The "Green Run" was a secret U.S. Government release of radioactive fission products on December 2–3, 1949, at the Hanford Site

Hanford Site

The Hanford Site is a mostly decommissioned nuclear production complex on the Columbia River in the U.S. state of Washington, operated by the United States federal government. The site has been known by many names, including Hanford Works, Hanford Engineer Works or HEW, Hanford Nuclear Reservation...

 plutonium

Plutonium

Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...

 production facility. Radioisotopes released at that time were supposed to be detected by U.S. Air Force reconnaissance. Freedom of Information Act

Freedom of Information Act (United States)

The Freedom of Information Act is a federal freedom of information law that allows for the full or partial disclosure of previously unreleased information and documents controlled by the United States government. The Act defines agency records subject to disclosure, outlines mandatory disclosure...

 (FOIA) requests to the U.S. Government have revealed some of the details of the experiment. Sources cite 5500 Ci of iodine-131

Iodine-131

Iodine-131 , also called radioiodine , is an important radioisotope of iodine. It has a radioactive decay half-life of about eight days. Its uses are mostly medical and pharmaceutical...

 released, and an even greater amount of Xenon-133. The radiation was distributed over populated areas, and caused the cessation of intentional radioactive releases at Hanford until 1962 when more experiments commenced.

There are some indications contained in the documents released by the FOIA requests that many other tests were conducted in the 1940s prior to the Green Run, although the Green Run was a particularly large test. Evidence suggest that filters to remove the iodine were disabled during the Green Run.

The project gets its name from the processing of uranium at Hanford. Due to the higher radioactivity involved, batch processing waited 83 to 101 days to allow the radioactive isotopes to decay. For the Green Run test, a batch was run with only a 16 day cooling period. The unfiltered exhaust from the production facility was therefore much more radioactive than during a normal batch.

Oral History

Health Physicist Carl C. Gamertsfelder, Ph.D. described his recollections as to the reasons for the Green Run by attributing it to the intentions of the Air Force to be able to track Soviet releases. "Herb Parker called me to request that I, and the groups that I supervised, cooperate with the Air Force in the conduct of an experiment which be came known as the Green Run... And we didn't recommend, we wouldn't have recommended, that they operate it. We told them that. They wanted to run anyway, and they did run."

See also

• Atomic testing
• Nuclear fallout
  Nuclear fallout
  Fallout is the residual radioactive material propelled into the upper atmosphere following a nuclear blast, so called because it "falls out" of the sky after the explosion and shock wave have passed. It commonly refers to the radioactive dust and ash created when a nuclear weapon explodes...
  
  
• Unethical human experimentation in the United States