Radiological Characterization Survey Report, 1964 B-58 Accident Site, Grissom Air Reserve Base, Bunker Hill, Indiana

摘要

On December 8, 1964, during a routine Operational Readiness Inspection, a B-58 strategic bomber skidded off the runway at Bunker Hill AFB, IN (later named Grissom Air Force Base). The consequence of the accident was a fire and destruction of five nuclear weapons on the aircraft. The high explosives in the weapons did not detonate, but melted and burned, leaving some residual radioactive contamination in soils adjacent to the runway. The contaminated area was excavated and buried along with the aircraft wreckage at a different location on base. In June 1996, the Air Force Safety Center conducted a review of both classified and unclassified documents in its possession and concluded that sufficient data did not exist to support closure of the site. Since that time, the State of Indiana and this organization performed small- scale scoping surveys that identified a small area with elevated gamma radiation exposure levels. Soil samples collected from the area indicated the presence of depleted uranium. This report details the historical site assessment, the results of the scoping surveys, and details of the comprehensive characterization survey that was accomplished in October 1999. The results of the survey confirm that a small area of the site investigated contains depleted uranium contamination. The investigation area was about 8,800 square meters and had an estimated excess surface activity concentration of 1 pCi/g averaged over entire area. Within this area, the contamination zone is limited to an area of 1000 square meters, with a mean excess uranium activity concentration of 7 pCi/ g.