FATEFUL HOUR

Evening Star, Issue 25632, 5 November 1945, Page 4

FATEFUL HOUR

THE CRISIS OF DECISION THREAT AND PROMISE OF ATOMIC ENERGY (Special to ' Star.') [By Professor P. W. Burbidge, Professor of Physics, Auckland University College.] Human affairs are rapidly moving to a crisis unparalleled in history—the crisis of decision on the development of atomic energy, whether it shall be limited by international control to peaceful purposes or whether the nations embark on another armament competition with weapons a millionfold more powerful than in the recent struggle. This is a most fateful hour for the human race. It is essential that there be a general understanding of the issues involved and that all contribute as far as possible to their determination. Because of the scale of the possibilities, this is the most serious matter that man has had -to consider; it therefore cannot be done blindly, nor can we afford to trust others with our fate. New Zealand must make its own decision, and throw its weight into the right scale. It is the purpose, therefore, olf these article to draw attention to the crisis, to give relevant technical information and to suggest lines of thought for constructive action. The matter is one to which all serious citizens must give their considered attention, for now_ is the appointed hour of decision in which wo determine our destiny, in which man will make his choice. PRESENT STAGE OF ATOMIC ENERGY. The report compiled by Professor Smyth (U.S.A.) shows that to .date two materials—uranium 235 and plutonium —have been developed as large-scale sources of energy for explosive purposes. The manufacture has been carried out in war factories created in the United States, using United States money and almost entirely United States personnel. Most ofthe British Empire scientists worked in Canada", where development is still proceeding; a Ifew, and a few from European countries, were in U.S.A. Three processes were used in manufacture, two for U 235 and one for plutonium. The former were separation processes, to separate the one part of U23s.that occurs in 140 parts of ordinary uranium; the plant for these processes extended over many acres, and used enormous quantities of power. The plutonium process, on the other hand, involves the creation of the new element plutonium (No. 94 in the element table) frompure uranium, which, along with pure graphite, is built into a " pile " of regular geometrical structure.

As the pile increases in size the action " warms up," enormous continuous heat is developed, .intense radioactive radiation occurs, and this transforms the uranium by a physical change into plutonium. The heat is controlled by a water-cooling system of large flow, and at the calculated time for maximum change the uranium rods are withdrawn and dissolved in chemicals; the plutonium is then separated chemically, the pure uranium recovered, fashioned again to rod, and replaced in the pile. The process is thus a continuous one giving off large amounts of energy The rate of action can be simply controlled by inserting suitable metal screens in the pile. The radiations are exceedingly dangerous, so that the whole plant must be housed \n thick underground structures and operated automatically. A large pile will generate 10,000 k.w. in heat, so that a few such are equivalent to a medium-sized hydro-electric station. The intense radiation produced (neutrons and gamma rays) can be used for transmuting other elements, e.g., the formation of mercury from gold, sulphur from phosphorus, etc., in small amounts.

RAW MATERIALS. The only element used so far in actual manufacture been uranium. This occurs in the proportion four parts in a million in the earth's crust, and is therefore relatively rare. The richest known source is in Canada, the next richest in Belgian Congo, and in Czecho-Slovakia. United States *of America has large quantities of lowgrade ore; Great Britain, a small deposit in Cornwall; Australia, in South i Australia; New Zealand "has minor quantities. Russia has one small deposit for certain, and there are indications that others exist. ~. Thorium is also another possible raw material, but the processes for this have not been worked out nor are the supplies any better. -This whole subject of nuclear fission is, however, a very new one, and it is likely that further research, or the lifting of secrecy bans, will disclose other possibilities. Taking the present known position, the three major Powers have probably each ample supplies for war purposes, and with the existing knowledge Great Britain could probably develop manufacture for bomb use within two years; Russia probably within three. ATOMS SPLIT ASUNDER. The pure materials, U 235 and platinum, are, in small quantities, quite safe. A small action occurs in them, but very little. When, however, they are rapidly assembled in larger quantites' the action becomes explosive. Details on this are lacking, but apparently a bomb contains a source of neutrons to start the process, and the isolated " atomic " material is fired together, probably by some triggered explosion, and, on assembly, instantly itself explodes —i.e., the atoms are split asunder and proceed outwards with enormous energy, giving the explosive action. ' But of much greater -importance than this use of explosive action will be the uses of atomie energy for peaceful purposes. The plutonium piles provide large sources of power—they must be large to work efficiently—and as such they will be o>f interest to engineers. They also can change matter into new forms that are radio-active like radium and that possess very valuable properties for medical applications and for the study of functions.in plant and 'animal physiology, subjects of prime interest to an agricultural country like New Zealand. y:

Again, the weight efficieu% for the production of atomic energy is some million times that for combustion energy from coal or petrol, so that very little material gives a large yield of energy. If the exploitation of this in small amounts becomes possible (and the drive to this end will be intense), then long-distance transport will be revolutionised by the

omission of fuelling stops and the reduction of fuel load. Indeed, at the moment it is not beyond speculation to envisage atomic " piles " on ocean liners, continuous in action, but " damped down " by controls as required. Sir James Chadwick has put a period *of 10 to 12 years as the development time for peace purposes. The energy output is so enormous in comparison with fuel that it is certain that man will develop it. EFFECT IN WAR. The assessment of the present position demands that there be full realisation of the hideous possiblities latent in the new discoveries. The new explosive can replace the old in any of its various uses—it is limted only by the necessity that the explosion be a large one! Special methods are needed, but these are known, and can be # applied in any o!f the ordinary explosive devices of war shells, mines, torpedoes, bombs, etc. ..

The power of the explosive is on a totally different scale—some million times as large. This must be'emphasised—in one act.of discovery the devastating power has been raised to an enormously higher level; where the older bombs destroyed acres, the new ones destroy square miles. The effect in submarine explosions for production of "tidal" waves, or in boring bombs for " earthquake " ' action has not yet been published, if investigated, but sufficient is known to be able to prophesy terrible action on waterfront regions and on ordinary underground shelters. The relatively light explosive can be utilised with great advantage in long-distance rocket bombs, and forms a light load for bombers so that their effective range is increased while, if atomic energy can be used in engines of the future, their range will be completely global. POISONING OF AREAS. There is a further horrible possibility. By the use.of the pile, large quantities of new radio-active materials can bs made, some of which are gasses. These materials* give off dangerous rays like radium, and this creates a possibility of radio-active attack by the liberation of such matter over enemy country. The result would_ be the "poisoning" of areas for periods of months or years, depending on product used, and this possibility was serious enough for the atomic physicists m America to consider it as a danger and plan counter-measures. What these were has not been revealed, but, although detection would be easy, removal of the radio-activo matter would seem to be exceedingly difficult, It would form an invisible film on everything, be harmful to life, producing at least anaemia, at worst forms of cancerand internal complaints. [ln his second and concluding article, to be published to-morrow, Professor Burbidge discusses counter-measures.]