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The Medical Implications of Nuclear War, Institute of Medicine. ~ 1986 by the National Academy of Sciences. National Academy Press, Washington, D.C. Possible Fatalities from Superfires Following Nuclear Attacks in or near Urban Areas THEODORE A. POSTOL, PH.D. Stanford University, Stanford, California INTRODUCTION During the period of peak energy output, a 1-megaton (Mt) nuclear weapon can produce temperatures of about 100 million degrees Celsius at its center, about four to five times that which occurs at the center of the Sun. Because the Sun's surface is only about 6,000C and it heats the Earth's surface from a range of more than 90 million miles (about 145 million km), it should be clear that such a nuclear detonation would be accom- panied by enormous emanations of light and heat. So great is the amount of light and heat generated by a 1-Mt airburst, that if one were to occur at a high enough altitude over Baltimore, observers in Washington, D.C., might see it as a ball of fire many times brighter than the noonday Sun. Even if such a detonation were to occur near dawn over Detroit, out of line of sight because of the Earth's curvature, enough light could well be scattered and refracted by atmospheric effects for it to be observed as a glare in the sky from Washington, D.C. This intense light and heat from nuclear detonations is capable of setting many simultaneous fires over vast areas of surrounding terrain. These fires, once initiated, could efficiently heat large volumes of air near the Earth's surface. As this heated air buoyantly rises, cool air from regions beyond the vast burning area would rush in to replace it. Winds at the ground could reach hurricane force, and air temperatures within the zone of fire could exceed that of boiling water. 15

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16 PHYSICAL EFFECTS AND ENVIRONMENTAL CONSEQUENCES The ferocious hurricane of fire would also be accompanied by the release of large amounts of potentially lethal toxic smoke and combustion gases, creating an environment of extreme heat, high winds, and toxic agents in target areas. Although the smoke from these fires has been the subject of considerable attention, as it is possible that significant climate effects could result from its sudden injection into the upper atmosphere, there has been no com- prehensive evaluation of the implications of these fires for those in target areas. In this paper, the potential implications of these fire environments on casualty estimates is assessed. The standard model for calculating deaths and nonfatal injuries from hypothetical nuclear attacks assumes that the same casualty rates will occur at each level of blast overpressure as that which occurred at Hiroshima. This methodology, which will henceforth be referred to as blast elect, or simply blast scaling, is the standard methodology used by government agencies to estimate casualties in nuclear war. The preliminary analysis presented in this paper indicates that if fire effects are included in assessments of possible fatalities from nuclear attacks using megaton or near megaton airbursts in or near urban areas, about two to four times more fatalities might be expected relative to those which might be expected from blast scaling calculations. This enormous increase in projected fatalities is partly a result of the very large expected range of superfires, which would extend well beyond that in which large numbers of blast fatalities would be expected, and partly because of the high lethality in the blast-disrupted and fire-swept environments within the burning region. The very great uncertainties in the speculated differences between blast and fire scaling are due to the great uncertainties in the radius of the potential fire zone, as well as to uncertainties in the exact nature of the environments within these zones. Another feature that emerges from the analysis is that the projected number of injured requiring medical treatment would be drastically re- duced relative to that projected by blast scaling, as many injured that would otherwise require treatment would be consumed in the fires. This is consistent with the findings of German review commissions which were set up during World War II to evaluate the effects of large-scale incendiary raids against their cities and with the findings of the U.S. Strategic Bombing Survey after World War II.2 Both reviews found that the ratio of fatalities to injuries was much higher when the effects of incendiaries, rather than high explosives, was the major source of damage from air raids.

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POSSIBLE FATALITIES FROM SUPERFIRES 17 In this paper, the following will be discussed. First, the blast and incendiary effects that would accompany the detonation of a 1-Mt airburst will be described. A baseline estimate of the radius of potential incendiary effects from the airburst will then be established; and the distinctive char- acteristics of the resulting giant area fires, high winds, and unusually high average air temperatures will be described. Evidence is presented to show that contrary to what has been previously believed, 3-5 attacks on lightly built-up, sprawling American cities, where the amount of combustible material per unit area is relatively low, could well result in extreme con- ditions somewhat comparable to those of the firestorms experienced in Japan and Germany during World War II. Estimates of noxious gas con- centrations then will be made using data presented in the previous section, and it will be shown that the combination of these toxic agents within the fire zone are likely to be lethal to all unprotected individuals. Anecdotal and medical observations from World War II firestorm experiences will be reviewed, and a very crude cookie cutter model will be discussed. It is argued that more sophisticated models are unjustified in view of the large uncertainties in possible fire radius but that the simplicity of this model still allows a preliminary assessment of the importance of fire effects. The currently standard blast effect scaling method will be reviewed and compared and contrasted with the fire effect scaling method. Projec- tions of casualties using both blast and fire scaling will then be presented for airburst antipopulation attacks. This establishes a reference case for the comparison of casualty projections by both methods and for different target sets. It will be shown that blast scaling may underestimate fatalities from airburst attacks in or near urban areas by factors of about two to four. Casualty projections are then compared for the antipopulation ref- erence attack and a very limited anti-industrial attack, which is not de- signed to kill large numbers of people. However, the inclusion of superfires in casualty predictions indicates that this more limited attack might actually result in about two to three times more fatalities than that predicted by the government for the antipopulation attack. This serves to underscore the need for a better understanding of these weapons effects. INCENDIARY EFFECTS OF NUCLEAR WEAPONS In this section, the events associated with the detonation of a 1-Mt airburst are described. Because the weapons' effects of interest here, blast and thermal radiation (heat emanating from the fireballs, do not change dras- tically with yield and because many of the weapons in today's arsenals are of comparable yield, this discussion will provide background infor

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18 PHYSICAL EFFECTS AND ENVIRONMENTAL CONSEQUENCES mation that will allow the reader to construct a picture of an urban target area following a nuclear attack. When a nuclear weapon is detonated, an enormous amount of energy is released in an extraordinarily short interval of time. Nearly all of this energy is initially released in the form of fast-recoiling nuclear matter which is then deposited into the surrounding environment within hun- dredths of millionths of a second. Unlike a comparable chemical explosion, in which almost all the ex- plosive power is in expanding gaseous bomb debris, more than 95 percent of the explosive power is at first in the form of intense light. Since this intense light is of very short wavelength (it is soft x-rays), it is efficiently absorbed by the air immediately surrounding the weapon, heating it to very high temperatures creating a "ball" of fire. Because the early fireball is so hot, it quickly begins to violently expand, initially moving outward at several millions of miles per hour while it also radiates tremendous amounts of light and heat. This rate of expansion slows rapidly, and by the time the fireball begins to approach its maximum size, its average speed of expansion is no more than 5,000 to 10,000 miles/in (about 8,000 to 16,000 km/h). During the course of its expansion, almost all of the air that originally occupies the volume within and around it is compressed into a thin shell of superheated, glowing, high-pressure gas. This shell of gas, which continues to be driven outward by hot expanding gases in the fireball interior, itself compresses the surrounding air, forming a steeply fronted luminous shock wave of enormous extent and power (see Figure 1A). By the time a 1-Mt fireball is near its maximum size, it is a highly luminous ball of more than 1 mile (1.6 km) in diameter. At 0.9 second after detonation begins, it is at its brightest. Its surface, which masks the much hotter interior of the fireball from the surroundings, still radiates two and a half to three times more light and heat than that of a comparable area of the Sun's surface. By taking into account atmospheric attenuation (12-mile About 19.3- km] visibility), at a distance of 6 miles (about 9.7 km), it would be 300 times brighter than a desert Sun at noon; and at 9 miles (about 14.5 km), it would still be 100 times brighter. Thus, extensive fire ignitions would accompany such an airburst over an urban/industrial area. Figure 1 shows the development of a 1-Mt airburst detonated at an altitude of 6,500 feet (about 2 km) at five distinct points of time during the process.6 At 1.8 seconds (Figure 1A), the fireball is no longer expanding very rapidly, although it is still like a giant luminous and buoyant bubble in the Earth is atmosphere. It has already passed the time of maximum bright

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POSSIBLE FATALITIES FROM SUPERFIRES 19 ness, and the shock wave has broken away from it, already reaching a range of more than 0.5 mile (about 0.8 km) from its point of origin. When the primary shock wave from the explosion reaches the ground (see Figure 1B), a secondary shock wave is generated by reflection. The primary and secondary shock waves then propagate outward along the ground, forming a single vertical shock wave called the reinforced Mach front (see Figure 1C). The overpressure in this shock is roughly twice that of either the primary or the secondary shock. By judicious choice of height of burst, it is possible to maximize the area over which this Mach front delivers a predetermined level of destruc- tive overpressure. For the choice of burst height in this example, the area over which 15 pounds per square inch (psi) or more occurs has been . . maxlmlzec .. Figure 1C shows the situation at roughly 11 seconds after detonation. The shock wave would be about 3 miles (about 4.8 km) from the point on the Earth's surface over which the detonation occurred (this point is called ground zero), and the peak shock overpressure would be 6 psi. In the next 5 seconds, the shock would reach a range of 4 miles (about 6.4 km) and decay to a peak overpressure of 5 psi. Figure 2 shows the sequence of events as they might occur at a wood frame house at a distance of 4 miles. Since the shock wave would take 16 seconds to arrive at the 4-mile range, when the detonation begins, a bright flash of growing intensity would be observed at the house within tenths of seconds. Because the shock wave would take a long time to arrive, this is the only initial indication of a detonation (see Figure 2A). Hence, sounds and noise levels around the house, at least at this moment, would be relatively unaltered. The fireball, of course, continues to grow in brightness. Within 1 sec- ond, it is at its maximum brightness, appearing 800 to 900 times brighter than a desert Sun at noon. The tremendous rate of arrival of radiant power would result in the effusion of black smoke from the front of the house, as paint would be burned off the wood surfaces (see Figure 2B). If the building has interior household materials in it, and they are in the line of sight of the fireball, they would explode into violently burning fires almost instantly. Fifteen seconds after the peak in the thermal pulse, the shock wave arrives (see Figures 2D, 2E, and 2F). Unlike a shock wave of comparable peak overpressure from a high explosive bomb, which persists for about 0.1 second as it passes, this shock wave persists for nearly 3 seconds. As a result, it is accompanied by winds of more than 150 miles/in (about 241 km/h). The shock wave therefore would first strike the building and then envelope it in a region of high-pressure air and high winds. The building

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20 PHYSICAL EFFECTS AND ENVIRONMENTAL CONSEQUENCES A 1 MEGATON AIR BURST-1.8 SECONDS ~ Nuclear and Thermal Radiation /~ Fireball A/ Primary Blast Wave Front 1 Mt I I I I I I I Miles 0 1 2 3 4 5 6 B 1 MEGATON Al R BURST-4.6 SECONDS /: aft:: : X~' ,' Nuclear and Thermal Radiation / ~ Primary Blast Wave Front , Reflected Blast Wave Front 0~ t/C/ommencementof Mach Reflection \~ ~1~/ Overpressure 16 psi A.. ~ 1 Mt I I I I I I I Miles 0 1 2 3 C 1 MEGATON AIR BURST-11 SECONDS / / ~ ........ , ................................. ~ .~ Wind Velocity 180 mph A....... Nuclear and Thermal Radiation an\/ Primary Blast Wave Front Reflected Blast Wave Front Mach Front ~ Overpressure 6 psi AL = ;= _ ~3 1 Mt ~ I I ~ I I Miles 0 1 2 3 4 5 6 FIGURE 1 The sequence of events for a 1-Mt airburst detonated at 6,500 feet (about 2 km) altitude are shown in A through E. This altitude maximizes the range from ground zero at which the primary and secondary shock waves coalesce

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POSSIBLE FATALITIES FROM SUPERFIRES D Rate of Rise 1 Mt 250 mob 1 MEGATON Al R BURST-37 SECONDS : - - Reflected Blast Wave Front _ ~ \ it, Nuclear Radiation r'''''a'Y clan \ \ , Wave Front \, of Bomb Resiclue |~ Mushroom Stem Mach Front | Overpressure 1 psi ~ Afterwinds Wind Velocity 40 mph ~ I - ~= 1 Mt r I I l ' ~ ' ~ Miles 0 1 2 3 4 5 6 7 8 9 10 l 1 Mt-Total Thermal Radiation 30 20 8 5 cal/sq cm r E Rate of Rise 1 Mt 130-170 mph Radioactive Cloud 1 MEGATON Al R BURST-1 10 SECONDS Wind Velocity 1 Mt 275 mph b~ ~AftenNinds 1 Mt r I I ~I ~ Miles 0 1 2 3 4 5 6 7 8 9 10 21 to give a 15-psi peak overpressure on the ground (see text). By adjusting the detonation altitude to 11,000 feet (about 3,353 m), the 5-psi distance could be increased from 3.8 to 4.3 miles (about 6 to 7 km), but the 15-psi range would shrink to near zero. Source: Glasstone (19621.6

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- ~ :: PHYSICAL EFFECTS AND ENVIRONMENTaL CONSEQUENCES FIGURE 2 The sequence of prompt nuclear effects as observed at a range of about 4 miles (about 6.5 km). Light from the fireball begins to illuminate the structure a few tenths of seconds after the detonation (A). As the brightness of the fireball increases (B), the front of the house gives off a thick black smoke as paint is burned off by the heating action of the very intense light. After the paint is burned off, the house is bathed in light of decreasing intensity as the fireball rises and cools (C). About 16 seconds after the detonation, the shock wave arrives (D). As it propagates across the building, the front wall begins to cave in, and tiles are stripped from the roof. When the building is completely engulfed by the passing shock wave (E and F), the high pressure that now surrounds the building crushes the structure, and the high winds cause further damage to the building as it collapses. Source: Glasstone and Dolan (1977~3 and Glasstone (19621.6

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POSSIBLE FATaLITIES FROM SUPERFIRES 23 _ _ . _a~ __ - ~ I_ ad_ ICY -

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24 PHYSICAL EFFECTS AND ENVIRONMENTAL CONSEQUENCES thus would be simultaneously knocked down and crushed as the shock wave propagates past. Figures 3A and 3B show typical urban residential structures that have been subjected to overpressures of about 5 psi from nuclear bursts at the Nevada Test Site. Because these structures were constructed to study the effects of blast, precautions were taken to prevent them from burning. The exteriors were painted white to reflect rather than to absorb light from the fireball, windows facing the explosion were equipped with light-re- flecting aluminum finish, metal Venetian blinds, and roofs were made of light gray asbestos cement shingles. Also, there were no utilities (gas lines, electric lines, stoves, etc.) that could be sources of secondary fires from blast effects. Of course, if fires from thermal and secondary blast effects had been allowed to initiate in these structures, they would clearly burn with great or. ~ eruclency. It would take 37 seconds from the time of detonation for the shock wave to reach a distance of about 9.5 miles (about 15.3 km). At this distance, 35 to 36 seconds before its arrival, the fireball would be about 100 times brighter than the Sun at noon. This is bright enough to cause first- or second-degree skin burns on those in line of sight. It is also possible, but much less certain, that some scattered fires could be set in very highly combustible items (possibly some dry grass, leaves, or news- papers, and also interior curtains and other lightweight materials). When the shock wave finally arrives, it will have a peak overpressure between 1 and 1.5 psi, which would knock windows (possibly with their frames) out, along with many interior building walls and some doors (see Figures 4 through 7 and their figure captions). By 110 seconds, the characteristic mushroom cloud will have reached about 7 miles (about 11.3 km) altitude (see Figure 1E). However, from the ground within the target area, it might be difficult to observe, as great amounts of dust kicked up by the blast wave and the accompanying high winds, as well as smoke from the fires initiated by the bright thermal flash of the fireball, could obscure the vision of those inclined to look. For those in the target area who are uninjured or still alert enough to be aware of their surroundings, the drama would not yet be over, as fires would begin to simultaneously develop and intensify over a vast area. The situation in the target area therefore would be one of extremely severe blast damage to a range of 3 to 4 miles (about 4.8 to 6.4 km) from ground zero and very slowly diminishing levels of serious damage out to ranges well beyond 10 miles (about 16 km). Streets would be blocked with debris, water pressure would drop to zero, gas lines would be opened in places, and power would be off. Essentially all windows would have been broken, buildings that were not knocked down would have suffered

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POSSIBLE FATALITIES FROM SUPERFIRES FIGURE 3 The effects of 5 psi of overpressure from a nuclear detonation are shown for two structures (A and B) that are typical of those in the United States. Since the structures were built to study the effects of blast, precautions were taken to minimize the possibility that fires would be initiated by light from the fireball or blast disruption effects. For this reason, neither of the buildings contained utilities of any kind. In addition, the roofs were made of light gray asbestos shingles, and windows facing the blast were equipped with metal Venetian blinds with an aluminum finish. Source: Glasstone (1962~.6

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62 PHYSICAL EFFECTS AND ENVIRONMENTAL CONSEQUENCES A B C 100 80 LL 40 80 z 60 Cal CC 60 20 o 100 .., , ~-. ~1 . , , ~,. ~ .............. Killed + I Injured 2.'...', ''' '''' "'"" " ''""""'""""""""'"" """""""''"' 40 20 o 100 80 60 .............. .. . . .. .......... An.. ~ ................................. . , ~;; _ . ~ ................................... . ~. .......... .......... ...... ....................................... ............................................................. ......... ' ' ' ' "'"""''""". ... . . .. ~, ,. . ............. ...... ......... . . A. : Killed , . . ... . . ~ .... .. .... :::::::::::::: ::::::-::::::::: -:::::::~:::::::::::::::::::::: Hiroshima Deaths: Blast Scaled to Megaton Air Burst U.S. Office of Technology ~ Assessment GZ 2 4 6 8 10 12 14 16 18 DISTANCE FROM GROUND ZERO (km) r . ........ . Hiroshima Casualties: Blast Scaled to Megaton Air Burst U.S. Office of Technology Assessment ' it. ~ ~'~ ~ ~ GZ 2 4 6 8 10 12 14 16 18 DISTANCE FROM GROUND ZERO (km) U.S. Off ice of Technology Assessment 40 _ .................. Injured: 20 _ ~ GZ 2 4 6 8 10 12 14 16 18 DISTANCE FROM GROUND ZERO (km) FIGURE 23 The three graphs show an application of rules used by the OTA to estimate fatalities and injuries from a 1-Mt airburst over an urban area. The solid curve in A shows the assumed probability of death as a function of range from ground zero. The broken curve shows fatality data from Hiroshima scaled by assuming that the probability of death is purely a function of the peak overpressure at each range from the detonation. In B similar curves are shown for total cas- ualties, which is defined to be the sum of those killed and those injured. In C the OTA rules for those injured (but not killed) are shown as a function of range from ground zero.

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POSSIBLE FATALITIES FROM SUPERFIRES 63 The calculations that I performed for the presumed 100-city attack, using first the OTA/DOD rules and then a blast scaling of Hiroshima data, gave identical predictions within a few percent. It is therefore clear that the government rules for estimating fatalities and injures are virtually indistinguishable from blast scaling of data from Hiroshima. Figure 24 shows the range dependence of the government's probability of injury assumptions for a 1-Mt airburst. At selected ranges below the horizontal axis, the overpressure and thermal energy deposited from the fireball of a 1-Mt airburst is shown (12-mile [19.3-km] visibility). Above the axis is the thermal fluence which occurred at a similar overpressure loo 80 60 Cal cr UJ 40 _ 20 _ o t U.S. Office of Technology Assessment 23 car/cm I L 13 cal/cm2 1 ! 7cal/jcm2 3callcm2 Thermal Fluence at Same Overpressure at Hiroshima GZ 2 4 6 8 10 12 14 16 18 8 psi 5 psi 3 psi 2 psi DISTANCE FROM GROUND ZERO (km) 1 45 cal/cm2 1 10 cal/cm2 90 cal/cm2 20 cal/cm2 Thermal Fluence and Blast for One Megaton Air Burst FIGURE 24 Some aspects of the physical environment that could influence the probability of death at different ranges from a ground zero are compared for 1- Mt and 12.5-kt detonations. The solid curve shows the probability of blast injury as a function of range from ground zero derived by applying the OTA rules to the case of a 1-Mt airburst. (These rules are also discussed in the legend to Figure 23 and the text.) The 3-psi range at Hiroshima occurred at about 1.5 miles (about 2.3 to 2.4 km) from ground zero. As indicated on the upper side of the range axis, the amount of thermal radiation delivered along with the blast was about 7 cal/cm2. Individuals subjected to these effects at Hiroshima would not have been in the region of mass fire that occurred after the attack. At the 3-psi range for a 1-Mt airburst, about 20 cal/cm2 could be delivered along with the blast. Many fires would be set at this range, and many additional fires might even be set at much greater range (perhaps at the 12-km range or greater). Individuals injured by the 3-psi blast at the 9-km range might therefore have to walk 3 or more km through a zone heavily damaged by blast and with fires of increasing intensity. By comparison, an injured individual who survived blast and radiation effects at ground zero in Hiroshima would have had to walk less than 2 km to escape the fire zone. It is therefore clear that using blast alone as the criterion for estimating fatalities could well result in a serious underestimate of the probability of death.

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64 PHYSICAL EFFECTS AND ENVIRONMENTAL CONSEQUENCES at Hiroshima. Thus, at Hiroshima, about 12 to 13 calories per square centimeter was deposited at the range at which 5 psi occurred. In contrast, at the 5-psi range for the 1-Mt airburst, about 45 cal/cm2 occurs. Because this environment is created at about 6.5 km from the detonation point and, as shown earlier, it is plausible that a mass fire could rage to a range of 12 km, it appears unlikely that a simple scaling rule of the kind used in the OTA/DOD methodology adequately accounts for the circumstance of those at the 6.5-km range. Figure 25 shows estimates of fatalities and casualties for the 100-city reference case. Blast scaling predicts that there would be 14 million to 15 million fatalities and 22 million to 23 million injured. An alternative postulate, discussed in the previous section, is that su- perfires of uncertain scale would occur, killing all within a range of 6 to 8 miles (9.5 to 13 km) from each ground zero. For the area outside the range of the superf~re, then, it can be postulated that the blast injury rules derived from Hiroshima data apply. Under these assumptions, the number of outright fatalities increases by a factor of between 2.5 and 4, resulting in a prediction of from 36 million to 56 million fatalities, while the number of injured decreases dramatically to between 3 million and 11 million. This is in accord with German experiences during World War II, in which medical surveys determined that incendiary raids always resulted in a much higher ratio of killed to . . nJurec .. The reason for this dramatic change in distribution of fatalities and injuries can be quickly grasped from Figure 23C. The result of the new assumption is that many who would be counted as injured in the blast methodology instead are counted as dead; it also counts uninjured indi- viduals within the fire zone among the dead as well. The only nonfatal injured are therefore those who are injured by the effects of the blast but are outside the perimeter of the superfine. Even though the scale, ferocity, and effects of these superfires are as yet highly uncertain, it is not difficult to test the sensibility of this hy- pothetical casualty estimate. Because the area covered by such fires is proportional to the square of the fire radius, if the average fire radius were to increase or decrease by 10 to 15 percent, the result would be an increase or decrease in the affected area of about 20 to 30 percent. The population density is, to a first approximation, relatively constant for such small changes in fire radius.44 This means that a 10 or 15 percent increase or decrease in fire radius results in about a 20 to 30 percent increase or decrease in predicted fatalities. Thus, the minimum postulated superfire radius used in the calculations

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POSSIBLE FATALITIES FROM SUPERFIRES 80 70 60 50 LL 40 of o ' 30 - 20 10 o 100-Mt ATTACKS Blast /// 8-Mile Fire Radius ,... Blast 8-Mile Fire Radius ~:~ . . . i .............. ....... . . .... .... .~1 ......................... ........... ......... ....... ........ ... ANTI-POPU LATION 65 ANTI-MI LITARY-INDUSTRIAL FIGURE 25 The potential effects of differing assumptions about the causes of fatalities and injures. A reference attack that assumes that a single 1-Mt detonation occurs over the population center of each of the 100 largest metropolitan areas is used to determine the potential significance of differing fatality and injury rules. When only blast scaling from Hiroshima is used to estimate fatalities and injures, about 14 million fatalities and 23 million injured are projected. If it is assumed that mass fires kill everyone within 6 miles (about 9.7 km) of the ground zeros and injures beyond that range occur because of blast at the same rate as that which occurred at Hiroshima, 33 million would be killed and 12 to 13 million would be injured. If the fire zone extends to 8 miles (about 12.9 km) instead, 56 million would be killed and 6 to 7 million would be injured. Similar results are also shown for a reference attack that does not seek to kill population but only attempts to destroy 100 of the most important industrial facilities that would provide military products that could directly support a war effort. summarized in Figures 25 and 26 (6 miles or 9.5 km) would have to be reduced by a factor of somewhat less than the square root of two before predictions of fatalities could be similar to those of blast scaling metho- dologies. High survival rates at a range of about 4 miles (6.5 km) would therefore

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66 PHYSICAL EFFECTS AND ENVIRONMENTAL CONSEQUENCES be required. At this range, however, the thermal fluence from the fireball would be about 45 cal/cm2, which is enough to set almost any interior household material in line of sight of the fireball on fire immediately (Figure 2B shows the emission of smoke from the front of a wood frame house from 25 cal/cm21. If, instead, it is assumed that all those who are not injured by blast could miraculously escape the hostile effects of near-hurricane-force winds and air temperatures above that at which water boils, and only those who are injured according to the blast scaling rules shown in Figure 23C die in superf~res of radius 6 to 8 miles (9.5 to 13 km), then the number of deaths would increase by a factor of around two, to 27 million to 33 million. It is therefore difficult to see how casualty rules that do not include the hostile effects of mass fires over such vast areas can result in projections more plausible than even those that follow from the preliminary specu- lations contained in this study. COMPARISON OF OTHER TARGET SETS WITH THE REFERENCE CASE Daugherty, Levi, and van Hippel44 have made a very complete and uniquely systematic study of possible fatalities and injuries from nuclear attacks against the United States. They have not only systematically ex- amined a wide range of possibilities by varying the assumptions about the biological consequences of given nuclear environments (for example, var- iations in the 50 percent lethal dose [LDso] for radiation exposure) and the behavior of individuals within these environments (how fallout pro- tection factors, and hence casualties, differ if sheltered people make short excursions from their shelters), but they have also examined the potential consequences of plausible variations in the nuclear environment itself (how injury and fatality estimates vary if populations are subject to fires as well as to blast). Furthermore, they have systematically examined the implications of their assumptions for different potential target classes on both an individual and multiply aggregated basis. By doing this, they have created a menu of possibilities from which analysts or decision makers may choose to contemplate, or to reject as implausible, any of a wide range of potential nuclear attacks. This kind of analysis is, so far, absent from studies and results of studies published by government agencies. Two interesting reference cases studied by Daugherty et al.44 are note- worthy:

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POSSIBLE FATALITIES FROM SUPERFIRES 67 1. An attack of 100 single 1-Mt airbursts on 100 U.S. urban centers. 2. An attack of 101 nuclear airbursts on 101 key military-industrial targets. As noted by Daugherty et al., because the first reference case has no areas of overlap from the effects of multiple weapons detonations, the 100-city reference case provides a baseline of analytic interest for com- parison with other cases in their menu of possibilities. In addition, if the reference case is calculated using blast scaling casualty rules derived from data following an attack on a city center (Hiroshima), an unambiguous estimate of the potential significance of fire effects is established. The second reference case is of interest relative to the first since it provides just such a comparative case from their menu. This attack is of interest not only because of its central role in many policy statements and deliberations but also because it does not target population per se. Instead it uses essentially the same number of warheads (101 versus 100) to attack a small number of very-high-value military- industrial end product facilities, and therefore represents what some might argue is a minimal attack that could quickly interrupt U.S. conventional war production capabilities. As shown in Figure 26, if I assume that the 100 detonations are airbursts of 1-Mt yield and that the hypothesized superfire casualty rules of the previous section apply, 25 million to 37 million deaths and 2 million to 7 million injured would result. Thus, if fires kill substantial numbers of people in target areas, the attack that does not target population per se might result in the death of between 1.5 and 2.5 times more people than the blast scaling would predict for the antipopulation attack of a similar size. It is also of interest to examine the potential effects of choice of weapon yield. If the rules for guessing the radius of superfire are scaled by as- suming that the fire radius occurs at the 10-cal/cm2 range (12-mile t19.3- km] visibility), then Figure 27 shows the predicted results for the anti- industrial attack, assuming that the attack is instead executed with 101 weapons of either 500- or 100-kiloton (kt) yield. In this case, the SOO-kt attack would kill 23 million people, 1.5 times that predicted by blast scaling for the antipopulation reference attack, and the 100-kt attack would kill about 8 million people, about two-thirds that predicted by the application of blast scaling to the antipopulation reference attack. However, it is noteworthy that the fire radius derived for the 100-kt weapon is about 4.5 km, and the already speculative cookie cutter fire

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68 PHYSICAL EFFECTS AND ENVIRONMENTAL CONSEQUENCES 80 70 60 ILL a 50 o LL o 40 En lo o J 30 20 10 o 100M' ATTACKS I Juries Deaths ANTI-MI LITARY-INDUSTRIAL ANTI- 8-Mile POPU LATION Fire Radius Blast Only Smile Fire Radius .~ FIGURE 26 Some of the results shown in Figure 25 are rearranged to illustrate that when the proposed alternative method of assessing casualties is applied to attacks aimed at industrial facilities rather than population centers, the result could be greater casualties than in the antipopulation attack. Since such attacks have sometimes been proposed as relatively limited, and hence more sensible and more plausible than antipopulation attacks, this comparison serves to underscore the potentially misleading character of such arguments. model is still more speculative, as it is more likely that many of those who would not have been severely injured would have some chance to attempt to escape the fire region. CONCLUSION During World War II the extraordinary power of science was turned to building a weapon that could create energy densities and temperatures comparable to those that normally exist in the interiors of stars. Today,

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. POSSIBLE FATALITIES FROM SUPERFIRES 80 70 60 50 CL o LL o 40 An a o J 30 20 10 69 -ANTI-POPULATION 1 _ - : 100 1-Mt Weapons Blast Injuries Deaths ANTI-MILITARY-INDUSTRIAL 100 0.5-Mt Weapons Fire Scaling L 100 0.1 -Mt Weapons Fire Scaling FIGURE 27 The effects of applying the hire casualty rules discussed in the legend to Figure 25 and the text to attacks that utilize weapons of lower yield. The predicted casualties when 100 0.5-Mt weapons are substituted for 1-Mt weap- ons are only slightly diminished. When 0.1-Mt weapons (100 kt) are substituted, casualties drop significantly. It should be noted, however, that for these much lower yield detonations, blast scaling from Hiroshima data may be no less un- certain than alternative rules discussed in this paper. the results of those and subsequent efforts have given us weapons with effects that are of vast and nonintuitive scales. One of these effects is superfires; they would accompany nuclear det- onations in or near urban areas and might result in two to four times as many fatalities as that predicted by standard government blast scaling rules. The effects of such fires, while recognized by many during and at the end of World War II, has remained an issue of discussion and research only among a small group of dedicated researchers. As such, an under

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70 PHYSICAL EFFECTS AND ENVIRONMENTAL CONSEQUENCES standing of their effects and the possible scale of unpredictable conse- quences that could accompany the use of nuclear weapons in many applications remains poorly understood, or absent, from the cognition of planners and decision makers. Without this understanding, the probability of misjudgment and miscalculation could be considerable. NOTES ~Bond, H., ed. 1946. Fire and the Air War. National Fire Protection Association. 2The U.S. Strategic Bombing Survey. 1946. Washington, D.C.: U.S. Government Print- ing Office. 3Glasstone, S., and P. J. Dolan, eds. 1977. The Effects of Nuclear Weapons. Report no. 0-213-794. Washington, D.C.: U.S. Government Printing Office. 4Federal Emergency Management Agency. 1982. Attack Environment Manual. CPG-2- 1A2. Washington, D.C.: Federal Emergency Management Agency. sDefense Civil Preparedness Agency. 1973. DCPA Attack Manual. CPG-2-lA1. Wash- ington, D.C.: Department of Defense. 6Glasstone, S., ed. 1962. The Effects of Nuclear Weapons. Washington, D.C.: U.S. Government Printing Office. 7Brode, H. L., and R. D. Small. 1983. Fire Damage and Strategic Targeting. PSR Note 567. Los Angeles, Calif.: Pacific-Sierra Research Corp. ~Hassig, P. J., and M. Rosenblatt. 1983. Firestorm Formation and Environment Char- acteristics After a Large-Yield Nuclear Burst. Proceedings of the 17th Asilomar Conference on Fire and Blast Effects of Nuclear Weapons. CONF-8305107, May 30-June 3. 9Brode, H. L., D. A. Larson, and R. D. Small. 1983. Hydrocode Studies of Flows Generated by Large Area Fires. Proceedings of the 17th Asilomar Conference on Fire and Blast Effects of Nuclear Weapons. CONF-8305107. May 30-June 3. Larson, D. A., and R. D. Small. 1983. The Large Urban Fire Environment: Trends and Model City Predictions. Proceedings of the 17th Asilomar Conference on Fire and Blast Effects of Nuclear Weapons. CONF-8305107. May 30-June 3. iiSmall, R. D., and D. A. Larson. 1983. Analysis of the Large Urban Fire Environment. Proceedings of the 17th Asilomar Conference on Fire and Blast Effects of Nuclear Weapons. CONF-8305107. May 30-June 3. i2Small, R. D., D. A. Larson, and H. L. Brode. 1983. Fluid dynamics of large area fires. In Fire Dynamics and Heat Transfer. J. G. Quintiere, R. L. Alpert, and R. A. Altenkirch, eds. New York: The American Society of Mechanical Engineers. i3Brode, H. L., and R. D. Small. 1983. Fire Damage and Strategic Targeting. PSR Note 567. Los Angeles, Calif.: Pacific-Sierra Research Corp. i4Small R. D., and H. L. Brode. 1980. Physics of Large Urban Fires. PSR Report 1010. Los Angeles, Calif.: Pacific-Sierra Research Corp. Larson, D. A., and R. D. Small. 1982. Analysis of the Large Urban Fire Environment: Part I. Theory. PSR Report 1210. Los Angeles, Calif.: Pacific-Sierra Research Corp. Larson, D. A., and R. D. Small. 1982. Analysis of the Large Urban Fire Environment: Part II. Parametric Analysis and Model City Simulations. PSR Report 1210. Los Angeles, Calif.: Pacific-Sierra Research Corp. i7Brode, H. L. 1980. Large-Scale Urban Fires. PSR Note 348. Los Angeles, Calif.: Pacific-Sierra Research Corp. i8Feldstein, M., S. Duckworth, H. C. Wohlers, and B. Linsky. 1963. The contribution of the open burning of land clearing debris to air pollution. J. Air Pollut. Control Assoc. 13:(11).

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POSSIBLE FATALITIES FROM SUPERFIRES 71 t9Darley, E. F., F. R. Burleson, E. H. Mateer, J. T. Middleton, and V. P. Osterli. 1966. Contribution of burning of agricultural wastes to photochemical air pollution. J. Air Pollut. Control Assoc. 1 1:(12). 20Gerstle, R. W., and D. A. Kemnitz. 1967. Atmospheric emissions from open burning. J. Air Pollut. Control Assoc. 2~wiersma, S. J. 1975. Characteristics of fires in structural debris. Silver Spring, Md.: Naval Surface Weapons Center. 22Wilton, C., K. Kaplan, B. Gabrielsen, and J. Zaccor. 1976. Blast/Fire Interaction, Blast Translation, and Toxic Agents. Final Report, URS 7030-6. Redwood City, Calif.: URS Research Co. See also note 45. 23Pryor, A. J., D. E. Johnson, and N. N. Jackson. 1969. Hazards of Smoke and Toxic Gases Produced in Urban Fires. San Antonio, Tex.: Southwest Research Institute. 24Takata, A. N., and T. E. Waterman. 1972. Fire Laboratory Tests Phase II, Interaction of Fire and Simulated Blast Debris, IITRI-J6217(2). Chicago, Ill.: IIT Research Institute. 2sLonginow, A., T. E. Waterman, and A. N. Takata. 1982. Assessment of Combined Effects of Blast and Fire on Personnel Survivability. Chicago, Ill.: IIT Research Institute. 26Lee, W., H. C. Leong, C. Jee, and M. Gayle Hershberger. 1966. Design of Tests for the Effects of Mass Fires on Shelter Occupants. Final Report. Palo Alto, Calif.: Isotopes, Inc. 27Police President of Hamburg. 1971. Short Version of Report on Experiences of the Hamburg Fire Department During the Air Attacks from July 24 to August 3, 1943. Reprinted as Appendix 1 in Fire Fighting Operations in Hamburg, Germany During World War II, by C. F. Miller, Final Report, URS 7030-6. Redwood City, Calif.: URS Research Com- pany. 28Christian, W. J., and R. C. Wands, eds. 1972. An Appraisal of Fire Extinguishing Agents. Proceedings of a Symposium at the National Academy of Sciences, April 11-12. Washington, D.C.: National Academy of Sciences. 29Goodale, T. 1971. An Attempt to Explore the Effect of High Blast Overpressures on the Persistence of Smouldering Combustion in Debris. Summary Report, URS 7030-6. Redwood City, Calif.: URS Research Company. 30Braker, W., and A. L. Mossman. 1971. Matheson Gas Data Book, 5th ed. East Ruth- erford, N.J. 3~Jacobs, M. B. 1949. The Analytic Chemistry of Industrial Poisons, Hazards, and Sol- vents, 2nd ed. New York: Interscience Publishers, Inc. 32Jacobs, M. B. 1967. Chemical Analysis XXII, The Analytic Toxicology of Industrial Inorganic Poisons. New York: Interscience Publishers, Inc. 33Henderson and Haggard. 1943. Noxious Gases and the Principles of Respiration Influ- encing Their Action, 2nd ed. Oxford, England: Clarendon Press. 34Pryor, A. J., D. E. Johnson, and N. N. Jackson. 1969. Hazards of Smoke and Toxic Gases Produced in Urban Fires. San Antonio, Tex.: Southwest Research Institute. 35Kehrl, Police President of Hamburg. 1946. Secret Report by the Police President of Hamburg on the Heavy Raids on Hamburg in July/August 1943, I.O.(t)45 (translated and published by the United Kingdom Home Office, Civil Defense Department, Intelligence Branch, Document Number 43097, January 1946). 36Report of the Technical Services Division of the Hamburg Fire Protection Police During the Major Catastrophe and Summary of Reports on Actions During the Air Attacks on Hamburg from July 24 to August 3, 1943. 1971. Reprinted as Appendix 2 in Fire Fighting Operations in Hamburg, Germany During World War II, by C. F. Miller, Final Report, URS 7030-6. Redwood City, Calif.: URS Research Company. 37Miller, C. F. 1971. Fire Fighting Operations in Hamburg, Germany During World War II. Final Report, URS 7030-6. Redwood City, Calif.: URS Research Co.

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72 PHYSICAL EFFECTS AND ENVIRONMENTAL CONSEQUENCES 38Taylor, D. H. 1978. Methodology for Estimating High Intensity Attacks. SAI-77-803- LJ. La Jolla, Calif.: Science Applications Inc. 39In fact, a fourth raid occurred on August 3, 1943; however, it took place during a severe thunderstorm. Police reports indicate that the substantial numbers of available fire fighting forces were not overwhelmed, as was the case in the three previous raids. It should be kept in mind, however, that the most successful attacks are known to have been those of highest intensity, since they started so many potentially controllable fires so quickly, that by the time some fires were put out, others had grown beyond control. The weather's major contribution could well have been interference with the placement of bombs, rather than expungement of fires. In Japan, reports indicate that successful incendiary attacks were made even during periods of light rain and often within hours of heavier rain. For example, 37 percent of the Nishinomiya-Mikage area was destroyed in a single raid despite the fact that heavy rain had fallen for the previous 48 hours. On the other hand, German cities were much more fire resistant than Japanese (and incidentally American) cities, as building construction was cellular, relying on internal and external masonry walls to protect against fire propagation. Hence, in the absence of more complete data on these events, the effects of weather must be considered to be quite ambiguous. 40Horatio Bond, private communication. National Fire Protection Association. 4iU.S. Congress, Office of Technology Assessment. 1979. The Effects of Nuclear War. Washington, D. C.: U. S. Government Printing Office. 42Peter Sharfman, private communication, project director of The Effects of Nuclear War, U.S. Congress Office of Technology Assessment. 43British Medical Association. 1983. The Medical Effects of Nuclear War. The Report of the British Medical Association's Board of Science Education. London: John Wiley and Sons. 44Daugherty, W., B. Levi, and F. von Hippel. Casualties Due to the Blast, Heat and Radioactive Fallout from Various Hypothetical Nuclear Attacks on the United States. This volume. 45Bucheim, R. W., and the staff of the Rand Corporation. 1958. Space Handbook: Astronautics and Its Applications. New York: Random House.