The redox chemistry of neptunium in γ-irradiated aqueous nitric acid

B. J. Mincher; M. Precek; S. P. Mezyk; G. Elias; L. R. Martin; A. Paulenova

doi:10.1524/ract.2013.2013

The redox chemistry of neptunium in γ-irradiated aqueous nitric acid

B. J. Mincher, M. Precek, S. P. Mezyk, G. Elias, L. R. Martin, A. Paulenova

Research output: Contribution to journal › Article › peer-review

22 Scopus citations

Abstract

The redox chemistry of neptunium in irradiated 4M nitric acid was investigated using γ-ray irradiation and UV/Vis spectroscopic measurements. Irradiation caused changes in the abundances of Np(V and Np(VI) regardless of the initial fractional components of these oxidation states. At low absorbed doses Np(V) was oxidized to Np(VI) in irradiated solution, due to its reaction with oxidizing, radiolytically-produced, free radicals. However, when sufficient radiolytically-produced nitrous acid accumulated, the reduction of Np(VI) to Np(V) occurred, even at this high nitric acid concentration. Neptunium(IV) was not produced. A kinetic model which incorporates the standard water radiolysis reactions, estimated radical yields for 4M HNO₃, and rate constants for neptunium reactions available from the literature was used to successfully reproduce the experimental results.

Original language	English
Pages (from-to)	259-265
Number of pages	7
Journal	Radiochimica Acta
Volume	101
Issue number	4
DOIs	https://doi.org/10.1524/ract.2013.2013
State	Published - Apr 2013
Externally published	Yes

Funding

Acknowledgment. This work was supported through the INL Laboratory Directed Research and Development (LDRD) program, under DOE Idaho Operations Office Contract DE-AC07-05ID14517.

Funders	Funder number
U.S. Department of Energy	DE-AC07-05ID14517
Laboratory Directed Research and Development

Keywords

Neptunium
Nitrous acid
Radiation chemistry
Redox chemistry

Access to Document

10.1524/ract.2013.2013

Cite this

@article{61c52c40f8b74cc58d2c6fd53ee069f0,

title = "The redox chemistry of neptunium in γ-irradiated aqueous nitric acid",

abstract = "The redox chemistry of neptunium in irradiated 4M nitric acid was investigated using γ-ray irradiation and UV/Vis spectroscopic measurements. Irradiation caused changes in the abundances of Np(V and Np(VI) regardless of the initial fractional components of these oxidation states. At low absorbed doses Np(V) was oxidized to Np(VI) in irradiated solution, due to its reaction with oxidizing, radiolytically-produced, free radicals. However, when sufficient radiolytically-produced nitrous acid accumulated, the reduction of Np(VI) to Np(V) occurred, even at this high nitric acid concentration. Neptunium(IV) was not produced. A kinetic model which incorporates the standard water radiolysis reactions, estimated radical yields for 4M HNO3, and rate constants for neptunium reactions available from the literature was used to successfully reproduce the experimental results.",

keywords = "Neptunium, Nitrous acid, Radiation chemistry, Redox chemistry",

author = "Mincher, {B. J.} and M. Precek and Mezyk, {S. P.} and G. Elias and Martin, {L. R.} and A. Paulenova",

year = "2013",

month = apr,

doi = "10.1524/ract.2013.2013",

language = "English",

volume = "101",

pages = "259--265",

journal = "Radiochimica Acta",

issn = "0033-8230",

publisher = "De Gruyter",

number = "4",

}

TY - JOUR

T1 - The redox chemistry of neptunium in γ-irradiated aqueous nitric acid

AU - Mincher, B. J.

AU - Precek, M.

AU - Mezyk, S. P.

AU - Elias, G.

AU - Martin, L. R.

AU - Paulenova, A.

PY - 2013/4

Y1 - 2013/4

N2 - The redox chemistry of neptunium in irradiated 4M nitric acid was investigated using γ-ray irradiation and UV/Vis spectroscopic measurements. Irradiation caused changes in the abundances of Np(V and Np(VI) regardless of the initial fractional components of these oxidation states. At low absorbed doses Np(V) was oxidized to Np(VI) in irradiated solution, due to its reaction with oxidizing, radiolytically-produced, free radicals. However, when sufficient radiolytically-produced nitrous acid accumulated, the reduction of Np(VI) to Np(V) occurred, even at this high nitric acid concentration. Neptunium(IV) was not produced. A kinetic model which incorporates the standard water radiolysis reactions, estimated radical yields for 4M HNO3, and rate constants for neptunium reactions available from the literature was used to successfully reproduce the experimental results.

AB - The redox chemistry of neptunium in irradiated 4M nitric acid was investigated using γ-ray irradiation and UV/Vis spectroscopic measurements. Irradiation caused changes in the abundances of Np(V and Np(VI) regardless of the initial fractional components of these oxidation states. At low absorbed doses Np(V) was oxidized to Np(VI) in irradiated solution, due to its reaction with oxidizing, radiolytically-produced, free radicals. However, when sufficient radiolytically-produced nitrous acid accumulated, the reduction of Np(VI) to Np(V) occurred, even at this high nitric acid concentration. Neptunium(IV) was not produced. A kinetic model which incorporates the standard water radiolysis reactions, estimated radical yields for 4M HNO3, and rate constants for neptunium reactions available from the literature was used to successfully reproduce the experimental results.

KW - Neptunium

KW - Nitrous acid

KW - Radiation chemistry

KW - Redox chemistry

UR - http://www.scopus.com/inward/record.url?scp=84875728995&partnerID=8YFLogxK

U2 - 10.1524/ract.2013.2013

DO - 10.1524/ract.2013.2013

M3 - Article

AN - SCOPUS:84875728995

SN - 0033-8230

VL - 101

SP - 259

EP - 265

JO - Radiochimica Acta

JF - Radiochimica Acta

IS - 4

ER -

The redox chemistry of neptunium in γ-irradiated aqueous nitric acid

Abstract

Funding

Keywords

Access to Document

Other files and links

Fingerprint

Cite this