TAB L - Research Report Summaries

This tab provides a summary of some of the major research efforts regarding the military use of depleted uranium. While this listing is not intended to be all-inclusive, it does provide a sense of the depth and breadth of research conducted to date. The studies listed below are summarized on the pages to follow.

Report Number 1

Hanson, Wayne C. Ecological Considerations of Depleted Uranium Munitions, LA-5559. Los Alamos, NM: Los Alamos Scientific Laboratory, June 1974.

This report concluded that the major ecological hazard from expended DU munitions would be chemical toxicity rather than radiation. Because DU munitions are composed of alloys, the mobility of the DU is substantially decreased compared to uranium. However, the report stated that the chemical toxicity of expended DU to terrestrial ecosystems could not be ignored and must be seriously considered.

Report Number 2

Environmental Assessment, Depleted Uranium (DU) Armor Penetrating Munitions for the GAU-8 Automatic Cannon, Development and Operational Test and Evaluation, AF/SGPA, April 1975.

This was the Environmental Assessment for the US Air Force’s GAU-8 Program. It covered the manufacturing, transportation, storage, use and disposal of GAU-8 ammunition and resulted in a finding of no significant environmental impact.

Report Number 3

Elder, J.C., M.I. Tillery, and H.J. Ettinger. Hazard Classification Test of GAU-8 Ammunition by Bonfire Cookoff with Limited Air Sampling, LA-6210-MS, Informal Report. Los Alamos, NM: Los Alamos Scientific Laboratory of the University of California, February 1976.

On August 26, 1975, the Los Alamos Lab (under contract to the US Air Force Armament Laboratory, Eglin AFB, FL) tested the GAU-8 ammunition to establish its hazard classification. The new armor-piercing version of the GAU-8 (30-mm) contained a DU core. In addition to "fragment pattern scoring" (the usual objective of a bonfire cookoff test), testers sampled the air to evaluate the potential for airborne DU. One hundred and eighty live GAU-8 rounds were set off in the bonfire cook-off. The test plan did not include the measurement of aerosol size characteristics and mass concentrations.

Analysis of the air sampling data concluded nothing beyond the obvious fact that DU aerosol was released. All but one of the 180 rounds remained within 400 feet of the bonfire. The exception was a shell base. The DU penetrators lost a good deal of mass in the bonfire—about 30% of the penetrators lost visually detectable amounts of DU. The remaining rounds escaped the high temperatures that normally turn DU into aerosol and ash. As the report notes, "Almost total dispersion of several penetrators to aerosol and ash illustrated the probable fate of any penetrator remaining in a high temperature region." In other words, in fires, the potential for DU aerosol dispersion is greater than in other scenarios.

Report Number 4

Prado, Captain Karl L. External Radiation Hazard Evaluation of GAU-8 API Munitions, TR 78-106. Brooks Air Force Base, TX: USAF Occupational and Environmental Health Laboratory, 1978.

The study concluded that the standards for protection against radiation (10CFR20.105) were met during typical field conditions, provided that: "(1) occupancy of any area 100 cm from any accessible surface of stored CNU-309/E containers by non-occupationally exposed personnel does not exceed a total of 1,000 hours per year, and that (2) the PGU-14/B cartridge is in a case when handled (If the cartridge is handled directly, the total contact time with the projectile surface should not exceed 180 hours per calendar quarter)."

Report Number 5

Bartlett, W.T., R.L. Gilchrist, G.W.R. Endres, and J.L. Baer. Radiation Characterization, and Exposure Rate Measurements From Cartridge, 105-mm, APFSDS-T, XM774, PNL-2947. Richland, WA: Battelle Pacific Northwest Laboratory, November 1979.

This was one of three studies recommended by the Joint Technical Coordinating Group for Munitions Effectiveness Working Group on Depleted Uranium Munitions in their initial 1974 environmental assessment of DU. This study focused on the health physics problems associated with the assembly, storage, and use of the 105 mm, APFSDS-T, XM774 ammunition. The conclusion of the report was that the "radiation levels associated with the XM774 ammunition are extremely low. The photon emissions measured did not exceed a maximum whole-body or critical organ exposure of 0.26 mR/hr. Even if personnel were exposed for long periods to the highest levels of radiation measured, it is doubtful that their exposure would reach 25% of the maximum permissible occupational dose listed in Title 10 of the Code of Federal Regulations, Part 20."

Report Number 6

Gilchrist, R.L., J.A. Glissmyer, and J. Mishima. Characterization of Airborne Uranium From Test Firings of XM774 Ammunition, PNL-2944. Richland, WA, Battelle Pacific Northwest Laboratory, November 1979.

This was the last of three studies recommended by the Joint Technical Coordinating Group for Munitions Effectiveness (JTCG/ME) in the late 1970s. The purpose of this particular test was to gather data necessary to evaluate the potential human health exposure to airborne DU. (The other two studies were: "Radiological and Toxicological Assessment of an External Heat (Burn) Test of the 105 mm Cartridge, APFSDS-T, XM774" and "Radiation Dose Rate Measurements Associated with the Use and Storage of XM774 Ammunition.") Data collected during this test included the following:

1. Size distribution of airborne DU
2. Quantity of airborne DU
3. Dispersion of airborne DU from the target vicinity
4. Amount of DU deposited on the ground
5. Solubility of airborne DU compounds in lung fluid
6. Oxide forms of airborne and fallout DU

The study included extensive assessment of total and respirable DU levels above the targets and at downwind locations, fallout and fragment deposition around the target, and high-speed movies of the smoke generated by the penetrator impact to estimate the cloud volume. Although technical problems were encountered during the test with filter overload, etc., the following conclusions were drawn:

1. Each test firing generated approximately 2.4 kg of airborne DU.
2. Approximately 75% of the airborne DU was U₃O₈ and 25% was UO₂.
3. Immediately after the test, about 50% of the airborne DU was respirable, and about 43% of that amount was soluble in simulated lung fluid within seven days. After seven days the remaining DU was essentially insoluble.
4. Particles in the respirable range were predominantly U₃O₈. Iron and traces of tungsten, aluminum and silicon compounds were found in the airborne particles.
5. The report stated that "Measurement of airborne DU in the target vicinity (within 20 ft) after a test firing showed that personnel involved in routinely changing targets could be exposed to concentrations exceeding recommended maximums. This may have resulted in part from mechanical resuspension of DU from the soil or other surfaces."

Numerous problems were encountered during the sampling for total particulates, which contributed to the conclusion that the average fraction of the penetrator being aerosolized was 70%. These problems included:

• the particulate samplers became clogged and the flow rates dropped to zero which required that the sampling time be estimated,
• the number of fallout trays near the target was inadequate to determine the amount of DU deposited on the ground, and
• the cloud volumes could not be fully evaluated because of inadequate films of the cloud.

Despite the technical problems encountered during the test, 70% is frequently cited as the average level of penetrator aerosolized during hard impact.

Report Number 7

Davitt, Richard P. A Comparison of the Advantages and Disadvantages of Depleted Uranium and Tungsten Alloy As Penetrator Materials, Tank Ammo Section Report No. 107. Dover, NJ: US Army Armament Research and Development Command, June 1980.

This report provides an excellent history of the logic behind the Army’s decision to use DU as a kinetic energy, armored-piercing munition. The final selection of DU over Tungsten was based on a combination of reasons, including the lower initial cost of the penetrator itself and its overall improved performance. DU and Tungsten were rated even for "producibility." Tungsten had the advantage for safety, environmental concerns, and deployment.

Report Number 8

Ensminger, Daniel A. and S.A. Bucci. Procedures to Calculate Radiological and Toxicological Exposures From Airborne Release of Depleted Uranium, TR-3135-1. Reading, MA: The Analytic Sciences Corporation, October 1980.

This report provided a description of the models for assessing radiological and toxicological exposures from airborne dispersions of DU under given release conditions—particularly APFSDS-T (Armor-Piercing, Fin-Stabilized, Discarding Sabot-Tracered) XM774 and M735A1 rounds.

Report Number 9

Elder, J.C. and M.C. Tinkle. Oxidation of Depleted Uranium Penetrators and Aerosol Dispersal at High Temperatures, LA-8610-MS. Los Alamos, NM: Los Alamos Scientific Laboratory of the University of California, December 1980.

This was an early test to evaluate the consequences of exposing DU penetrators to a variety of thermal conditions ranging from 500� C to 1,000� C in different atmospheres for 2 to 4 hours. The general conclusions of these tests were:

1. DU aerosols with respirable-sized particles are produced when penetrators are exposed to temperatures above 500� C for one-half hour or more.
2. When the penetrators were exposed to sustained fires; forced drafts and temperature cycling enhanced the production of oxide and aerosol.
3. Since the penetrators are not in themselves flammable, complete oxidation required adequate fuel and a fire of more than 4 hours.

Report Number 10

Chambers, Dennis R., Richard A. Markland, Michael K Clary, and Roy L. Bowman. Aerosolization Characteristics of Hard Impact Testing of Depleted Uranium Penetrators, Technical Report ARBRL-TR-02435. Aberdeen Proving Ground, MD: US Army Armament Research and Development Command, Ballistic Research Laboratory, October 1982.

This is the early documentation required by the NRC to support indoor, confined testing of 105 and 120mm kinetic energy DU rounds. NRC initially approved the test firing of 10 rounds to verify the integrity of the test facility; then it approved the firing of 20 DU penetrators to characterize the aerosol generated by a penetrator impact with an armor target. The study contradicted a previous study by Battelle for the XM774, which indicated that up to 70% of the DU penetrator was aerosolized upon impact. During this study, approximately 3% of the penetrator was aerosolized 2-3 minutes after impact, and accounting for error, it was highly unlikely that more than 10% was aerosolized. The test data was consistent with previous test data for small caliber ammunition. For the aerosolized particulates, the mass mean diameter was 1.6 microns and approximately 70% was less than 7 microns, which is considered the upper range of respirable particulates for DU. The study raised many questions concerning the nature of aerosols generated by hard impact testing of DU penetrators.

Report Number 11

Hooker, C.D., D.E. Hadlock, J. Mishima, and R.L. Gilchrist. Hazard Classification Test of the Cartridge, 120 mm, APFSDS-T, XM829, PNL-4459. Richland, WA: Battelle Pacific Northwest Laboratory, November 1983.

The purpose of this test was to determine the behavior of the XM829 cartridge when subjected to (1) detonation of an adjacent XM829 cartridge, and (2) a sustained hot fire. The test concluded that detonating a XM829 cartridge in one container would not cause the immediate detonation of XM829 cartridges in adjacent cartridges. But if a fire starts and continues to burn, adjacent cartridges may ignite, scattering debris up to 40 feet. A mass analysis for the two tests conducted under this project indicated that at least 80% of the cartridge’s mass was recovered in the 1982 test and 100% was recovered in the 1983 test. No DU contamination was detected in samples from the sand taken from ground zero. An analysis of the filters from 7 high volume air samplers also indicated that the airborne level of DU remained at natural background levels. The report noted that "great care was taken during this time to prevent the residue from being scattered by winds and that under different conditions these values could vary." An analysis of the respirator canisters also revealed no measurable levels of DU.

Report Number 12

Mishima, J., M.A. Parkhurst, R.L. Scherpels, and D.E. Hadlock. Potential Behavior of Depleted Uranium Penetrators under Shipping and Bulk Storage Accident Conditions, PNL-5415. Richland, WA: Battelle Pacific Northwest Laboratory, March 1985.

The purpose of this test was to characterize the particle size, morphology, and lung solubility of DU oxide samples from 120 mm M829 DU rounds exposed to an external heat test and to conduct a literature search on "uranium oxidation rates, the characteristics of oxides generated during the fire, the airborne release as a result of the fire, and the radiological/toxicological hazards from inhaled uranium oxides."

The test results indicated that a maximum of 0.6% by weight of the DU oxide generated was in the respirable range (i.e., less than 10 m m Aerodynamic Equivalent Diameter) and that the respirable fraction of the oxide was insoluble (i.e., 96.5% had not dissolved within 60 days). The study concluded that DU oxides formed during burning should be classified as insoluble (Class Y-dissolution half-times in the lung of more that 100 days).

Report Number 13

Wilsey, Edward F. and Ernest W. Boore. Draft Report: Radiation Measurement of an M1A1 Tank Loaded with 120-MM M829 Ammunition. Aberdeen Proving Ground, MD: US Army Ballistic Research Laboratory, undated.

This work was supported by the Project Manager, M1A1 Abrams Tank System, US Army Tank and Automotive Command. The tank was loaded with forty M829 120mm rounds to evaluate crew radiation exposure levels. "Preliminary results of the radiation exposures to M1A1 tank crews were well within the Nuclear Regulatory Guidelines for the general population and there was no undue radiation hazard when the tank was fully loaded with M829 rounds."

Report Number 14

Magness, C. Reed. Environmental Overview for Depleted Uranium, CRDC-TR-85030, Aberdeen Proving Ground, MD, Chemical Research & Development Center, October 1985.

This is an excellent environmental overview of DU—its relation to natural uranium, its applications (both commercial and military), and its long-term effects on man and the environment. The Army conducted this study to fulfill the relevant background information for Army documentation requirements as detailed in Army Regulation (AR) 200-2.

Report Number 15

Scherpelz, R.I., J. Mishima, L.A. Sigalla, and D.E. Hadlock. Computer Codes for Calculating Doses Resulting From Accidents involving Munitions Containing Depleted Uranium, PNL-5723. Richland, WA: Battelle Pacific Northwest Laboratory, March 1986.

The report described the Army’s computer modeling to determine whether or not an exclusion zone should be imposed around an accident site, where a boundary should be located, and whether the potential effects farther downwind would be significant or trivial based the characteristics of the incident, the actual munitions involved, and the packaging of the munitions.

Report Number 16

Haggard, D.L., C.D. Hooker, M.A. Parkhurst, L.A. Sigalla, W.M. Herrington, J. Mishima, R.I. Scherpelz, and D.E. Hadlock. Hazard Classification Test of the 120-MM, APFSDS-T, M829 Cartridge: Metal Shipping Container, PNL-5928. Richland, WA: Battelle Pacific Northwest Laboratory, July 1986.

This was a follow-up test to the Hazard Classification Test summarized in PNL 4459 (Report Number 11 above), which was conducted with a wooden shipping container. This follow-up test was conducted to evaluate a new PA-116 metal shipping container. The results:

1. Igniting a round in a metal shipping container by way of an external source did not cause the detonation of the entire package contents.
2. Ignition of one round surrounded by other rounds did not cause sympathetic detonation of the other rounds.
3. Igniting the cartridges’ propellant with a sustained fire caused individual rounds to explode. These explosions caused perceptible blast pressure pulses up to 20 feet away.
4. The individual explosions blew cartridge and shipping container fragments into the air. The penetrators were recovered within 20 feet of the fire. Most of the fragments fell within 200 feet. Two fragments were recovered between 300 to 600 feet from the fire.
5. Four of the 12 penetrators from the fire test showed evidence of oxidation. One penetrator core had oxidized almost completely to oxide powder.

The test also revealed these radiological aspects:

1. About 9.5% of the total DU in the 12 cores was converted to oxide during the fire.
2. The oxide was predominantly U₃O₈.
3. The fraction of generated oxide that was aerodynamically small enough to be suspended in air and carried by the wind was 0.002 to 0.006 (0.2% to 0.6%).
4. The fraction of generated oxide that was small enough to be inhaled was about 0.0007 (0.07%).
5. The solubility of the DU oxide in simulated lung fluid indicated that 96% was essentially insoluble. Four percent was dissolved in the fluid within 10 days.
6. During the test, winds were relatively calm. "Air monitors (detection limit of 1m g DU) set up to intercept downwind DU aerosol detected no DU on their filters and tended to confirm that there was no significant airborne DU oxide."

The study concluded that, "the minute quantity of oxide that was of respirable size and the calm winds limited the downwind disposal and posed no biological hazard to cleanup crews or others in the area."

Report Number 17

Hooker, C.D. and D.E. Hadlock. Radiological Assessment Classification Test of the 120-MM, APFSDS-T, M829 Cartridge: Metal Shipping Container, PNL-5927. Richland, WA: Battelle Pacific Northwest Laboratory, July 1986.

This was the follow-up study to a 1983 study evaluating potential health problems when the M829 cartridge is shipped and stored in wooden containers. This follow-up assessment was necessary to evaluate radiation levels when the M829 cartridge is packaged in a metallic container. Results of the study indicate the following:

1. The components of the M829 effectively shield out the predominant nonpenetrating radiation emitted from the bare penetrator; the 1 MeV photons resulting from the decay of the ^234m Pa can penetrate both the components of the projectile and the metal container.
2. The radiation levels emanating from the assembled M829 cartridge are no different from the 1983 study, and the slightly higher radiation measurements at the surface of the package are a function of the reduced distance between the penetrator and the outer package surfaces.
3. The radiation levels associated with the M829 ammunition do not present a significant potential hazard to personnel handling and storing the ammunition.
4. The radiation levels at the surface of the single shipping container, measured with field-use-exposure-rate instruments, do not exceed 0.5 mR/hr, and all other criteria given in 49 CFR 173.421 and 173.424 are satisfied by the M829 shipping package. The package therefore qualifies for shipment as "excepted from specification package, shipping paper and certification, marking and labeling requirements." The inner or outer package must, however, bear the word "Radioactive."
5. The ammunition prepared for shipment must be certified as acceptable for transportation by having a notice enclosed in or on the package, included with the packing list, or otherwise forwarded with the package. This notice must include the name of the co-signer and the statement, "This package conforms to the conditions and limitations specified in 49 CFR 173.424 for articles manufactured from depleted uranium, UN 2909."

Report Number 18

Life Cycle Environmental Assessment For the Cartridge, 120MM: APFSDS-T, XM829. Picatinny Arsenal, NJ: US Army Armament Research, Development and Engineering Center, Close Combat Armament Center, December 12, 1988.

This was the initial Environmental Assessment (EA) for the M829 armor piercing round. The M829 replaced the XM827 (the American analog of the German DM 13), which was the initial APFSDS-T round. The program included the development and testing of four rounds: Target Practice (M831), High Explosive (M830), Armor Piercing (XM827), and Target Practice (M865). The EA incorporates all of the previous supporting studies on the M829 round (e.g., the radiological and hazard classification of the metal and wooden shipping containers). The conclusion of the EA was a "Finding of No Significant Impact" for the design, production, test and evaluation, deployment, and demilitarization of the M829.

Report Number 19

Parkhurst, M.A. and K.L. Sodat. Radiological Assessment of the 105-MM, APFSDS-T, XM900E1 Cartridge, PNL-6896. Richland, WA: Battelle Pacific Northwest Laboratory, May 1989.

In this study the XM900E1 round was packaged in the PA-117 steel container. The conclusions of the report are as follows:

1. The components of the XM900E1 effectively shield out the predominant non-penetrating radiation emitted from the bare penetrator and significantly reduce the majority of the penetrating radiation. The 1MeV photons resulting from the decay of ^234mPa can penetrate both the components of the projectile and the metal canister but are somewhat reduced.
2. Radiation levels associated with the XM900E1 ammunition do not present a significant potential hazard to personnel handling and storing the ammunition.
3. Radiation levels at the surface of the single shipping package, measured with field-exposure-rate instruments, do not exceed 0.5 mR/hr and all other criteria specified by the US Department of Transportation (DOT) in 49 CFR 173.21 and 49 CFR 173.424 are satisfied by the XM900E1 shipping package."

Report Number 20

Wilsey, Edward F. and E.W. Bloore. M774 Cartridges Impacting Armor-Bustle Targets: Depleted Uranium Airborne and Fallout Material, BRL-MR-3760. Aberdeen Proving Ground, MD: Ballistic Research Laboratory, May 1989.

This study was one of several conducted on the M774 ammunition (105mm). It addresses only one objective—the documentation of the amount of DU aerosol and fallout around and downwind of the armor-bustle target. "Very little of the depleted uranium of the M774 penetrator left the immediate target area as an aerosol." The highest value—regardless of the wind conditions—was so low that over 1,400 such tests would have to be fired in a week before tolerance limits would begin to be reached. While the threshold limit value was exceeded when the cloud passed over the samplers, the time-weighted-average exposure for a 40-hour workweek was only 0.07% of the occupational Threshold Limit Value.

Report Number 21

Erikson, R.L., C.J. Hostetler, J.R. Divine, and K.R. Price. Environmental Behavior of Uranium Derived From Depleted Uranium Alloy Penetrators, PNL-2761. Richland, WA: Battelle Pacific Northwest Laboratory, June 1989.

This report covers some of the factors affecting the conversion of DU metal to oxide, the subsequent influences on the leaching and mobility of uranium through surface water and groundwater pathways, and the absorption of uranium by growing plants. Although the report is not directly related to the Gulf War, it demonstrates the Army’s efforts to understand the environmental fate of uranium.

Report Number 22

Fliszar, Richard W., Edward F. Wilsey, and Ernest W. Bloore. Radiological Contamination from Impacted Abrams Heavy Armor, Technical Report BRL-TR-3068. Aberdeen Proving Ground, MD: Ballistic Research Laboratory, December 1989.

The objective of this test was to evaluate DU aerosol levels generated inside and outside a heavy armor Abrams tank (i.e., DU armor) impacted by various types of rounds. The test also evaluated particle size distributions of DU puffs generated by the impact near the point of impact and within 100 meters from the tank, resuspension levels within 100 meters of the tank, and DU contamination in air from a burning M1A1 tank with heavy armor after being hit.

The following types of rounds were used in the seven tests:

1. 120 mm APFSDS, KE - tungsten
2. 120 mm, Heat - MP
3. 100 mm AP-C steel rod
4. Anti-tank Mine
5. 120 mm APFSDS, KE - DU (Test 5A)
6. 120 mm APFSDS, KE - tungsten (Test 5B)
7. Hellfire equivalent

In evaluating the data from the test, it is important to recognize the difference between the aerosols typically generated as puffs from impact and aerosols generated from a fire plume involving DU penetrators. Numerous tests have demonstrated that "DU penetrators when burned in a fire for hazard classification, have formed highly insoluble DU oxides, at least in the respirable size range."

The following permissible exposure levels of uranium in the air and soil were extracted from Table 5 of the report:

Based on the test data, exposures from passing clouds are insignificant beyond 100 meters. The maximum estimated intake at distances greater than 100 meters was 0.82 micrograms of DU. The study noted that it would only take four minutes to reach the airborne limit for the general public, but the passing cloud from each test was present for only a few seconds at a given location. Within 100 meters, but outside the cloud path, air sample results were also insignificant. This included air samplers within 5 to 10 meters of the target. Air sample results in the cloud path varied with the highest level being recorded at a distance of 10 meters from the target (280 micrograms—an acute exposure). There was little additional intake after the puff passed by. Air sampling results for test #6 (a Hellfire equivalent caused a fire that consumed the vehicle) were still within the intake limit even though the air samplers were also exposed to the plume of the fire.

Cascade impactor data for puff of smoke generated at impact revealed that the particles within the cloud were primarily respirable particles (ranging from 76% at the point of impact to 85% just outside the cloud path and 79% along the cloud path). Results of the resuspension air samplers at a distance of 10 to 100 meters from the target revealed that at least for this test, resuspension was not a problem. The highest level recorded was 1.7 x 10^-14 microcuries/ml which was well within the limit for airborne uranium.

A personal sampler was worn in the breathing zone by a member of the initial reentry team to evaluate resuspension at the test pad and while climbing inside the crew compartment. All of the resuspension results were within acceptable limits except in Test 6B. For Test 6B, reentry occurred following the fire and the Test 6B sample was collected primarily from inside the crew compartment. The report indicated that a penetrator might have been ejected from one of the storage compartments into the crew compartment and then completely oxidized during the test. Even so, the report cited that the airborne concentration was just above the limit for soluble U-238 and that the limit for insoluble U-238 (5 x 10^-12 microcuries/ml) was probably appropriate. Based on the insoluble U-238 criteria, all resuspension data would be within acceptable limits.

Test data for representative welding operations lasting approximately 20 minutes revealed that exposure levels were above the unrestrictive release limits of 3 x 10 ^-12microcuries/ml of uranium. However, they were never above restricted area limits of 7 x 10^-11 microcuries/ml. Local exhaust ventilation was not used for these welding operations and the welding was performed both outside and inside the target, both indoors and outdoors. The report stated that "Even if airborne levels of DU had been above the restricted limit during welding, the welder probably would not have been overexposed. The exposure would be time-weighted to the actual amount of time the welder was working. The usual patchwork took about 20 minutes." However, the welder would still need to wear a respirator under the ALARA guidelines and to protect against other welding hazards such as iron oxide fumes.

For all of the tests, the highest fallout levels occurred on the test pad within 5 to 7 meters of the target. However it was noted that heavy armor material was blown out 76 meters (250 feet) or more from the target after several tests.

Interior air sampling was also taken during the three last impact tests when breakthrough into the crew compartment occurred. Data, though limited, was collected on the first two of those impact events. Data for the last impact was lost because the vehicle caught fire destroying all of the air samplers. During the two impact events in which the penetrators entered through the turret into the main crew area, the air samplers located in the Commander, Gunner and Loader crew positions all shut down during the initial minute following impact. This is probably attributable to either ballistic shock from the impact itself, and/or disruption by the short-lived electromagnetic field, which occurs during armor impact. All of the air samplers placed within the vehicle were small battery powered samplers.

In conducting an assessment of the data it was conservatively assumed that the samplers that shut off did so within the first second after impact. Based on that assumption and knowing the flow rate of the respective samplers, an estimate of intake by an individual was calculated with reference to an inhalation rate of 30 liters per minute (lpm). The maximum mass of DU on a filter in the first breakthrough impact was 3.7 mg DU total dust at the Gunner’s position. This equated to a projected intake of 26 mg DU total dust for that second in time. In the second breakthrough impact event, the maximum mass of DU measured on a filter was 4.6 mg DU total dust at the Driver’s position. This sampler, however, continued to run until turned off during re-entry activities, about 16 minutes after impact. Based on the sampler flow rate and an inhalation rate of 30 lpm, a projected intake to the driver over that 16-minute period would have been 28 mg DU total dust.

Although the filter for the driver collected 4.6 mg of DU over the 16-minute period, the highest filter reading in the main crew compartment during the event was 2.4 mg, presumably collected in a matter of moments before the sampler shut off. This fact suggests that appreciably higher concentrations of DU might have been collected in the main crew compartment, as opposed to that in the driver compartment, had the sampler not shut off.

Based on the circumstances surrounding each of the two impact breakthroughs for which samples inside the vehicle were collected, significantly higher results would have been predicted for the first impact breakthrough. In the first the turret armor impacted had already been hit on two prior occasions, that may have added to the DU residue inside the tank that was resuspended in the crew compartment at impact. In addition, a DU kinetic energy (KE) round was fired into the armor package during this breakthrough event. In contrast, the round fired for the second event was a non-DU KE round, and the DU turret armor package impacted was impacted for the first time. This discrepancy may be explained by the fact that in the first breakthrough event the vehicle's NBC exhaust air filtration exhaust system was running and the Loader's hatch opened upon impact. In the second breakthrough event, the NBC system was off, and none of the vehicle's hatches opened when impact occurred.

Report Number 23

Hadlock, D.E. and M.A. Parkhurst. Radiological Assessment of the 25-MM, APFSDS-T XM919 Cartridge, PNL-7228. Richland, WA: Battelle Pacific Northwest Laboratory, March 1990.

The purpose of the study was to assess the health issues associated with the handling, storage and shipment of 25mm, APFSDS-T, XM919 ammunition for the US Army Bradley M3A1 and the US Marine LAV-25. The DU cartridges for the M919 ammunition are packaged in the Army plastic (M-621) and metal (PA-125) shipping containers and the Marine metal (CNU-405) shipping container. The study evaluated radiation levels for shipping containers in storage configurations within and outside the fighting vehicles. The results are as follows:

1. The radiation levels associated with the M919 are low and do not present a significant hazard to personnel handling and storing the ammunition.
2. The radiation levels in the Bradley M3A1 and the LAV-25 are also low. Potential doses to personnel in these vehicles will depend on the length of occupancy in the vehicle and the configuration of the stored munitions.
3. The components of the M919 effectively shield out the predominant non-penetrating radiation emitted from the bare penetrator and significantly reduce the majority of the penetrating photon energy. The one MeV photons resulting from the decay of ^234mPa can penetrate both the components of the projectile and the plastic M-621 and metal shipping containers but are somewhat reduced.
4. Radiation levels at the surface of the single shipping container and the pallet of 27 shipping containers, measured with field-exposure-rate instruments, do not exceed 2.5 mR/h. The exposure rate is well within the US Department of Transportation’s (DOT) special exemption of 2.5 mR/h limit for DU munitions. Therefore, if the Army obtains approval from the Military Traffic Management Command (MTMC), the XM919 shipping container may be shipped under DOT exemption DOT-E96-49. Otherwise, the containers must be shipped under the provisions of 49 CFR 173.425 entitled "Transport Requirements for Low Specific Activity (LSA)."

Report Number 24

Parkhurst, M.A., J. Mishima, D.E. Hadlock, and S.J. Jette. Hazard Classification and Airborne Dispersion Characteristics of the 25-MM, APFSDS-T XM919 Cartridge, PNL-7232. Richland, WA: Battelle Pacific Northwest Laboratory, April 1990.

Although the 25mm, APFSDS-T M919 cartridge was not used during Desert Shield/Desert Storm, a summary of the Hazard Classification testing is included to demonstrate consistency with previous Hazard Classification tests performed on cartridges used in the Gulf War.

The Hazard Classification Tests performed on the XM919 included the Stack Test which evaluates propagation of detonation and the External Fire Stack Test which evaluates the explosive and fragmentation nature of the cartridge resulting from setting fire to boxes of cartridges. In addition, the M919 was tested against hard armor targets and against wood and masonry to determine the extent and nature of Du aerosols created.

The results of the M919 tests are as follows:

• There was no propagation of initiation demonstrated from the Stack Test. The effects of initiation of the donor cartridge were limited to the donor container. There was no propagation of initiation to the other shipping containers.
• The results of the External Fire Stack Test indicated there was no mass detonation of the cartridges. The cartridges exploded progressively and the effects were limited to the immediate test area.
• Many of the penetrators that remained in the fire showed some signs of oxidation. Approximately 35% of the total DU used in the External Fire Stack Test was oxidized. Between 0.1% and 0.2% of the oxide was within the respirable range. The lung solubility analysis of the DU oxide determined that 92.6% was insoluble and 6.8% was slightly soluble.
• There was no indication that any measurable DU became airborne as a result of the External Fire Stack Test.
• The fraction of DU made airborne from the hard target impact testing was less than 10%. Less than 0.1% of the initial DU penetrator weight was within the respirable size range. About 17% of the oxide present in the smallest size fraction was soluble while the remaining 83% was insoluble.

Report Number 25

Kinetic Energy Penetrator Long Term Strategy Study (Abridged), Final Report. Picatinny Arsenal, NJ: US Army Production Base Modernization Activity, July 24, 1990.

This report addressed battlefield DU exposures relative to peacetime occupational limits. Civilian battlefield exposures are not thought to be significant. "All combat-related internal and external radiation risks were in the range of 10^-7 to 10^-5. The most significant external radiation exposure occurs during the loading and unloading of ammunition lockers, with a lifetime increased cancer risk to the extremities as high as 3 x 10^-4 resulting from a worst case, 20-year exposure. Even minimal safety precautions would reduce this risk to levels well below those tolerated in most occupational environments."

The report also addressed the following theoretical exposures;

1. Tank Crew Radiation Exposure Maximum Exposure. Assuming � of a day, seven days/week, 52 weeks/year + .25 rem/year, and a half-filled DU kinetic penetrator ammunition rack, this level is well below the occupational limit of 5 rems/year.
2. Soldier Taking Refuge. Assuming a scenario of a tank hit by a DU penetrator, a soldier taking refuge would receive a maximum exposure of 23 mrem—equivalent to a lifetime increased cancer risk of less than 5 X 10^-6, which is three orders of magnitude less that the lifetime increased cancer risk calculated in the same manner resulting from all background radiation exposures.
3. Major Tank Battle. Assuming a two-month duration, the lifetime increased cancer risk for military personnel would be 1.5 X 10^-7. Downwind of such a battleground, the public would experience a lifetime cancer risk increase of about 3 X 10^-5.

The report also addressed the need for further evaluation of battlefield conditions. "Exposures to military personnel may be greater that those allowed in peacetime, and could be locally significant on the battlefield. Cleanup of penetrators and fragments, as well as impact site decontamination may be required." "Public relations efforts are indicated, and may not be effective due to the public’s perception of radioactivity." The Overview also indicated that further studies were needed on DU combat impacts for post-combat briefings and actions.

Report Number 26

Jette, S.J., J. Mishima, and D.E. Haddock. Aerosolization of M829A1 and XM900E1 Rounds Fired Against Hard Targets, PNL-7452. Richland, WA: Battelle Pacific Northwest Laboratory, August 1990.

The purpose of this study was to characterize particulate levels after hard impact with both complete and partial penetration of the armor. Tests were performed with both the M829A1 and XM900E1 rounds, as well as two non-DU rounds (the M865 and DM13). The purpose of the non-DU round firings was to evaluate DU resuspension during hard impact tests. The sample results were questioned when the percent aerosolized was initially estimated to be only 0.2% to 0.5% for the M829A1 and 0.02% to 0.04% for the XM900E1. These values were approximately two orders of magnitude below expected values. A value of 70% has frequently been cited in the popular press based on one of the initial studies performed by Battelle for the XM774. This study stated that it was highly unlikely that more than 10% was aerosolized upon impact. In keeping with other studies indicating that a high percentage of the respirable dust from hard-impact testing was soluble in the lungs, this study’s evaluation of the respirable dust fraction indicated that 57 to 76% was class "Y" material and 24 to 43% was class "D" material. (Class "D" materials have dissolution half-times less that 10 days; class "W" materials have dissolution half-times of 10 to 100 days; and class "Y" materials have dissolution half-times greater than 100 days.) The resuspension tests indicated that most of the resuspended dust was non-respirable—which is consistent with the theory that most of the respirable dust was removed by the filtering system in the enclosure.

Report Number 27

Munson, L.H., J. Mishima, M.A. Parkhurst, and M.H. Smith. Radiological Hazards Following a Tank Hit with Large - Caliber DU Munitions, Draft Letter Report. Richland, WA: Battelle Pacific Northwest Laboratory, October 9, 1990.

At the beginning of the Gulf War crisis, Battelle’s Pacific Northwest Laboratory was tasked to predict potential radiation hazards to personnel entering a site where a tank has been hit by DU. Their prediction was based on a DU penetrator for a 105-mm, APFSDS-T kinetic energy round striking an armored vehicle and penetrating one side of the vehicle. No live fire testing was performed under this tasking. Their estimates were based on previous tests and their "best educated estimates" of exposures for the following scenario: The vehicle contains no DU munitions or DU armor. The event occurs in a desert-like climate, which exhibits high daytime temperatures and low nighttime temperatures and large fluctuations in relative humidity between inland to coastal areas and from day to night. There are winds associated with the changes in surface temperature. Personnel are in the immediate area for inspections and observation within days after the event. Clean up and recovery activities occur within a few weeks to a few months.

The report stated that the "impact of a DU penetrator with an armored vehicle would be expected to result in aerosolization of 12% to 37% of the penetrator, smearing of DU metal around and through the penetration, and scattering of metal fragments both inside and outside the vehicle. The aerosolized DU would most likely be oxidized uranium and form particulate material which, depending upon its size, could deposit around the immediate area and preferentially downwind. The material smeared around and through the vehicle penetration would be both DU metal and DU oxide."

The report indicated that exposures to casual passers-by and cleanup personnel would be very low. "Occupational dose limits for external exposure are 5000 mrem/year to the whole body, 50,000 mrem/year to the skin, and 75,000 mrem/year to the hands and feet (extremities). Since the most likely organ to be exposed during contact with penetrator fragments is the skin, it would require over 800 hours of direct contact to bare skin to reach the current occupational limit for skin exposure." Because such direct and long exposure is quite unlikely, the report indicated the radiological hazard from external exposure to DU fragments was very low for causal passers-by and cleanup personnel.

The report stated that the "principal hazard from exposure to DU material is inhalation and lung deposition of particulate uranium. Alpha particle emissions to the lungs from inhaled DU constitute the main health concern from the inhalation of the mostly insoluble DU. Occupational exposure limits for the inhalation of ²³⁸U are 7 x 10^-11 microcuries/ml for soluble forms of uranium and 1 x 10^-10 microcuries/ml for insoluble uranium compounds. These exposure limits are based on continual intake of ²³⁸U for 13 weeks at 40 hour/week. In terms of mass the limit is an average of 0.2 mg/m³ of ²³⁸U aerosols in a 40-h work week."

The report noted that 44% to 70% of the DU material aerosolized would be equal to or less than the 3.3 micrometer Aerodynamic Equivalent Diameter (AED) which is the approximate size that would be inhaled into the deep lung. Characterization of the DU penetrators oxidized in various Hazard Classification testing indicated that 0.2% to 0.6% of the oxide was less than 10 micrometer AED—which is considered as respirable (inhaled into the nasal passages).

The report stated that any hazards from the presence of DU are relatively insignificant as compared to the other battlefield considerations and should not be considered during life saving and rescue activities.

During the recovery operations, the report expressed concerns that the large fragments could pose a potential hazard from external radiation and their surfaces could be a source of uranium oxide contamination as they erode. The report also expressed concern that aerosolized DU which had been deposited in and around the vehicle and on the soil in the immediate area could be resuspended by wind and during cleanup and recovery operations.

The following precautions during general clean up and recovery efforts are quoted from the report:

1. Restrict an area approximately 30 meters in radius from the vehicle to minimize unnecessary exposure to personnel and resuspension of DU material.
2. Perform a radiological survey of the restricted area using a thin window GM portable detector or a micro-R meter.
3. DU metal penetrator fragments detected during the survey should be placed in plastic bags, sealed in a container, and stored as appropriate for disposal.
4. DU oxidized penetrator fragments, identified as a black powder, should be placed in plastic bags and sealed in a container for removal. A small amount of sand around and under the oxidized material may also be contaminated and need to be removed. If piles of oxidized DU are not removed at the time of the survey, it is prudent to fix them in place when detected by covering them with an inverted can or similar mechanism to minimize potential movement.
5. The openings to the interior of the impacted armored vehicle should be closed. The DU penetrator opening and the immediate area around it should also be covered to provide containment and minimize spallation and removal of impacted material. It is assumed that the vehicle will be moved to another location for decontamination and disposition.
6. Intrusion into the restricted area during periods of high winds should be discouraged to minimize potential resuspension of radioactive material.
7. Precautions necessary for entry into the restricted area should depend on the purpose of the entry.

The report also provided general guidance on routine monitoring and decontamination procedures.

1. Radiation dosimeters should not be necessary for survey, vehicle closure, clean up, or recovery activities.
2. Entry for radiological survey of the vehicle’s exterior should require no special protective clothing—provided walking over piles of DU oxide is avoided and actions to disturb the soil are minimized.
3. Entry into the interior of the vehicle for any reason should require a single layer of protective clothing, shoe covering, coveralls, gloves, particulate filter respirator and head covering.
4. Entry for pickup of DU fragments and piles of oxide outside the vehicle should require a single layer of protective clothing, shoe covering, coveralls, gloves, particulate respirator, and head covering
5. Entry to close an opening in the target vehicle should require only gloves for hand protection.
6. After the penetrator fragments and piles of oxide are picked up and the vehicle is closed, entry to remove the vehicle should require no protective clothing.

The transmittal Memorandum recommended that all openings should be sealed and only external surfaces decontaminated in the field. Decontamination of the interior should only be performed in a facility set up for that purpose. The memorandum also recommended limiting intrusion into the cleanup/recovery area during periods of high winds because of the potential for contamination resuspension.

In summary, the report concluded that there is little potential for radiological hazard to personnel entering the site following the impact of a DU penetrator with a tank or other armored vehicle. (The prediction did not assume a DU round impacting an Abrams Heavy Armored vehicle with DU armor.) The report did recommend the use of respiratory protection to minimize the inhalation hazard and decontamination of the body of any fatalities before they are released.

Report Number 28

Memorandum for SMCAR-CCH-V from SMCAR, Radiological Hazards in the Immediate Areas of a Tank Fire and/or Battle Damaged Tank Involving Depleted Uranium, Letter Report, Picatinny Arsenal, NJ, December 4, 1990.

As noted in Report #27, Battelle’s Pacific Northwest Laboratory was tasked to predict potential radiation hazards to personnel entering a site where a tank has been hit by DU. Their prediction was based on a DU penetrator (105mm, APFSDS-T kinetic energy round) striking an armored vehicle and penetrating one side of the vehicle. The report did not evaluate a DU munition impacting an armored vehicle containing DU armor or DU munitions. The December 8, 1990 report comments on the Battelle Letter Report (Report Number 27) and expands the prediction to address DU munitions impacting an armored vehicle containing DU munitions and/or DU armor. Although no live fire testing was performed for this report, the conclusions and recommendations were drawn from BRL Technical Report BRL-TR3068, Radiological Contamination from Impacted Abrams Heavy Armor (Report Number 22 above).

The memo attempted to expand on the guidance included in TB 9-1300-278, "Guidelines for Safe Response to Handling, Storage, and Transportation Accidents Involving Army Tank Munitions Which Contain Depleted Uranium, which was the guideline for responding to peacetime accidents. The memo cited the following points:

• Intrusion into the cleanup/recovery area during periods of high winds should be discouraged due to the potential for unnecessary exposure to DU resuspended by that wind, or by the disturbances caused by people or equipment.
• Other than for decontaminating the outside of the vehicle and covering any openings, as provided in the TB, decontamination of the interior of the tank needs to be performed at a facility set up for such a purpose.
• Removal of deceased personnel from tanks will require radiation safety coordination to determine whether or not the clothing and /or body is radioactively contaminated. If so, decontamination will need to be conducted prior to further disposition of the deceased.
• The procedures in the referenced TB were written for a scenario in where an isolated tank accident involving DU occurred during peacetime conditions. Those same procedures still apply if the scenario were an arena of battle damaged tanks scattered about the surrounding area. In order to properly conduct a recovery/cleanup following the termination of a conflict, one would begin at the perimeter of that overall area, and gradually work your way in, clean up the immediate area, decontaminate the exterior of that tank, and remove it, before proceeding into the next sector. In other words, don’t cross-contaminate or re-contaminate things.

The report also addressed potential problems caused by the sand in Gulf Region and the implication for the Army’s standard radiation detection equipment. The report concluded that FIDLERS (field instrument for the detection of low energy radiation) would be more appropriate because of their larger probe areas. The report also provided supplemental procedures to TB 9-1300-278 by reiterating the radiation survey precautions cited in the Battelle Letter Report (Report #27).

Report Number 29

Mishima, J., D.E. Hadlock, and M.A. Parkhurst. Radiological Assessment of the 105-MM, APFSDS-T, XM900E1 Cartridge by Analogy to Previous Test Results, PNL-7764. Richland, WA: Battelle Pacific Northwest Laboratory, July 1991.

Due to administrative restrictions at the test ranges, this study was conducted by analogy to similar test rounds. The conclusions are that "neither propagation of initiation nor mass explosion have occurred with similar large-caliber ammunition, and it is extremely unlikely that either would occur with the M900/PA117" metal shipping container. In a stack fire, the likely extremes with the M900 cartridge are that either all projectiles would be ejected from the fire and show no evidence of oxidation or that all would remain in the fire and totally oxidize. The reality is that some would be ejected from the fire and some would be oxidized. The study cited similar tests for the M735 cartridge, which had maximum fragmentation distances up to 100 feet for the penetrator and 375 feet for the fragments.

Report Number 30

Parkhurst, M.A. Radiological Assessment of M1 and M60A3 Tanks uploaded with M900 Cartridges. PNL-7767. Richland, WA: Battelle Pacific Northwest National Laboratory, July 1991.

The purpose of the study was to assess the dose rate to which M1 and M60A3 crews would be exposed with the deployment of the 105mm M900 cartridge. The tests were conducted using worst case stowage configurations and placement of the bustle compartment near the driver. All cartridge locations were filled with M900 cartridges, rather than the mix of armor-piercing (M900) and high explosive (HE) cartridges. This is not a likely stowage situation. The dose to a crewmembers was calculated to approximate the actual radiation fields with HE stowed appropriately and taking the place of the excess DU cartridges. The results of the study are quoted as follows:

• Based on this unusual configuration, dose rates peaked in the M1 at 0.5 mR/h under the turret bustle and above the driver’s head and in the M60A3 at 1.5 mR/h in the vertical, exposed cartridge storage rack, as measured by portable radiation detection instrumentation. These levels are within the permissible levels of radiation in unrestricted areas. Using thermoluminescent dosimeters to measure specific points within the vehicle, researchers determined that the M1 commander, gunner, and loader received an average dose rate of about 0.01 mrad/h of penetrating radiation. The driver received an average dose of about 0.2 mrad/h with the bustle above him.
• Dose rates to the M60A3 crew were slightly higher than the dose rates for the M1 crew. The commander and gunner received about 0.05 mrad/h of penetrating radiation. The loader, who had well-shielded cartridges behind him, but a stack of unshielded DU cartridges in front of him, received an average of about 0.2 mrad/h. The driver, who had cartridges on three sides, received an average of 0.28 mrad/h.
• Assuming a crew occupied a fully loaded vehicle for 700-900 hours, none of the crew would be likely to exceed the 250 mrad/year administrative badging limit. Even with DU in all the 105mm ammunition slots, the only person approaching the limit would be the M60A3 driver, and this would only occur if the bustle were over his head during his entire time within the vehicle.
• The study revealed that the drivers of both vehicles had the highest potential exposure. The M1 driver received his entire DU dose from the bustle of cartridges over head. (Note: Most of the time, the gun rather than the bustle is over his head). His dose, measured with the hatch open, maximized the radiation field. Without the bustle, the exposure to the M1 driver is negligible. On the other hand, the driver of the M60A3 gets only a small portion of his exposure from the bustle storage. Most of his exposure comes from storage in the hull.
• The study estimated that dose rates for more ordinary configurations are less than 0.05 mrad/h for the M1 driver and about 0.1 mrad/h for the M60A3 driver.

Report Number 31

Life Cycle Environmental Assessment for the Cartridge, 105MM: APFSDS-T, XM900E1. Picatinny Arsenal, NJ: US Army Armament Research, Development and Engineering Center, Close Combat Armament Center, August 21, 1991.

This Environmental Assessment was developed to address environmental concerns when the service round for the M68 cannon on the M60A3 and M1 tanks (the M833 APFSDS-T) was replaced by the new XM900E1 APFSDS-T round, which has significantly greater armor-piercing capabilities. The Assessment included previous studies of the radiological hazards, etc. conducted on the XM900E1. The Assessment’s conclusion was that only the testing modes for armor penetration and accuracy and final disposal of the penetrators presented any significant potential for environmental impact; the report outlined mitigating measures to reduce the impact of testing. From a health and safety standpoint, the XM900E1 presents no greater risk than the existing M833. The XM900E1 program is not expected to have a significant environmental impact on air quality, water quality, ecology (flora and fauna), or health and safety to personnel associated with normal maintenance and life cycle operations.

Report Number 32

Life Cycle Environmental Assessment for the Cartridge, 120MM: APFSDS-T, XM829A2. Picatinny Arsenal, NJ: US Army Production Base Modernization Activity, February 2, 1994.

This is an environmental assessment (EA) of the third generation M829 round (M829A2). It builds on the EA for the previous M829 and M829A1 rounds (see Report Number 18) and concludes with a "Finding of No Significant Impact." This assessment excludes combat uses and fires or other severe and unlikely accidents and the testing modes for armor penetration and accuracy. The EA recognized that the resuspension of DU, environmental transport, and various health and safety issues as areas of concern requiring further evaluation. Consequently, the Army Environmental Policy Institute has been tasked to evaluate the risks associated with depleted uranium left on the battlefields during Desert Storm. In addition, studies on the health effects of DU fragments in soldiers have been funded. The Army is also developing special DU training courses for personnel engaged in fielding, firing, and retrieval operations.

Report Number 33

Parkhurst, M.A. and R.I. Scherpelz. Dosimetry of Large Caliber Cartridges: Updated Dose Rate Calculations, PNL-8983. Richland, WA: Battelle Pacific Northwest Laboratory, June 1994.

This report provides revised exposure levels for all of the previous radiological assessments performed by Pacific Northwest Laboratory (PNL) that used the lithium fluoride thermoluminescent dosimeter (TLD). PNL developed a new, more accurate algorithm for interpreting the response of the TLD used in the radiological assessment of various DU cartridges. As a result, PNL re-evaluated the previously reported exposure values for the following cartridges:

1. 120 mm M829 cartridges
2. 105 mm M333 cartridges
3. 120 mm M829A1 cartridges
4. 120 mm M829A2 cartridges
5. 105 mm M900 cartridges
6. M60A3 and M1 Tanks loaded with M900 cartridges.

The report also provides a comparison of the original versus recalculated values. "In all cases, the recalculated dose rates were significantly lower than the originally reported dose rates. Studies of dose rates in the tanks showed that crews in tanks loaded with DU rounds would pose no danger of exceeding administrative badging limits of 250 mrem/year and it was also unlikely that the more restrictive population limits of 100 mrem/year would be exceeded by personnel in the tanks." In other words, radiation exposure levels associated with uploaded DU munitions in the applicable tanks are within acceptable criteria, even for the general population.

All of the previously reported radiological assessment reports need to be corrected to reflect the results of the recalculations.

Report Number 34

Parkhurst, M.A., G.W.R. Endres, and L.H. Munson. Evaluation of Depleted Uranium Contamination in Gun Tubes, PNL-10352. Richland, WA: Battelle Pacific Northwest Laboratory, January 1995.

Routine radiation monitoring identified radiological contamination in gun tubes that fire developmental and production DU rounds. This report addresses the issues of how much DU is present in tubes that have fired DU, how this relates to unrestricted release standards, how cleaning techniques reduce the DU levels, and how the levels relate to personnel radiation protection.

Testing revealed that numerous tubes had detectable levels of DU in the gun barrels and some were above the unrestricted release limits, but none were high enough to pose a health risk. Firing non-DU training rounds is also effective in reducing the contamination in the tubes, but the practice is not recommended. The removable contamination makes up only a small percentage of the DU contamination that is generated in the firing process. The fixed contamination that is left behind after normal barrel field cleaning procedures was found in a number of instances to be above uncontrolled release limits. Presently, unless more satisfactorily decontaminated by other cleaning means, those barrels would have to be processed as radioactive waste at the time of turn in by the field of the barrel for disposal. Further studies were required to fully assess the problem. Induced flareback was also achieved during firing to determine if tank personnel were exposed in the turret, but no problems were identified for crew personnel.

Report Number 35

Parkhurst, M.A., J.R. Johnson, J. Mishima, and J.L. Pierce. Evaluation of DU Aerosol Data: Its Adequacy for Inhalation Modeling, PNL-10903. Richland, WA: Battelle Pacific Northwest Laboratory, December 1995.

As the name of the report implies, the purpose of this study was to evaluate the existing research data on the characteristics of DU aerosols generated under various conditions. The report is an excellent summary of the studies conducted to date, including many summarized in this report. Project summaries were included for over 20 studies conducted by Battelle Pacific Northwest Laboratory and over 20 additional studies conducted by other researchers. The evaluation focused on chemical composition, particle size, and solubility in lung fluid.

Although several areas such as resuspension and particle size distribution were cited as needing further research, the overall quality of the data was deemed as being adequate to make conservative estimates of dispersion and health effects. The report is an excellent summary of the studies conducted to date.

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