Appendix E
Analysis of Potential Inhalation Doses Due to Blast-Wave Effects at Operation PLUMBBOB, Shot HOOD, and Implications for Dose Reconstructions for Atomic Veterans

E.1 INTRODUCTION

This appendix presents an example analysis to investigate potential inhalation doses to participants in forward areas after detonation of Operation PLUMBBOB, Shot HOOD. This analysis is intended to illustrate the potential importance of resuspension caused by the blast wave produced in aboveground detonations at the NTS. The effect of a blast wave on resuspension of fallout that was previously deposited on the ground has been ignored in all dose reconstructions for atomic veterans, but the committee believes that the effect is potentially important and should be taken into account (see Section V.C.3.2, comment [7]).

The results of the example analysis have important implications for dose reconstructions for other exposure scenarios involving inhalation of resuspended fallout, and these implications also are discussed in this appendix.

E.2 RADIATION ENVIRONMENT IN FORWARD AREAS AT SHOT HOOD

Shot HOOD was detonated on July 5, 1957, and was one of the later shots during the period of aboveground testing at the NTS (Hawthorne, 1979). Shot HOOD provides a good example of the potential importance of resuspension caused by a blast wave on inhalation doses to participants because this shot had the largest yield of any aboveground test at the NTS (Hawthorne, 1979) and produced the most violent blast wave, an extensive cloud of dust was produced in the detonation (Maag et al., 1983; USMC, 1957), there was considerable fallout



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Appendix E Analysis of Potential Inhalation Doses Due to Blast-Wave Effects at Operation PLUMBBOB, Shot HOOD, and Implications for Dose Reconstructions for Atomic Veterans E.1 INTRODUCTION This appendix presents an example analysis to investigate potential inhalation doses to participants in forward areas after detonation of Operation PLUMBBOB, Shot HOOD. This analysis is intended to illustrate the potential importance of resuspension caused by the blast wave produced in aboveground detonations at the NTS. The effect of a blast wave on resuspension of fallout that was previously deposited on the ground has been ignored in all dose reconstructions for atomic veterans, but the committee believes that the effect is potentially important and should be taken into account (see Section V.C.3.2, comment [7]). The results of the example analysis have important implications for dose reconstructions for other exposure scenarios involving inhalation of resuspended fallout, and these implications also are discussed in this appendix. E.2 RADIATION ENVIRONMENT IN FORWARD AREAS AT SHOT HOOD Shot HOOD was detonated on July 5, 1957, and was one of the later shots during the period of aboveground testing at the NTS (Hawthorne, 1979). Shot HOOD provides a good example of the potential importance of resuspension caused by a blast wave on inhalation doses to participants because this shot had the largest yield of any aboveground test at the NTS (Hawthorne, 1979) and produced the most violent blast wave, an extensive cloud of dust was produced in the detonation (Maag et al., 1983; USMC, 1957), there was considerable fallout

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from previous shots in the area of the detonation (see Section IV.C.2.1.1, Table IV.C.1, and Section V.C.3.2, comment [6]), and participant groups undertook activities in the forward area soon after detonation (Maag et al., 1983; Frank et al., 1981; USMC, 1957). The locations of all shots at the NTS through Operation PLUMBBOB— excluding shots in Operation RANGER, which did not result in significant fallout on the NTS (Hawthorne, 1979)—are shown in Figures V.C.2 through V.C.6 (see Section V.C.3.2). As discussed in Section V.C.3.2, comment [6], the area near Shot HOOD experienced fallout from several previous shots, and there probably was additional fallout from other shots not mentioned. On the basis of locations of PLUMBBOB shots shown in Figure V.C.6 and fallout patterns reported by Hawthorne (1979), Shot SMOKY, which occurred after Shot HOOD, apparently deposited fallout in the same area. In addition, later safety shots in Operation HARDTACK-II—including OTERO, VESTA, JUNO, and GANYMEDE—deposited fallout in the area of Shot HOOD (Hawthorne, 1979). Concentrations of radionuclides in surface soil in Area 9, where Shot HOOD occurred, were measured during the 1980s (McArthur and Mead, 1987; McArthur, 1991). Estimated distributions of the photon-emitting radionuclides 241Am, 60Co, 137Cs, and 152Eu in the vicinity of Shot HOOD are shown in Figures E.1 through E.4; additional data on 154,155Eu are not shown. The high radionuclide concentrations to the south and southwest of Shot HOOD presumably are due mainly to fallout from HARDTACK-II safety shots that occurred after Shot HOOD (Hawthorne, 1979). Distributions of 90Sr and plutonium in surface soil were derived from the distributions of 137Cs and 241Am, respectively, and measured 90Sr-to-137Cs and 239,240Pu-to-241Am activity ratios in soil samples obtained from various locations in the area. Distributions of 238Pu also were estimated from measured 238Pu-to-241Am ratios in soil samples. The information summarized above can be used to estimate concentrations of important radionuclides that were present in the area of Shot HOOD at the time of detonation. On the basis of measured concentrations of longer-lived radionuclides in surface soil after the period of atomic testing shown in Figures E.1 through E.4, measured activity ratios obtained from soil samples (McArthur, 1991), and the ICRP’s current dose coefficients for inhalation of respirable particles (AMAD, 1 μm) given in Table V.C.2 (see Section V.C.3.1), 239,240Pu probably posed the most important inhalation hazard at the time of Shot HOOD, and the presence of 60Co, 90Sr, 137Cs, 152,154,155Eu, 238Pu, and 241Am probably increased potential inhalation doses by less than a factor of 2.1 1   A more rigorous analysis would need to consider the presence of additional radionuclides with half-lives sufficiently short that they were no longer present in detectable amounts when measurements were made during the middle 1980s. Additional fission products that could be important in aged fallout in the area of Shot HOOD include 89Sr, 95Zr, 106Ru, and 144Ce (see Table V.C.2).

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FIGURE E.1 Distribution of concentrations of 241Am in surface soil (nCi m−2) in vicinity of ground zero (GZ) of Operation PLUMBBOB, Shot HOOD based on measurements in middle 1980s (McArthur and Mead, 1987). Area shown is about 6.7 by 4.6 km. FIGURE E.2 Distribution of concentrations of 60Co in surface soil (nCi m−2) in vicinity of ground zero (GZ) of Operation PLUMBBOB, Shot HOOD based on measurements in middle 1980s (McArthur and Mead, 1987). Area shown is about 6.7 by 4.6 km.

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FIGURE E.3 Distribution of concentrations of 137Cs in surface soil (nCi m−2) in vicinity of ground zero (GZ) of Operation PLUMBBOB, Shot HOOD based on measurements in middle 1980s (McArthur and Mead, 1987). Area shown is about 6.7 by 4.6 km. FIGURE E.4 Distribution of concentrations of 152Eu in surface soil (nCi m−2) in vicinity of ground zero (GZ) of Operation PLUMBBOB, Shot HOOD based on measurements in middle 1980s (McArthur and Mead, 1987). Area shown is about 6.7 by 4.6 km.

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E.3 ANALYSIS OF POTENTIAL INHALATION DOSES This section presents an analysis of potential inhalation doses due to resuspension of radionuclides in surface soil caused by the blast wave at Shot HOOD. On the basis of data discussed above, the analysis assumes that only plutonium (239,240Pu) was present and ignores potential doses from inhalation of other radionuclides. This analysis is presented for illustrative purposes only, and it should not be interpreted as providing definitive estimates of inhalation doses to any atomic veterans who participated in activities in forward areas shortly after detonation of Shot HOOD. In this analysis, potential inhalation doses due to effects of the blast wave at Shot HOOD are estimated by taking into account subjective estimates of uncertainty in all input parameters. Assumed uncertainties in parameters that are used to estimate airborne concentrations of plutonium are intended to represent a range of plausible conditions at different distances from ground zero and at various times after the blast wave occurred; the assumed uncertainties are not intended to represent plausible conditions of exposure that would result in the highest estimates of dose at a particular location and time. When uncertainty in input parameters is taken into account, the result of the analysis is a subjective probability (uncertainty) distribution of potential inhalation doses. Again, inhalation doses are assumed to be due only to the presence of plutonium, and estimated concentrations of plutonium in surface soil are based on survey data on 241Am and measured 239,240Pu-to-241Am ratios in soil samples. The analysis is based on assumptions summarized in Table E.1 and described as follows. Concentrations of 241Am in surface soil in the forward area at Shot HOOD after the period of atomic testing ended are described by a lognormal probability distribution with an 80% confidence interval of 20-200 nCi m−2. This uncertainty takes into account that exposures to resuspended fallout occurred at various locations in the forward area as the participants carried out their assigned activities. The lower confidence limit of 20 nCi m−2 is an estimate in regions of Area 9 away from any shot locations (McArthur, 1991), and it represents a general background level of local fallout in Area 9 from all shots at the NTS. The upper confidence limit of 200 nCi m−2 is based on data in the area of Shot HOOD shown in Figure E.1. Much higher concentrations to the south and southwest of ground zero for Shot HOOD are excluded because, as discussed in the previous section, these concentrations presumably are due primarily to fallout from later safety shots in Operation HARDTACK-II (Hawthorne, 1979). The fraction of the activity of 241Am in surface soil in the forward area at Shot HOOD defined above that was present at the time of detonation is described by a uniform probability distribution over the range of 0.5-1.0. That is, at least half the contamination in the forward area at the time of Shot HOOD is assumed to be due to fallout from prior shots. Because areas of high contamination from later safety shots are excluded from the analysis, it appears unlikely that a smaller

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TABLE E.1 Summary of Assumed Probability (Uncertainty) Distributions of Input Parameters Used in Example Analysis of Inhalation Doses Caused by Blast-Wave Effects at Shot HOOD Parameter Assumed probability distribution Concentrations of 241Am in surface soil at end of period of atomic testing Lognormal distribution with 80% confidence interval of 20-200 nCi m−2 Fraction of 241Am in surface soil at end of period of atomic testing that was present at time of Shot HOOD Uniform distribution over range of 0.5-1.0 Concentrations of 239,240Pu in surface soil relative to 241Ama Lognormal distribution with 90% confidence interval of 4–18 Resuspension factor associated with blast wave Lognormal distribution with 90% confidence interval of 10−4–10−2 m−1 Fraction of resuspended activity attached to respirable particles (AMAD, 1 μm) Uniform distribution over range of 0.2-1.0 Breathing rate Lognormal distribution with 90% confidence interval of 0.6–1.7 m3 h−1 Organ-specific dose coefficients for inhalation of plutonium attached to respirable particles To account for uncertainties in dosimetric and biokinetic models used to calculate dose coefficients, lognormal distributions with 90% confidence interval of 0.1–10 times current ICRP recommendations for adult workers   To account for uncertainty in biological effectiveness of alpha particles relative to photons and electrons, replacement of standard value of 20 used in ICRP dose coefficients with lognormal distribution with 95% confidence interval of 3.2-100 Time after exposure when cancer occurred in exposed person Reduces dose of concern to all organs and tissues other than the lung by factor of 2 aOther radionuclides in fallout from prior shots that were present at time of Shot HOOD and could contribute to inhalation doses are neglected. fraction of the assumed contamination at the time of detonation is due to fallout from prior shots, and it is possible that nearly all the contamination is due to prior fallout. Concentrations of 239,240Pu relative to 241Am in surface soil in the forward area at Shot HOOD are described by a lognormal probability distribution with a 90% confidence interval of 4-18. That distribution is based on data obtained from soil samples in several areas on the NTS where extensive fallout occurred (McArthur, 1991; IT and DRI, 1995). However, measured 239,240Pu-to-241Am ratios in soil samples taken near the location of Shot HOOD (McArthur and Mead, 1987)

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are not used in this analysis. Only three soil samples were taken in the vicinity of Shot HOOD, and two of the samples, in which the concentrations of plutonium relative to 241Am of about 24 and 32 are much higher than the ratios in any other areas on the NTS, were taken in the vicinity of later safety shots. Ratios of plutonium to 241Am in safety shots are expected to be much higher than ratios in normal nuclear detonations and therefore are not relevant to estimating plutonium in deposited fallout at the time of Shot HOOD. Concentrations of plutonium in air caused by the blast wave at Shot HOOD relative to concentrations in surface soil are described by a resuspension factor that has a lognormal probability distribution with a 90% confidence interval of 10−4-10−2 m−1. The upper confidence limit is based on an assumption that all activity in surface soil was resuspended and that the height of the resulting dust cloud was about 100 m. The lower confidence limit is intended to take into account several factors, including that some of the activity in surface soil may not have been resuspended by the blast wave, that some of the resuspended material may have been in the form of large particles that fell to Earth quickly, that the height of the dust cloud may have been greater than 100 m, and that the effect of the blast wave should have diminished with increasing distance from ground zero. Resuspension factors substantially less than 10−4 m−1 do not appear to be credible, however, given that values as high as 10−4 m−1 have been observed under conditions of stress considerably less vigorous than a blast wave (Sehmel, 1984). The fraction of resuspended material that was in the form of small, respirable particles (AMAD, 1 μm) and remained in the air at times after detonation when exposures in the forward area occurred is described by a uniform probability distribution over the range of 0.2-1.0. That factor is intended to take into account that not all resuspended materials may have been in the form of respirable particles and that dilution of the dust cloud due to surface winds may have occurred at some locations in forward areas during the first several hours after detonation when participants were exposed. The breathing rate of a participant is described by a lognormal probability distribution with a 90% confidence interval of 0.6-1.7 m3 h−1. The lower confidence limit is the same as the value assumed in Section V.C.3.3 for participants engaged in light activity. The increase in the upper confidence limit compared with the assumption in Section V.C.3.3 is intended to take into account that heat exhaustion occurred in some participants (Maag et al., 1983) and that the excitement of being in the presence of dust and fires on a warm summer day could have resulted in an increase in breathing rate compared with that during normal light activity. Organ-specific dose coefficients for inhalation of plutonium attached to respirable particles (AMAD, 1 μm) by adult workers currently recommended by ICRP (2002) are assumed (see Section V.C.3.1, comment [1], and Table V.C.2), and the dose coefficient for the lung is assumed to represent the dose to regions of the lung where most lung cancers caused by radiation exposure occur (see Sec

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tion V.C.3.1, comment [7]). Inhalation of large particles is assumed to be relatively unimportant after a blast wave, because of the vigorous nature of the stress causing resuspension and the lower dose coefficients for inhalation of large particles compared with respirable particles (see Section V.C.3.1, comments [1] and [2], and Tables V.C.2 and V.C.4). Uncertainty in dose coefficients for inhalation of plutonium due to uncertainties in the dosimetric and biokinetic models used to calculate them is described by a lognormal probability distribution with a 90% confidence interval of 0.1–10 times the ICRP recommended values (see Section V.C.3.2, comment [1], and Table V.C.6). The uncertainty in dose coefficients for inhalation of plutonium due to the uncertainty in the biological effectiveness of alpha particles relative to photons and electrons is described by a lognormal probability distribution with a 95% confidence interval of 3.2-100 (see Section V.C.3.2, comment [2]). That probability distribution replaces the standard assumption of 20 used in calculating dose coefficients for plutonium and other alpha-emitting radionuclides (ICRP, 1991). On the basis of an assumption that a cancer was diagnosed in an exposed veteran at 35 years after exposure at Shot HOOD, the dose to all organs or tissues other than the lung calculated with the ICRP-recommended dose coefficients is reduced by a factor of 2. That reduction accounts for the difference between 50-year committed doses, as embodied in the ICRP dose coefficients, and the dose that could have caused the cancer, which is assumed to be the dose received during the first 25 years after exposure in this example (see Section V.C.3.1, comment [6]). The inhalation dose to an organ or tissue of concern per hour of exposure is the product of the assumed plutonium concentration in air, the breathing rate, and the organ-specific dose coefficient (see Section IV.C.2, Equation IV.C-1). By multiplying the assumed probability distributions of the different parameters described above with Latin Hypercube sampling techniques and the Crystal Ball® 2000 software (Decisioneering, 2001), central estimates (50th percentiles) and upper confidence limits (95th percentiles) of estimated inhalation doses per hour of exposure given in Table E.2 are obtained. Again, the estimated doses are based on an analysis only for plutonium (239,240Pu), and the estimates would increase somewhat if other radionuclides that were present in surface soil at the time of Shot HOOD were included. E.4 DISCUSSION OF EXAMPLE ANALYSIS AND IMPORTANCE OF INHALATION DOSES Assumptions about probability (uncertainty) distributions of parameter values used to obtain the results in Table E.2 clearly are subjective, and other

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TABLE E.2 Calculated Probability Distributions of Doses Due to Inhalation of Plutonium in Example Analysis of Blast-Wave Effects at Shot HOOD   Probability Distribution of Equivalent Dose (rem h−1)a Organ or Tissue 50th percentile 95th percentile Lung 0.06 3.7 Lymphatic tissues 0.3 19 Lower large intestine 0.0001 0.007 Red bone marrow 0.003 0.2 Bone surfaces 0.06 4.0 Liver 0.01 0.8 Bladder wall 0.0001 0.007 aFiftieth percentile represents central estimate of uncertain dose, and 95th percentile represents upper confidence limit used in dose reconstructions for atomic veterans. choices are plausible. It is partly for that reason that the results are intended to be illustrative rather than definitive. For example, the resuspension factor that describes the effect of a blast wave is highly uncertain. If the lower confidence limit of the resuspension factor were increased from 10−4 to 10−3 m−1, and all other assumptions were unchanged, central estimates (50th percentiles) of the doses in Table E.2 would increase by a factor of about 3 and the 95th percentiles would increase by a factor of about 1.7. Those comparisons also indicate, however, that substantial changes in assumed probability distributions of individual parameters would be required to give substantial changes in the results, given that at least some of the parameters, such as inhalation dose coefficients, would have large uncertainty in any credible analysis. The committee believes that two seemingly contradictory conclusions can be drawn from the example analysis summarized in Table E.2. First, because central estimates (50th percentiles) of inhalation doses are less than 0.1 rem h−1 in all organs or tissues except lymphatic tissues, high doses should occur only under conditions of unusually high concentrations of longer-lived radionuclides in surface soil and very high resuspension factors. For example, on the basis of data summarized by McArthur (1991), central estimates of inhalation doses due to resuspension caused by a blast wave in areas away from ground zeros of previous shots at the NTS would be about the same as doses in Table E.2 at locations, such as Area 4, where the background of local fallout is the highest. Thus, high inhalation doses are likely to have occurred only in cases of exposure in small areas near locations of previous shots where radionuclide concentrations are unusually high. Similarly, in scenarios in which resuspension was caused by light activity, such as walking, rather than a blast wave, a central estimate of the resuspension factor should be at least a factor of 1,000 less than the central estimate of 10−3 m−1 for a blast wave assumed in this analysis (see Section V.C.3.1, comment [8]), and central estimates of inhalation doses even at locations where radionuclide con-

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centrations are the highest, such as locations in Area 4 (McArthur and Kordas, 1985), should be less than central estimates obtained in this analysis. Second, although central estimates of inhalation doses obtained in this analysis are not high, credible upper bounds are considerably higher. If a credible upper bound of an uncertain dose is represented by the 95th percentile of a probability distribution, as assumed in the NTPR program, estimated upper bounds of doses given in Table E.2 exceed the central estimates by a factor of about 70. Estimated upper-bound doses to the lung, lymphatic tissues, bone surfaces, and liver are comparable to or greater than 1 rem h−1, and doses of this magnitude could be important in evaluating claims for compensation for radiation-related diseases when veterans are to be given the benefit of the doubt in estimating dose. Such doses clearly are important, for example, in cases of lung cancer in nonsmokers and liver cancer, for which claims for compensation normally have been granted when upper-bound estimates of dose to participants exceeded about 4 rem and 1 rem, respectively (see Section III.E). A blast wave occurred at many aboveground shots at the NTS, and participant groups engaged in various activities in forward areas after many of these shots (Barrett et al., 1986). Given the magnitude of credible upper bounds of inhalation doses obtained in the example analysis at Shot HOOD, it is evident to the committee that blast-wave effects are potentially important in dose reconstructions for the thousands of participants who engaged in activities in forward areas soon after shots at the NTS. The example analysis is but one of several instances in which substantial inhalation doses could have resulted from a blast wave. E.5 IMPLICATIONS OF EXAMPLE ANALYSIS FOR OTHER EXPOSURE SCENARIOS The upper-bound estimates of inhalation dose in Table E.2 also indicate that credible upper bounds could be important in other exposure scenarios in which resuspension was caused by vigorous disturbance of surface soil. For example, as discussed in Section IV.C.2.1.3 and summarized in Table IV.C.2, resuspension factors as high as 10−3 m−1 are assumed in scenarios involving assaults or marches behind armored vehicles at the NTS, and credible upper-bound estimates of inhalation doses in these scenarios could be within a factor of 10 of the estimated upper bounds in Table E.2. However, the upper-bound estimates of inhalation dose in Table E.2 indicate that credible upper bounds are unlikely to be important in exposure scenarios in which resuspension was caused by walking or other activities that did not involve vigorous disturbance of surface soil. In those types of scenarios, credible upper-bound estimates of inhalation dose probably are at least a factor of 100 less than upper bounds given in Table E.2. Such scenarios often occurred, for example, during normal activities of most participants on residence islands in the Pacific or

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when participants at the NTS engaged in various light activities in forward areas before a detonation, rather than immediately afterward when blast-wave effects were important. Pre-shot activities in forward areas occurred at several tests at the NTS. E.6 DISCUSSION OF DOSE RECONSTRUCTIONS FOR PARTICIPANT GROUPS AT SHOT HOOD As noted in Section V.C.3.2, comment [7], the effects of a blast wave on resuspension of radionuclides were ignored in all dose reconstructions for participant groups at the NTS. Furthermore, as noted in Section V.C.3.2, comment [6], the presence of previously deposited fallout in the forward area at Shot HOOD was not accounted for in dose reconstructions for participant groups at that test. The approach to assessing inhalation doses at Shot HOOD is indicated by a dose reconstruction for one of the participant groups (Frank et al., 1981). In that analysis, the possibility that participants received an inhalation dose due to deposited fallout that was resuspended by the blast wave was dismissed with the statement that “what dust was lofted by the shock wave had either settled or blown out of the shot area, away from the troops, before the HOOD radiation field was entered” (Frank et al., 1981). In addition, as noted in Section V.C.3.2, comment [6], dose reconstructions for all participant groups in forward areas at Shot HOOD apparently assumed that no fallout from prior shots was present (Barrett et al., 1986). The statement by Frank et al. (1981) given above is directly contradicted by a report of activities of participant groups at Shot HOOD (Maag et al., 1983). With reference to Figure E.5, which shows routes of troop movements after the detonation, this report states that “because dust was obscuring visibility in Loading Zone Two, the helicopters delayed their departure from Yucca Pass one hour [after detonation]”; an after-action report indicates that the elapsed time was about 85 min (USMC, 1957). The helicopters picked up troops who marched from the trenches toward ground zero and back starting within 15 min after detonation (Maag et al., 1983). Because Loading Zone Two is farther from ground zero than the trenches and the line of march of troops who went toward ground zero, the only reasonable assumption is that the troops encountered high dust concentrations during the maneuver, which lasted about 2 hours (Maag et al., 1983). The report by Maag et al. (1983) also notes that “because heavy dust obscured ground points, the … aerial survey team could not perform its survey until about six hours after the detonation.” Thus, the heavy dust cloud caused by the blast wave evidently persisted for several hours in the area near ground zero, and it is virtually certain that this cloud was encountered by troops who marched toward ground zero soon after the detonation. It also is plausible that significant remnants of the dust cloud, especially the smaller, respirable particles with very low deposition velocities (Sehmel, 1984; Luna et al., 1969), were present when

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FIGURE E.5 Diagram of troop movements in forward areas after detonation of Operation PLUMBBOB, Shot HOOD at location marked “GZ” (Maag et al., 1983). Movement of troops to Main Equipment Display Area after detonation is not shown.

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troops were trucked to the Main Equipment Display Area; trucking began within 6 hours of detonation and continued for about 3 hours (Maag et al., 1983). The committee, of course, does not know the exact conditions (airborne concentrations of radionuclides) that were encountered by maneuver troops in forward areas at Shot HOOD, nor do the analysts who performed dose reconstructions. And it is documented that troops who were in forward trenches at the time of detonation were issued gas masks in anticipation of high concentrations of dust and were instructed to wear them at least until the blast wave passed (Maag et al., 1983). However, the committee believes that it is implausible to assume that troops continued to wear gas masks during the entire time spent in forward areas after the initial blast wave passed, even though dust concentrations remained high. The high temperatures on a July day and the presence of many brush fires in the area, which added to the heat and obscured visibility, made it difficult to carry out maneuvers while wearing respiratory protection. Thus, without regard for whether a participant in the trenches maneuvered toward ground zero, marched west toward Loading Zone Two to await helicopter airlift, or waited in the trench area for transport to the vehicle assembly area (Maag et al., 1983), it is highly plausible that inhalation of dust resuspended by the blast wave occurred throughout the period from shortly after detonation until the tour of the equipment display area ended several hours later. Although airborne concentrations of radionuclides undoubtedly decreased over that time, the concentrations of respirable particles probably did not decrease by large amounts, because of their low deposition velocities and the low wind speeds. Furthermore, this dust cloud undoubtedly contained plutonium and other longer-lived radionuclides of importance in estimating inhalation dose. Dose reconstructions are supposed to be based on plausible assumptions that give the veterans the benefit of the doubt (see Section I.C.3.2). The approach taken in dose reconstructions for participant groups at Shot HOOD (Barrett et al., 1986; Frank et al., 1981) of completely ignoring blast-wave effects and inhalation of resuspended dust containing plutonium and fission products that undoubtedly was present in the exposure environment in the forward areas is not plausible, and it certainly does not give the affected veterans the benefit of the doubt. REFERENCES IN APPENDIX E Barrett, M., Goetz, J., Klemm, J., McRaney, W., Phillips, J. 1986. Low Level Dose Screen – CONUS Tests. McLean, VA: Science Applications International Corporation; Report DNA-TR-85-317. Decisioneering. 2001. Crystal Ball® 2000.2 User Manual. Denver, CO: Decisioneering, Inc. Frank, G., Goetz, J., Klemm, J., Thomas, C., Weitz, R. 1981. Analysis of Radiation Exposure, 4th Marine Corps Provisional Atomic Exercise Brigade, Exercise Desert Rock VII, Operation PLUMBBOB. McLean, VA: Science Applications, Inc.; Report DNA 5774F. Hawthorne, H. A. (Ed). 1979. Compilation of Local Fallout Data from Test Detonations 1945-1962 Extracted from DASA 1251. Volume I. Continental U.S. Tests. Santa Barbara, CA: General Electric Company; Report DNA 1251-1-FX.

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ICRP (International Commission on Radiological Protection). 1991. 1990 Recommendations of the International Commission on Radiological Protection. ICRP Publication 60, Annals of the ICRP 21(1-3). Elmsford, NY: Pergamon Press. ICRP (International Commission on Radiological Protection). 2002. The ICRP Database of Dose Coefficients: Workers and Members of the Public, Compact Disc Version 2.01. Stockholm, Sweden: International Commission on Radiological Protection. IT and DRI (IT Corporation and Desert Research Institute). 1995. Evaluation of Soil Radioactivity Data from the Nevada Test Site. Las Vegas, NV: U.S. Department of Energy Nevada Operations Office; Report DOE/NV-380. Luna, R. E., Church, H. W., Shreve, J. D., Jr. 1969. A Model for Plutonium Hazard Assessment Based on Operation ROLLER-COASTER. Albuquerque, NM: Sandia Laboratories; Report SC-WD-69-154. Maag, C., Wilkinson, M., Striegel, J., Collins, B. 1983. Shot HOOD – A Test of the PLUMBBOB Series. McLean, VA: JRB Associates, Inc.; Report DNA 6002F. McArthur, R. D. 1991. Radionuclides in Surface Soil at the Nevada Test Site. Las Vegas, NV: Desert Research Institute; Water Resources Center Publication #45077, Report DOE/NV/10845-02. McArthur, R. D., Kordas, J. F. 1985. Radionuclide Inventory and Distribution Program: Report #2. Areas 2 and 4. Las Vegas, NV: Desert Research Institute; Water Resources Center Publication #45-41, Report DOE/NV/10162-20. McArthur, R. D., Mead, S. W. 1987. Radionuclide Inventory and Distribution Program: Report #3. Areas 3, 7, 8, 9, and 10. Las Vegas, NV: Desert Research Institute; Water Resources Center Publication #45056, Report DOE/NV/10384-15. Sehmel, G. A. 1984. Deposition and Resuspension. In: Atmospheric Science and Power Production, ed. by D. Randerson. Washington, DC: U.S. Department of Energy; Report DOE/TIC-27601, pp. 533–583. USMC (U.S. Marine Corps). 1957. Provisional Atomic Exercise Brigade, Report of Exercise Desert Rock VII, Marine Corps. Camp Pendleton, CA: Headquarters, 4th Marine Corps.