Mass transfer and transport of radionuclides through backfill in a geologic nuclear waster repository

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:5510051

Kang, Chulhyung

Analytical models for the mass transfer and transport of radionuclides through waste package backfill material are developed and their numerical illustrations are demonstrated. These models can aid in the performance assessment of the waste package in nuclear waste repositories. The following analyses are considered to study the performance of the backfill barrier in a geologic nuclear waste repository. (1) The analysis for time and space dependent mass transfer and mass transport of a radioactive decay chain for a congruent release with the matrix species is studied. Non-recursive analytical solutions are derived for a semi-infinite medium and a finite medium. The theory is illustrated with the important decay chain {sup 234}U {yields} {sup 230}Th {yields} {sup 226}Ra. (2) The time and space dependent mass transport for high solubility nuclides, such as iodine or cesium, is analyzed. The approximate solution that is valid for all times is developed, and validated by comparison with an asymptotic solution and the solution obtained by the numerical inversion of a Laplace transform covering the entire time span. From this model one can determine the thickness of the backfill to satisfy a prescribed release rate limit for high soluble radionuclides. (3) The analysis of the transient radionuclide migration through the backfill into a fracture intersecting the waste form is developed. The nuclides are advected by water flowing in the fracture. The numerical illustrations show that the species transport for the short half-life nuclide can be stopped effectively within the backfill, but the backfill can no longer retard the migration for stable nuclides or long half-life nuclides after some initial time period. (4) The steady state mass transfer from a cylindrical waste form with flow through the backfill layer is examined.

• Research Organization: California Univ., Berkeley, CA (United States)
• OSTI ID: 5510051
• Country of Publication: United States
• Language: English

Related Subjects

052002* -- Nuclear Fuels-- Waste Disposal & Storage
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
54 ENVIRONMENTAL SCIENCES
540330 -- Environment
Aquatic-- Radioactive Materials Monitoring & Transport-- (1990-)
ACTINIDE ISO
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALKALI METAL ISOTOPES
ALKALINE EARTH ISOTOPES
ALPHA DECAY RADIOISOTOPES
BACKFILLING
CARBON 14 DECAY RADIOISOTOPES
CESIUM ISOTOPES
DAYS LIVING RADIOISOTOPES
ENVIRONMENTAL TRANSPORT
EVEN-EVEN NUCLEI
GROUND WATER
HALF-LIFE
HEAVY ION DECAY RADIOISOTOPES
HEAVY NUCLEI
HYDROGEN COMPOUNDS
IODINE ISOTOPES
ISOTOPES
MAGNESIUM 28 DECAY RADIOISOTOPES
MANAGEMENT
MASS TRANSFER
MATERIALS
MATHEMATICAL MODELS
NEON 24 DECAY RADIOISOTOPES
NUCLEI
OXYGEN COMPOUNDS
POLLUTION
RADIOACTIVE MATERIALS
RADIOACTIVE WASTE DISPOSAL
RADIOACTIVE WASTE MANAGEMENT
RADIOACTIVE WASTES
RADIOISOTOPES
RADIONUCLIDE MIGRATION
RADIUM 226
RADIUM ISOTOPES
SPONTANEOUS FISSION RADIOISOTOPES
THORIUM 230
THORIUM ISOTOPES
TIME DEPENDENCE
URANIUM 234
URANIUM ISOTOPES
WASTE DISPOSAL
WASTE MANAGEMENT
WASTES
WATER
WATER POLLUTION
YEARS LIVING RADIOISOTOPES