scholarly journals FORK EXPERIMENTS IN THE HOT CELL USING SPENT FUEL RODS FOR INTERNATIONAL NUCLEAR SAFEGUARDS

2021 ◽  
Author(s):  
Jianwei Hu ◽  
Robert Mcelroy Jr ◽  
Andrew Nicholson ◽  
Stephen Croft
Keyword(s):  
Nuclear Safeguards ◽  
Spent Fuel ◽  
Fuel Rods

scholarly journals Quantitative imaging and automated fuel pin identification for passive gamma emission tomography

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ming Fang ◽  
Yoann Altmann ◽  
Daniele Della Latta ◽  
Massimiliano Salvatori ◽  
Angela Di Fulvio
Keyword(s):  
Inverse Problem ◽  
Image Reconstruction ◽  
Image Resolution ◽  
Emission Tomography ◽  
Nuclear Safeguards ◽  
Activity Levels ◽  
Spent Fuel ◽  
Gamma Emission ◽  
Cross Sectional ◽  
Fuel Rods

AbstractCompliance of member States to the Treaty on the Non-Proliferation of Nuclear Weapons is monitored through nuclear safeguards. The Passive Gamma Emission Tomography (PGET) system is a novel instrument developed within the framework of the International Atomic Energy Agency (IAEA) project JNT 1510, which included the European Commission, Finland, Hungary and Sweden. The PGET is used for the verification of spent nuclear fuel stored in water pools. Advanced image reconstruction techniques are crucial for obtaining high-quality cross-sectional images of the spent-fuel bundle to allow inspectors of the IAEA to monitor nuclear material and promptly identify its diversion. In this work, we have developed a software suite to accurately reconstruct the spent-fuel cross sectional image, automatically identify present fuel rods, and estimate their activity. Unique image reconstruction challenges are posed by the measurement of spent fuel, due to its high activity and the self-attenuation. While the former is mitigated by detector physical collimation, we implemented a linear forward model to model the detector responses to the fuel rods inside the PGET, to account for the latter. The image reconstruction is performed by solving a regularized linear inverse problem using the fast-iterative shrinkage-thresholding algorithm. We have also implemented the traditional filtered back projection (FBP) method based on the inverse Radon transform for comparison and applied both methods to reconstruct images of simulated mockup fuel assemblies. Higher image resolution and fewer reconstruction artifacts were obtained with the inverse-problem approach, with the mean-square-error reduced by 50%, and the structural-similarity improved by 200%. We then used a convolutional neural network (CNN) to automatically identify the bundle type and extract the pin locations from the images; the estimated activity levels finally being compared with the ground truth. The proposed computational methods accurately estimated the activity levels of the present pins, with an associated uncertainty of approximately 5%.

scholarly journals DEVELOPMENT OF A MODELING APPROACH TO ESTIMATE RADIATION FROM A SPENT FUEL ROD QUIVER

2021 ◽  
Vol 247 ◽  
pp. 16006
Author(s):  
Zs. Elter ◽  
V. Mishra ◽  
S. Grape ◽  
E. Branger ◽  
P. Jansson ◽  
...  
Keyword(s):  
Gamma Radiation ◽  
Spent Nuclear Fuel ◽  
Radiation Transport ◽  
Neutron Radiation ◽  
Nuclear Safeguards ◽  
Monte Carlo Code ◽  
Spent Fuel ◽  
Fuel Rods ◽  
History Of ◽  
New Type

Before encapsulation of spent nuclear fuel in a geological repository, the fuels need to be verified for safeguards purposes. This requirement applies to all spent fuel assemblies, including those with properties or designs that are especially challenging to verify. One such example are quivers, a new type of containers used to hold damaged spent fuel rods. After placing damaged rods inside the quivers, they are sealed with a thick lid and the water is removed. The lid is thick enough to significantly reduce the amount of the gamma radiation penetrating through it, which can make safeguards verification from the top using gamma techniques difficult. Considering that the number of quivers at storage facilities is foreseen to increase in near future, studying the feasibility of verification is timely. In this paper we make a feasibility study related to safeguards verification of quivers, aimed at investigating the gamma and neutron radiation field around a quiver designed by Westinghouse AB and filled with PWR fuel rods irradiated at the Swedish Ringhals site. A simplified geometry of the quiver and the detailed operational history of each rod are provided by Westinghouse and the reactor operator, respectively. The nuclide inventory of the rods placed in the quiver and the emission source terms are calculated with ORIGEN-ARP. The radiation transport is modeled with the Serpent2 Monte Carlo code. The first objective is to assess the capability of the spent fuel attribute tester (SFAT) to verify the content for nuclear safeguards purposes. The results show that the thick quiver lid attenuates the gamma radiation, thereby making gamma radiation based verification from above the quiver difficult.

scholarly journals Experimental Approaches for Manufacturing of Simulated Cladding and Simulated Fuel Rod for Mechanical Decladder

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Young-Hwan Kim ◽  
Yung-Zun Cho ◽  
Jin-Mok Hur
Keyword(s):  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Spent Fuel ◽  
Energy Research ◽  
Fuel Rods ◽  
Fuel Rod ◽  
Compressive Stresses ◽  
Simulated Fuel ◽  
Ceramic Fuel ◽  
Experimental Approaches

We are developing a practical-scale mechanical decladder that can slit nuclear spent fuel rod-cuts (hulls + pellets) on the order of several tens of kgf of heavy metal/batch to supply UO2 pellets to a voloxidation process. The mechanical decladder is used for separating and recovering nuclear fuel material from the cladding tube by horizontally slitting the cladding tube of a fuel rod. The Korea Atomic Energy Research Institute (KAERI) is improving the performance of the mechanical decladder to increase the recovery rate of pellets from spent fuel rods. However, because actual nuclear spent fuel is dangerously toxic, we need to develop simulated spent fuel rods for continuous experiments with mechanical decladders. We describe procedures to develop both simulated cladding tubes and simulated fuel rod (with physical properties similar to those of spent nuclear fuel). Performance tests were carried out to evaluate the decladding ability of the mechanical decladder using two types of simulated fuel (simulated tube + brass pellets and zircaloy-4 tube + simulated ceramic fuel rod). The simulated tube was developed for analyzing the slitting characteristics of the cross section of the spent fuel cladding tube. Simulated ceramic fuel rod (with mechanical properties similar to the pellets of actual PWR spent fuel) was produced to ensure that the mechanical decladder could slit real PWR spent fuel. We used castable powder pellets that simulate the compressive stress of the real spent UO2 pellet. The production criteria for simulated pellets with compressive stresses similar to those of actual spent fuel were determined, and the castables were inserted into zircaloy-4 tubes and sintered to produce the simulated fuel rod. To investigate the slitting characteristics of the simulated ceramic fuel rod, a verification experiment was performed using a mechanical decladder.

Dry Storage of Spent Research Reactor Fuel in Castor BR3® Casks at Belgoprocess in Belgium

2001 ◽  
Author(s):  
Marnix Braeckeveldt ◽  
Luc Ooms ◽  
Gustaaf Geenen
Keyword(s):  
Radioactive Waste ◽  
Nuclear Research ◽  
High Level Waste ◽  
Spent Fuel ◽  
Fuel Rods ◽  
Dry Storage ◽  
Nuclear Site ◽  
Test Reactor ◽  
Intermediate Storage ◽  
High Level

Abstract The BR3 reactor (10.5 MWe) at the Nuclear Research Center SCK•CEN was the first PWR plant installed in Europe and has been shut down in 1987. The BR3 reactor is from 1989 in a decommissioning stage and most of the spent fuel is presently still stored in the deactivation pool of the BR3 plant and has to be evacuated. The BR3 was used as a test-reactor for new fuel types and assemblies (Mixed Oxide (MOX) fuel, fuel rods containing burnable poison (Gd2O3) and other types of fuels). Some fuel rods, having undergone a destructive analysis, are stored in different laboratories at the SCK•CEN. In total, the BR3 spent fuel comprises the equivalent of almost 200 fuel assemblies corresponding to some 5000 fuel rods. Beside the spent BR3 fuel, a limited number of spent fuel rods, with equivalent characteristics as the BR3 fuel but irradiated in research reactors outside Belgium and stored in other buildings at the SCK•CEN nuclear site, were added to the inventory of spent fuel to be evacuated. Various options such as reprocessing and intermediate storage awaiting final disposal were evaluated against criteria as available techniques, safety, waste production and overall costs. Finally the option of an AFR (away-from-reactor) intermediate dry storage of the BR3 and other spent fuel in seven CASTOR BR3® casks was adopted. As the SCK•CEN declared this spent fuel as radioactive waste, NIRAS/ONDRAF, the Belgian radioactive waste management agency became directly involved and the decision was taken to construct a small building at the Belgoprocess nuclear site for storing the CASTOR BR3® casks. Loading at the SCK•CEN followed by transport to Belgoprocess and storage is scheduled to take place at the end of 2001. The CASTOR BR3® cask weighing some 25 tonnes, consists of a monolithic body and has two independent lids with metal seals guaranteeing the long term leak-tightness of the cask. The CASTOR BR3® cask is designed for transport and the intermediate storage of at least 50 years. Although a defect of the leaktightness of a CASTOR BR3® cask is very unlikely to occur, an intervention scenario had to be developed. As no pool is present at the Belgoprocess nuclear site to unload the fuel, an innovative procedure is developed that consists of transferring the basket, containing the spent fuel, into another CASTOR BR3® cask. This operation can be performed in the hot cell of the existing storage building for high level waste at the Belgoprocess site.

Nuclear Waste

2014 ◽  
Author(s):  
Michael H. Fox
Keyword(s):  
Nuclear Power ◽  
Nuclear Reactor ◽  
Spent Nuclear Fuel ◽  
Nuclear Fission ◽  
Spent Fuel ◽  
Fuel Rods ◽  
Fuel Pellets ◽  
Water Filling ◽  
Nuclear Fuel Waste ◽  
Ranch House

I gazed over the railing into the crystal clear cooling pool glowing with blue Cherenkov light caused by particulate radiation traveling faster than the speed of light in water. I can see a matrix of square objects through the water, filling more than half of the pool. It looks like you could take a quick dip into the water, like an indoor swimming pool, but that would not be a good idea! It is amazing to think that this pool, about the size of a ranch house, is holding all of the spent fuel from powering the Wolf Creek nuclear reactor in Burlington, Kansas, for 27 years. The reactor was just refueled about a month before my visit, so 80 of the used fuel rod assemblies were removed from the reactor and replaced with new ones. The used fuel rods were moved underwater into the cooling pool, joining the approximately 1,500 already there. There is sufficient space for the next 15 years of reactor operation. There is no danger from standing at the edge of this pool looking in, though the levels of radon tend to be somewhat elevated and may electrostatically attach to my hard hat, as indeed some did. What I am gazing at is what has stirred much of the controversy over nuclear power and is what must ultimately be dealt with if nuclear power is to grow in the future—the spent nuclear fuel waste associated with nuclear power. What is the hidden danger that I am staring at? Am I looking at the unleashed power of Hephaestus, the mythical Greek god of fi re and metallurgy? Or is this a more benign product of energy production that can be managed safely? What exactly is in this waste? And is it really waste, or is it a resource? To answer that question, we have to understand the fuel that reactors burn. The fuel rods that provide the heat from nuclear fission in a nuclear reactor contain fuel pellets of uranium, an element that has an atomic number of 92 (the number of protons and also the number of electrons).

Revised Eh-pH Diagrams (25 C, One Bar) for Uranium and Transuranic Elements: Application to Radioactive Waste Studies

1988 ◽  
Vol 125 ◽  
Author(s):  
D. G. Brookins
Keyword(s):  
Radioactive Waste ◽  
Spent Fuel ◽  
Radionuclide Migration ◽  
Fuel Rods ◽  
Major Phase ◽  
Geochemical Behavior ◽  
Wide Range ◽  
Carbonate Complexes ◽  
Generic System ◽  
Very High

ABSTRACTEh-pH diagrams are useful for comparing the probable geochemical behavior of many elements including U and the transuranics Np, Pu, Am. Revised Eh-pH diagrams have been constructed for U, Np, Pu and Am at 25 C, 1 bar conditions. These diagrams, based on new and revised thermodynamic data, include aqueous and solid species in the generic system M-C-O-H. The species M(OH)− is considered herein, although it's existence has not been verified.Aqueous U(VI) species are dominated by below pH 5 and by carbonate complexes at higher pH. U(IV) species include important fields of UO2, and U(OH)4. If Si is present, USiO4 may be important. U3O8, occurs between the U(IV) and U(VI) species.Np(IV) solid species are problematic. NpO2 covers a wide range of Eh-pH, but its precursors, NpO. (OH)2 and Np(OH)4 cover more restrictive Eh-pH ranges with more important. This increases potential for radionuclide migration. Np(V, VI) carbonate complexes are important only at high Eh.Pu(IV) species are dominated by PuO2, but Pu(OH)4 does not occupy as much Eh-pH space, being replaced in large part by . With carbonate present, Pu(III) species also replace part of the Pu(OH)4 field, and Pu2 (CO3)3 becomes important. Pu(VI) carbonate complexess occur only at high Eh.Am(III) species dominate Eh-pH space in the system Am-C-O-H, with Am2 (CO3)3 a major phase. Under carbonate-poor conditions, Am(OH) 3 is important. AmO2 occurs at high Eh, pH, and at high Eh and very high pH.The importance of the M(OH)4 precursors to MO2 species is the enhanced possibility of radionuclide migration from buried spent fuel rods, even under reducing condtions.

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