Preliminary performance assessment of the engineered barriers for a low- and intermediate-level radioactive waste repository

Journal Article · Tue Oct 01 04:00:00 EDT 1996 · Nuclear Technology

OSTI ID:379826

Cho, W J; Lee, J O; Hahn, P S; Chun, K S ^[1]

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1. Korea Atomic Energy Research Inst., Taejon (Korea, Republic of). Nuclear Environment Management Center

Radionuclide release from an engineered barrier in a low- and intermediate-level waste repository is evaluated. The results of experimental studies conducted to determine the radionuclide diffusion coefficients and the hydraulic conductivities of calcium bentonite and crushed granite mixtures are presented. The hydraulic conductivity of the mixture is relatively low even at low dry density and clay content, and the principal mechanism of radionuclide migration through the mixture is diffusion. The measured values of apparent diffusion coefficients in calcium bentonite with a dry density of 1.4 Mg/m{sup 3} are of the order of 10{sup {minus}13} to 10{sup {minus}12} m{sup 2}/s for cations and 10{sup {minus}11} m{sup 2}/s for iodine. These values are similar to those in sodium bentonite. The radionuclide release rates from the engineered barrier composed of the concrete structure and the clay-based backfill were calculated. Carbon-14 and {sup 99}Tc are the important nuclides; however, their maximum release rates are <10{sup {minus}5} GBq/yr. To quantify the effect of uncertainties of input parameters on the radionuclide release rates, Latin Hypercube sampling was used, and the ranges of release rates were estimated statistically with a confidence level of 95%. The uncertainties of the assessment results of the radionuclide release rate are larger in the case of the sorbing nuclides such as {sup 137}Cs. Finally, the sensitivity of the input parameter to release rate is also evaluated.

• OSTI ID: 379826
• Journal Information: Nuclear Technology, Journal Name: Nuclear Technology Journal Issue: 1 Vol. 116; ISSN 0029-5450; ISSN NUTYBB
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
BACKFILLING
CARBON 14
CESIUM 137
DATA COVARIANCES
ENGINEERED SAFETY SYSTEMS
INTERMEDIATE-LEVEL RADIOACTIVE WASTES
LOW-LEVEL RADIOACTIVE WASTES
PERFORMANCE
RADIOACTIVE WASTE FACILITIES
RADIONUCLIDE MIGRATION
TECHNETIUM 99
UNDERGROUND DISPOSAL