Electrochemical Corrosion Studies for Modeling Metallic Waste Form Release Rates

Technical Report · Mon Aug 01 00:00:00 EDT 2016

DOI:https://doi.org/10.2172/1303154· OSTI ID:1303154

Poineau, Frederic ^[1]; Tamalis, Dimitri ^[2]

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1. Univ. of Nevada, Las Vegas, NV (United States)
2. Florida Memorial Univ., Miami Gardens, FL (United States)

The isotope ⁹⁹Tc is an important fission product generated from nuclear power production. Because of its long half-life (t_1/2 = 2.13 ∙ 10⁵ years) and beta-radiotoxicity (β⁻ = 292 keV), it is a major concern in the long-term management of spent nuclear fuel. In the spent nuclear fuel, Tc is present as an alloy with Mo, Ru, Rh, and Pd called the epsilon-phase, the relative amount of which increases with fuel burn-up. In some separation schemes for spent nuclear fuel, Tc would be separated from the spent fuel and disposed of in a durable waste form. Technetium waste forms under consideration include metallic alloys, oxide ceramics and borosilicate glass. In the development of a metallic waste form, after separation from the spent fuel, Tc would be converted to the metal, incorporated into an alloy and the resulting waste form stored in a repository. Metallic alloys under consideration include Tc–Zr alloys, Tc–stainless steel alloys and Tc–Inconel alloys (Inconel is an alloy of Ni, Cr and iron which is resistant to corrosion). To predict the long-term behavior of the metallic Tc waste form, understanding the corrosion properties of Tc metal and Tc alloys in various chemical environments is needed, but efforts to model the behavior of Tc metallic alloys are limited. One parameter that should also be considered in predicting the long-term behavior of the Tc waste form is the ingrowth of stable Ru that occurs from the radioactive decay of ⁹⁹Tc (⁹⁹Tc → ⁹⁹Ru + β⁻). After a geological period of time, significant amounts of Ru will be present in the Tc and may affect its corrosion properties. Studying the effect of Ru on the corrosion behavior of Tc is also of importance. In this context, we studied the electrochemical behavior of Tc metal, Tc-Ni alloys (to model Tc-Inconel alloy) and Tc-Ru alloys in acidic media. The study of Tc-U alloys has also been performed in order to better understand the nature of Tc in metallic spent fuel. Computational modeling and simulations were performed to shed light on experimental results and explain structural and kinetics trends.

• Research Organization: Battelle Energy Alliance, LLC, Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE Office of Nuclear Energy (NE)
• DOE Contract Number: AC07-05ID14517
• OSTI ID: 1303154
• Report Number(s): 12-4026; 12-4026; TRN: US1601787
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
STAINLESS STEELS
INCONEL ALLOYS
SPENT FUELS
ELECTROCHEMICAL CORROSION
WASTE FORMS
TECHNETIUM
TECHNETIUM 99
ELECTROCHEMISTRY
COMPUTERIZED SIMULATION
RUTHENIUM
KINETICS
RADIOACTIVE WASTE MANAGEMENT
TECHNETIUM ALLOYS
NICKEL ALLOYS
RUTHENIUM ALLOYS
URANIUM ALLOYS
INORGANIC ACIDS