Diffusion of the [sup 241]Am [r arrow] [sup 237]Np decay chain limited by their elemental solubilities in the artificial barriers of high-level radioactive waste repositories

Journal Article · Fri Jan 01 04:00:00 EST 1993 · Nuclear Technology; (United States)

OSTI ID:6446909

Ahn, Joonhong; Suzuki, Atsuyuki ^[1]

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1. Univ. of Tokyo, Bunkyoku (Japan)

A mathematical analysis of the diffusion of the [sup 241]Am [r arrow] [sup 237]Np decay chain in the artificial barrier of a high-level radioactive waste repository is presented. First, analytical solutions obtained are for the space- and time-dependent concentration of [sup 241]Am in the artificial barrier and the time-dependent amount of americium precipitated at the surface of the waste glass, based on the assumption of the congruency of the radionuclides with solubility-limited dissolution of the glass matrix. The effects of solubility sharing with coexisting [sup 243]Am are considered. Transport and precipitation of [sup 237]Np in the artificial barrier are analyzed by dividing the time domain into a small time domain, where the [sup 241]Am concentration is so large that [sup 237]Np precipitation is dominant, and a large time domain, where the [sup 241]Am becomes negligible and the precipitation region shrinks by diffusion from the precipitation front. The equation for the movement of the precipitation front is obtained. As the overpack lifetime increases, the effect of neptunium precipitation becomes less significant. With a lifetime longer than [approximately]6000 yr, an earlier model, where neptunium is treated as a mother nuclide and the precipitation occurs only at the glass surface, can be used.

• OSTI ID: 6446909
• Journal Information: Nuclear Technology; (United States), Journal Name: Nuclear Technology; (United States) Vol. 101:1; ISSN 0029-5450; ISSN NUTYBB
• 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
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
AMERICIUM 241
AMERICIUM ISOTOPES
ANALYTICAL SOLUTION
ATOM TRANSPORT
DAYS LIVING RADIOISOTOPES
DECAY
DIFFUSION
GLASS
HALF-LIFE
HEAVY NUCLEI
HIGH-LEVEL RADIOACTIVE WASTES
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MANAGEMENT
MATERIALS
NANOSEC LIVING RADIOISOTOPES
NEPTUNIUM 237
NEPTUNIUM ISOTOPES
NEUTRAL-PARTICLE TRANSPORT
NUCLEAR DECAY
NUCLEI
ODD-EVEN NUCLEI
PERMEABILITY
POROSITY
RADIATION TRANSPORT
RADIOACTIVE MATERIALS
RADIOACTIVE WASTE DISPOSAL
RADIOACTIVE WASTE MANAGEMENT
RADIOACTIVE WASTES
RADIOISOTOPES
ROCKS
SOLUBILITY
SPONTANEOUS FISSION RADIOISOTOPES
TIME DEPENDENCE
UNDERGROUND DISPOSAL
WASTE DISPOSAL
WASTE MANAGEMENT
WASTES
YEARS LIVING RADIOISOTOPES