The Medical Implications of Nuclear War (1986) / Chapter Skim
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8 Radioactive Fallout
8 Radioactive Fallout
Pages 167-204
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From page 167... ...
Dose estimates are made for both a normal atmosphere and an atmosphere perturbed by smoke produced by massive fires. A separate section discusses the additional doses from nuclear fuel facilities, were they to be targeted in an attack.
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From page 168... ...
Exposure to local fallout, which has the greatest potential for producing human casualties, is very sensitive to assumptions about height of burst, winds, time of exposure, protection factor, and other variables. For global fallout, the dose commitments are sensitive to how these fission products are injected into various regions of the atmosphere, which depend on individual warhead yield as well as burst location.
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From page 169... ...
The inclusion of rainout processes would probably not significantly affect the answers to generic questions pertaining to largescale nuclear war phenomena (for example, What percentage of Western Europe would suffer lethal levels of gamma radiation from local fallout in a large-scale nuclear exchange?
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From page 170... ...
compared to the size of the fallout areas created by particles with large settling velocities. Thus, to first order rainout areas can be ignored in calculating the radiological hazard from a large-scale nuclear war scenario.
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From page 171... ...
A m~dcontinental Northern Hemisphere summer wind profile was used. The double-lobed pattern is due to a strong directional wind shear that is typical during this season.
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From page 172... ...
The rationale for this scaling law is that the thermodynamics and hydrodynamics of fallout development are insensitive to fission fraction because particle characteristics and lofting altitudes are determined predominantly by total energy yield. For yields that are only part fission, each particle has a fraction of the gamma radioactivity that it would otherwise have if the weapon were an all-fission weapon.
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From page 173... ...
For example, a person leading a normal lifestyle is likely to achieve an average K of 2 to 3 for gamma radiation from time spent inside buildings and other structures. Basements can provide K values of 10 to 20.
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From page 174... ...
Dose Estimation from Multiple Explosions In a major nuclear exchange, thousands of nuclear warheads could be detonated. For such an exchange, realistic wind patterns and targeting scenarios could cause individual weapon fallout patterns to overlap in complicated ways that are difficult to predict and calculate.
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From page 175... ...
Approximately 1,000 population centers in the United States were targeted, each with a 1-Mt, 50 percent fission weapon. The assumed winds were westerly with small vertical shear and were nearly constant over the continent (taken from Harvey, 19821.
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From page 176... ...
Sample Calculation of Multiple-Weapon Fallout To illustrate the fallout prediction method presented here, an escalating nuclear exchange scenario, which is consistent with that described in the SCOPE-ENUWAR study (Pittock et al., 1985) , is used to estimate fallout areas.
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From page 177... ...
Besides the attack on Soviet missile silos, 425 0.1-Mt weapons are assumed to be surface-burst against other Soviet military targets, with approximately 28 Mt west of the Urals and 14 Mt to the east. The 425 fallout patterns from these weapons have been modeled with the NO model.
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From page 178... ...
· Debilitating, but not lethal, radiation doses (~200 reds or more) would be received over much larger areas than areas receiving lethal doses.
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From page 179... ...
· External beta exposure, not treated here, could add significantly to plant and animal exposures in local fallout areas. · Targeting of nuclear fuel cycle facilities could contribute to radiation doses.
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From page 180... ...
As a result, there is some uncertainty in the results of explosions centered around the Northern Hemisphere middle latitudes, but little uncertainty in the Northern Hemisphere subpolar latitude calculations since the stratospheric fallout there would deposit much the same as the global fallout from the polar bursts used to generate the polar deposition tables in the model. Global Dose in an Unperturbed Atmosphere Using Specific Scenarios A variety of scenario studies have been performM using GLODEP2 (Knox, 1983; Edwards et al., 1984~.
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From page 181... ...
5,000-Mt reference nuclear war) Total Yield/Warhead (Mt)
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From page 182... ...
Table 5 presents results comparing the 5,300-Mt baseline scenario with two variations. In scenario Aa, the number of devices in the baseline scenario A is increased from 6,235 to 13,250, while the total yield is held at 5,300 Mt.
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From page 183... ...
TABLE 5 Global Fallout: Sensitivity of Dose to Warhead Yielda Global Global Average Dose Population Total Number of Average Yield 30-50°N per Person Dose (10~° Dose (reds) (reds)
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From page 184... ...
(1983) models assumed fission product depositions from a normal atmosphere in calculating global fallout.
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From page 185... ...
The increases in Southern Hemisphere dose, however, are not large, and the resulting doses are still about a factor of 20 lower than those in the Northern Hemisphere. This is because the increased transfer to the Southern Hemisphere is mitigated by the decay in activity during the time before the radionuclides are deposited on the ground.
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From page 186... ...
(smoke) 90-70°N 7.8 6.4 8.2 5.8 70-50°N 21.3 17.2 24.6 18.0 50-30°N 22.3 20.1 23.9 20.4 30-10°N 7.6 7.5 7.2 7.2 10°N- 10°S 1.3 1.6 1.0 1.4 10-30°S 0.6 0.8 0.4 0.6 30-50°S 0.7 0.8 0.4 0.5 50-70°S 0.5 0.5 0.3 0.3 70-90°S 0.2 0.2 0.1 0.1 Area averaged Northern Hemisphere 12.8 11.5 13.7 11.5 Southern Hemisphere 0.7 0.8 0.4 0.6 Global 6.8 6.1 7.1 6.1 Population average Global 11.5 10.7 12.0 10.7 Global population dose ( x 10~°)
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From page 187... ...
Suburban residents within the local fallout pattern would encounter heavily contaminated water supplies and would have to rely on stored water. Surface water supplies would be directly contaminated by fission products.
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From page 188... ...
As stated earlier, introducing smoke and soot into He troposphere and stratosphere would probably slightly reduce Northern Hemisphere values and slightly increase 90Sr deposition in the Southern Hemisphere. Significant doses to individual human organs can also arise from specific radionuclides via food pathways.
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From page 189... ...
Calculations of local fallout fields were performed using the KDFOC2 model and an escalating nuclear exchange scenario. In this illustrative example, where simple assumptions are made about the overlap of fallout plumes, these estimates indicate that about 7 percent of the land surface in the United States, Europe, and the USSR would be covered by external gamma-ray doses exceeding 450 reds in 48 hours, assuming a protection factor of 1 (i.e., no protective action is taken)
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From page 190... ...
For global fallout, different computer models and scenarios have been intercompared. The calculations predict that the 50-year unsheltered, unweathered average external total body gamma-ray dose levels in the Northern Hemisphere would be about 10 to 20 reds, and about 0.5 to 1 red in the Southern Hemisphere.
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From page 191... ...
There is general agreement that enormous reservoirs of long-lived radionuclides exist in reactor cores, spent fuel rods, fuel reprocessing plants, and radioactive waste storage facilities. Disagreement arises when the feasibility and extent of such a targeting strategy are considered.
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From page 192... ...
Figure 7 shows the gamma radiation dose rate-area integrals from a 1Mt, all-f~ssion nuclear weapon and from possible commercial fuel cycle facilities. In the first few days, the higher activity of the nuclear weapon debris dominates over the gamma radiation of the reactor.
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From page 193... ...
Thus, for doses from a 1-Mt, all-fission weapon detonated on a reactor, Me core gamma radiation would be comparable to the weapon's radiation at about 5 days. By 2 months the gamma radioactivity from the weapon would have decayed by a factor of over 1,000 from its value at 1 hour.
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From page 194... ...
warhead dominates the fuelcycle gamma radioactivity, even if one assumes a worst case assumption in which all the radioactivity from the attacked nuclear fuel cycle facility is lofted with the weapon products. For lower yields and thermonuclear weapons, the core gamma radiation becomes more important and could be potentially greater than the dose from the nuclear weapons, even at very early times.
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From page 195... ...
civilian nuclear power industry would also be attacked. The results should be viewed as providing estimates that approach maximum global fallout for an attack on a commercial nuclear power industry of 100 GW(e)
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From page 196... ...
196 cr.
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From page 197... ...
Using GLODEP2 and a Northern Hemisphere winter scenario, the resulting unsheltered, unweathered doses are shown in Table 8. The largest value of 95 reds for the total of weapons plus the nuclear power industry occurred in the 30-50°N latitude band.
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From page 198... ...
In summary, using some worst-case assumptions for a speculative nuclear war scenario wherein 100 GW(e) of the nuclear power industry is included in the target list, the 50-year global fallout dose is estimated to increase by a factor of 3 over similar estimates wherein nuclear power facilities are not attacked.
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From page 199... ...
From 50 to 75 percent of the global fallout dose is due to tropospheric injections of radionuclides that are deposited in the first month. Additional calculations, utilizing GRANTOUR and assuming a perturbed nuclear winter atmosphere, indicate that the above dose assessments would be about 15 percent lower in the Northern Hemisphere and marginally higher (to approximately 1 red)
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From page 200... ...
In Table 9, structure protection factors from fallout gamma rays are listed. An additional important consideration for humans is the assumption of what are the lethal acute external whole-body dose levels (50 percent lethal dose [LDso]
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From page 201... ...
As an example, the SCOPE-ENUWAR study reported that about 7 percent of the land masses of the United States, the USSR, and Europe would receive a minimum of 450 reds within 48 hours. The figure for the continental United States was about 8 percent.
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From page 202... ...
exposure rate. Global fallout would result in a small statistical increase, of the order of 1 or 2 percent, above the current incidence of cancers and genetic mutations in the decades following the occurrence of a nuclear war.
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From page 203... ...
1979. Dose-rate conversion factors for external exposures to photon and electron radiation from radionuclides occurring in routine releases from nuclear fuel cycle facilities.
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