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. DRAFT FOR DISCUSSION PURPOSES MEMORANDUM TO: Members of the Santa Fe Small Panel FROM: Advisory Committee Staff DATE: 1/10/95 RE: Fact Sheet on Radiolanthanum (RaLa) Tests Los Alamos is preparing a report on the RaLa test series, winch it plans to present to the Committee during its testimony at the Santa Fe panel meeting. What follows is a summary and preview of that report. The RaLa tests were a series of tests that used lanthanum-140 or radiolanthanum (hence the name RaLa) as part of the diagnostic for high-explosive implosion devices. Lanthanum-140 has a half-life of 40 hours, emitting at least one highly penetrating gamma ray in its decay. The absorption of these gamma rays provides a measure of the compression induced by the implosion. Sources of roughly 100 curies and roughly 1,000 curies were used, and even larger ones were contemplated. These sources were dispersed in the cloud resulting from the detonation. Lanthanum-140 is itself the decay product of barium-140, which has a half-life of 13 days and makes up a plentiful 6% of typical fission products. The barium was separated by Oak Ridge and transported in heavily-shielded containers to Los Alamos, where chemists would periodically separate the decay product lanthanum for use in the implosion tests. The RaLa tests would take place in series over a period of a month as each barium source decayed and was milked for lanthanum. 254 RaLa tests are known to have occurred between 1944 and 1962, when other diagnostic techniques replaced the use of lanthanum. Three of these tests appear in the Advisory Committee's charter because they were identified in a report by the General Accounting Office (the "Charter Thirteen"). During these three tests in early 1950, Air Force B-17 aircraft used an Atmospheric Conductivity Apparatus to track the radioactivity in the resulting clouds, in one case as far as 17 miles downwind, as it passed over a nearby town. Los Alamos is currently preparing a summary report and environmental dose reconstruction for the 254 known RaLa tests. Most of the available source data will be made public as part of this dose reconstruction study. Monitoring of meteorological and fallout data was rare for the first 125 tests from 1944-1949, was phased in from 1950-1954, and was more or less complete thereafter. The releases ranged in magnitude from 25-60 curies to 4200 curies. Strontium-90 was a minor contaminant with total releases of about 75. The quantity of high explosive -- which determine the size and altitude of the radioactive cloud -- will 1 remain classified but will be described in terms of five size ranges. The RaLa tests took place at Bayo Canyon in the side of a mesa two miles from the town of Los Alamos. The prevailing winds blow toward the east or northeast, with communities seven and eleven miles downwind. The Air Force reported tracking one cloud as far as 70 miles downwind over the town of Watrous, New Mexico. In about 1952, safety personnel began to track the radioactive clouds on wads near Bayo Canyon. On occasion they would close roads when the radioactive cloud was detected. In several instances the cloud blew back toward Los Alamos, but in later years only tests were only allowed when the wind was blowing away from Los Alamos. According to Jerome Dummer (unedited interview transcript), "one of these occurred at quitting time and was a great inconvenience to important people who lived in Santa Fe, I believe. That had a lot to do with changing the regime." The people most at risk from, these tests were the participants, particularly the chemists who separated the lanthanum source. As far as hazards to the general community, the monitoring and road closings appear to be the main attempts to reduce these hazards. There is no indication of any warnings to or consultation with the local community. Most of this community was connected with Los Alamos and may have been in a position to know of the tests. Principal sources: Los Alamos; GAO Report "Examples of Post World War II Radiation Releases at U.S. Nuclear Sites," GAO/RED-94-51FS; Interview by Gilbert Whittemore with Jerome Dummer, Los Alamos, November 4, 1994. 2