contractor
For purposes of this section, the term “contractor” includes a contractor or cost reimbursement subcontractor of any tier participating in the conduct of the United States atomic weapons testing program for the Department of Energy (or its predecessor agencies, including the Manhattan Engineer District, the Atomic Energy Commission, and the Energy Research and Development Administration). Such term also includes facilities which conduct or have conducted research concerning health effects of ionizing radiation in connection with the testing under contract with the Department of Energy (or any of its predecessor agencies).