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Generation and Study of Am(IV) by Temperature-Controlled Electron Pulse Radiolysis

Conference ·
DOI:https://doi.org/10.1039/D4DT00991F· OSTI ID:2440487
 [1];  [1];  [1];  [1];  [2];  [2];  [3]
  1. Idaho National Laboratory
  2. Brookhaven National Laboratory
  3. California State University, Long Beach
+ Show Author Affiliations
Used nuclear fuel (UNF) separation techniques that strive to separate radiotoxic americium (Am) from trivalent lanthanide fission products through oxidation state control have increased research efforts surrounding Am(V) and Am(VI). However, equivalent knowledge of the tetravalent state, Am(IV), has remained elusive, particularly in conditions more representative of UNF reprocessing, i.e., in concentrated nitric acid (HNO3). With this in mind, we have used electron pulse radiolysis to study the radiation-induced redox reaction of Am(III) with the oxidizing nitrate radical (NO3•) in 6 M HNO3: Am(III) + NO3• ? Am(IV) + NO3– . These experiments enabled us to observe the growth and decay of Am(IV) in a concentrated acidic solution for the first time. The transient Am(IV) species was found to have a lifetime of ~16 µs—sufficiently long-lived to play a critical mechanistic role in UNF reprocessing systems. Additionally, we performed the first-ever temperature-dependent kinetics study of an actinide element, elucidating unprecedented Arrhenius and Eyring activation parameters for the reaction of Am(III) with NO3•. This new knowledge provides much-needed molecular-level insights into the radiation-induced behavior of Am.
Research Organization:
Idaho National Laboratory (INL), Idaho Falls, ID (United States)
Sponsoring Organization:
58
DOE Contract Number:
AC07-05ID14517;
OSTI ID:
2440487
Report Number(s):
INL/CON-24-78311-Rev000
Conference Information:
ECRA and Postdoc Programs Poster Session, Idaho National Laboratory, 06/04/2024 - 06/04/2024
Country of Publication:
United States
Language:
English

References (9)

Chemical Kinetics for the Oxidation of Californium(III) Ions with Select Radiation-Induced Inorganic Radicals (Cl2•– and SO4•–) journal January 2024
Decay Mechanism of NO 3 • Radical in Highly Concentrated Nitrate and Nitric Acidic Solutions in the Absence and Presence of Hydrazine journal May 2016
Higher Oxidation States of Americium: Preparation, Characterization and Use for Separations journal September 2011
Pulse-radiolysis studies of americium ions in aqueous perchlorate media journal February 1978
Ultra-Efficient Americium/Lanthanide Separation through Oxidation State Control journal March 2022
Curium( iii ) radiation-induced reaction kinetics in aqueous media journal January 2021
Critical Review of rate constants for reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals (⋅OH/⋅O − in Aqueous Solution
  • Buxton, George V.; Greenstock, Clive L.; Helman, W. Phillips
  • Journal of Physical and Chemical Reference Data, Vol. 17, Issue 2 https://doi.org/10.1063/1.555805
journal April 1988
Separations and Transmutation Criteria to Improve Utilization of a Geologic Repository journal April 2006
Spectroelectrochemical Studies of the Actinides: Stabilization of Americium(IV) in Aqueous Carbonate Solution journal January 1982

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Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
Actinide
Americium
Electron Pulse Radiolysis
Nitrate Radical
Radiation Chemistry
Radiochemistry
Redox Chemistry