Effects of Nuclear War
From Thermal-FluidsPedia
Nuclear bombs can result in a wide range of destruction in any of the following ways:(1, a)
1. Blast: Blast damage from a nuclear weapon comes from the overpressure in the air and from winds which result from the pressure. Right after the bomb detonates, a shock initiates at the center and moves outward at a rate several times faster than the speed of sound, and a large overpressure develops across the shock wave (b). Depending on the yield and distance from the blast, the blast wind can reach several thousand kilometers per hour and overpressure can exceed several atmospheres. Most buildings suffer moderate to severe damage when subjected to only 35 kilopascals (0.35 atmospheres). As for the human body, the shock causes a pressure wave to travel through the body, with the most damage occurring in junctions between materials of different densities, such as the interface between bones and muscles or between tissues and air. Most eardrums rupture at around 100 kPa (one atmosphere), and lungs are damaged at around 70 kPa (0.7 atmospheres) overpressure. Roughly, 50% of the energy of the low-altitude atmospheric detonation is released in the initial shockwave.
2. Heat: Depending on yield, fireballs as large as one mile in diameter, with temperatures of several thousand degrees, are possible immediately after the explosion. Such fireballs practically vaporize everything near ground zero and causes extensive, rapidly spreading fires. As the weapon explodes, it produces a brilliant flash of light and a heat wave beyond the tolerance of the human retina, causing severe eye injuries, including blindness. 35% of the energy of the nuclear blast is in the form of heat, and visible radiation.
3. Radiation: Both short and long term effects of ionizing radiation are important. Shortly after the blast, the heat of the fireball vaporizes weapon residue into small particles that are quickly drawn up into the stratosphere. Larger particles settle and contaminate the earth, while smaller particles are carried by the stratospheric wind across the globe, eventually showing up as radioactive fallout. If detonation occurs over water, sea salts will act as condensation nuclei to seed the clouds, causing highly radioactive rainout. In addition, the large flux of neutrons released during the first few seconds after detonation travels outward and is absorbed by the soil, air, water, and other materials, making them radioactive. In turn, these radioactive materials release gamma and beta radiation over an extended period of time.
4. Electromagnetic pulse: In addition to various radioactive isotopes, nuclear blasts emit a significant amount of x-rays into the atmosphere. X-rays can ionize the air at high altitudes and produce large numbers of fast-moving electrons. The moving electric charge produces a pulse so powerful that long metal objects would act as antennae and electrify all electronic devices on its path. The resulting voltage and the associated high current could destroy unshielded electronics and interfere with electric signals, resulting in failures of critical medical and transportation equipment. The ionized air also disrupts radio traffic that would normally bounce from the ionosphere. Ionizing radiation and EMP account for the remaining 15% of the detonation energy.
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Nuclear Arms Treaties and International Conflicts
Following WWII and the explosion of the two powerful nuclear bombs on Hiroshima and Nagasaki, the Allies, mainly the United States and Soviet Union, engaged in a rapid buildup of nuclear weapons. So many weapons were amassed that if one country decided to use its nuclear option, the entire planet could have been destroyed many times over in a matter of hours. At the peak of the nuclear weapons stockpile in 1967, the US and USSR (Union of Soviet Socialist Republics or Soviet Union) maintained over 40,000 active warheads (2). The rapid proliferation of the nuclear arsenal, and with it the escalation of Cold War rhetoric, required a new way of thinking and bold initiatives to save the world by preventing an accidental nuclear war (3).
In 1970, the five great nuclear powers (the US, USSR, UK, France, and China) signed a non-proliferation treaty which mandated that those countries would “pursue negotiations in good faith on effective measures relating to the cessation of the nuclear arms race at an early date and to nuclear disarmament.” In exchange, nations without nuclear weapons pledged never to acquire them and, as signatories, open their nuclear facilities to the Vienna-based International Atomic Energy Agency (IAEA), to monitor nuclear program activities and assure no nuclear weapons are being developed.
In the years that followed, the US and the Soviet Union negotiated the Strategic Arms Limitation Treaty (SALT-I, 1971 and SALT-II, 1979). These treaties aimed at limiting the number of strategic offensive weapons on each side (b). Furthermore, the Anti -Ballistic Missile Treaty (ABM) constrained the numbers of launchers and interceptors available to each country. The underlying assumption prevalent during this time was that if each country had enough nuclear power to survive an enemy’s first strike and was still able to retaliate with overwhelming nuclear response, then neither country would undertake such madness. The policy commonly referred to as Mutually Assured Destruction (MAD) left no doubt that both countries would be destroyed in the event of any nuclear attack.
In 1983, US President Ronald Reagan announced his intention to initiate a program for research and development of a space-based system to defend the nation from attack by strategic ballistic missiles. The Strategic Defense Initiative (SDI), popularly referred to as “Star Wars,” would supposedly eliminate the threat of a nuclear arms confrontation by installing lasers and other space-based defensive systems that detected and destroyed all incoming missiles. The critics charged that this would be in violation of the ABM treaty and would encourage the militarization of space and destabilize the nuclear balance of power. Furthermore, SDI was based on untested technologies and was unable to defend against cruise missiles, airplanes, and several other possible delivery systems. Following the dissolution of the Soviet Union in 1991 and the end of the cold war, the selection of a new administration temporarily put the SDI program on hold.
The reality of the new world order and the demise of communism provided a unique opportunity not only to limit the nuclear arsenal, but also to actually reduce it. The STrategic Arms Reduction Treaties (START-I, II, and III) are the first comprehensive arms-control agreements that require a reduction of offensive nuclear weapons. Under these treaties, the United States, the former Soviet Union, and its successor states (Russia, Ukraine, Belarus, and Kazakhstan) had to cut down their nuclear warheads and delivery systems that included intercontinental bombers and land-based and submarine-launched ballistic missiles. Based on these treaties, the US and Russia agreed to reduce the total number of strategic nuclear warheads to about 2,000-2,500 warheads each by 2007. Although some progress has been made in reducing the size of nuclear arsenals, talks have reached impasse as NATO announced plans to build a missile defense system in Poland and Czech Republic. There are new proposals by the Obama administration to restart talks to reduce the size of nuclear stockpiles.
Terrorism
The end of the Cold War and the resulting reduction in tensions between the Former Soviet Union and the United States brought about a new spirit of cooperation. This resulted in a number of treaties which have reduced the number of nuclear warheads each country possesses, and with them, the threat of nuclear war. The end of the Cold War also raised a new threat: terrorism. As nuclear warheads are dismantled, an abundant amount of weapons-grade nuclear fuel and accessories which must be disposed of accumulate. In addition, thousands of tons of uranium have been refined and converted to plutonium or enriched to weapons-grade material. Less than 8 kg of plutonium is all that is needed to make a Nagasaki-sized bomb. The possibility exists that terrorist groups with no access to reprocessing plants could steal or buy enriched uranium and plutonium fuels on the black market and disperse them throughout cities and other population centers or use them in making crude and dirty bombs. Equally important is the danger of attack on or accidental spillage of nuclear waste en route to a proposed permanent repository site. Nuclear reactors themselves could also be the subject of sabotage and therefore must be designed with many layers of safety in the event of a loss of coolants, damage to the containment structure, or the possibly of the reactor control rooms being taken over by terrorists and their internal collaborators. The key defense against large radioactive leaks to the outside is to keep the containment intact. The containment dome is shaped such that it can withstand internal pressure resulting from the buildup of gas pressures. Unfortunately, existing containments may not withstand external overpressures that may result from major rocket attacks or car bombs (4). In light of the September 11 terrorist attacks on New York and Washington D.C., (d) nuclear reactors may be particularly vulnerable.
References
(1) Glasstone, S. “The Effect of Nuclear Weapons,” US Atomic Energy Commission, 1962.
(2) Nuclear Notebook, Bulletin of Atomic Scientists, March/April 2000. 17 An excellent website on nuclear arm treaties can be found at http://www.nautilis.org/library/security/natotreaty.html.
(3) A good reference on the history of nuclear arms treaties can be found at http://www.nautilis.org/library/security/natotreaty.html.
(4) For an excellent overview of nuclear terrorism risks see: Leventhal, P. L., and M. M. Hoenig, “Nuclear Terrorism: Reactor Sabotage and Weapons Proliferation Risks,” Contemporary Policy Issues, July 1990, V. 8, No. 3, pp.106-121.
(5) Toossi Reza, "Energy and the Environment:Sources, technologies, and impacts", Verve Publishers, 2005
Additional Comments
(a) A good sorce of information on nuclear weapon effects is the Federation of American Scientists. See http://www.fas.org/nuke/intro/nuke/effects.htm
(b) For a 10-megaton fission bomb, overpressure can reach one thousand atmospheres close to ground zero (GZ), but drops to about 15 atmospheres when it becomes a fireball about one mile in radius. The wind speed can reach 1700 mph (2700 km/hr). The overpressure becomes negligible at around 20 miles from ground zero, where wind has slowed down to about 55 mph (90 km/hr).
(c) Nuclear arsenals can be divided into either strategic or tactical categories. Strategic nuclear weapons are weapons designed to target cities and other large areas. Tactical nuclear weapons are smaller weapons used to destroy specific military targets. Depending on delivery method, weapons are classified as bombs, ballistic missiles, cruise missiles, artillery shells, or hand-held. Ballistic missiles are long-range missiles that use ballistic orbital trajectories, whereas cruise missiles use low altitude trajectories and are suitable for short range and smaller payloads. Artillery shells and hand-held devices are purely for tactical use.
(d) Early in the morning of September 11, 2001, Al Qaeda terrorists hijacked four commercial jets and crashed three of them into the World Trade Center in New York and the Pentagon in Washington D.C. The fourth aircraft was heading toward the White House, but crashed in Pennsylvania. Over 3,000 innocent lives were lost, 265 aboard the airplanes and the rest in the buildings that collapsed as a result of the tragic incident.