Looking Back at Hanford’s “Atomic Man”
More than 40 years ago, chemical operations technician Harold McCluskey worked inside the Americium Recovery Facility at the Plutonium Finishing Plant (PFP) at the Hanford Site in Washington state. The facility was used during the Cold War to recover americium, a man-made radioactive chemical. On Aug. 30, 1976, an americium-241 (also known as 241Am or Am-241) ion exchange column exploded, exposing McCluskey to a mixture of nitric acid and the highest dose of radiation from 241Am ever recorded. McCluskey, who became known as the “
Atomic Man
,” was exposed to at least 37 megabecquerels (MBq) of 241Am.
According to the Agency for Toxic Substances and Disease Registry (ATSDR), the Nuclear Regulatory Commission’s occupational exposure limit for 241Am in workplace air is 3x10-12 microcuries per milliliter (μCi/mL).
The room in which McCluskey was injured was demolished earlier this year. As this issue went to press, demolition of Hanford’s PFP was scheduled to be completed in September 2017.
Information about the incident appears below.
From CDC’s “Radioisotope Brief: Americium-241 (Am-241)”:
“As a dust or fine powder, Am-241 can cause certain cancers. When Am-241 powder is swallowed, absorbed through a wound, or inhaled, it can stay in the body for decades. Am-241 concentrates in the bones, liver, and muscles, exposing these organs to alpha particles.”

ToxFAQs for Americium
” (April 2004).
ATSDR: “Toxicological Profile for Americium” (
, April 2004).
Carbaugh, Eugene: “The 1976 Hanford Americium Accident, Then and Now,” continuing education lecture at the 59th Annual Meeting of the Health Physics Society in Baltimore, Md., (
, July 2014).
CDC: “
Radioisotope Brief: Americium-241 (Am-241)
” (2014).
International Atomic Energy Agency: “Strengthening the Safety of Radiation Sources & the Security of Radioactive Materials: Timely Action” (
, 1999).

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In August, The Knoxville News Sentinel reported that a student intern and a researcher at Oak Ridge Associated Universities had devised an experiment to replicate the McCluskey incident in order to study the effects of radiation on the body. By irradiating vials of their own blood for different lengths of time, the researchers hope to generate data that clinicians and first responders can refer to following an exposure incident.

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