Dissolution of spent nuclear fuel fragments at high alkaline conditions under H2 overpressure

MRS Advances ◽  
2016 ◽  
Vol 1 (62) ◽  
pp. 4163-4168
Author(s):  
E. González-Robles ◽  
M. Herm ◽  
V. Montoya ◽  
N. Müller ◽  
B. Kienzler ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Partial Pressure ◽  
Nuclear Fuel ◽  
Alkaline Solution ◽  
Spent Nuclear Fuel ◽  
Dissolution Tests ◽  
The Matrix ◽  
Alkaline Conditions ◽  
Long Term Behavior

ABSTRACTThe long-term behavior of the UO2 fuel matrix under conditions of the Belgian “Supercontainer design” was investigated by dissolution tests of high burn-up spent nuclear fuel (SNF) in high alkaline solution under 40 bar of (Ar + 8%H2) atmosphere. Four fragments of SNF, obtained from a pellet previously leached during two years, were exposed to young cement water with Ca (YCWCa) under 3.2 bar H2 partial pressure in four single/independent autoclave experiments for a period of 59, 182, 252 and 341 days, respectively. After a decrease of the concentration of dissolved 238U, which is associated with a reduction of U(VI) to U(IV), the concentration of 238U in solution is constant in the experiments running for 252 and 341 days. These observations indicate an inhibition of the matrix dissolution due to the presence of H2. A slight increase in the concentration of 90Sr and 137Cs in the aqueous solution indicates that there is still dissolution of the grain boundaries. These findings are similar to those reported for spent nuclear fuel corrosion in synthetic near neutral pH solutions.

UO2 dissolution in high pH conditions of the Belgian Supercontainer

2012 ◽  
Vol 1475 ◽  
Author(s):  
Th. Mennecart ◽  
C. Cachoir ◽  
K. Lemmens
Keyword(s):  
Spent Fuel ◽  
Dissolution Rates ◽  
High Ph ◽  
Neutral Ph ◽  
Dissolution Tests ◽  
Alkaline Conditions ◽  
Ph Conditions ◽  
Ph Range ◽  
Long Term Behavior

ABSTRACTTo assess the long-term behavior of spent fuel in alkaline conditions representative for the Belgian Supercontainer design, static and dynamic dissolution tests were performed with depleted and Pu-doped UO2 , simulating medium burn-up UOX fuels of different fuel ages. The experiments were performed under argon atmosphere at 25 – 30°C in cement waters in the pH range 11.7 – 13.5 and at different SA/V ratios. This paper presents the observed UO2 matrix dissolution rates based on the (238U or 233U) release, and proposes a selection of reference dissolution rates for performance assessment. We demonstrate that the dissolution rates at high pH are equivalent to the dissolution rates reported in the literature for neutral pH conditions. The α-activity threshold below which radiolytical fuel oxidation becomes negligible, seems to be close to the threshold reported for anoxic media at neutral pH.

Radionuclides Release Model for Performance Assessment Studies of Spent Nuclear Fuel in Geological Disposal

2004 ◽  
Vol 824 ◽  
Author(s):  
Christophe Poinssot ◽  
Patrick Lovera ◽  
Cécile Ferry
Keyword(s):  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Hydrogen Effect ◽  
Spent Fuel ◽  
Geological Disposal ◽  
The Matrix ◽  
Simple Kinetic Model ◽  
Scientific Results ◽  
Release Model

AbstractIn the framework of the research conducted on the long term evolution of spent nuclear fuel in geological disposal conditions, a source term model has been developed to evaluate the instantaneous release of RN (Instant Release Fraction IRF) and the delayed release of the RN which are embedded within the matrix. This model takes into account all the scientific results currently available in the literature except the hydrogen effect. IRF was assessed by considering the evolution with time of the RN inventories located within the fuel microstructure to which no confinement properties can be allocated on the long term (rim, gap, grain boundaries). It allows to propose some reference bounding values for the IRF as a function of time of canister breaching and burnup. The matrix radiolytic dissolution was modeled by a simple kinetic model neglecting the radiolytic species recombination and the influence of aqueous ligands and radiolytic oxidants were supposed to completely react with the fuel surface. Spent fuel performance was therefore demonstrated to deeply depend on the reactive surface area.

scholarly journals Corroded spent nuclear fuel examined with EELS

1996 ◽  
Vol 54 ◽  
pp. 562-563
Author(s):  
Edgar C. Buck ◽  
Nancy L. Dietz ◽  
John K. Bates
Keyword(s):  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Yucca Mountain ◽  
Radiological Hazard ◽  
Geologic Repository ◽  
Simulated Groundwater ◽  
Long Term Behavior

Direct disposal of spent nuclear fuel (SNF) into the proposed unsaturated geologic repository at Yucca Mountain, NV is being studied at several laboratories, including Argonne National Laboratory. Corrosion tests with SNF are being conducted to understand the long-term behavior of SNF under conditions designed to simulate the unsaturated conditions at the site. The SNF used in this study was the Approved Testing Material (ATM)-106 with a bum-up of 43 MW·d/kg U. A sample of ATM-106 fuel was exposed to dripping simulated groundwater for 271 days; after this time the experiment was terminated and the material removed for further study. Details of the testing methodology have been given by Finn et al.,.Previous attempts to study SNF with TEM have used ion milled samples, in this study we prepared the samples by ultramicrotomy which reduced the radiological hazard substantially.

Effect of alpha irradiation on UO2 surface reactivity in aqueous media

2005 ◽  
Vol 93 (1) ◽  
Author(s):  
Christophe Jégou ◽  
B. Muzeau ◽  
V. Broudic ◽  
A. Poulesquen ◽  
Danièle Roudil ◽  
...  
Keyword(s):  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Aqueous Media ◽  
Surface Reactivity ◽  
Geological Formation ◽  
Interim Storage ◽  
Long Term Behavior ◽  
Alpha Irradiation ◽  
Deep Geological Formation

AbstractThe option of direct disposal of spent nuclear fuel in a deep geological formation raises the need to investigate the long-term behavior of the UOInterim storage in air of UO

scholarly journals Decay heat power of spent nuclear fuel of power reactors with high burnup at long-term storage

2017 ◽  
Vol 153 ◽  
pp. 07035 ◽  
Author(s):  
Mikhail Ternovykh ◽  
Georgy Tikhomirov ◽  
Ivan Saldikov ◽  
Alexander Gerasimov
Keyword(s):  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Heat Power ◽  
Decay Heat ◽  
Long Term Storage ◽  
High Burnup ◽  
Term Storage

scholarly journals Modeling of decay heat removal from CONSTOR RBMK-1500 casks during long-term storage of spent nuclear fuel

Energy ◽  
2019 ◽  
Vol 170 ◽  
pp. 978-985 ◽  
Author(s):  
R. Poškas ◽  
V. Šimonis ◽  
H. Jouhara ◽  
P. Poškas
Keyword(s):  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Heat Removal ◽  
Decay Heat ◽  
Long Term Storage ◽  
Term Storage

Landscape Modeling for Dose Calculations in the Safety Assessment of a Repository for Spent Nuclear Fuel

2007 ◽  
Author(s):  
Tobias Lindborg ◽  
Ulrik Kautsky ◽  
Lars Brydsten
Keyword(s):  
Nuclear Fuel ◽  
Safety Assessment ◽  
Spent Nuclear Fuel ◽  
Landscape Model ◽  
Landscape Development ◽  
Surface Hydrology ◽  
Site Investigations ◽  
Time Period ◽  
The Individual

The Swedish Nuclear Fuel and Waste Management Co., (SKB), pursues site investigations for the final repository for spent nuclear fuel at two sites in the south eastern part of Sweden, the Forsmark- and the Laxemar site (figure 1). Data from the two site investigations are used to build site descriptive models of the areas. These models describe the bedrock and surface system properties important for designing the repository, the environmental impact assessment, and the long-term safety, i.e. up to 100,000 years, in a safety assessment. In this paper we discuss the methodology, and the interim results for, the landscape model, used in the safety assessment to populate the Forsmark site in the numerical dose models. The landscape model is built upon ecosystem types, e.g. a lake or a mire, (Biosphere Objects) that are connected in the landscape via surface hydrology. Each of the objects have a unique set of properties derived from the site description. The objects are identified by flow transport modeling, giving discharge points at the surface for all possible flow paths from the hypothetical repository in the bedrock. The landscape development is followed through time by using long-term processes e.g. shoreline displacement and sedimentation. The final landscape model consists of a number of maps for each chosen time period and a table of properties that describe the individual objects which constitutes the landscape. The results show a landscape that change over time during 20,000 years. The time period used in the model equals the present interglacial and can be used as an analogue for a future interglacial. Historically, the model area was covered by sea, and then gradually changes into a coastal area and, in the future, into a terrestrial inland landscape. Different ecosystem types are present during the landscape development, e.g. sea, lakes, agricultural areas, forest and wetlands (mire). The biosphere objects may switch from one ecosystem type to another during the modeled time period, from sea to lake, and from lake to mire and finally, some objects are transformed into agricultural area due to favorable farming characteristics.

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