Risks from Past, Current, and Potential Hanford Single Shell Tank Leaks

Abstract

ph: (865) 576-8401 fax: (865) 576-5728 email: reports@adonis.osti.gov Available to the public from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Rd., Springfield, VA 22161 ph: (800) 553-6847 fax: (703) 605-6900 email: orders@ntis.fedworld.gov online ordering: http://www.ntis.gov/ordering.htmThis document was printed on recycled paper. SummaryDue to significant delays in constructing and operating the Waste Treatment Plant, which is needed to support retrieval of waste from Hanford's single shell tanks (SSTs), SSTs may now be required to store tank waste for two to three more decades into the future. Many SSTs were built almost 70 years ago and all SSTs have greatly exceeded their design lives. Recent examination of monitoring data suggests several of the tanks that were interim stabilized a decade or more ago may be experiencing small leaks (perhaps 150-300 gallons per year) to the subsurface environment. A potential leak from tank T-111 is estimated to have released approximately 2,000 gallons into the subsurface. Observations of past leak events, recently published simulation results, and new simulations all suggest that recent leak events are not likely to impact underlying groundwater above regulatory limits. However, these recent observations remind us that much larger source terms are still contained in the tanks and are also present in the vadose zone from historical intentional and unintentional releases. Recently, significant improvements have been made in methods for detecting and characterizing soil moisture and contaminant releases, understanding and controlling mass-flux, and remediating deep vadose zone and groundwater plumes. To ensure extended safe storage of tank waste in SSTs, the following actions are recommended:1. Improve capabilities for intrusion and leak detection. Develop defensible conceptual models of intrusion and leak mechanisms.3. Apply enhanced subsurface characterization methods to improve detection and quantification of moisture changes beneath tanks.4. Maintain a flux-based assessment of past, present, and potential tank leaks to assess risks and to maintain priorities for applying mitigation actions.5. Implement and maintain effective mitigation and remediation actions to protect groundwater resources.These actions will enable limited resources to be applied to the most beneficial actions. A systems-based approach will support extended safe storage of tank waste, reduce the risks from tank leaks, and protect human health and the environment.

Plasma filtering techniques for nuclear waste remediation

“…Double shell carbon-steel tanks were built starting in 1968 to provide better confinement. Waste was then pumped from single shell to double shell tanks, yet, 2.8 million gallons were still stored in single shell tanks in 2012 [6]. Moreover, leaks have also been discovered between shells of double shell tanks [7].…”