National Emission Standards for Hazardous Air Pollutants, June 2005

The sources of radionuclides include current and previous activities conducted on the NTS. The NTS was the primary location for testing of nuclear explosives in the Continental U.S. between 1951 and 1992. Historical testing has included (1) atmospheric testing in the 1950s and early 1960s, (2) underground testing between 1951 and 1992, and (3) open-air nuclear reactor and rocket engine testing (DOE, 1996a). No nuclear tests have been conducted since September 23,1992 (DOE, 2000), however; radionuclides remaining on the soil surface in many NTS areas after several decades of radioactive decay are re-suspended into the atmosphere at concentrations that can be detected by air sampling. Limited non-nuclear testing includes spills of hazardous materials at the Non-Proliferation Test and Evaluation Complex (formerly called the Hazardous Materials Spill Center), private technology development, aerospace and demilitarization activities, and site remediating activities. Processing of radioactive materials is limited to laboratory analyses; handling, transport, storage, and assembly of nuclear explosive devices or radioactive targets for the Joint Actinide Shock Physics Experimental Research (JASPER) gas gun; and operation of radioactive waste management sites (RWMSs) for low-level radioactive and mixed waste (DOE, 1996a). Monitoring and evaluation of the various activities conducted onsite indicate that the potential sources of offsite radiation exposure in calendar year (CY) 2004 were releases from (1) evaporation of tritiated water (HTO) from containment ponds that receive drainage water from E Tunnel in Area 12 and water pumped from wells used to characterize the aquifers at the sites of past underground nuclear tests, (2) onsite radioanalytical laboratories, (3) the Area 3 and Area 5 RWMS facilities, and (4) diffuse sources of tritium (H{sup 3}) and re-suspension of plutonium ({sup 239+240}Pu) and americium ({sup 241}Am) at the sites of past nuclear tests. The following sections present a general description of the present sources on the NTS and at the North Las Vegas Facility (NLVF). At the NLVF, parts of Building A-1 were contaminated with tritium by a previous contractor in 1995. The incident involved the release of tritium as HTO. This unusual occurrence led to a very small potential exposure to an offsite person. The HTO emission has continued at lower levels (probably re-emanation from building materials), even after cleanup activities in November and December 1997. A description of the incident and the potential effective dose equivalent (EDE) for offsite exposure are set forth in Appendix A