The beginning of the "nuclear era" of humanity can be considered July 16 1945 of the year. Then, at the White Sands test site in the desert near the city of Alamogordo in the state of New Mexico, the first successful test of an explosive nuclear device called the "Thing" was held as part of the Manhattan project. The power of a nuclear explosion in TNT equivalent was about 21 kt.
Prior to this, on May 7, a “capital rehearsal” took place here: on a six-meter wooden platform, 110 tons of powerful explosives were blasted with the addition of a certain amount of radioactive isotopes. A test explosion using conventional explosives revealed a number of weak points in the test process and allowed us to work out the instrumentation and communication lines, as well as the method for collecting soil and air samples immediately after the test.
Metal tower built for nuclear testing
To detonate a nuclear charge on top of a thirty-meter-high metal tower, it was decided to better understand how the destructive factors of an explosion would affect the surrounding terrain with a real explosion of a battle bomb dropped from a bomber. Even in the process of working out a possible combat use of a nuclear bomb, calculations showed that the maximum destructive effect on targets in the form of urban development would be obtained precisely by air blasting. After the metal sphere with a plutonium charge of the implosive type was hoisted to the top of the tower with a winch, a truck with mattresses was installed under it in case of a bomb falling from a height.
Norris Bradbury, the leader of the assembly of an explosive nuclear device, was photographed next to a partially assembled nuclear charge on top of a test tower.
Due to the thunderstorm, the tests scheduled for 04:00 local time had to be postponed for an hour and a half. After a nuclear explosion that vaporized a multi-ton steel tower and incinerated the whole district, a glassy crust of sintered sand formed in a radius of hundreds of meters. Within a few hours to the place of the explosion on tank "Sherman", additionally protected from radiation by lead sheets, went a group of scientists who took measurements of radiation and took soil samples. Despite the protection, they all received significant doses of radiation.
Aerial view of the explosion site, taken shortly after the test
In general, the test at White Sands, codenamed Trinity, confirmed the calculations of American physicists and proved the possibility of using nuclear decay energy for military purposes.
On December 21, 1965, after radiation levels reached safe values, the New Mexico test area was declared National historical monument and entered the National Register of Historic Places.
Google Earth Satellite Image: The Place of the First American Nuclear Test in New Mexico
Currently, the area of the first nuclear explosion is open to the public as part of the excursion groups. At the point where there was once a tower with a nuclear device, a memorial is installed.
The 16 test of July 1945 of the year opened the way for the combat use of nuclear decay energy. In August, the 1945 of the year at the disposal of the US military had two ready-to-use nuclear bombs.
The first, uranium, "gun type", weighing about 4000 kg and a length of 3000 mm, contained a 64 kg of highly enriched U-235. This bomb, dubbed the "Baby", had a relatively simple and reliable design. Its body was made thick enough to withstand the hit of anti-aircraft shell fragments and large-caliber bullets. To bring the uranium charge up to the supercritical mass, a three-inch caliber sea bore trimmed to 1,8 was used, on the muzzle of which there was a main cylindrical uranium charge of 38,5 kg and an initiator made of beryllium and polonium alloy mounted on the back side of the target. The gun fired a “shell” of tungsten carbide, on the head of which was attached a uranium rod weighing 25,5 kg. As a result of the collision of the “projectile” with the “target”, the formation of a supercritical mass occurred, and a chain reaction began. This scheme was considered so reliable that it did not require preliminary tests.
Taking into account the use of such a device, the form of fissile materials is calculated on the basis that it will allow for some time to withstand the force of the collision of the “projectile” and “target” and not to collapse long enough before the start of the chain reaction. With relative simplicity, this scheme has a very low efficiency, since most of the uranium is scattered before it has time to react. For this reason, nuclear charges of this type are not currently in operation.
About 700 grams of uranium, that is a little more than 1% of fissile material, took part in the chain reaction of the “Kid” nuclear explosion. But this was quite enough. The power of a nuclear bomb dropped by 6 on August 1945 of the year in 08: 15 local time on the Japanese city of Hiroshima from a B-29 bomber flying at an altitude of more than 9000 meters, turned out to be in the TNT equivalent in trotyl equivalent.
The atomic bomb worked at an altitude of about 600 meters at the command of the radio altimeter APS-13. As a result of an explosion in a radius of more than 1,5 km, almost all buildings were destroyed. In areas larger than 11 km², severe fires have occurred. About 90% of all buildings in the city were destroyed or seriously damaged. It is believed that atomic bombing killed from 70 to 80 thousand people, about 160 thousand people died of injuries, burns and radiation sickness during the year.
The second American atomic bomb, which virtually destroyed 9 on August 1945, the port city of Nagasaki, Japan, was a plutonium-implosive type. By design, it is basically similar to the charge tested at the site in New Mexico. The form of the Fat Plutonium “Fat Man” was very far from aerodynamic perfection, and a parachute had to be used to stabilize after dropping a bomb from a bomber.
Nuclear Bomb "Fat Man" in preparation for use
The plutonium bomb, called the “Fat Man”, was much more complicated compared to the “Kid”. Pu-239 acted as a fissile material in an amount close to the critical mass. In nature, plutonium found in uranium ores is very rare. In significant quantities, it is produced in nuclear reactors when U-238 is irradiated with neutrons.
In Fatty, there was about 6 kg of plutonium surrounded by a shell of uranium-238, fissile materials, in turn, were placed in an aluminum crimping sphere. The aluminum envelope, doped with boron, ensured uniform compression of the nuclear charge and prevented it from starting a premature chain reaction and destruction by explosion products. In the hollow plutonium nucleus formed by two hemispheres, there was a neutron initiator - a ball with a diameter of about 2 cm from beryllium, covered with an alloy of polonium and yttrium. The neutron initiator served as the primary source of neutrons when a plutonium nucleus was compressed by an explosive wave. An explosive charge was assembled from the 64 segments over the aluminum shell, resembling a giant soccer ball. The explosive weight exceeded 2300 kg. For a uniform compression of the plutonium nucleus, a ball of explosives was literally all stuck with electric detonators that worked simultaneously. Such a complex construction of a bomb made its assembly and preparation for use a very difficult task, requiring increased attention and close monitoring.
The energy output during the explosion of "Fat Man" was higher than that of the uranium "Kid." The utilization rate of fissile materials was 17%. The power of the explosion was within 22 kt. Although the energy output was greater than in Hiroshima, the number of dead and injured in Nagasaki was less.
Nagasaki aerial view before and after nuclear bombing
The large deviation of the bomb from the aiming point, which exploded over the industrial zone, the terrain, and also the fact that shortly before that, in anticipation of American aviation a significant part of the population was evacuated. As a result of the bombing, about 80 thousand people died, about 60 thousand people died before the end of the year. On an area of about 84 km², approximately 19500 buildings were destroyed and damaged.
The story of the Japanese Tsutomu Yamaguchi, who survived both nuclear bombings, is noteworthy. 6 August 1945 years Tsutomu Yamaguchi was 29 years. He was in Hiroshima, about three kilometers from the epicenter of the explosion. His hair was burned, the left side of his face was burned, and the eardrum in his left ear burst. On August 8, he returned to Nagasaki, where he worked at the Mitsubishi shipyards and sought medical help at the hospital. And again fell under the nuclear bombardment. This time he was almost not injured, but soon after the fires were extinguished, he rushed to the city to look for his missing relatives. During the search, Yamaguchi received large doses of radiation, and he subsequently showed signs of radiation sickness - his hair fell out, long healing ulcers formed and long nosebleeds began. However, Tsutomu Yamaguchi survived despite everything, he died on January 4 2010 of the year 93 in Nagasaki.
The effect of using nuclear bombs against Japanese cities, much of which was built up with wooden buildings, turned out to be even higher than expected, and after Japan’s surrender, the American leadership began to consider nuclear weapon as an element of pressure on the Soviet Union. If in the 1947 year, the United States had 32 nuclear bombs, preparation for the use of which required considerable time, after five years in 1952, the US had 1005 nuclear charges. Five years later, the number of charges increased by more than six times.
For testing new types of nuclear bombs in the Pacific atolls of Bikini and Enyvetok nuclear test sites were created. From 1946 to 1958, the 67 nuclear tests were carried out here, including surface and underwater tests.
In the summer of 1946, during the operation “Crossroads”, two submarine nuclear explosions with a capacity of about 23 kt were produced. These were the first test nuclear explosions, which were reported in the media, and they were invited to foreign observers, including from the USSR.
The purpose of these tests was to test the ability of military and merchant ships fleet resist the damaging factors of nuclear weapons. To increase the reliability of the test results, experimental animals were placed on decks and in the internal compartments. In the tests involved a fleet of 95 target ships. These were captured German and Japanese ships and ships, as well as American, which were considered by the admirals of the US Navy obsolete or superfluous. Tests have shown that ships within a radius of 1000 meters from the epicenter of an underwater explosion can be sunk or seriously damaged. Ships located at a greater distance also suffered damage, but they could well be repaired. Based on the test results, it was concluded that a submarine armed with nuclear torpedoes for warships could be more dangerous than a heavy bomber. A squadron of warships in the open sea, traveling at a speed of 20-25 knots, is quite able to evade a nuclear bomb dropped from an altitude of 8-9 km. The explosion will occur at a distance of 2-2,5 km from the squadron. In the absence of a large number of explosive and combustible substances and personnel on decks, a nuclear explosion with a capacity of 20-25 kt will not cause much damage to warships.
In an air explosion, the main radiation factors were penetrating and induced radiation, contamination by radioactive fallout was minimal. Radiation contamination during underwater explosions turned out to be many times higher than that of the air, and after the tests, considerable effort was required to clean the ships. For this reason, part of the test fleet exposed to radiation has not been decontaminated, but has been submerged in the ocean.
Google Earth Satellite Image: Enyvetok Atoll Funnels from Nuclear Tests
November 1 The 1952 of the year on Enolvetok Atoll held the first test of a stationary thermonuclear device. The power of the explosion of the first hydrogen bomb was 10,4 Mt, which is 450 times the power of the charge dropped on Nagasaki. And although it was a purely stationary device with a mass of 62 tons and the size of a three-story house that did not have any prospects for practical military use, this test showed the possibility of using fusion energy for military purposes.
1 March 1954 on a Bikini Atoll was blown up by a two-stage thermonuclear device with a capacity of 15 Mt. Compared with the first test explosion, solutions were developed in this device, which were subsequently embodied in fusion bombs adopted for service. Solid lithium-6 deuteride was used as a "thermonuclear fuel". This explosion was the most powerful in the history of American nuclear testing.
Stationary test thermonuclear device "Castle Bravo", exploded 1 March 1954
The stationary thermonuclear device which received the designation “Castle Bravo” weighed more than 10 t and looked like a cylinder about 4,5 m long. According to the test results of “Castle Bravo”, work began on creating thermonuclear charges suitable for use on strategic carriers.
Satellite image of Google Earth: a crater formed during testing of the Castle Bravo hydrogen bomb is visible on the north-western cape of Bikini Atoll
The physicists involved in calculating the power of the charge were wrong, and the amount of energy released turned out to be 2,5 times the planned one. The explosion made a great impression on the observers. A huge mushroom cloud with a diameter of 100 km, with a leg thickness of -7 km, within minutes rose to a height of more than 40 km, reaching its largest size 8 minutes after the explosion. After the explosion, the atoll’s outlines have changed dramatically. At the north-western tip of the Bikini Atoll, a giant funnel with a diameter of about 1,8 km was formed, which quickly filled with water. As a result of the explosion, the atoll itself and its environs were subjected to the strongest radioactive contamination. A zone in the form of an oval 100 km wide and over 550 km long was subjected to serious contamination by radioactive fallout. This led to an emergency evacuation of American servicemen and civilians from nearby islands, some of whom received very high doses of radiation. The crews of fishing vessels fishing in the area also received large doses of radiation. It is believed that "Castle Bravo" was not only the most powerful, but also the "dirty" American nuclear test. Experts attribute a large emission of radiation to the fission reaction of the uranium envelope, which surrounded a thermonuclear charge, it worked as the third stage of the explosion.
American nuclear tests on the Marshall Islands and significant radiation pollution caused a great response from the world community. The heads of several regional states demanded their cessation. This, as well as the great distance, the difficulties in maintaining the infrastructure and the unpredictable weather made it necessary to transfer nuclear tests to the US territory.
In the 1951, the Nevada test site with an area of about 3500 km² began its operations. As it turned out, the choice of location for the landfill was made very well, the structure of the rocks and the terrain allowed here to conduct underground test explosions in wells and tunnels. The first tactical nuclear charge with a power of 1 kt was tested at the 27 January January 1951 test site. In total, 928 thundered nuclear explosions, about 100 of which were atmospheric. After the Treaty on the Limitation of Testing in Three Environments, signed at 1963, entered into force in three environments, only underground tests were conducted at the Nevada site.
Google Earth Satellite Image: Nevada Nuclear Test Site Test Field
In the 50s, nuclear weapons were held at the Nevada training ground, which involved significant quantities of military equipment and US military personnel. At the nuclear test site, various fortifications and engineering structures were erected, as well as typical urban buildings.
In the 50s of the early 60s, mushroom clouds of nuclear explosions could be observed at a considerable distance from the landfill. They were seen from Las Vegas and even from Los Angeles.
In addition to the testing of nuclear weapons and the development of military operations in the conditions of use of nuclear weapons, at the Nevada test site were conducted research on the use of nuclear charges for "peaceful purposes". 6 July 1962, a thermonuclear explosion with a power of 104 CT, shot up a huge dome of ground into the air to a height of about 100 meters. The explosion emitted more than 11 million tons of sand and rock. The sensors recorded a seismic wave equivalent to an earthquake of magnitude greater than the Richter scale 4,7 scale.
Google Earth Satellite Image: Storax Sedan Crater
The purpose of the Storax Sedan nuclear test was to study the possibility of using nuclear charges for the formation of craters, the creation of cavities for the storage of oil and gas, mining, and other "peaceful" purposes.
As a result of a ground explosion a very large amount of radionuclides was formed. 1 an hour after the explosion, the radiation level at the edge of the crater was 500 X-rays per hour. This test was the dirtiest of all conducted in the United States. With the explosion, the Storax Sedan emitted about 7% of the total amount of radioactive fallout that fell on the adjacent US territory during all nuclear tests at the Nevada test site.
The last nuclear test at the Nevada test site took place on 23 September 1992. From those on the landfill continues to function, but there are studies without achieving a critical mass of charges and the beginning of a large-scale uncontrolled chain reaction. In 2006, an experiment was planned with the explosions of 1100 tons of conventional explosives, but in 2007, this project was closed. According to data leaked to the media at the test site in underground wells, there are still several unused nuclear charges, which could not be raised.
On the nuclear ground in Nevada, the administration monthly conducts guided tours of the territory, the queue for them is scheduled for many months in advance. During the tour, visitors are not free to get out of buses, have binoculars, mobile phones, cameras and camcorders with them. It is forbidden to memorize stones, and any objects from the landfill.