Evaluation of Iodine Remediation Technologies in Subsurface Sediments (Interim Status Report)
Isotopes of iodine were generated during plutonium production from nine production reactors at the U.S. Department of Energy Hanford Site. The long half-life 129I generated at the Hanford Site during reactor operations was 1) stored in single-shell and double-shell tanks, 2) discharged to liquid disposal sites (e.g., cribs and trenches), 3) released to the atmosphere during fuel reprocessing operations, or 4) captured by off-gas absorbent devices (silver reactors) at chemical separations plants (PUREX, B-Plant, T-Plant, and REDOX). Releases of 129I to the subsurface have resulted in several large, though dilute, plumes in the groundwater, including the plume in the 200-UP-1 operable unit. There is also 129I remaining in the vadose zone beneath disposal or leak locations. Because 129I is an uncommon contaminant, relevant remediation experience and scientific literature are limited. Iodine cannot be degraded/transformed to a less toxic form. Therefore, the primary metric for remediation is changing the fate and transport properties in a way that works to decrease radioiodine concentrations in groundwater. To this end, targeted laboratory experiments were conducted to provide proof-of-principle screening of remedial options and to evaluate scale-up and performance elements. The evaluation of different iodine remediation technologies will occur over multiple years and fall into three different categories: 1) geochemical/biological sequestration, 2) microbial volatilization, and 3) enhanced pump-and-treat. This report provides status on two in situ sequestration methods (apatite and iron oxides) and two methods examining enhanced pump-and-treat.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1985693
- Report Number(s):
- PNNL-26957; RPT-DVZ-AFRI-051; TRN: US2403711
- Country of Publication:
- United States
- Language:
- English
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Evaluation of Iodine Remediation Technologies in Subsurface Sediments: Interim Status Report
Laboratory report on iodine (129I and 127I) speciation, transformation and mobility in Handford groundwater, suspended particles and sediments