How Many Nukes in North Korea"s Arsenal?
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작성자 Lee Wha Rang 작성일05-04-27 05:03 조회2,217회 댓글0건관련링크
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Lee Wha Rang, Updated April 26, 2005
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It is now accepted that North Korea has the technical expertise and the parts to make nuclear weapons. What is not clear is i how many nukes North Korea has on hand.
<##IMAGE##> The US CIA says North Korea may have one or two or up to five "crude" nukes. Some intelligence sources of South Korea, Russia and China cite a larger number - as high as 100 nukes or more. How can the intelligence estimates vary so widely? In order to answer this question, one needs to trace the history of North Korea"s nuclear program and study the basics of nuclear bomb design principles.
Contrary to the common belief, the only reactor North Korea received from the Soviets was a tiny 0.1 megawatts thermal (MWt) reactor at Yongbyon. This reactor went into operation in early 1960s. Its primary function was isotope production for biomedical research.
A few years before its collapse, the Soviet Union agreed to build two nuclear reactors for power generation, about 1,000 megawatts electric (MWe) each, provided that North Korea joined the Nuclear Non-Proliferation Treaty (NPT). Accordingly, North Korea joined the NPT but it never got the reactors. Unable to find other sources, North Korea designed and built a 5MWe reactor on its own. This reactor, code-named Reactor I, was based on a 1950 MAGNOX technology (graphite moderator, aluminum-magnesium clad natural uranium fuel , CO2 gas cooling). The reactor was completed in 1984 and activated in February 1987 under Prof. Ha Kyong Won, a Korean physicist educated in the United States. This reactor can generate more than 30 MWt of energy.
A 50 MW MAGNOX-type reactor (Reactor II) was started in 1984. N Korea built a military nuclear complex next to this reactor. This complex was completed in 1989 and the reactor was tentatively activated in 1992. A 200 MWe MAGNOX-type reactor was started at Taechon, 60 miles north of Pyongyang in 1988. A 600-800 MWe reactor was also started at Taechon. A third reactor, 635 MWe, based on a German design was under construction at Simpo. The completion of these reactors was on hold in accordance with the 1994 Agreed Framework until the current nuclear crisis began. It is believed that North Korea is working to complete these reactors post haste..
A plutonium separation facility ("Radiological Research Lab") was built at Yongbyon in 1987. This plant is capable of handling several hundreds of tons of fuel a year, enough to handle fuel from all of the reactors. The plutonium factory for the nuclear weapons is a single story building constructed on top of the main plutonium reprocessing facility, deep underground. In 1993, N Korea completed a second plant, doubling its capacity for plutonium production to more than 100 lbs per year.
It is believed that North Korea removed about 30 lb of plutonium from Reactor I in 1988, and 60 lbs more in 1989-1991. If these figures are correct, North Korea would have about 90 lbs of plutonium. According a Russian source, North Korea bought 120 lb of plutonium from a former Soviet block country in 1992. In addition, North Korea may have acquired additional nuclear materials or nuclear weapons from the former Soviet republics. North Korea has conducted several hundred "cold explosion" tests of nuclear bombs. In a "cold" explosion, an actual nuclear bomb, with a limited amount of fissile matter, is detonated.
<##IMAGE##>In addition to the plutonium bomb, North Korea is believed to have perfected an implosion uranium bomb design. This design requires only enriched uranium and no plutonium is used. The Pakistani bomb is of a similar design. North Korea has a large reserve of uranium ores and enriched uranium for nuclear bombs can be produced in large volume using small devices that can be hidden in underground chambers. Bomb grade uranium can be made by separating out U-235 by mass separation or charge separation. In the latter method, laser beams ionized U-235 atoms and high-voltage fields extract U-235 ions. The former method separates U-235 using centrifugal force.
There are two basic designs of nuclear bomb: gun-type assembly and implosion. As shown in the figure below, in the gun-type design, two blocks of uranium enriched to about 80% U-235 are shot into each other by conventional high-explosives.
The bomb dropped on Hiroshima, the Little Boy, was of this design. It had 64.1 kg of uranium enriched to about 80% of U-235. It had the explosive power of 15,000 tons of TNT and killed about 200,000 people. Tampers?are made of U-238 blocks that hold in high pressure and temperature and reflect neutrons back to the fissile blocks. Other than the United States, South Africa is the only nation that has built gun-type nukes.
<##IMAGE##>The implosion type uses a spherical geometry ?see the figure below. High explosives or other firing means are placed evenly on the surface and fissile materials ?uranium and/or plutonium ?are placed at the center. The trigger implodes the sphere and the surface collapses squeezing the fissile matter into a state of high density, high pressure and temperature. If things are set right, nuclear explosions occur.
The bomb dropped on Nagasaki (the Fat Man) was an implosion type. It had 6.2 kg of plutonium and the destructive power of 22,000 ton of TNT. About 70,000 residents of Nagasaki were killed.
The US CIA says North Korea may have made 1 or 2 crude?bombs. The basis of this estimate is as follows. A crude plutonium bomb requires 35.2 lbs (16 kg). The US CIA estimates that North Korea has at least 70 lbs (31.5 kg) of plutonium and so it could theoretically have made 1-3 (31.5 kg / 16 kg) plutonium bombs.
The critical mass?of fissile matter drops sharply with the fissile density as the inverse square of the density - that is, even the tiniest amount of fissile matter can be made critical if squashed hard enough. The Nagasaki bomb had 6.2 kg of plutonium and North Korea could have built as many as five Nagasaki bombs. Modern plutonium nukes of China, Russia and the United States contain as little as one kg of plutonium. Using this figure, North Korea may have or could produce as many as 32 nukes from the Reactor I plutonium alone. If the report of North Korean acquisition of plutonium is true, then this figure goes up by a factor of 2 or 3 - in another word, North Korea may have or could have one hundred or so nukes..
The picture gets much more complicated when you take into account the possibility that North Korea may know how to make thermonuclear bombs ?the H-bomb. The basic physics of the H-bomb is that high-energy neutrons can break apart the abundant U-238, and so the basic design principle is to produce high-energy neutrons using nuclear fusion. Since the probability of explosion increases with particle density, extremely high pressure is created inside the bomb. In brief, a small fission bomb is used to triggers nuclear fusion, which creates high-energy particles, which in turn, creates high pressure and temperature that lead to nuclear fission of U-238.
A simplified diagram of the H-bomb is shown. A small amount of LiD (Lithium-6 deutride) placed in the inner core of an implosion bomb can significantly boost the bomb yield. LiD powder turns into Li, D, and tritium gases that undergo fusion releasing fast neutrons, which in turn enhance nuclear fission of plutonium, U235 or U-238. Any nation that can make implosion bombs can make fusion booster?bombs.
Referring to the figure below, one can see that in the H-bomb design, an implosion bomb is used as a trigger, which ignites fusion on a larger scale than in a booster bomb. Fusile substances surround the implosion bomb trigger and another much larger implosion bomb, and the whole thing is placed inside an explosion bomb made of a uranium-238 casing. U-238 nuclei fission if bombarded by high-energy neutrons, photons and alpha particles.
<##IMAGE##>The secondary stage is made of a hollow lithium-6 deutride cylinder or ellipsoid case in by a layer of U-238. At the core of the cylinder is a Pu-239 or U-235 rod about one inch in diameter. The casing is wrapped in a layer of plastic foam and a plug of U-238 separates the secondary from the trigger.
The Teller-Ulam bomb is often called a "2-stage bomb" because the fission trigger ignites the fusion stage. Since the shock wave dies out in a few microseconds, a 2-stage bomb has a limit on the bomb yields and additional stages are required for super bombs.
Photo: The US Mk-28 H-bomb, dating back to 1958, is still an active weapon system. It is capable of a ground or air burst and may be carried internally or externally, with a free-fall or parachute retarded drop, depending upon its configuration. MK-28 can be carried on bombers, submarines or ground vehicles.
The rule of thumb is each stage can be 10-100 times the previous stage in explosive power. It is believed the Soviets had a design for the Dooms Bomb ?a large freighter stuffed full of fissile materials. Such a super-bomb would have destroyed much of the world, as we know it.
It should be clear by now the significance of North Koreas enriched uranium program. It is most likely that North Korea has the technical expertise to manufacture the H-bomb. Using enriched uranium in the nuclear trigger, North Korea would not need any plutonium. Furthermore, the spent rods ?in the thousands ?in the storage pool may be used in the H-bomb with any reprocessing for plutonium extraction.
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It is now accepted that North Korea has the technical expertise and the parts to make nuclear weapons. What is not clear is i how many nukes North Korea has on hand.
<##IMAGE##> The US CIA says North Korea may have one or two or up to five "crude" nukes. Some intelligence sources of South Korea, Russia and China cite a larger number - as high as 100 nukes or more. How can the intelligence estimates vary so widely? In order to answer this question, one needs to trace the history of North Korea"s nuclear program and study the basics of nuclear bomb design principles.
Contrary to the common belief, the only reactor North Korea received from the Soviets was a tiny 0.1 megawatts thermal (MWt) reactor at Yongbyon. This reactor went into operation in early 1960s. Its primary function was isotope production for biomedical research.
A few years before its collapse, the Soviet Union agreed to build two nuclear reactors for power generation, about 1,000 megawatts electric (MWe) each, provided that North Korea joined the Nuclear Non-Proliferation Treaty (NPT). Accordingly, North Korea joined the NPT but it never got the reactors. Unable to find other sources, North Korea designed and built a 5MWe reactor on its own. This reactor, code-named Reactor I, was based on a 1950 MAGNOX technology (graphite moderator, aluminum-magnesium clad natural uranium fuel , CO2 gas cooling). The reactor was completed in 1984 and activated in February 1987 under Prof. Ha Kyong Won, a Korean physicist educated in the United States. This reactor can generate more than 30 MWt of energy.
A 50 MW MAGNOX-type reactor (Reactor II) was started in 1984. N Korea built a military nuclear complex next to this reactor. This complex was completed in 1989 and the reactor was tentatively activated in 1992. A 200 MWe MAGNOX-type reactor was started at Taechon, 60 miles north of Pyongyang in 1988. A 600-800 MWe reactor was also started at Taechon. A third reactor, 635 MWe, based on a German design was under construction at Simpo. The completion of these reactors was on hold in accordance with the 1994 Agreed Framework until the current nuclear crisis began. It is believed that North Korea is working to complete these reactors post haste..
A plutonium separation facility ("Radiological Research Lab") was built at Yongbyon in 1987. This plant is capable of handling several hundreds of tons of fuel a year, enough to handle fuel from all of the reactors. The plutonium factory for the nuclear weapons is a single story building constructed on top of the main plutonium reprocessing facility, deep underground. In 1993, N Korea completed a second plant, doubling its capacity for plutonium production to more than 100 lbs per year.
It is believed that North Korea removed about 30 lb of plutonium from Reactor I in 1988, and 60 lbs more in 1989-1991. If these figures are correct, North Korea would have about 90 lbs of plutonium. According a Russian source, North Korea bought 120 lb of plutonium from a former Soviet block country in 1992. In addition, North Korea may have acquired additional nuclear materials or nuclear weapons from the former Soviet republics. North Korea has conducted several hundred "cold explosion" tests of nuclear bombs. In a "cold" explosion, an actual nuclear bomb, with a limited amount of fissile matter, is detonated.
<##IMAGE##>In addition to the plutonium bomb, North Korea is believed to have perfected an implosion uranium bomb design. This design requires only enriched uranium and no plutonium is used. The Pakistani bomb is of a similar design. North Korea has a large reserve of uranium ores and enriched uranium for nuclear bombs can be produced in large volume using small devices that can be hidden in underground chambers. Bomb grade uranium can be made by separating out U-235 by mass separation or charge separation. In the latter method, laser beams ionized U-235 atoms and high-voltage fields extract U-235 ions. The former method separates U-235 using centrifugal force.
There are two basic designs of nuclear bomb: gun-type assembly and implosion. As shown in the figure below, in the gun-type design, two blocks of uranium enriched to about 80% U-235 are shot into each other by conventional high-explosives.
The bomb dropped on Hiroshima, the Little Boy, was of this design. It had 64.1 kg of uranium enriched to about 80% of U-235. It had the explosive power of 15,000 tons of TNT and killed about 200,000 people. Tampers?are made of U-238 blocks that hold in high pressure and temperature and reflect neutrons back to the fissile blocks. Other than the United States, South Africa is the only nation that has built gun-type nukes.
<##IMAGE##>The implosion type uses a spherical geometry ?see the figure below. High explosives or other firing means are placed evenly on the surface and fissile materials ?uranium and/or plutonium ?are placed at the center. The trigger implodes the sphere and the surface collapses squeezing the fissile matter into a state of high density, high pressure and temperature. If things are set right, nuclear explosions occur.
The bomb dropped on Nagasaki (the Fat Man) was an implosion type. It had 6.2 kg of plutonium and the destructive power of 22,000 ton of TNT. About 70,000 residents of Nagasaki were killed.
The US CIA says North Korea may have made 1 or 2 crude?bombs. The basis of this estimate is as follows. A crude plutonium bomb requires 35.2 lbs (16 kg). The US CIA estimates that North Korea has at least 70 lbs (31.5 kg) of plutonium and so it could theoretically have made 1-3 (31.5 kg / 16 kg) plutonium bombs.
The critical mass?of fissile matter drops sharply with the fissile density as the inverse square of the density - that is, even the tiniest amount of fissile matter can be made critical if squashed hard enough. The Nagasaki bomb had 6.2 kg of plutonium and North Korea could have built as many as five Nagasaki bombs. Modern plutonium nukes of China, Russia and the United States contain as little as one kg of plutonium. Using this figure, North Korea may have or could produce as many as 32 nukes from the Reactor I plutonium alone. If the report of North Korean acquisition of plutonium is true, then this figure goes up by a factor of 2 or 3 - in another word, North Korea may have or could have one hundred or so nukes..
The picture gets much more complicated when you take into account the possibility that North Korea may know how to make thermonuclear bombs ?the H-bomb. The basic physics of the H-bomb is that high-energy neutrons can break apart the abundant U-238, and so the basic design principle is to produce high-energy neutrons using nuclear fusion. Since the probability of explosion increases with particle density, extremely high pressure is created inside the bomb. In brief, a small fission bomb is used to triggers nuclear fusion, which creates high-energy particles, which in turn, creates high pressure and temperature that lead to nuclear fission of U-238.
A simplified diagram of the H-bomb is shown. A small amount of LiD (Lithium-6 deutride) placed in the inner core of an implosion bomb can significantly boost the bomb yield. LiD powder turns into Li, D, and tritium gases that undergo fusion releasing fast neutrons, which in turn enhance nuclear fission of plutonium, U235 or U-238. Any nation that can make implosion bombs can make fusion booster?bombs.
Referring to the figure below, one can see that in the H-bomb design, an implosion bomb is used as a trigger, which ignites fusion on a larger scale than in a booster bomb. Fusile substances surround the implosion bomb trigger and another much larger implosion bomb, and the whole thing is placed inside an explosion bomb made of a uranium-238 casing. U-238 nuclei fission if bombarded by high-energy neutrons, photons and alpha particles.
<##IMAGE##>The secondary stage is made of a hollow lithium-6 deutride cylinder or ellipsoid case in by a layer of U-238. At the core of the cylinder is a Pu-239 or U-235 rod about one inch in diameter. The casing is wrapped in a layer of plastic foam and a plug of U-238 separates the secondary from the trigger.
The Teller-Ulam bomb is often called a "2-stage bomb" because the fission trigger ignites the fusion stage. Since the shock wave dies out in a few microseconds, a 2-stage bomb has a limit on the bomb yields and additional stages are required for super bombs.
Photo: The US Mk-28 H-bomb, dating back to 1958, is still an active weapon system. It is capable of a ground or air burst and may be carried internally or externally, with a free-fall or parachute retarded drop, depending upon its configuration. MK-28 can be carried on bombers, submarines or ground vehicles.
The rule of thumb is each stage can be 10-100 times the previous stage in explosive power. It is believed the Soviets had a design for the Dooms Bomb ?a large freighter stuffed full of fissile materials. Such a super-bomb would have destroyed much of the world, as we know it.
It should be clear by now the significance of North Koreas enriched uranium program. It is most likely that North Korea has the technical expertise to manufacture the H-bomb. Using enriched uranium in the nuclear trigger, North Korea would not need any plutonium. Furthermore, the spent rods ?in the thousands ?in the storage pool may be used in the H-bomb with any reprocessing for plutonium extraction.
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