Current Status of the Thermodynamic Data for Technetium and Its Compounds and Aqueous Species

Journal Article · Mon May 16 04:00:00 EDT 2005 · Journal of Nuclear and Radiochemical Sciences

DOI:https://doi.org/10.14494/jnrs2000.6.3_197· OSTI ID:883820

Rard, J A

{sup 99}Tc is a major fission product from nuclear reactors. Because {sup 99}Tc has few applications outside of scientific research, most of this technetium will ultimately be disposed of as nuclear waste. The radioactive decay of {sup 99}Tc to {sup 99}Ru produces a low energy {beta}{sup -} particle, but because of its fairly long half-life of t{sub 1/2} = 2.13 x 10{sup 5} years, {sup 99}Tc is a major source of radiation in low level waste. Technetium forms the soluble TcO{sub 4}{sup -} anion under oxic conditions and this ion is very mobile in groundwater, but technetium is reduced to less soluble Tc(IV) hydrolyzed species under anoxic conditions. Geochemical modeling of the dissolution of nuclear waste, and of the solubility and speciation of the dissolved radionuclides in groundwaters, is an integral part of the Performance Assessment of the safety of a nuclear waste repository, and this modeling requires a critically-assessed thermodynamic database. Such a database for technetium was published in the book Chemical Thermodynamics of Technetium, with literature coverage through 1998. This database is described herein, along with more recent relevant studies. Gaps in the knowledge of the chemical and thermodynamic properties of technetium are pointed out, and recommendations are made for measurements that are needed to eliminate these gaps.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 883820
• Report Number(s): UCRL-JRNL-212334
• Journal Information: Journal of Nuclear and Radiochemical Sciences, Journal Name: Journal of Nuclear and Radiochemical Sciences Journal Issue: 3 Vol. 6; ISSN 1345-4749
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
ANIONS
DECAY
DISSOLUTION
FISSION PRODUCTS
HALF-LIFE
RADIATIONS
RADIOACTIVE WASTES
RADIOISOTOPES
REACTORS
SAFETY
SIMULATION
SOLUBILITY
TECHNETIUM
THERMODYNAMIC PROPERTIES
THERMODYNAMICS