SUMMARY OF ECOLOGY PROBLEMS I have tried to show, in a general way, and in an ecological frame of reference, the types of damage which may occur following a nuclear attack. The threats of large-scale fires, erosion, and radiation have been pointed out. Detailed biological and local geographical data must be compiled and then related to particular types and levels of attacks. Much information exists already and needs only to be collected. How much additional experimental and field research will be needed remains to be seen. Selective concern for those forms of life most needed for our survival should be examined first. Coincidentally, those forms which may become unmanageably destructive pests, such as insects, rodents, and weeds, should receive early priority for study. Radioecology is the qualitatively new consideration. The comparative radiosensitivity catalog must be enormously increased. The combined efforts of land-management experts, engineers, agriculturists, radiobiologists, and others, will be needed to define and handle the complex problems raised by extensive damage to the biosphere from fire, radiation, and the concatenated consequences. Thank you. Mr. HOLIFIELD. Thank you, Dr. Mitchell. Any questions, Mr. Roback? DISTRIBUTION OF STRONTIUM 90 Mr. ROBACK. This discussion of strontium 90 is based on the sup position that the fallout is a homogeneous hazard, that is, that the hazard is the same wherever the radioactive material is deposited. Is that right? Dr. MITCHELL. It is both homogeneous and nonhomogeneous. Mr. ROBACK. What I am asking about is this: Isn't it the case that the strontium 90 deposition usually occurs much further away from the point of explosion, as in worldwide or delayed fallout? Dr. MITCHELL. I would say the bulk of the strontium 90, percentagewise, will come within our local fallout pattern areas. This would be my impression. And that the subsequent worldwide fallout, coming down much more slowly-well, what would you say the division is, Dr. Hill, between the two? Dr. HILL. As far as total fallout is concerned, oh, on the order of 80 percent or more would be local fallout, but there is the problem of fractionation which I think Mr. Roback was referring to. However, the local fallout areas would still be the most substantially contaminated with strontium 90 even so. Mr. HOLIFIELD. I think the information we had before our Atomic Energy Committee does not quite agree with that. As I remember, about 75 percent of the fission products went into the stratosphere and only 25 percent was deposited locally. The other 75 percent came down later. Dr. MITCHELL. Yes; but that would be spread over thousands of unit areas. Mr. HOLIFIELD. That is right. Dr. HILL. There are good reasons for that, because most of our shots or a large percentage of our shots were not surface burst, in the test series. That is the main reason for that. Mr. ROBACK. Well, Mr. Chairman, I was not referring to total estimates of distribution worldwide as against local fallout, but I was referring to the fact that the composition of the radioactive elements or the radioactive production, you might say, after an explosion is such that not everything is affected the same way. There are materials which have different volatilities and rates of condensation. Strontium, being highly volatile, condenses more slowly, and since radioactive elements are taken up more efficiently by carrier material (dust and debris) offer condensation from the gaseous state, it could well be that particles which fall far downward or in worldwide fallout contain more strontium than closein fallout. Dr. MITCHELL. Not per unit area, sir, which is what we are interested in. In other words, even if there were and I do not know what the numbers are some really wide discrimination-let us say, 10 percent coming down in the target area and 90 percent going up into the stratosphere, distributed worldwide then the amount which would then come back and fall on the United States over the local area, would still be only a small addition per unit area. In other words, it would be the local fallout problem which would probably determine the effect on our agriculture in that area. For an area that escaped completely and was out of the local fallout area, then the contribution from the strontium in the worldwide distribution would be significant there. Mr. ROBACK. Is it conceivable in some circumstances that it might be important or less hazardous to do agricultural work closein rather than far away? Dr. MITCHELL. I cannot conceive of it; no. Mr. ROBACK. You cannot conceive of it? Dr. MITCHELL. No. Mr. ROBACK. We will discuss that at a subsequent point. Mr. HOLIFIELD. Any other questions? Mr. ROBACK. No. Mr. HOLIFIELD. Thank you, sir. STATEMENT OF DR. JERALD È. HILL, RAND CORP. Mr. HOLIFIELD. Proceed, Doctor. Dr. HILL. I will state my background first. I have a B.S. degree from Western Michigan University, an A.M. degree from the Ůniversity of Michigan, and a Ph. D. degree from the University of Rochester-all in physics. I taught physics for 7 years. I was a postdoctorate Westinghouse research fellow and a research physicist at research laboratories of the Westinghouse Electric Corp. I attended the first postdoctorate course in atomic energy at Oak Ridge National Laboratory following World War II and worked as a research physicist there. Since 1948, I have been employed by the RAND Corp. where I have specialized in the area of nuclear weapon effects and technology. PROBLEMS OF FIRE IN NUCLEAR WARFARE INTRODUCTION Mr. Chairman and members of the committee, I welcome the opportunity to discuss briefly with you the possible impact of fire in the unfortunate event of a nuclear attack on the United States. Let me state at the outset that the opinions I express are my own and do not represent any official position of the RAND Corp., where I am employed. Also my remarks are based on a study which has been in progress for only a few weeks and is not yet complete. Furthermore, my field of specialization is nuclear physics and while I have been concerned with the effects of nuclear weapons for a considerable part of the past 12 years, I make no claim to being an expert in the field of fire protection or prevention. I also wish to emphasize that all my remarks are unclassified. GENERAL CONSIDERATIONS However, as the study has progressed, I have become increasingly convinced that, while fire damage which might be caused by a nuclear attack on the United States could be very serious, it need not be catastrophic in the sense of preventing postwar recovery from rather heavy nuclear attacks. Furthermore, I am convinced that there are many actions which could be taken before such an attack that would greatly reduce the fire damage inflicted. In addition, if appropriate plans and preparations are made beforehand, many things could be done after the attack to minimize the long-term undesirable consequences of the fire damage which might be experienced. Concern has been expressed that fire from nuclear attacks on various targets might spread far beyond the area of serious damage from blast, thus mutiplying the area of destruction many times and that free-running fires would spread through forest and grasslands which would burn over such wide areas that the ecological consequences of soil erosion and floods might make postwar recovery impossible. The problem of estimating fire damage from hypothetical nuclear wars involves many difficulties and uncertainties. In very general terms, the procedure would involve making assumptions about the enemy choice of time and targets for attack and the number, yield and altitude of burst of weapons delivered on designated ground zeros. These assumptions would be much the same as have been made in previous studies of the effects of blast and fallout, except that one would have to decide whether or not forest and grasslands would constitute a primary target subsystem to which enemy weapons would be assigned or be regarded as a bonus from attacks on other targets such as urban areas or military installations, et cetera. To estimate the fire damage, assumptions about a number of additional factors become important. Among these are: meteorological factors such as wind velocity, temperature, relative humidity, visibility, lapse of time since the last precipitation and presence or absence of inversion layers and cloud cover in the target area; fuel characteristics such as types of combustible materials, their surface density, uniformity of distribution and moisture content; topography, geometrical form, and degree of built-upness in the target area; and finally numbers and distribution of sources of primary and secondary ignition from thermal and blast effects. The problem of estimating areas within which initial ignitions would occur for given weapon and target characteristics is relatively straightforward, but estimating the spread of fire from these initial ignitions is much more difficult. Thus far our study has not progressed to the stage of evaluating fire damage for complete nuclear campaigns, but work has been aimed at understanding the significance and interaction of the various factors outlined above. One of the most important facts to realize is that in an area as large as the United States, not all of the factors influencing the ignition and spread of fire would be at their worst extremes all over the country during the short period of time required to deliver a nuclear attack. For example, the seasonal periods of worst fire danger are different in different areas of the country and the overall conditions can vary marketly from year to year which means that careful study of the variations of these conditions for various climatological areas over long periods of time should be evaluated statistically. For example, southern California, Nevada, and parts of Arizona have experienced extreme drought for the past 3 years, but large regions in Texas have had such excessive rainfall this year that crops are being severely damaged. Similarly, the normal periods of maximum fire danger in parts of Maine are July, August, and September, while in parts of Florida, Alabama, and Mississippi the period from October to March is the most dangerous. Also in the coastal region of southern California during the months of July and August when virtually no rain falls, even in normal years, there are almost daily foggy periods which would tend to limit the areas of initial ignition and the degree of fire spread in the event of a nuclear attack during such periods. One could multiply these examples for each of the factors influencing fire damage showing wide variations in time and place. The implication is clear that an exaggerated, misleading picture will be obtained unless average conditions are considered as well as extremes. FIRE DAMAGE IN URBAN AREAS Since the only experience with fire damage from actual nuclear attacks resulted from the bombings of Hiroshima and Nagasaki, it is instructive to examine the conditions at the time of these attacks and the resulting fire damage. Table H-1 summarizes the bombing data, meteorological conditions and target characteristics at the time of the atomic bomb attacks on Hiroshima and Nagasaki. TABLE H-1.-Significant target parameters in the atomic bomb attacks on Hiroshima and Nagasaki Date Time of Day Weapon Yield Ground Zero Altitude of Burst Visibility Cloud Cover Number of Days Since Climate Surface Winds at Time of Detonation Temperature Densely Built-up Area Geometrical Shape of Builtup Area Topographical Features Builtupness of Damaged Predominant Structural Warm, Sunny Summer Broad, fan shape, Flat, split into 5 Residential Light Wood It is significant to note that the bomb yield, altitude of burst, meteorological conditions and target fuels were very similar in the two cities at the time of the attacks. The major differences were the positions of the ground zeros relative to the more densely built-up areas of the cities, their geometrical shapes and their topography. |