Project 57: Explosion dispersed plutonium near secret Groom Lake base

Project 57: Explosion dispersed plutonium near secret Groom Lake base
By Peter W. Merlin

A secret place in the desert

During the late 1950s, the Nevada desert near Groom Dry Lake echoed with the roar of jet engines as Lockheed's U-2 spyplane was put through its paces. The small airbase on the southern edge of the lakebed was called Watertown. There, Lockheed test pilots developed the airplane and its systems, while pilots assigned to the Central Intelligence Agency (CIA) trained for operational reconnaissance missions. Just over the hills at Yucca Flat, the Atomic Energy Commission (AEC) was detonating nuclear bombs. Since Watertown was downwind of the Nevada Test Site (NTS), it received much of the radioactive fallout. Consequently, there was a standing agreement that Watertown personnel would be evacuated prior to a nuclear shot to limit their exposure. Most of the tests, and all of those involving full-scale nuclear explosions, took place more than 10 miles away. One shot however took place on Watertown's doorstep.

One-Point Safe

The 1957 nuclear test series, called Operation Plumbbob, included 24 nuclear detonations and six safety experiments. The first shot of the series was a safety experiment called Project 57. A test of this type is usually conducted to determine that a weapon or warhead damaged in an accident will not detonate with a nuclear yield, even if some or all of the high explosive components burn or detonate. While not producing a nuclear explosion, such a detonation usually spreads a substantial amount of plutonium into the atmosphere and across the surrounding landscape. As such, safety experiments are also known as plutonium dispersal tests.

Such experiments were necessary because aircraft crashes and other operational and logistical accidents involving nuclear weapons could result in one-point detonation of the weapon's high explosive components, producing no nuclear yield but contaminating the local area with radioactive materials. Project 57 was designed to study the particle physics of plutonium, biomedicine of animals exposed to the fallout, radiation monitoring, and decontamination of plutonium-contaminated surfaces. According to Chuck Hansen, in U.S. Nuclear Weapons: The Secret History, the weapon used was an XW-25 warhead, with a design yield of 1.5 kilotons. The XW-25 was 26.7-inches long, 17.4-inches wide, and weighed about 218 pounds. It was designed to be the warhead for the Douglas MB-1 Genie air-to-air-missile. A formerly secret document detailing the minutes of the first meeting on Project 57 states that the weapon was to be "fired on the ground at the bottom detonator."

Area 13

This map shows the location of the Project 57 site in Area 13 and its relation to Area 51. The groom lake airbase is shown much as it appears today.

The first challenge of Project 57 was to select a test site. A lengthy discussion at the first project meeting focused on a choice between "Papoose Lake with adjoining valleys and the Groom Lake Valley lying due north of it," both outside the Nevada Test Site. Both sites were considered equal from an operational viewpoint, but the decision was ultimately based on soil contamination levels from previous testing. Samples taken by K. H. Larson of the University of California at Los Angeles (UCLA) indicated that "in the first inch of cover, maximum plutonium backgrounds differed by a factor of 60." Soil in the Groom Lake area contained a maximum of 0.5-micrograms of plutonium per-square-meter versus 30-micrograms per-square-meter around Papoose Lake. After reviewing these results, according to the minutes of the first meeting, "the choice of Groom Lake Valley went uncontested."

The Project 57 test site was added to the NTS as Area 13, an approximately 10-by-16-mile block of land abutting the northeast boundary of the Test Site, and partially overlapping the Watertown facility. The overlap area was not considered part of Area 13. Ground Zero for the shot was only five miles northwest of Groom Lake and seven miles from the main cantonment area of the airbase. Personnel approaching the site from the NTS would drive over Groom Pass from Yucca Flat, then head north on Valley Road for about eight miles to reach the turnoff for Ground Zero.

A formerly secret AEC report dated 14 March 1957 described the new test area, stating that it "is not contaminated to a degree that would effect the experiment, and, when contaminated, will not interfere with the conduct of the PLUMBBOB nuclear tests which are scheduled to begin in May 1957. The Armed Forces Special Weapons Project has obtained approval for the use of the land for the test." An appendix to the report contained a letter to Brigadier General Alfred D. Starbird from Maj. Gen. Alvin R. Luedecke, USAF, Chief of the AFSWP, further explained that "entry into the area has also been approved and has been coordinated with the agency which has been using the Range." The XW-25 warhead was flown to the airstrip at Yucca Flat, then trucked to Watertown. It was stored in Building 10 prior to being moved to Area 13 for final placement.

The Project 57 shot was originally scheduled for early April, but was pushed back several times. Personnel at Watertown were undoubtedly evacuated before the shot in case of unfavorable winds that could spread plutonium over the airbase, or an unexpected nuclear yield. Evacuation must have been terribly inconvenient to flight test and training operations at Watertown. According to declassified documents, most of the delays were due to unfavorable weather conditions.

Finally, on the morning of 24 April, the signal was sent to the detonator, and the warhead's high explosive charge destroyed the weapon. Although there had been no obvious atomic explosion, a three-man team in protective clothing was dispatched to determine whether or not any beta or gamma radiation hazard existed from a partial nuclear yield. There was none, but all personnel entering the area were required to wear full protective suits and respirators to shield themselves from alpha radiation emitted by plutonium.

Plutonium hazards

This Russian satellite image shows Area 51 and Area 13. Groom Lake is about three miles long from north to south. Ground Zero for the Project 57 plutonium dispersal test was located five miles northwest of the edge of Groom Lake.

Several isotopes of plutonium (Pu) are typically found at safety experiment sites: Pu-238 (with a half-life of 89 years), Pu-239 (24,300 years), Pu-240 (6,600 years), and Pu-241 (14 years). Pu-239 is the most abundant. The decay of Pu-241 produces an americium isotope, Am-241, which emits gamma rays and has a half-life of 432 years. Radiation Safety (Rad-Safe) technicians measure gamma emissions from Am-241 with a device called a FIDLER (Field Instrument for the Determination of Low-Energy Radiation). Am-241 activity in contaminated soil provides a reasonable indication of Pu-239/240 levels.

Plutonium emits alpha particles, the weakest form of radiation. A sheet of paper is sufficient shielding against alpha radiation. Although alpha particles are highly energetic, they are not capable of penetrating the dead layers of skin on the surface of the human body. If inhaled, however, even microscopic quantities will cause damage to soft tissues. Particles of plutonium that are absorbed into the bloodstream may be deposited in the lungs, liver, lymph nodes, or in the surfaces of newly formed bone. There, they can cause damage leading to cancer, chronic anemia, osteoporosis, or bone necrosis that may produce spontaneous bone fractures. Such results may not manifest until 10, 20, or even 30 years after deposition, depending on the size of the dose. Lung damage may become apparent in only a few years.

Project 57 contaminated over 895 acres with plutonium and americium dust and fragments. The primary hazard to personnel is from resuspension of small particles of plutonium dust in the air. Soil samples taken in the late 1990s indicate that plutonium particles at Area 13 are mostly smaller than 40 microns across. The exact amount of plutonium expended for the test remains classified, but one pound of plutonium involved in a fire or explosion could produce, under moderate wind conditions, hazardous contamination as far as a mile downwind.

Alpha contamination at Watertown

During Project 57, air samplers were set up in the contaminated area and at Watertown, and readings were averaged for 24-hour periods for 28 days. According to The Hazards and Characteristics of Plutonium and Uranium Contamination, published by the Atomic Weapons Training Group in 1962, "no consideration was made for wind changes or rain, and the averaged readings...were lower than is reasonable."

Initial readings at radiation monitoring sites indicated no detectable fallout at Watertown. According to a declassified telex dated from the day after the shot, air samplers were "operating in all populated areas," and would be checked "after a five day seasoning period and it [was] expected that readings [would] be minor." After all samples were studied, it was determined that there was minor alpha activity for 12 days following the shot, but it was "well below operational guidelines." Nevertheless, this meant that resuspended plutonium dust was reaching the airbase in small amounts.

As described in an AEC report on Off-Site Radiological Safety Activities For Project 57, there were two high-volume air samplers located at Watertown and fallout trays located on the roofs of the Air Weather Building, and a building behind the Maintenance Shop. Minor alpha counts were detected in the trays. Samples of rainwater were collected eleven hours after shot time when a brief shower passed across Area 13 and then across Watertown. The samples contained both alpha and beta particles. Water from the Deer Camp Watering Hole east of Area 13 was also sampled, but only contained a small amount of alpha radiation.

Decontamination techniques

A Project 57 technician in anti-contamination gear picks up a sample tray with a magnetic device.

Rad-Safe workers from Task Group 57 at the NTS collected data on particulate physics, plutonium inhalation, alpha monitoring, and decontamination techniques on experimental surfaces at Area 13.

For the particulate physics study, surface and airborne plutonium levels were measured as a function of time after detonation. Air samplers, balloon-borne precipitators, soil samples, and photographic methods were used. Scientists constructed a fallout pattern model using a grid of more than 4,000 sticky pans distributed over a 43-square-mile area. They also analyzed the fractionation characteristics and physical nature (size, shape, and distribution) of the fallout particles. Interestingly, the maximum air concentration levels of alpha contaminants were found at a distance of 5,000 feet from the detonation point.

A biomedical field study examined environmental short-term and chronic effects of plutonium inhalation and persistency of debris resulting from subcritical bursts. For this experiment, a group of test animals (dogs) were exposed to the radioactive cloud to test the effects of acute exposure. A larger group of dogs was placed in the contaminated zone for a longer period of time to study the effects of chronic exposure. Test animals were periodically sacrificed and autopsied by veterinary scientists to collect data.

A third study was undertaken to practice monitoring of alpha contamination on various surfaces. This effort correlated alpha monitoring data from sticky pan collectors with field study data from broom-finished concrete slabs. The slabs and sticky pans were placed adjacent to each other at various locations throughout Area 13. The monitors also took readings from nearby soil and vegetation.

The largest effort was expended on developing techniques for decontamination of large surface areas. Technicians studied plutonium removal from large land surface areas, concrete and asphalt pads, and materials used in equipment and building construction (aluminum, steel, galvanized and tar-paper roofing, glass, brick, stucco, wood, etc.). Methods of soil decontamination and fixation included wetting, oiling, leaching and stabilizing agents, and spraying with fire-fighting foam, as well as disking, plowing, and scraping. The top two inches of soil was scraped and hauled away for burial at the NTS. The ground was plowed to a depth of 12 inches. Rad-safe technicians decontaminated test materials by washing, steam cleaning, and vacuuming. Contaminated equipment was disposed of in waste burial sites adjacent to Valley Road within Area 13.

Radiation safety procedures

This map shows the location of Project 57 ground zero (GZ) and the fence surrounding the Alpha Contaminated Zone.

Reynolds Electrical and Engineering Company (REECo) provided operational radiation safety support for Project 57. Prior to the day of the test, REECo personnel erected a temporary decontamination facility at the entrance to the access road to ground zero. It was stocked with supplies of radiation detection instruments, protective clothing, and other equipment. The building also contained an equipment issue room, showers, and a dressing room. All personnel entering or leaving the contaminated zone had to pass through the Rad-Safe building. Containers were made available to dispose of contaminated clothing. Northwest of the building, a parking area was established for contaminated vehicles. Uncontaminated vehicles parked on the south side of the building. There was also an area for processing fallout trays and soil samples for shipment to Sandia Corporation for analysis.

To protect workers at Area 13 against the hazards of plutonium inhalation, personnel were required to wear full protective clothing with all openings taped to their skin and full-face respirators with high-efficiency filters. Heavy respiratory protection made breathing difficult during hard physical labor. Supplied-air respirators were used during the biomedical study program. These provided positive pressure inside protective clothing so that any leaks would be outwards to prevent contaminants from entering the suit. After the extent of hazardous conditions in the test area was determined, workers were given the option of wearing supplied-air respirators or full-face filter respirators. As restrictions were further reduced, half-face respirators with high-efficiency filters were adopted for areas with less than 100 micrograms of plutonium contamination per square meter. All participants in field activities for Project 57 received bioassay tests to check for exposure to plutonium. These tests consisted primarily of nasal swabs and, occasionally, urinalysis.

Once members of Task Group 57 had mapped the extent and distribution of the remaining plutonium contamination within Area 13, the contaminated zone was fenced off and posted with signs denoting Internal Radiation Hazard to unprotected personnel. Warning signs were also posted at the equipment burial trench, approximately 300 feet west of the "No. 36 Marker" on Valley Road. The Project 57 site lay abandoned and nearly forgotten for almost 20 years as nearby Watertown (designated Area 51 in June 1958) grew into a thriving clandestine flight test center.

Return to Area 13

Map illustrating radioactive contamination levels within the fenced section of Area 13.

In the 1970s, the contaminated area was studied by the DOE Nevada Applied Ecology Group (NAEG) to estimate the amount and distribution of plutonium in the soil. NAEG scientists took numerous soil samples for analysis. In 1974, A. Wallace and E. M. Romney (UCLA Laboratory of Biomedical and Environmental Sciences) inspected the Area 13 test plots to evaluate vegetation recovery and compare soil surface conditions. They found that the plowed and scraped areas had recovered about 25% of their vegetation, compared to the surrounding undisturbed landscape. Areas treated with road oil appeared approximately the same as untreated areas except for some remaining oil residue. Based on a FIDLER survey, R. O. Gilbert estimated (in a paper included in Transuranics in Desert Ecosystems, NVO-181, 1977) that the inventory of Pu-239/240 remaining in the top two inches of soil at Area 13 was approximately 46-Curies, covering a 4,017,000-square-meter area. An aerial survey in 1979 by A. E. Fritzsche yielded an estimated inventory of 62.1 to 90.5-Curies of Pu-239/240, based on Am-241 levels. In their 1980 report, Estimates of Soil Removal for Cleanup of Transuranics at NAEG Offsite Safety-Shot Sites, R. R. Kinnison and R. O. Gilbert used available summary data to determine the amount of soil removal necessary to decontaminate the project 57 site down to 160-picoCuries of plutonium. They determined that roughly 198,000 tons of the top six inches of soil would need to be removed from an area covering 269 acres. Soil profiles studies indicated that most of the plutonium contaminants are located in the top two inches.

In 1981, the Department of Energy Nevada Operations (DOE-NV) sought funding through the Surplus Facilities Management Program (SFMP) for the decontamination and decommissioning of Area 13. The application for funding was submitted by Arden E. Bicker of REECo. In the application, Bicker describes Area 13 as being "approximately five miles from a public road and directly adjacent to the site of a rapidly growing military installation." In fact, the contaminated zone was located just east of Valley Road, which is the primary thoroughfare from Area 51 to the town of Rachel in Sand Springs Valley to the north of Area 13. The "public road" described by Bicker was the road to Groom Mine. Three years later, the road, the mine, and most of the Groom Mountains were seized by the Air Force to prevent public access, and provide additional security for Area 51.

Decontamination plan

A draft of the SFMP response to the application describes the request "to provide funding beginning in fiscal year 1983 to enable DOE to remove contaminated surface soil from Area 13 and dispose of it in appropriate disposal facilities on the Nevada Test Site." Estimates of contaminated soil volumes indicated that it would take 10 years to complete the cleanup if the funding was made available. The application was reviewed by the SFMP Facility Acceptance Review Board to determine whether the site was eligible.

The Review Board discussed the fact that Area 13 was off-site from the NTS, on the Nellis Air Force Range. Presumably then, it might be the responsibility of the Air Force to decontaminate the site (or leave it alone). Also, the Board wondered if it was even appropriate to include a parcel of contaminated ground in the SFMP since it was not actually a "facility" per se.

The Review Board's most pressing questions were rooted in the "Requirements for Acceptance" portion of the SFMP Facility Acceptance Procedure, the rules and regulations for inclusion in the SFMP. These requirements stated that "the facility shall be in a radiologically safe condition." Specifically, a current radiation/contamination survey of the facility and surrounding area had to be available, structures and monitoring equipment had to be adequate to contain and monitor any radioactivity, and security systems and procedures had to be adequate to prevent unauthorized entry. The Review Board was very concerned about these points.

At the time of the original application for SFMP acceptance, the most recent radiological survey of Area 13 had been taken in 1977. Results were reported only for land within the 895-acre contaminated zone. The Board took issue with the fact that "additional Pu migration within the site since the time of the 1977 survey, and dispersal of Pu outside the site boundaries were not discussed in the DOE-NV request." The application had also stated that "minimal DOE surveillance is being performed at Area 13 because the contaminated area is not within direct control of DOE." The Board held off on accepting Area 13 into SFMP, stating that "with the limited information available, the board was unable to assess the current radiological safety of Project 57."

The Board made several recommendations to DOE-NV that would allow the Project 57 site to meet the guidelines for SFMP funding. A new radiological survey was required to determine the extent and migration of plutonium from the fenced contaminated zone. A hazards analysis had to be performed, with particular emphasis on assessing the predicted radiation exposure of workers at the new construction site. DOE-NV had to determine an acceptable concentration level for plutonium in the soil (for any levels detected after the cleanup). The Board also required that DOE-NV provide a description of safety measures that would ensure that plutonium would not continue to migrate off-site.

Cleanup costs

DOE-NV followed the Board's recommendations, and the site was subsequently accepted into the Surplus Facilities Management Program. According to DOE documents, the initial phase of the operation was set to begin in October 1982. First of all, a preliminary site characterization was made for both the Project 57 contaminated zone and the inactive contaminated waste dump adjacent to Valley Road. Also included in the Fiscal Year (FY) 1983 budget were plans for perimeter survey work, pathway and criteria analysis, clean-up technique investigation, engineering design and equipment specification, and procurement of mobile laboratory equipment. This phase was scheduled to be completed in September 1983 at a total cost of $500,000.

Next, heavy equipment was to be procured for the excavation of contaminated soil. Four 30-ton ore-haulers and one earth-mover were to be purchased for $1,250,000. A water-well was to be drilled for dust suppression support in order to prevent resuspension of plutonium into the atmosphere. Actual decontamination was set to begin in January 1984, with an initial effort to remove 40,000 cubic yards of soil. Estimated expenses for FY-1984 were $2,500,000.

Three more 30-ton ore-haulers and a 5,000-gallon water tanker were to be purchased in FY-1985 to support the removal of an additional 90,000 cubic yards of soil. Total costs for FY-1985 were estimated at $2,500,000. The plan called for removal of 100,000 cubic yards of soil per year from FY-1986 through FY-1991 at an annual cost of $2,500,000.

The fate of Area 13?

The decontamination and decommissioning project was scheduled for completion in FY-1992. Tasks included final decontamination, revegetation, demobilization, certification, and production of a final report. Total cost for FY-1992 was estimated to be $500,000. The total cost of the project was estimated at $21,000,000. No documents have yet surfaced to show whether or not the project remained on schedule and within budget. A Russian spy satellite photo from 1988 apparently shows that large amounts of soil had been recently removed from an area just north of the Project 57 contaminated zone in Area 13.

However, cleanup of the Project 57 site was still a concern during environmental studies in the late 1990s. A preliminary site characterization was completed in 1998 and a complete assessment of plutonium cleanup was scheduled for FY 1999. According to Steve L. Hoeffner et al (Clemson University-Research Park) and Richard Smalley (Waste Policy Institute, Savanna River Research Campus) in Evaluation of Remediation Methods for Plutonium Contaminated Soil, "a limited amount of data is available for the Area 13 soils," and cleanup of the site is a "low priority."