Using hot isostatic pressing for radioactive waste isolation purposes

The paper summarizes the findings of a study focused on hot isostatic pressing (HIP) technique implemented by the Khlopin Radium institute. The equipment was designed and manufactured at the Kharkov’s Physics and Technology Institute. The installation provided a pressure of up to 400 NPa with the pressing temperature of up to 1250°C. The experiments were carried out on installations located in hot cells in the radiochemical department (Gatchina city). Samples of materials for HLW immobilization (titanate ceramics of the synroc type, stabilized cubic zirconia) and matrices for 129I immobilization based on copper iodide and metallic copper were obtained. The leaching rate from these samples of HLW elements (simulators) amounted to (0.5—1.5)·10–9 g/(cm2 ·day). Despite the high-performance characteristics of the materials obtained, some problems were revealed associated with the remote maintenance of equipment and the lack of industrial design analogues. Considering the experience gained, we believe that fairly simple equipment can be designed implying no complex systems and providing minimum preparatory operations. Joint efforts of technologists and designers will enable the automatization of equipment management and control through local control systems. Material loading and unloading operations can be robotized as well. Such technical solutions are expected to be in demand at industrial facilities for HLW final disposal (or when handling damaged fuel during the decommissioning of radiation and nuclear hazardous facilities).

BSUIN – Baltic Sea Underground Innovation Network

<p>The Baltic Sea region hosts numerous underground facilities or underground laboratories (Uls). The Baltic Sea Underground Innovation Network (BSUIN) there are six such facilities, all unique in their characteristics and operational settings, e.g. located in existing or historical mines, research tunnel networks or as a dedicated underground laboratory for a specific purpose. BSUIN project concentrates on the making the Uls more accessible for current and new users,  helping the Uls to understand their infrastructural challenges and possibilities, and through joint marketing to attract a broader spectrum of users into their facilities.</p><p>The underground laboratories participating in BSUIN are Callio Lab (Pyhäjärvi Finland), ÄSPÖ Hard Rock Laboratory (Oskarshamn, Sweden), Ruskela Mining Park (Ruskeala, Russia), Educational and research mine Reiche Zeche (Freiberg, Germany), Underground Low Background Laboratory of the Khlopin Radium Institute (St.Petersburg, Russia) and the Conceptual Lab development co-ordinated by KGHM Cuprum R&D centre (Poland).</p><p>We will present the overview of the project, key outcomes, findings and recommendations for underground laboratories in general. The key outcomes of the project for the individual underground laboratories consist of characterisation of the structural, geological and operational environments together with information on the governing legislation and authorities for the underground sites. Underground risks and challenges in the underground working environment have been documented to help the further development of the individual underground laboratories. Service designs were developed together with the ULs to enhance user support and to attract a broader spectrum of users.  To help users with innovation and innovation management the variety of the innovation services was documented to be used as bases for the future operational development of the ULs. To support the marketing, coordinate activities and develop the cooperation an umbrella organisation European Underground Laboratories association (EUL) will be established to carry on the work started in BSUIN.</p><p>The Baltic Sea Underground Innovation Network, BSUIN, is funded by the Interreg Baltic Sea Region Programme. </p>

Synthesis of Crystalline Ceramics for Actinide Immobilisation

Methods for the synthesis of ceramic wasteforms for the immobilization of actinides are common to those for non-radioactive ceramics: hot uniaxial pressing (HUP); hot isostatic pressing (HIP); cold pressing followed by sintering; melting (for some specific ceramics, such as garnet/perovskite composites). Synthesis of ceramics doped with radionuclides is characterized with some important considerations: all the radionuclides should be incorporated into crystalline structure of durable host-phases in the form of solid solutions and no separate phases of radionuclides should be present in the matrix of final ceramic wasteform; all procedures of starting precursor preparation and ceramic synthesis should follow safety requirements of nuclear industry. Synthesis methods that avoid the use of very high temperatures and pressures and are easily accomplished within the environment of a glove-box or hot cell are preferable. Knowledge transfer between the V. G. Khlopin Radium Institute (KRI, Russia) and Immobilisation Science Laboratory (ISL, UK) was facilitated in the framework of a joint project supported by UK Royal Society. In order to introduce methods of precursor preparation and ceramic synthesis we selected well-known procedures readily deployable in radiochemical processing plants. We accounted that training should include main types of ceramic wasteforms which are currently discussed for industrial applications.

Porous Alumina Silicate Matrix Gubka for Solidification of 137Cs Strip Product

Separated liquid highâlevel radioactive waste (HLW) fractions, in particular, about 100 l of 137Cs strip product with activity up to ∼ 100 Ci/l (3.7 TBq/l) have been produced during the development and testing of partitioning technology and temporary stored at “V.G. Khlopin Radium Institute” (SaintâPetersburg, Russia). The benchâscale experimental unit designed for operation in the hot cell was developed for 137Cs strip product solidification with using of alumina silicate porous inorganic material (PIM) called Gubka.Conditions of saturation, drying and calcinations of the salts into Gubka pores were optimized and the operations under remote control regime were executed during tests with using of simulated strip product doped with 137Cs. The volume reduction coefficients were equal by a factor of 3.2â3.9 and 137Cs discharge into offâgas system was not detected. 137Cs leach rates from Gubka blocks after calcination at 800 °C were 1.0â1.5*10-3 g/m2*day.

Ceramics for the Immobilization of Plutonium and Americium: Current Progress of R&D of the V.G. Khlopin Radium Institute

ABSTRACTSince 1990, the Laboratory of Applied Mineralogy and Radiogeochemistry of the V.G. Khlopin Radium Institute (KRI) has been developing several different types of crystalline host-phases acceptable for the economically feasible and environmentally safe immobilization of actinide wastes. We proposed that ceramics that are based on host phases similar to naturally occurring accessory minerals including zircon, (Zr,Hf,…)SiO4; hafnon, (Hf,Zr,…)SiO4; baddeleyite (monoclinic zirconia), (Zr,Hf,…)O2; tazheranite (cubic zirconia), (Zr,Hf,Ca,Ti,…)O2; garnet, (Ca,Fe,Gd,…)3(Al,Fe,Si,…)5O12; perovskite, (Ca,Gd,…)(Al,Fe,Ti,…)O3, and monazite, (La,Ce,…)PO4, are the most efficient materials for actinide immobilization in deep geological formations. Solid solution of Pu in zirconia, (Zr,Pu)O2, could be used as a ceramic nuclear fuel that is competitive with mixed oxide fuel (MOX). To date, the following crystalline materials doped with 239Pu, 238Pu and 243Am have been successfully synthesized and studied at KRI: zircon; hafnon; cubic and tetragonal zirconia; monazite; aluminate garnet and perovskite. The maximum actinide loading was (in wt.% el.): 239Pu -37; 238Pu-10; 243Am-23. All Pu-Am-doped samples were made in air atmosphere under glove boxes conditions. Polycrystalline (ceramic) materials were made by sintering or melting of sol-gel, co-precipitated hydroxides, oxalates and phosphates or ground oxide precursors; single crystals were grown by a flux method. It was demonstrated that all ceramic samples obtained are characterized by high chemical durability and typical normalized actinide losses in deionized water at 90°C do not exceed 10−2–10−3 g/m2 (without correction for ceramic porosity). However, investigation of long-term behavior of ceramic waste forms requires taking into account the results of accelerated radiation damage study and modeling of ceramic alteration by underground solutions. The principal features of Pu-Am-doped samples obtained so far at KRI and their synthesis conditions are discussed.

Vitrification of DOE Simulated Radioactive Waste by Induction-Heated Cold-Crucible Melter Technology

Certain waste streams of the US DOE contain radioactive refractory oxides and other components like aluminum zirconium and chromium, which present difficulties during their processing and immobilization. The vitrification of such waste in joule-heated melters at high waste loading is possible only at a temperature exceeding 1150°C. The Khlopin Radium Institute (St.-Petersburg, Russia) jointly with the US Department of Energy has performed a feasibility study on the suitability of the Cold-Crucible Induction Heated Melter (CCIM) technology for the single-stage solidification of a surrogate sludge (C-106/AY-102 HLW Simulant), similar in composition to the High Level Waste (HLW) found at DOE’s Hanford Site (Richland, USA). During the experiments, slurry of simulated sludge and glass formers was metered directly to the CCIM, melted, and the glass product was poured from the melter. The melts were conducted at a mean melt temperature of 1350°C. The experiments produced borosilicate glass wasteforms with a waste oxide loading of 70 weight percent. According to the X-Ray diffraction analysis, the final product had a glass-crystalline structure. The crystalline phase was represented by spinel, (Fe,Mn)Fe2O4, uniformly distributed over the wasteform. The chemical durability of the samples was tested by the Product Consistency Test (PCT), and was considered durable according to the DOE specifications for HLW. In the course of the experiments, data were accumulated on the specific electric power consumption and the throughput of the facility.

Porous Crystalline Silica (Gubka) as a Inorganic Support Matrix for Novel Sorbents

ABSTRACTInorganic ion exchange media typically exist as fine powders, making large-scale use impractical, unless the media can be affixed to an appropriate matrix. Likewise, organic chelating agents are typically dissolved in a solvent and absorbed into porous matrices for use in extraction chromatography. The most common matrices utilized in both cases are organic materials, that are not compatible with high radiation fields or acceptable as final waste forms. Recent investigations have shown that ion exchange sorbents can be effectively loaded within a porous crystalline silica (Gubka) matrix. This approach allows for target radionuclides to be adsorbed into a porous micro-crystalline glass matrix which encapsulates the contaminant and becomes the final waste form. Subsequent to adsorption of the radionuclides, the Gubka matrix can be compressed in a hot uniaxial press, resulting in an even greater volume reduction. The porous glass matrix is produced in Russia using fly ash residue from coal combustion power generating plants. It consists of consolidated arrays of hollow glass cenospheres and is termed Gubka which is the Russian word for sponge. This paper describes results of a collaborative research program between the Khlopin Radium Institute, St.Petersburg, Russia, the Institute of Chemistry and Chemical Technologies, Krasnoyarsk, Russia, the Mining and Chemical Combine, Zheleznogorsk, Russia, and the Idaho National Engineering and Environmental Laboratory. Ammonium molybdophosphate (AMP) for the removal of cesium from acidic liquid waste has been successfully incorporated into Gubka matrices. Test results for cesium removal, using AMP-Gubka, are discussed.