Tritium is a radioactive variation of the chemical element hydrogen (radioactive hydrogen-3 or 3H) and has a half-life of about 12.5 years, which means that half of the radioactive atoms will decay naturally in that time. Although tritium can be a gas under controlled conditions, its most common form is liquid, because, like hydrogen, tritium reacts with oxygen to form water. Like ordinary water, water containing tritium, or tritiated water, is colorless and odorless. Of the three primary types of radiation, alpha, beta and gamma, tritium emits only a very low energy beta radiation. While tritium is naturally occurring (cosmic rays in the upper atmosphere can convert a minor fraction of hydrogen into deuterium and tritium), it is normally present in background levels in the environment, predominantly due to atmospheric testing of nuclear weapons testing in the 1960s.
The U.S. Nuclear Regulatory Commission (NRC) requires any person to have a license to manufacture, process, produce or transfer products containing tritium. Devices containing high levels of tritium must be handled and disposed of within the requirements of the NRC license and regulations. (see 10 CFR 32.51 and 10 CFR 31.5 at http://www.nrc.gov)
In Dececember 2006, the NRC issued a notice to all distributors and owners of generally licensed tritium exit signs entitled "NRC Regulatory Issue Summary 2006-25, Requirements for the Distribution and Possession of Tritium Exit Signs and the Requirements in 10 CFR 31.5 and 32.51a" (PDF)
The Department of Environmental Protection (DEP) recently completed a comprehensive two-year study at 54 landfills within the Commonwealth, testing for the presence of radioactive materials in landfill leachate. The study was performed as a follow-up to DEP's new requirements for radiation monitoring at all solid waste management facilities in Pennsylvania. Although sample results quantified certain naturally occurring elements within natural background levels, including uranium, thorium and potassium, above-normal levels of tritium were noted in leachate at many facilities. Results of the Department's studies are available for download from the "Documents" section below.
The source of higher-than-background levels found in landfill leachate samples was presumed to originate from the improper disposal of self-luminescent exit signs found in construction/demolition (C/D) waste and other solid waste streams. There are no other known sources of tritium in industrial or consumer products that would cause elevated levels of tritium in landfill leachate. Thus, it is apparent that tritium exit signs, which when new may contain up to 25 curies, or 25,000,000,000,000 picocuries (pCi) of tritium, are entering landfills via municipal or residual waste streams. A single tritium emergency exit sign has the potential to cause the tritium levels observed.
The Department has assessed potential tritium exposure to on-site workers and the off-site public, based on a review of many factors, including review of authorized discharges of treated leachate to treatment facilities, locations of public water supply intakes, and the uses of treated leachate or landfill gas. Although DEP concluded that there are no current threats to the public's health or safety associated with those discharges or practices, the Department is deploying a proactive strategy to include monitoring and assessment of tritium at waste management facilities in order to provide continued protection of public health and safety and our natural resources. Implementation of this tritium strategy will involve a collective effort of interdisciplinary resources within the Department, primarily within the Bureau of Radiation Protection, the Bureau of Water Quality, Bureau of Air Quality, Office of Community Revitalization and Local Government Support, and the Bureau of Waste Management, as well as the landfill operators.
The Department has created these Fact Sheets on the subject of radioactive tritium:
The Department has issued the following reports documenting the landfill leachate sample events and results.
The U.S. Nuclear Regulatory Commission (NRC) has published the following on tritium in groundwater and drinking water:
The Conference of Radiation Control Program Directors (CRCPD), has published a resolution stating that:
The following agencies have extensive information regarding the use, handling and disposal of radioactive materials and devices, including those containing tritium:
If you need additional assistance, or have additional questions please contact the Bureau of Radiation Protection, Radioactive Materials Licensing Section at 717-787-3720 or email the Radioactive Materials Licensing Section.