Gerald Lalor, ContributorWITH THE looming petroleum shortage and concerns about global warming, it is expected that a large number of new nuclear reactors will be commissioned within a few years. China alone plans eighteen and even when completed these will supply only four per cent of their electrical demand. This resurgence of nuclear technology will lead to greater efforts to ensure that there is no diversion of materials for nuclear weapons, as so powerful are these that even a single nuclear explosion in a highly populated would be a catastrophe.
The principle of operation of both nuclear reactors and nuclear weapons is the nuclear fission chain reaction, in which a heavy nucleus, uranium or plutonium, is split by a neutron into two lighter particles and more than one neutron. When this process is repeated in a cascade of additional events the available energies are millions of times greater than in coal or conventional explosives. Nuclear reactors use this energy as heat for electricity generation, but under quite a different set of conditions an enormously powerful explosion can occur.
A one-megaton bomb can destroy an area of about 80 square miles, and atomic weapons can be made much larger than this. The carnage in a modern city would overwhelm even the largest and most advanced medical resources. It is little wonder that nuclear war inspires such fear.
THE ATOMIC BOMB
The discovery of nuclear fission in Germany in 1938 initiated a series of speculations on the feasibility of atomic weapons. The calculations of two German exiles in England, Otto Frisch and Rudolph Pierls, were the basis of a brief report presented to the government of Great Britain entitled 'The MAUD Report 1941 Report by MAUD Committee on the Use of Uranium for a Bomb', one of most significant documents of the 20th century. "... It will be possible to make an effective uranium bomb which, containing some 25 pounds of active material, would be equivalent as regards destructive effect to 1,800 tons of T.N.T. and would also release large quantities of radioactive substance, which would make places near to where the bomb exploded dangerous to human life for a long period." In the United States on July 16, 1945, the world's first atomic explosion was set off at Alamogordo, New Mexico.
The next month, two quite crude bombs devastated Hiroshima and Nagasaki and destroyed Japan's will to fight.
As the 1940s ended, the United States had a world monopoly on these weapons and had every intention to maintain it. But the biggest secret about nuclear weapons was that they could be made and this was dramatically made public over Japan. Post-World War II, some 30 countries are thought to have at least seriously considered the development of nuclear weapons.
Several succeeded, but since great secrecy is usually maintained even long after a programme has ended, there can be debates on details. There are several reasons such as pride, domestic gains, political and military advantages, equality or influence or power, national survival, why a country might seek nuclear weapons. In addition, a chain of concerns has pushed countries: the Americans feared the Germans would build a bomb; the Soviet Union could not accept American arms superiority, so they too developed nuclear weapons; the British, French, and the Chinese felt impelled to follow to maintain 'great power' status; the Israeli saw the weapons as a final insurance against their destruction in a hostile region as perhaps so did the South Africans; and so it has gone on, with each new success adding to global peril.
NUCLEAR CHAIN REDUCTION
The nuclear chain reaction occurs once a critical mass of the nuclear fuel is present under the appropriate conditions and the principle of the bomb is to rapidly obtain the critical mass of fissile material from a sub-critical arrangement. As illustrated in the diagram, this can be done either by rapidly merging two sub-critical masses or by rapid compression of a core to criticality.
In the first bomb, a wedge of highly-enriched uranium is driven into a similar target by an explosive in a gun-type arrange-ment. This design does not work with plutonium and instead high explosives placed around the central mass are detonated simultaneously to implode and compress the core into a supercritical mass. At that instant, neutrons are injected from the beryllium-polonium core to initiate the chain reaction and subsequent explosion. The implosion type design is also suitable for the uranium bomb. The gun-type uses the simpler engineering but uranium enrichment is more difficult even than the specialised chemical processes required to separate plutonium from irradiated fuel.
Atomic weapons kill by blast; heat and light radiation that destroy flesh and start fires over a wide region; by high-energy gamma rays that will kill exposed persons immediately, and can cause sickness and death over a long time.
The destruction of infra-structure and the radioactive fallout add to the appalling damage illustrated by the Hiroshima bomb. In Hiroshima and Nagasaki the estimated number of acute deaths from two bombs ranges from 150,000 to 220,000 out of a total population of 560,000 and these were 'small' weapons. These still haunting data helped inspire the levels of fear and repugnance that led to efforts to ensure that never again would such weapons be used in anger.
THE NON-PROLIFERATION TREATY
In 1953, President Dwight Eisenhower in his famous 'Peaceful Uses of Atomic Energy' address to the United Nations General Assembly emphasised the terrible dangers of atomic warfare and the possibility that the knowledge then "possessed by several nations will eventually be shared by others possibly all others." He urged the creation of an international atomic energy agency to be made responsible for fissionable and other materials that would be allocated to enhance the needs of agriculture, medicine, and other peaceful activities.
Many years later, a treaty on non-proliferation of nuclear weapons (NPT) was built around the triple aims of nuclear disarmament, non-proliferation, and the right of nations to the peaceful use of nuclear technology. Bound by this treaty, non-weapons states agree not to seek nuclear weapons and to accept International Atomic Energy (IAEA) safeguards to prevent diversion of nuclear material and technology from peaceful uses to a weapons programme.
Next week: Some national nuclear programmes.
Professor Gerald Lalor is director general of the International Centre for Environment and Nuclear Sciences at the University of the West Indies, Mona.
The five states that had detonated nuclear devices prior to January 1, 1967 (China, France, the Soviet Union, the United Kingdom, and the United States) agreed not to help non-nuclear states gain access to nuclear weapons, and to offer them access to peaceful nuclear technology. All states agree to work towards the eventual elimination of nuclear weapons.
The Non-Proliferation Treaty is the most widely adhered to treaty in the area of arms control and disarmament. Only four countries, India, Pakistan, Israel, and North Korea are not parties to this and all have developed nuclear arsenals. Jamaica signed The NPT in 1970 and the additional protocol that strengthens the already formidable ability of the IAEA to monitor and detect violations, came in force here in 2003.
