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Behaviour of neptunium in deep groundwater environments

Technical Report:

Abstract

Spent nuclear fuel contains substantial amounts of long lived isotopes of actinide elements e.g. neptunium-237. The behaviour of these isotopes in repository environments and migration in deep geological formations must be well known for realistic safety assessments. In this work the redox and sorption behaviour of neptunium was studied with laboratory experiments simulating conditions in deep crystalline rock formations. Under oxic conditions the sorption of Np(V) on tonalite was independent of the initial Np-concentration (5 x -10{sup -}1{sup 2} to 5 x 10{sup -}8 M) indicating an exchange type sorption mechanism. In unoxic water-rock-system the Np(V) was reduced to Np(IV) by components of the waters. Sorption of Np(V) on mineral surface slowered the reduction to Np(IV). Even under highly reducing environments the sorbed phases were of mixtures of Np (IV) and Np(V). After initial reduction to Np(IV) the oxidation of part of neptunium to Np(V) was not followed by dissolution of Np(V). The solubility of neptunium in reducing groundwater was smaller than or equal to 10{sup -}1{sup 3} M. Sorption of neptunium with initial Np-concentration of 10{sup -}1{sup 4} M on polished rock surfaces indicated a Ka-value about 100 x 10{sup -}4 m{sup 3}/m{sup 2}. (orig.).
Authors:
Hakanen, M; [1]  Lindberg, A [2] 
  1. Helsinki Univ. (Finland). Dept. of Radiochemistry
  2. Geological Survey of Finland, Helsinki (Finland)
Publication Date:
Dec 01, 1989
Product Type:
Technical Report
Report Number:
YJT-89-15
Reference Number:
SCA: 052002; PA: AIX-24:007820; SN: 93000932592
Resource Relation:
Other Information: PBD: Dec 1989
Subject:
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; NEPTUNIUM 237; SOLUBILITY; SORPTION; RADIOACTIVE WASTE DISPOSAL; GRANITES; GROUND WATER; NEPTUNIUM 235; OXIDATION; RADIONUCLIDE MIGRATION; REDOX REACTIONS; REDUCTION; SIMULATION; SPENT FUELS; UNDERGROUND DISPOSAL; 052002; WASTE DISPOSAL AND STORAGE
OSTI ID:
10119254
Research Organizations:
Voimayhtioeiden Ydinjaetetoimikunta, Helsinki (Finland)
Country of Origin:
Finland
Language:
English
Other Identifying Numbers:
Other: ON: DE93612759; TRN: FI9200092007820
Availability:
OSTI; NTIS; INIS
Submitting Site:
FIN
Size:
[31] p.
Announcement Date:
Jun 30, 2005

Technical Report:

Citation Formats

Hakanen, M, and Lindberg, A. Behaviour of neptunium in deep groundwater environments. Finland: N. p., 1989. Web.
Hakanen, M, & Lindberg, A. Behaviour of neptunium in deep groundwater environments. Finland.
Hakanen, M, and Lindberg, A. 1989. "Behaviour of neptunium in deep groundwater environments." Finland.
@misc{etde_10119254,
title = {Behaviour of neptunium in deep groundwater environments}
author = {Hakanen, M, and Lindberg, A}
abstractNote = {Spent nuclear fuel contains substantial amounts of long lived isotopes of actinide elements e.g. neptunium-237. The behaviour of these isotopes in repository environments and migration in deep geological formations must be well known for realistic safety assessments. In this work the redox and sorption behaviour of neptunium was studied with laboratory experiments simulating conditions in deep crystalline rock formations. Under oxic conditions the sorption of Np(V) on tonalite was independent of the initial Np-concentration (5 x -10{sup -}1{sup 2} to 5 x 10{sup -}8 M) indicating an exchange type sorption mechanism. In unoxic water-rock-system the Np(V) was reduced to Np(IV) by components of the waters. Sorption of Np(V) on mineral surface slowered the reduction to Np(IV). Even under highly reducing environments the sorbed phases were of mixtures of Np (IV) and Np(V). After initial reduction to Np(IV) the oxidation of part of neptunium to Np(V) was not followed by dissolution of Np(V). The solubility of neptunium in reducing groundwater was smaller than or equal to 10{sup -}1{sup 3} M. Sorption of neptunium with initial Np-concentration of 10{sup -}1{sup 4} M on polished rock surfaces indicated a Ka-value about 100 x 10{sup -}4 m{sup 3}/m{sup 2}. (orig.).}
place = {Finland}
year = {1989}
month = {Dec}
}