Park officials announced in February that they were investigating whether anyone was exposed to radiation at unsafe levels while samples of uranium ore sat in plastic buckets in a park research building.
Three 5-gallon (18.93-liter) buckets were removed from a building near the South Rim that houses the park's archives and artifacts. About 550 people tour the collections each year. In March, preliminary findings indicated no uranium ore exposure for park employees and visitors. A final report released Thursday confirmed those findings.
Park officials say it appeared the previous reported radiation levels taken last year at the museum collection building were significantly overstated.