accident as a secret at that time, the public knew little about the radiation hazards, so it did not immediately cause a rebound among the public.

However, the military has also begun to be alert to radiation and questioned the military's security measures. Before Baker's nuclear test, the navy had no experience in cleaning up nuclear radiation and knew nothing about the harm to human body in the process of cleaning up. The navy did not expect that the radiation water mist would flood almost all warships, underestimating the degree of damage. Because of lack of experience, equipment and danger awareness, American sailors often adopt traditional cleaning methods and have no protective equipment at all.

Operation Crossroads was scheduled to conduct the third nuclear test code-named Charlie, which was detonated in the deep water off Bikini Island. However, since Zibek's nuclear test on July 25th, there has been almost no progress in the ship's radiation cleaning work, and it is even more impossible to make arrangements by dragging it to the open sea. By August 3rd, stafford warren (then an army colonel), the scientist in charge of operating radiation monitoring, believed that the nuclear test had caused serious danger to many sailors and demanded that the cleaning work be stopped immediately. Warren pointed out that when sailors clean up on the ship, radiation will immediately pollute human skin, clothes and even lungs. When the sailors return to the support ship to take a bath and wash clothes, the radiation will be transferred to the support ship and carried by the sailors. Warren also questioned that sailors did not follow the safety rules, and some fire boats were forced to abandon their ships because they were too close to the target ship, which was then polluted. What's more, the protection ship will accumulate radiation when it enters and exits the polluted waters many times. From August 6 to 9, 67 people took excessive radiation; Geiger counter is not enough for application.

Some officers and men of the navy were not alert to this at first. In the eyes of sailors, saving the warships that once fought side by side is their primary task. For example, the veterans of the destroyer Wainewright, who took excessive radiation because they boarded the old ship again, should be sent back to the United States immediately. The captain of the battleship New York even accused Warren of measuring data deviation and hoped to sail the New York back to the United States. In addition, after the nuclear test, sodium continued to drop, which made the radiation reading drop and made sailors mistakenly think that cleaning was effective. However, Warren is most worried about plutonium that sailors' instruments can't detect. If the ship has been contaminated with plutonium, the crew may have been exposed to plutonium.

Brandy held a meeting on the heavy cruiser Wichita and gathered nearly 1400 officers to listen to Warren's report. On August 9th, Brandy finally learned that the Geiger counter used by sailors could not detect plutonium -239, but scientists found plutonium in the material samples of the captain's cabin of prinz eugen that day. This made Brandi suspect that plutonium might have spread all over warships. On August 10, Valen submitted an X-ray photograph to brandy, in which the body of stickleback was exposed to X-rays due to serious radiation pollution. Brandi immediately ordered to suspend all cleaning activities after reading the photos. As a result, the third round of nuclear tests was cancelled and Operation Crossroads ended immediately on the same day. The U.S. military finally conducted a deep-water nuclear test in Operation Wigwam in 1955.