Diffusion of iodine and Technetium-99 through waste encasement concrete and unsaturated soil fill material

Conference · Sat Oct 30 04:00:00 EDT 2004

OSTI ID:15011285

Mattigod, Shas V; Whyatt, Greg A; Serne, R JEFFREY; Wood, Marcus I

An assessment of long-term performance of low level waste-enclosing cement grouts requires diffusivity data for radionuclide species such as, 129I and 99Tc. The diffusivity of radionuclides in soil and concrete media was collected by conducting soil-soil and concrete-soil half-cell experiments. The soil diffusivity coefficients for iodide were 7.03 x 10-8 cm2/s and 2.42 x 10-7 cm2/s for soils at 4% and 7% moisture contents, respectively. Iodide diffusivity in soil is a function of moisture content and is about an order of magnitude slower at lower moisture content. The soil diffusivity coefficients for 99Tc were 5.89 {+-} 0.80 x 10-8 cm2/s (4% moisture content) and 2.04 {+-} 0.57 x 10-7 cm2/s (7% moisture content), respectively. The soil diffusivity of iodide and 99Tc were similar in magnitude at both water contents, indicating that these ions have similar diffusion mechanisms in unsaturated coarse-textured Hanford soil. The diffusivity of iodide in concrete ranged from 2.07 x 10-14 cm2/s (4% soil moisture content) to 1.31 x 10-12 cm2/s (7% soil moisture content), indicating that under unsaturated soil moisture conditions, iodide diffusivity is highly sensitive to changing soil moisture conditions. Depending on the soil moisture content, the diffusivity of 99Tc in concrete ranged from 4.54 x 10-13 cm2/s to 8.02 x 10-12 cm2/s. At 4% soil moisture content, iodide diffused about 20 times more slowly than 99Tc, and at 7% soil moisture content, iodide in concrete diffused about 6 times slower than 99Tc.

• Research Organization: Pacific Northwest National Lab., Richland, WA (US)
• Sponsoring Organization: US Department of Energy (US)
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 15011285
• Report Number(s): PNNL-SA-43964; 830403000
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
CEMENTS
CONCRETE
CONCRETES
DIFFUSION
GROUTING
IODIDES
IODINE
MANAGEMENT
MOISTURE
PERFORMANCE
RADIOACTIVE WASTES
RADIOISOTOPES
SOIL FILL MATERIAL
SOILS
TECHNETIUM 99
TECHNETIUM-99
WASTES