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New Zealand Listener, Volume 30, Issue 768, 9 April 1954, Page 6

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HE Japanese fishermen who were caught within the penumbra of the hydrogen bomb explosion at Bikini last month themselyes set upa shock-waye which circled the world, shook the windows of Cabinet rooms and. chancellories, and raised perplexing questions in the minds of everyone. The comments which we print below are the result of an attempt to find answers to these questions. Some can be answered reassuringly, a few (at this stage at least) cannot be answered at all, m hy only breed more questions. Ot SS a ee ee ae ee 3 Pale

ttt N the early morning of March 1 scientists of the U.S. Atomic Energy Commission exploded a thermo-nuclear bomb on an unnamed island in the Bikini-Eniwe-tok test area. A Marine corporal Who saw it, wrote, "The sky lighted up, a bright orange, and remained that way for what seemed like a couple of minutes." Japanese fishermen mistook it for an unusual sunrise-till they noticed the "sun" was in the west. ‘ As the ‘debris settled and the lighter, wind-borne ash moved outward, a number of disquieting facts began to emerge: The Atomic Energy Commission admitted that the explosion had been considerably greater then anticipated. Unofficial sources estimated it as between 500 and 600 times more powerful than the Hiroshima bomb, and between three and five times more powerful than the first hydrogen bomb éxploded in November, 1952. On March 11, AEC announced that 236 natives and 28 Americans had been unexpectedly exposed to radio-activity during the test. Their exposure was ten times greater than scientists consider safe, but they were reported not to have suffered burns. The 100-ton fishing craft Daigo Fukuryu Maru returned to its home port on March 14 coated in whitish ash. All 23 of its crew suffered burns and Tadiation sickness. Two were in a serious condition. At the time of going to press they were reported to be improving. The vessel was said to have been 70 miles from the centre of the explosion. Three other Japanese fishing craft and the tanker Patapsco were reported to have been exposed to lesser degrees of radio-activity, but their crews were apparently unharmed. One of the vessels,.the Shunyo Maru, was believed to have been operating 600 miles from the testing grounds, and to have. passed through an ocean current carrying radio-

active ash. Another was said to have been no .closér than 1200 miles. The cargo of a third, the Sumiyoshi Maru, was found to be contaminated, though not to a dangerous extent. The U‘S. Government increased the danger zone in the vicinity of Bikini to about three times its former size, extending it to 450 miles in each. direction in which winds normally blow at this time of year. The total area will be up to 315,000 miles. A member of AEC, Mr. C. Holifield, blamed unpredictable upper winds for the distribution of ash in the March 1 test. According to the American news magazine Time the results of the latest nuclear bomb test forced AEC to reclassify its previous test of November, 1952, as a misfire. The fireball of this "misfire" was reported to have been 28 miles in diameter, its force equal to that of 5,000,000 tons of TNT. The mushroom cloud extended to 90,000 feet.

An observation aircraft at 30,000 feet, 50 miles distarit, had to turn and run to avoid being caught under the lip of the mushroom. Scientists at Kyoto University, Tokio, reported a jump in their cosmic ray count from a normal of 40 to 50 to a peak of 225, two days after last month’s explosion. This was higher than any previous reading obtained after a bomb test, either Russian or American. MISCALCULATION NOT LARGE | COKING for elucidation of these reports, The Listener spoke first to C. N. Watson-Munro, Professor of Physics at Victoria University College. He appeared not unduly concerned at the extent of the error in calculation attributed to the scientists. "Assuming the reports to be true," he said, "a four times stronger bomb would have only a 50 per cent greater effect. The straight radiation would increase by 100 per cent, but the radiation from fission products near thé bomb, carried by the air, would not increase so greatly." If such an error of calculation could be made, the professor was asked, could the scientists also be wrong in their assurance that a chain reaction was impossible? "No," he said. "One is an error of degree, the other would be an error of kind. We could not achieve the intensity necessary to make a miniature sun of the earth. Besides, a miscalculation of factor four is not large. There are some things in nuclear physics in which we would like to achieve an accuracy equal to a mistake of four times." The professor discounted the suggestion that radio-active ash reportedly falling on Japan would be sufficiently active to be harmful. The increased’ activitv recerded by cosmic tay equipment at Tokio was similar to that which wou!d occur if the equinoment were moved to the summit of Mt. Everest.

"But there is no doubt that the dust can be nasty, and no doubt that it could be very harmful to eat radio-active’ fish. The material cannot ‘be assimilated ‘and finds its way into the bone structure. Fortunately, it’s easy to monitor suspected fish before eating." According to Profes3or Watson-Munro the: widespread éffects of the March 1 explosion were probably due to. unexpected weather couplel with the fact that a greater blast may have carried dust to heights not foreseen by me*éorologists. "A normal A-bomb cloud goes to about 35,000 feet..One 600 times that power may well go to over 100,000 feet." From the reports, he said, the dust which reached Japan appeared to have travelled slowly by comparison with that which reached New Zealand. after the Australian test. This had arrived’ over Wellington some 18 hours after the. ex-plosion-at an average speed of about 60 miles per hour. Asked whether statements. of the destructive potentialities of the so-called cobalt bomb were true or exaggerated, the professor said he thought them exaggerated. "An enormous amount of cobalt would be required to spread all over the earth. There is. probably not as much as that available." On the moral issues raised by atomic weapons, Professor Watson-Munro drew attention to the following statement of David Lilienthal, one-time chairman of AEC. In his book This I Do Believe, Lilienthal wrote: "If the myth that atomic energy is simply a _ military weapon becomes a fixed thing in’ our minds, if we accept the error, it can never be anything else but a weapon. . . The myth will cause us to fall into an even deeper pit of error. We will grow forgetful of the true sources of democracy’s vitality and the true’ source of our nation’s strength. We will’ be misled into believing that America is strong because of military strength (continued on next page)

(continued from previous page) alone, when in*truth, the foundation of our Strength and amazing vitality is not in material things, but rather in the spirit »of this nation, in the faith we cherish." WINDS AND WAVES O inquire into the weather conditions bearing on the recent test at Bikini, The Listener visited Dr. J. F. Gabites, of the N.Z. Meteorological Service. Dr. Gabites said no information was available about the weather conditions on March 1, but the winds in the test area would be known up to 60,000 feet, and possibly up to 100,000, In the lowest 5000 feet there was a marked predominance of east to north-east winds, but whatever their direction on the day of the explosion their part in distributing ash would proBably be mainly local. The winds at higher levels were far more variable, and winds from no particular direction predominated. Calculations as to thé direction in which ash would be carried could be upset by the material being thrown higher than expected. According to Dr. Gabites, the Pacific test area lies in the path of the North Equatofial Current. Any deposit on the sea would be likely to travel west with the current at an average speed of 15 nautieal miles per day. The main current Ts | as it nears the Philippines d vels along the coast of Japan, but mts of it are thought to turn south atthe same point. It was possible, but extremely unlikely, that it eventually touched New. Zealand at some points. "The contrast between water-borne and air-borne dissemination of radioactive debris is a question of time," said D. W. McKenzie, of the Geography Department, Victoria University. "It is possible for the spread of air-borne dust to be very quick if it gets into the highaltitude rapidly-moving westerly air of the jet streams which circulate in both hemispheres at altitudes around 30,000 feet and at speeds up to 400 miles an hour.’ The Marshall Islands, however, lie across 10 degrees north in a latitude farther south than the movement of the jet Stream as so far mapped, and radioactive dust can get into the jet stream only by mixing from turbulence on the margin. ‘of equatorial air, which is a slow process: However, knowledge of jet stream movement is far from complete,

for it seems evident that the volcanic dust. of the great eruption of Krakatoa in 1883 did reach the jet streams, because it circulated several times around the world. Krakatoa is no further south of the equator than the Marshall Islands are north, and though jet stream movement does differ in each hemisphere meteordlogists today would hardly anticipate the way the dust of Krakatoa circulated, "There seems to be no mechanism by which the radio-active dust from the March 1 explosion could have‘ reached Japan, and most definitely none by which it could .reach as far south in this hemisphere as New Zealand. "The contamination of water and the things that live in it must again be offset against the slow movement of water masses. Under the conditions of ,natural movement the water in ocean currents, which passes the Marshall Islands from the east at speeds varying from ten to fifteen miles a day, will take a long time to disseminate radio-activity widely. But where a man. short-circuits this by taking fish from contaminated water, as did the Japanese fishermen recently, he finds himself in trouble at once. How long radio-active plankton* will maintain its dangerous condition, and pass this on to the chain of life that depends on it, only the physicist and the biologist can tell us.. The American proposal to declare an area of over 300,000 square miles dangerous is looking very different ‘from the conditions of -the first Bikini explosion, placed as it was on the most remote atoll available. This 300,000 square miles is in an area in which Japanese fishermen regularly work, and the only international law operating seems to be the one which says, ‘The larger my fist, the further you must stay away from it.’ It is to be hoped the owner of the fist knows enuvugh about. its powers to keep it from poking its finger in the world’s eye." Acquired radio-activity has been demonstrated in both fish and plankton, according to L. R. Richardson, Professor ***Plankton" is the name given to the small drifting organisms which form the basic food of free-swimming animals in the sea, or other waters.

_ of Zoology at Victoria College. There had been several cases of fresh water fish being affected by the accidental discharge of waste from atomic plants. Large doses. of radiation would, of course, be lethal, he said, but the genetic effects of lesser doses were not known. From information reported to date, said Professor Richardson, the test explosion had brought with it no disaster for sea life on the scale of the "Red Tide" -experienced off the coasts of Texas and Florida in the thirties. The "tide" consisted of a reddish planktonic organism toxic to fish, and was estimated to have destroyed 400,000,000 fish in a short period. "We would surely have heard," he said, "if there had been _any destruction on this scale as a result of the bomb." TESTS NECESSARY? SKED if scientists consider the con- " tinuation of experimental atomic explosions is strictly necessary, Professor PP. W. Burbidge, head of the Physics Department at. Auckland University College, said: "This is not a matter for scientists in general. As things are, a ballistics war weapon is being tried out, and it is presumably necessary to do so to check details of laboratory calcula- tions and to discover how the weapon may be used. The explosions are of general scientific interest only to the extent of the publication of their results to give evidence of particular phenomena. But, of course, little is published." Speaking of possible risk of contamination, Professor Burbidge said the tests. should be carried out where the risk to inhabited regions was the smallest possible. "One thinks naturally of such places as the polar regions. There is not sufficient evidence yet to say there .is no risk. We have a right to hear the

_- ----4 | evidence, and there should be authoritative pronouncements made to cover the possible biological danger to human beings, to animals and to crops. "In general, however, the air and sea circulations are ‘such as to remove hazard to ‘New Zealand’s main islands arising from atomic explosions in such places as Monte Bello and Bikini. The distances that any radio-active’ material would have to travel are huge, the dilution large, the decay rapid, and the prevailing movements of air and water unfavourable to their movement towards " us. Professor G. C. J. Dalton, Professor of Mechanical Engineering at Auckland University College, who worked at the Harwell Atomic Energy Research Establishment before coming to this country, told The Listener that so far as New Zealand is concerned there is no danger at all from contamination by radio-active materials. "Radio-activity can be very readily detected -in minute quantities, but the normal person who has had an X-ray examination has been subjected to much more radio activity than we are ever likely to experience here from the experimental explosions," he said. "I believe the tests will do a great deal of good, if they serve to wake up the politicians to the power of this new. force. There is certainly nothing in the whole thing yet likely to cause trouble on a world scale, however."A much more serious problem arises from the need to dispose of the continuously produced byproducts of atomic energy applied to peacetime purposes. Casualties caused by atomic research so far can be re garded as almost negligible when compared with the deaths and injuries inflicted in more mundane pursuits, such as testing new aircraft, or even when compared with the normal daily risk of being run over on the street."