AREA 13-A PLUTONIUM DISPERSAL EXPERIMENT (Plutonium Fields Forever)

The bomb test called "Project 57," commonly known as the "Area 13 experiment," took place in Area 13 on April 24, 1957-6 years before the Atmospheric Test Ban Treaty went into effect. One of about 30 surface so-called "safety tests" conducted at and near the Nevada Test Site, the experiment aimed to scatter plutonium particles so that scientists could study dispersal patterns for developing monitoring and cleanup procedures. Of all the "safety tests," only the Area 13 experiment involved a real nuclear warhead.(1) The bomb itself was not detonated in a nuclear reaction - instead it was blown up with a built-in high-explosive that fragmented the warhead, and scattered plutonium fragments across more than 1,000 acres(2) Because this experiment emulated possible-to-likely scenarios of terrorist attacks using nuclear materials, it is of great interest today, following the September 11, 2001, terrorist attacks on U.S. soil.

Area 13 is on Nellis Air Force Base, about 6.5 miles northwest of the center of Groom Dry Lake - itself part of Area 51, famous for highly-publicized 1950's weird-phenomena and extra-terrestrial speculations. The test area may be found on a US Geological Survey topographic map quadrangle, named Groom Mine SW 7.5'.(3) The plants growing at Area 13 are typical for the Great Basin Desert,(4) and sandy loam soils contain about equal amounts of sand and silt, with some clay.(5) About 17% of the surface is occupied by mounds(6) - some are coppice dunes, formed from wind-blown sand collected around shrubs, and the remainder may have been heaped up by colonies of small burrowing animals.(7)

The Area 13 experiment can be considered an unqualified "success," in that it certainly dispersed highly toxic and flammable plutonium widely into the environment. The area remains highly contaminated today and will remain so for some 240,000 years, however, so the project did not yield a method for cleaning up plutonium, either at Area 13 or anywhere else. Soon after the explosion, experimenters placed caged dogs in the contaminated area to examine what would happen to them after inhaling plutonium in the dust(8) - 70 to 80 dogs were exposed sequentially from 4 to 161 days after the detonation, and then killed and dissected. Numerous follow up studies on other Area 13 effects between 1970 and 1986, included: examining the sizes of plutonium fragments formed in the explosion; the effects of plutonium-contaminated vegetation and soil on cattle and kangaroo rats, and other small native mammals; the various ways that plant foliage traps plutonium;(9) and the effect of contaminated vegetation on animals that eat it. Unfortunately, studies of Area 13 were mostly preliminary and terminated in the mid-1980s, before long-term consequences of plutonium surface contamination could be fully understood.

Striking contamination maps of Area 13, apparently produced nearly 20 years apart, appear in NTS Environmental Impact Statements (EISs) dated 1977 and 1996. The two maps have relatively small (but unexplained) discrepancies and no data collection dates. Both maps display an unusual two-lobed pattern of plutonium contamination in Area 13 soils. Two "radiation fences" identify concentric contamination areas: an inner fence encircles the zone of highest contamination around ground zero, and an outer fence delimits a zone of plutonium concentrations greater than 10 pCi/g - a fatal human dose. The total estimated Area 13 plutonium inventory, both plutonium-239 and plutonium-240 isotopes in soils, sampled to a depth of 2 inches, is about 46 Curies(10) - four times the average at nine other safety test sites.(11)

Researchers(12) concluded that up to 99% of fragmented plutonium at Area 13 is in particles small enough to be picked up by wind and water and redeposited elsewhere(13) - a process called "resuspension." At Area 13, scientists did not monitor disturbance effects from raking the ground surface, but at other safety test sites surface disturbances put 27 times more plutonium-239 dust in the air, and wildfires produced 12 times more airborne plutonium than come from undisturbed surfaces. These results suggest that the highly-contaminated Area 13 has 10 times the plutonium exposure hazard for humans and other animals exposed to resuspension and dust inhalation than at other safety experiment sites.

Some Area 13 ground areas were disturbed during experimental "decontamination" efforts. A 1988 Soviet spy satellite photograph of the area shows large, unexplained, apparently scraped areas beyond Area 13's outer radiation fence(14) - perhaps related to the decontamination experiments. The decontamination methods ranged from irrigation to plowing, all of which would disturb contaminants below the soil surface but not remove them, suggesting that decontamination efforts primarily aimed to reduce resuspension. Later studies apparently never rigorously addressed important questions of whether resuspendable contamination came into Area 13, or where material carried away from the site might go. Resuspendable wind-borne contaminants could have moved a substantial distance to the northeast, whereas contaminants carried in surface water would move to the southeast.

Plants grown in Area 13 have plutonium concentrations of 5.2 to 1,200 pCi/g (dry weight)(15) - as much as a hundred times more than a fatal human dose - in plant stems and in dust coatings on stems and leaves. Laboratory experiments on untreated Area 13 soils(16) showed that plants absorb little plutonium through their roots, but that plutonium absorption increased significantly after treating the soils with agricultural grade sulfur and acetic acid.(17) The studies showed further that soil fungi and bacteria can modify plutonium compounds that form over time, in ways that enhance the compound's absorption by roots.(18)

One study grazed cattle in Area 13 to examine the path of plutonium in their bodies, on the presumption that plutonium transfers similarly from the blood system to organs in both cows and humans, despite differences in bovine and human metabolisms.(19) In these experiments, the cattle - including some pregnant females - ate mostly plant materials but also licked off and consumed soil particles from their snouts the cattle.(20) The ingested material contained a range of plutonium and americium concentrations - as much as 400,000 pCi of plutonium-239 and 56,000 pCi of americium-241. The smaller amounts came from grazing inside the outer fence and larger amounts from grazing inside the inner fence, closer to ground zero.(21)

Gonad, bone, liver, and lung tissue samples from butchered Area 13 cattle(22) contained concentrations of plutonium. Gonads and femurs (upper leg bones) contained median levels of plutonium-239 that were 25 times higher than muscle tissue, while liver and lung tissues contained twice as much - or more - than gonads.(23) These results suggest that plutonium may also concentrate in human gonads, bone, liver, and lungs. The most important finding from this research is that Area 13 cows' uterine placentas transferred plutonium to their unborn calves: the femurs of calf fetuses contained 20% of the plutonium-239 level in the femurs of their dams.(24) Rumen in Area 13 cattle stomachs showed higher plutonium concentrations in later summer and fall than at other times of year from eating winterfat, a seasonal fodder plant with pods that accumulate dust particles - including plutonium dust.(25) The seasonal difference continued for many years, showing that dust-sized plutonium kept on blowing around Area 13.

High winds can, and probably do, carry radionuclides away from Area 13 and the other test sites - but researchers cannot find any monitoring data on the topic of radionuclide resuspension and movement away from the site. This suggests that the radiation boundary is not now and never was monitored to detect resuspension and escape. Plutonium also can escape from radioactive test sites in and on native wildlife, taking it into the ecosystem food chain. Many kinds of animals, including birds, bees and other insects, rodents (mice, rats), and lizards live on or pass through Area 13. Only limited plutonium-239 and americium-241 studies have been done on native animals, however - most were on kangaroo rats that lived on Area 13 for at least 6 months.(26) Potential routes for plutonium into and through the food-chain are very complex, depending on the type of animal and whether it has a burrowing or surface-dwelling life style. Burrows have higher humidity and temperature levels than surrounding soil, and food stored in burrows provides an ideal substrate for fungi and bacteria. Defecation in the burrows adds soluble nutrients and gases. Invertebrate animals may take portions of stored food from the burrows and distribute them through soil and to the surface.(26)

Soil fungus can alter plutonium oxides to more soluble compounds or organic complexes. Since the fungus is a major food source for Darkling beetles, the Area 13 Darkling beetles contain measurable plutonium (500 pCi) in their tissues.(26) Darkling beetles are a food source for many small vertebrates, which take in the plutonium with their prey. Soil-eating animals such as earthworms add another dimension to the movement of plutonium into both plants and animals, because earthworms have a broader range of movement than soil fungi or bacteria, and their predators are even more mobile.(26) Adding birds to the range of possibilities only expands the potential for broad ecological contamination by plutonium.

In the post-September 11 world, the practice of leaving plutonium dispersal test debris in the accessible environment is a problem. Russia and the United States have joined forces to hunt down stray radioactive materials to thwart dirty bombers.(27) Concerns have already arisen that terrorists could fashion non-nuclear "dirty bombs" from contaminated soil in former Soviet atom-test areas of now-independent Kazakhstan. A large plutonium hot spot, probably resulting from dispersal tests, is being buried under a reinforced concrete cap six feet thick to prevent terrorists from getting the contaminated soil.(28) Although the focus is on contaminated Russian and former Soviet territories, similar radioactive soils are easy to find in the U.S. as well.

Endnotes

1. P.W. Merlin, 1995, Project 57 - Plutonium Dispersal Took Place Near Groom Lake, Unpublished manuscript, 4 p.; the warhead was a XW-25 MB-1 "Genie" air-to-air missile, with a design yield of 1.5 Kt.

2. The contaminated area shows plutonium concentrations above 10-40 picocuries per gram (pCi/g) (see chapter endnote 24). Air-suspended plutonium particulates spread over much greater areas. High-volume air monitors at Tempiute, about 28 miles north northeast of ground zero (GZ) recorded alpha-particle emission levels of 6 disintegrations per minute per cubic meter (d/m/m3) and 1.0 d/m/m3 at Caliente, about 150 km (80 mi.) east of GZ (see Box MCB-1) (O.R. Placak, M.W. Carter, and R.A. Gilmore, Report of Off-Site Radiological Safety Activities for Project 57 Nevada Test Site, U.S. Atomic Energy Commission, Office of Test Operations, Albuquerque, New Mexico (1957), M-7003). The orientation of the high-concentration plumes near GZ suggest that the Caliente measurements sampled only the edges of the airborne plume.

3. Ground zero for the experiment is assigned different coordinates in three different documents. The coordinates given by the State of Nevada and U.S. Department of Defense place ground zero in a different quadrangle than the site location shown by the U.S. Geological Survey (USGS), and are almost certainly in substantial error. Another document places the center of Area 13 in the Desert Wildlife Range, more than 22 miles to the southeast, and also is clearly in error; (U.S. Department of Defense, Defense Environmental Restoration Program, Annual Report to Congress for Fiscal Year 1995, U.S. Department of Defense (1996), 621 p. (specific page); U.S. Department of Energy, 1988, CERCLA Preliminary Assessment of DOE's Nevada Operations Office Nuclear Weapons Testing Areas, U.S. Department of Energy (1988), Prepared for DOE by the Desert Research Institute II, Off-Site Areas, Figure 3.10.3.

4. Prominent perennial shrub and grass species include four-winged saltbush (Atriplex canescens), shadscale (Atriplex confertifolia), winterfat (Eurotia lanata), Bud sagebrush (Artemisia spinescens), spiny hop-sage (Grayia spinosa), Green-Molly (Kochia americana), wolfberry (Lycium andersonii), and Indian ricegrass (Oryzopsis hymenoides). Nine additional perennial shrub and grass species and 43 species of annuals and herbaceous perennials were identified on the site (E.M. Romney, A. Wallace, R.O. Gilbert, S.A. Bamberg, J.D. Childress, J.E. Kinnear, and T.L. Ackerman, Some Ecological Attributes and Plutonium Contents of Perennial Vegetation in Area 13, in The Dynamics of Plutonium in Desert Environments, ed. P.B.Dunaway and M.G. White, U.S. Atomic Energy Commission, Nevada Operations Office, NVO-142 (1974), 91-106; A. Wallace, E.M. Romney, and R.B. Hunter, The Challenge of a DesertÑRevegetation of Disturbed Desert Lands, in Transuranics in Desert Ecosystems, ed. M.G. White, P.B. Dunaway, and D.L. Wireman, U.S. Department of Energy, Nevada Operations Office, NVO-181 (1977) 17-40 [M, A-13 Box]; J. Barth, K.R. Giles, and K.W. Brown, Solubility of Plutonium and Americium-241 from Rumen Contents of Cattle Grazing on Plutonium-Contaminated Desert Vegetation in in vitrio Bovine Gastrointenstinal FluidsÑAugust 1975 to January 1977, in The Radioecology of Transuranics and Other Radionuclides in Desert Ecosystems, ed. W.A. Howard, P.B. Dunaway, and R.G. Fuller, U.S. Department of Energy, Nevada Operations Office, NVO-224 (1985), 243-281).

5. The soil has well-developed horizons to depths of about 5 feet. These desert soils typically are layered with a surface layer of vesicular silt, an underlying oxidized layer in which clay is relatively concentrated, and a lower layer enriched in calcium carbonate. Old soils commonly have a lower zone composed primarily of calcium carbonate (caliche) (V.D. Leavitt, Soil Surveys of Five Plutonium-Contaminated Areas on the Test Range Complex in Nevada, in The Dynamics of Plutonium in Desert Environments, ed. P.B.Dunaway and M.G. White, U.S. Atomic Energy Commission, Nevada Operations Office, NVO-142, 1974), 21-27).

6. Gilbert, R.O. and Essington, E.H., Estimating Total 239+240Pu In Blow-Sand Mounds of Two Safety-Shot Sites, in Transuranics in Desert Ecosystems, ed. M.G. White, P.B. Dunaway, and D.L. Wireman, U.S. Department of Energy, Nevada Operations Office, NVO-181 (1977), 367-408.

7. Gilbert and Essington imply that mounds other than coppice dunes around the bases of shrubs are "blow sand." In tabulations they assign a very small percentage of mounds to animal activities and call the non-coppice dunes "complex mounds." Mounds formed by colonies of burrowing animals in the Mojave Desert commonly are much larger than coppice dunes.

8. U.S. Defense Nuclear Agency, Plumbob Series 1957ÑUnited States Atmospheric Nuclear Weapons Tests, Nuclear Test Personnel Review, U.S. Defense Nuclear Agency (1981) 6005F [The 1981 date of publication of this document is uncertain].

9. R.O. Gilbert, Shinn, J.H., Essington, E.H., Tamura, T., Romney, E.M., Moor, K.S., and O'Farrell, T.P., Radionuclide Transport From Soil to Air, Native Vegetation, Kangaroo Rats and Grazing Cattle on the Nevada Test Site, Health Physics 55 (1988): 869-887.

10. The National Academies of Sciences (National Academy of Sciences, Management and Disposition of Excess Weapons Plutonium (Washington, DC, National Academy Press, 1994), 19) use a figure of 4 kilograms Pu per weapon; actual figures are classified. Nearly 9 pounds of plutonium-239 emits 252 Curies, so the figure of 46 Curies probably represents only about one-fifth of the actual plutonium originally dispersed in this experiment.

11. R.O. Gilbert, Revised Total Amounts of 239,240Pu in Surface Soil at Safety-Test Sites, in Transuranics in Desert Ecosystems, ed. M.G. White, P.B. Dunaway, and D.L. Wireman, U.S. Department of Energy, Nevada Operations Office, NVO-181 (1977), 423-429. The average plutonium inventory at 9 other saftey test sites is 11 Curies per site.

12. E.M. Romney, A. Wallace, J.E. Kinnear, and R.A. Wood, Plant Root Uptake of Pu and Am, in The Radioecology of Transuranics and other Radionuclides in Desert Environments, ed. W.A. Howard, P.B. Dunaway, and R.G. Fuller, U.S. Department of Energy, Nevada Operations Office, NVO-224 (1985), 185-199.

13. Most of the radioactivity at Area 13 is in the 20-53 micrometer (m) soil size fractionÑdimension less than a millionth of an inch. The respirable fraction (<5 m) contains about 5% of the total soil radioactivity. The mean percentage of total-soil plutonium-239 in the resuspendable (<100 m) soil fraction was 88% (range: 73-99% for 10 samples).

14. The caption of a portion of the photograph Brown used (1994) reads: "A Russian spy satellite took this commercially available photo of Groom Lake on July 17, 1988. Changes apparent over 20 years include new taxiways and extension of the main runway's surface to 18,000 feet. It has since been lengthened to 27,000 feet to accommodate high-speed test aircraft. The satellite image poster is for sale from the Area 51 Research Center Bookstore." We are not certain that the poster is still for sale.

15. Includes plutonium-239 and plutonium-240 isotopes; these isotopes are normally not separated.

16. E.M. Romney, A. Wallace, R.O. Gilbert, and J.E. Kinnear, 239-240Pu and 241Am Contamination of Vegetation in Aged Plutonium Fallout Areas, in The Radioecology of Plutonium and Other Transuranics in Desert Environments, ed. M.G. White and P.B. Dunaway, U.S. Department of Energy, Nevada Operations Office, NVO-153 (1975), 43-88; Romney, E.M., A. Wallace, P.A.T. Wieland, and J.E. Kinnear, Plant Uptake of 239-240Pu and 241Am Through Roots from Soils Containing Aged Fallout Materials, in Environmental Plutonium on the Nevada Test Site and Environs, ed. M.G. White, P.B. Dunaway, and W.A. Howard, Nevada Applied Ecology Group, U.S. Energy Research and Development Administration, Nevada Operations Office, NVO-171 (1977), 53-63.

17. Diethylene triamine pentaacetic acid (DTPA).

18. F.H.F. Au and W.F. Beckert, Influence of Microbial Activities on Availability and Biotransport of Plutonium, in Environmental Plutonium on the Nevada Test Site and Environs, ed. M.G. White, P.B. Dunaway, and W.A. Howard, Nevada Applied Ecology Group, U.S. Energy Research and Development Administration, Nevada Operations Office, NVO-171 (1977), 219-226.

19. D.D. Smith and D.E. Bernhardt, Actinide Concentrations in Tissues from Cattle Grazing a Contaminated Range, in Transuranics in Desert Ecosystems, ed. M.G. White, P.B. Dunaway, and D.L. Wireman, U.S. Department of Energy, Nevada Operations Office, NVO-181 (1977), 281-303.

20. C. Blincoe, V.R. Bohman, and D.D. Smith, Studies of Transuranic Element Ingestion by Fistulated Steers Grazing Area 13 of the Nevada Test Site, in The Radioecology of Transuranics and Other Radionuclides in Desert Environments, ed. W.A. Howard, P.B. Dunaway, and R.G. Fuller, U.S. Department of Energy, Nevada Operations Office, NVO-224 (1985), 289-301; R.G. Patzer, W.W. Sutton, and G.D. Potter, Passage of Sand Particles Through the Gastrointestinal Tract of Dairy Cows, in Environmental Plutonium on the Nevada Test Site and Environs, ed. M.G. White, P.B. Dunaway, and W.A. Howard, Nevada Applied Ecology Group, U.S. Energy Research and Development Administration, Nevada Operations Office, NVO-171 (1977), 151-165. The ingested material contained 3,600 to 11,100 pCi of plutonium-238, 85,000 to 400,000 pCi of plutonium-239, and 11,000 to 56,000 pCi of americium-241 (D.D. Smith, Grazing Studies on a Contaminated Range of the Nevada Test Site, in Environmental Plutonium on the Nevada Test Site and Environs, ed. M.G. White, P.B. Dunaway, and W.A. Howard, Nevada Applied Ecology Group, U.S. Energy Research and Development Administration, Nevada Operations Office, NVO-171 (1977), 139-149).

21. Smith and Bernhardt, Actinide Concentrations in Tissues from Cattle, 281-303; cattle ingested about 2 pounds of forage per 100 pounds of body weight.

22. Blincoe et al.,Studies of Transuranic Element Ingestion, 289-301.

23. Barth, K.R. Giles, and K.W. Brown, Solubility of Plutonium and Americium-241 from Rumen Contents of Cattle, 139-149.

24. Smith and Bernhardt, Actinide Concentrations in Tissues from Cattle, 281-303.

25. Barth, K.R. Giles, and K.W. Brown, Solubility of Plutonium and Americium-241 from Rumen Contents of Cattle, 139-149.

26. Concentrations of plutonium-239 were measured in kangaroo rat (Dipodomys microps) pelts (2,400 pCi), gastrointestinal tracts (4,700 pCi), and carcasses (8.6 pCi). Kangaroo rats move substantial amounts of soil in their burrowing activities, exposing themselves to radionuclide contaminants, and may ingest contaminants on or in leaves and seeds (K.S. Moor and W.G. Bradley, Ecological Studies of Vertebrates in Plutonium-Contaminated Areas of the Nevada Test Site, in The Dynamics of Plutonium in Desert Environments, ed. P.B. Dunaway and M.G. White, U.S. Atomic Energy Commission, Nevada Operations Office, NVO-142 (1974), 187-212.

27. Richard Stone, New Effort to Thwart Dirty Bombers, Science 296 (2002): 2117-2118.

28. Richard Stone, Plutonium Fields Forever, Science 300 (2003): 1220-1224.