Leaching of zirconolite ceramics under H+ and He2+ irradiation

Zirconolite is a candidate host material for conditioning minor tri- and tetra-valent actinides arising from enhanced nuclear spent fuel reprocessing and partitioning, which can be disposed in a geological repository for nuclear waste. Its chemical durability has been studied here under charged particle-induced radiolysis (He

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Spent Fuel Reprocessing and Nuclear Waste Transmutation

Lecture Notes in Energy - Nuclear Waste Management ◽

10.1007/978-94-024-2106-4_8 ◽

2021 ◽

pp. 341-384

Author(s):

Man-Sung Yim

Keyword(s):

Nuclear Waste ◽

Spent Fuel ◽

Spent Fuel Reprocessing ◽

Nuclear Waste Transmutation ◽

Fuel Reprocessing

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REE and TRU Incorporation into Monazite Structure Ceramics

MRS Proceedings ◽

10.1557/proc-824-cc4.4 ◽

2004 ◽

Vol 824 ◽

Cited By ~ 2

Author(s):

S. I. Rovnyi ◽

G. M. Medvedev ◽

A. S. Aloy ◽

T. I. Koltsova ◽

S. E. Samoylov

Keyword(s):

Thin Film ◽

Solid Solution ◽

Rare Earth ◽

Rare Earth Elements ◽

Chemical Durability ◽

Spent Fuel ◽

Waste Streams ◽

Oxalate Precipitation ◽

Spent Fuel Reprocessing ◽

Fuel Reprocessing

AbstractOne of the high levels of actinide, and in particular Cm, waste streams at the Russian radiochemical Production Association (PA) Mayak was generated during spent fuel reprocessing. Using oxalate precipitation, the rare earth elements (REE) and transuranic elements (TRU) settled out in the form of oxalate residues. Due to in high REE contents in this residue, the mineral-like matrix based on (REE)PO4 solid solution, with monlclinic monazite structure have been proposed to use as a suitable ceramics form for final actinide immobilization. For this purpose the synthetic REE oxalates were first transformed into REE orthophosphates in a thin-film evaporator (TFE). Then the (REE)PO4 powder was compacted both by either hot uniaxial pressing (HUP) or cold uniaxial pressing followed by sintering (CUP). This ceramic with the monazite structure has a high density and exhibits chemical durability by leaching.

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Development of New Waste Forms to Immobilize Iodine-129 Released from a Spent Fuel Reprocessing Plant

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.73.158 ◽

2010 ◽

Vol 73 ◽

pp. 158-170 ◽

Cited By ~ 16

Author(s):

Hiromi Tanabe ◽

Tomofumi Sakuragi ◽

Kenji Yamaguchi ◽

Taemi Sato ◽

Hitoshi Owada

Keyword(s):

Radioactive Wastes ◽

Behavior Modeling ◽

Spent Fuel ◽

Waste Forms ◽

Reducing Conditions ◽

Geological Repository ◽

Spent Fuel Reprocessing ◽

Immobilization Techniques ◽

Reprocessing Plant ◽

Fuel Reprocessing

I-129 is a very long-lived radionuclide that is released to an off-gas stream when spent fuels are dissolved at a reprocessing plant. An iodine filter can capture I-129 in the form of AgI. However, because AgI is unstable under the reducing conditions of a geological repository and I-129 has a very long half-life, I-129 can migrate to the biosphere. These characteristics make I-129 a key radionuclide for the safety assessment of a geological disposal of radioactive wastes generated from a reprocessing plant (TRU wastes). To improve disposal safety, several new waste forms have been developed to confine I-129 for a very long period in order to reduce the leaching of I-129 from radioactive wastes. These new waste forms have technical objectives of solidifying more than 95% of I-129 into the waste form and achieving a leaching rate of less than 10-5/y. Several iodine immobilization techniques have been examined. This paper presents experimental results concerning the treatment process, leaching behavior, modeling, and related elements of these immobilization techniques.

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Enhancement of Zirconolite Dissolution Due to Water Radiolysis

MRS Proceedings ◽

10.1557/proc-985-0985-nn09-04 ◽

2006 ◽

Vol 985 ◽

Cited By ~ 1

Author(s):

Nelly Toulhoat ◽

Nathalie Moncoffre ◽

Pierre Toulhoat ◽

Christophe Jegou ◽

...

Keyword(s):

Charged Particle ◽

Surface Water ◽

Pure Water ◽

Water Radiolysis ◽

Water Interface ◽

Spent Fuel ◽

Enhanced Dissolution ◽

Order Of Magnitude ◽

Spent Fuel Reprocessing ◽

Fuel Reprocessing

AbstractZirconolite is a candidate host material for conditioning minor tri- and tetra-valent actinides arising from enhanced nuclear spent fuel reprocessing and partitioning, in the case of disposal of the nuclear waste. Its chemical durability has been studied here under charged particle-induced radiolysis (He2+ and proton external beams) to identify the possible effects of water radiolysis on the dissolution rates in pure water and to describe the alteration mechanisms. Two experimental geometries have been used in order to evaluate the influence of the following parameters: solid irradiation, water radiolysis. In the first geometry the beam gets through the sample before stopping at the surface/water interface. In the second one the beam stops before the surface/water interface. Results on the elemental releases due to the enhanced dissolution of the zirconolite surface during charged particle-induced irradiation of water are presented. Under radiolysis, an increase of one order of magnitude is observed in the Ti, Zr and Nd elemental releases. No difference in the total elemental releases can be noticed when the solid is also irradiated.

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