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.