DISCLAIMER The following is a staff memorandum or other working document prepared for the members of the Advisory Committee on Human Radiation Experiments. It should not be construed as representing the final conclusions of fact or interpretation of the issues. All staff memoranda are subject to revision based on further information and analysis. For conclusions and recommendations of the Advisory Committee, readers are advised to consult the Final Report to be published in 1995. TAB H PART 2 xxx DRAFT x FOR DISCUSSION PURPOSES xxxx MEMORANDUM TO: Members of the Advisory Committee on Human Radiation Experiments FROM: Advisory Committee Staff DATE: November 9, 1994 RE: The Facts and Unknowns of the Green Run The Green Run was a release of radioactive gases from Hanford's T Plant, which occurred on the night of December 2-3, 1949. Roughly 8,000 curies of iodine-131 and 20,000 curies of xenon-133 were released into the atmosphere. This release resulted from the reprocessing of three tons of irradiated uranium fuel that had been allowed to cool only 16 days after its removal from the reactor. Because of this short time, it was known as "green metal" and the dissolving run as the "green run." A more typical 100-day cooling period would have allowed the radioactivity in iodine to decay by a factor of roughly 1000, and that in xenon by a factor of roughly 60,000. I. PURPOSE The primary source documents that describe the purpose of the Green Run remain classified by the Air Force. The secondary documents state that the primary purpose was to test the ability to detect at long range foreign nuclear weapons production and testing. The Soviet Union had tested its first nuclear weapon in August 1949. The extensive monitoring of radioactivity in the air, on vegetation, and on surface water suggest that a variety of detection techniques were tested. II. NOTIFICATION AND SECRECY The public received no advance notice of plans for the Green Run. In fact the test remained secret until 1986, and the Air Force has kept some information from the Green Run secret to this day. 1 III. PUBLIC SAFETY According to the General Accounting Office, which interviewed several of the participants, "the test was not considered unsafe at the time." The Health Instruments Divisions (H. I. Divisions) at Hanford were responsible for worker and public health, and established certain restrictions on the weather conditions under which the Green Run could occur. These restrictions appear to have been designed both to limit radiation hazards near the site and to ensure that radioactive gases emitted would be dispersed and detectible at long range. As it turned out, the weather conditions were not ideal, and much of the radioactive cloud remained relatively close to Hanford, where relatively large amounts of iodine-131 were deposited on the ground. One document reports that "the resultant activity came close enough to significant levels, and its distribution differed enough from simple meteorological predictions that the H. I. Divisions would resist a proposed repetition of the test."1 [H. M. Parker, Health Instruments Divisions Report for Month of December, 1949, HW-E-15550-DEL, 1/6/60 (declassified with deletions in 1990).] The highest level of radioactivity measured on vegetation was 28 microcuries/kg on site. Several nearby communities had levels ranging from .1 to 4.3 microcuries/kg, compared to the 1949 "permissible permanent concentration" on vegetation of .01 microcuries/kg. The current intervention level in Washington state is .013 microcuries/kg, at which point the health department intervenes to prevent the sale of radioactive food products.2 [Al Conkland, Washington state Department of Health, personal communication, 11/7/94.] According to a dose reconstruction specific to the Green Run, the maximum human thyroid dose was estimated at 188 millirad, equivalent to 6 millirem.3 [Bruce Napier, Battelle Pacific Northwest Laboratory, personal communication, 10/28/94.] The current standard under the Clean Air Act is 10 millirem/year. Given a lower average individual dose and an affected population of roughly 100,000 the total population dose may have come close to the 100 person-rem (the total exposure aggregated over the exposed population) standard that would trigger DOE's current special reporting requirement. The individual exposure level was relatively low in large part because the Green Run took place in the winter when people were not eating garden vegetables and dairy cattle were not grazing in open pastures.4 [The milk pathway for human exposure to radioiodine -- from dairy cattle grazing on contaminated fields -- was unknown at the time.] 2 IV. UNKNOWNS AND SECRECY The specific objectives of the Green Run experiment, who was responsible for planning and carrying it out, and what role radiological health concerns played in the decision making process, remain largely unknown. Purpose. The general purpose of the Green Run was to test atomic energy intelligence methods. Beyond that questions remain about the specific objectives of the experiment, and how the experiment was designed to satisfy those objectives. Air sampling programs at Oak Ridge and Hanford in late 1948 and early 1949 appear to be the predecessors to the Green Run, but the Green Run provided a more easily detectible signal. Was this larger release based on the need to show a positive result or on a real expectation that the Soviets would be reprocessing uranium after a short cooling period, releasing large amounts of radioactivity in the process? Others have suggested additional purposes for the Green Run but these purposes, if they existed, remain classified. Responsibility. The H. I. Divisions were responsible for much of the monitoring of radioactivity in the Green Run, and the Air Force provided added resources for meteorological measurements and prediction. Still, we do not know who -- either individuals or organizations -- was responsible for other aspects of the Green Run. Who proposed the experiment? Who approved it? Who was responsible for planning and carrying it out? Safety. We are particularly interested in understanding what consideration, if any, was given to radiological health risks, either for the direct participants, who carried out the release and associated radiation monitoring activities, or for the public. What measures were considered and taken to minimize risks to participants and the public? How did planners analyze the tradeoffs between protecting the public and the needs of national security, including secrecy? V. ATTACHMENTS The documents describing the Green Run were included in the second briefing book (Briefing Book volume 2, Tab N). The Committee has received no additional documents related to the Green Run since then. We reproduce two of those documents here: 1. Technical Steering Panel, Hanford Environmental Dose Reconstruction Project, "The Green Run," Fact Sheet 12, March 1992. 2. General Accounting Office, "Nuclear Health and Safety: Examples of Post World War II Radiation Releases at U.S. Nuclear Sites," GAO/RCED-94-51FS, November, 1993, pp. 6-12. 3