Conversion of Small Modular Reactors Fuel to Use Mixed (U-Th)O2 Fuel

The concept of Integral Small Modular Reactor (SMR) isn’t new but it seems that the proper time for using this idea has been coming. According to the International Atomic Energy Agency (IAEA), the reactors with electrical power lower than 300 MW have been defined as small reactors, although SMRs are categorized by this fact that more advantages and design features are attained when intentionally make reactors small. In fact, these reactors use their size as advantage to attain more design purposes. The scalability, modularity, improved safety characteristics and more important than other, lower up-front cost of the SMRs, offer great advantages over large common nuclear power plants. According to the IAEA reports there are many interests all over the world to move toward using of these kinds of reactors. There are many different type of SMRs under various stages of design, licensing and construction. Nowadays, there are many initiatives to use thorium in nuclear reactors and fuel cycles. Thorium is three times more abundance than Uranium, however, despite of several initiatives and researches on Th-232 utilization in many types of reactors, this fuel hasn’t been commercialized yet. Most of The SMRs have been designed to have long cycle, so they must use a lot of poisoning material in the beginning of the cycle. Taking in the account that Thorium can be used as a absorber in the beginning of the cycle and also be used as a fertile material during the cycle, it seems to be a good option to use mixed (U-Th)O2 as SMR’s fuel. This paper briefly is going to review the research about Thorium utilization as a nuclear fuel and the possibilities of using mixed (U-Th)O2 fuel as an alternative option for SMRs fuel. The Korean System Integrated Modular Advanced Reactor (SMART) categorized as SMR that has received its standard design approval, was chosen as reference core for our calculations. The calculations have been performed by MCNPX code as a well-known Monte Carlo code. Geometry and all materials were kept the same as the SMART core, and the only variable was the fuel pin material, in which we use several mass proportion of uranium and thorium but keeping the enrichment in U-235, lower than 5 wt%. The results confirm that it’s possible to use mixed (U-Th)O2 with lower burnable absorber at the beginning of the cycle and have a longer burnup cycle

Small modular reactor full scope core optimization using Cuckoo Optimization Algorithm

Small Modular Reactors (SMRs) with their excellent safety and economic features will be in high demand in the near future. Most SMR designs have longer burn-up cycle length with more fuel enrichment and smaller core size in comparison to the large conventional nuclear reactors. The small size of these reactors causes more neutron leakage (less core radius results in a higher area to volume ratio and more relative leakage). This feature of SMRs causes high values of maximum Power Peaking Factors (PPFs) through the core, so optimizing the safety parameters is of high necessity. Also, long burn-up cycle length needs a high initial excess reactivity, which results into use of some materials and methods to control this high excess reactivity. One of these methods is using a high number of Integral Fuel Burnable Absorber (IFBA) rods.In the present designs of IFBA rods, usually some amounts of fuel with lower enrichment are used at the top and bottom parts of the IFBA rods (known as cutback fuel) to flatten the axial PPFs. The small size of the SMRs (using a lower number of FAs) helps to have much less possible radial loading patterns (in comparison to the large reactors) and provides the possibility to optimize the axial variations in amounts of cutback fuel in IFBA rods simultaneously. Accordingly, the best axial and radial loading pattern according to the objective functions could be achieved. At the present work, the main goal is to optimize radial core loading pattern and axial variations of cutback fuel lengths at the IFBA rods of an SMR simultaneously using a multi-objective neutronic and thermal-hydraulic fitness function. The multi-objective fitness function includes burn-up cycle length, Minimum Departure from Nucleate Boiling (MDNBR), maximum and average radial and axial PPFs during the entire cycle lengths. The Cuckoo Optimization Algorithm (COA) as a new robust metaheuristic algorithm with high convergence speed and global optima achievement has been used. For the thermo-neutronic calculation, DRPACO package consists of the coupling system of DRAGON/ PARCS/COBRA codes have been used. Finally, the results of SMR core axial and radial loading pattern optimization using COA presents a core configuration with improvement in the core safety and economic parameters in comparison to the reference SMR cor

General rules for bosonic bunching in multimode interferometers

We perform a comprehensive set of experiments that characterize bosonic bunching of up to 3 photons in interferometers of up to 16 modes. Our experiments verify two rules that govern bosonic bunching. The first rule, obtained recently in [1,2], predicts the average behavior of the bunching probability and is known as the bosonic birthday paradox. The second rule is new, and establishes a n!-factor quantum enhancement for the probability that all n bosons bunch in a single output mode, with respect to the case of distinguishable bosons. Besides its fundamental importance in phenomena such as Bose-Einstein condensation, bosonic bunching can be exploited in applications such as linear optical quantum computing and quantum-enhanced metrology.Comment: 6 pages, 4 figures, and supplementary material (4 pages, 1 figure

Phospholipid hydroperoxide glutathione peroxidase is the 18-kDa selenoprotein expressed in human tumor cell lines.

Human tumor cell lines cultured in 75Se-containing media demonstrate four major 75Se-labeled cellular proteins (57, 22, 18, and 12 kDa) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Among these selenoproteins, an enzymatic activity is known only for the 22-kDa protein, since this protein has been identified as the monomer of glutathione peroxidase. However, all tested cell lines also contained a peroxidase activity with phospholipid hydroperoxides that is completely accounted for by the other selenoenzyme, phospholipid hydroperoxide glutathione peroxidase (PHGPX) (Ursini, F., Maiorino, M., and Gregolin, C. (1985) Biochim. Biophys. Acta 839, 62-70). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography of 75Se-labeled proteins separated by gel permeation chromatography supported the identification of PHGPX as the monomeric protein matching the 18 kDa band. This paper is the first report on the identification of PHGPX in human cells

A MoU to create a COnsortium of Academics from Universities promoting the use of THORrium (COAUTHOR)

Nuclear Energy, primarily to produce electricity and other use, and the enveloping Nuclear Technology, as inherited from the XX Century, constitutes a controversial issue for political and economic reasons. On the one hand, the energy source is promoted in several Countries and an unavoidable mean to ensure growth for the human civilization ad suitable living standard with reduced or no impact upon the environment, on the other hand it is abandoned or going to be abandoned in other Countries which did benefit of stable economic growth. Thorium is an emblem for such a situation: huge reserves are available all over the world (primarily India, Turkey, and Brazil, but not only) and its technological worth for exploitation in current generation of thermal fission reactors is demonstrated, on the other hand no industrial use is ongoing or planned for the near future (with an exception constituted by situation in India). Moreover, research on thorium utilization in nuclear reactors and associated fuel cycles has been of academic interest for many researchers around the world. These researches are being conducted to increase the natural resource utilization, reduces the radiotoxicity, and other criteria of sustainability, by using thorium in the present time advanced reactors (Generation III), as well for the future Generation IV, mainly in Molten Salt Reactors (MSR) and in hybrid fusion/ accelerators driven system. Here we are going to describe a MoU signed by the authors to promote the utilization of thorium as nuclear fuel, and shortly describe the research activities conducted by the MoU partners

COAUTHOR - a MoU to create a COnsortium of Academics from Universities promoting the use of THORium

This paper describes the Memorandum of Understanding (MoU) signed by the authors to create a future consortium of academics from universities to promote the utilization of thorium (COAUTHOR). Besides the description of the MoU, also results of the research conducted in each participating partner or collaborative work performed among them will be described. Finally, the future work planned in the framework of the MoU, will be discussed

Selenoprotein gene nomenclature

The human genome contains 25 genes coding for selenocysteine-containing proteins (selenoproteins). These proteins are involved in a variety of functions, most notably redox homeostasis. Selenoprotein enzymes with known functions are designated according to these functions: TXNRD1, TXNRD2, and TXNRD3 (thioredoxin reductases), GPX1, GPX2, GPX3, GPX4 and GPX6 (glutathione peroxidases), DIO1, DIO2, and DIO3 (iodothyronine deiodinases), MSRB1 (methionine-R-sulfoxide reductase 1) and SEPHS2 (selenophosphate synthetase 2). Selenoproteins without known functions have traditionally been denoted by SEL or SEP symbols. However, these symbols are sometimes ambiguous and conflict with the approved nomenclature for several other genes. Therefore, there is a need to implement a rational and coherent nomenclature system for selenoprotein-encoding genes. Our solution is to use the root symbol SELENO followed by a letter. This nomenclature applies to SELENOF (selenoprotein F, the 15 kDa selenoprotein, SEP15), SELENOH (selenoprotein H, SELH, C11orf31), SELENOI (selenoprotein I, SELI, EPT1), SELENOK (selenoprotein K, SELK), SELENOM (selenoprotein M, SELM), SELENON (selenoprotein N, SEPN1, SELN), SELENOO (selenoprotein O, SELO), SELENOP (selenoprotein P, SeP, SEPP1, SELP), SELENOS (selenoprotein S, SELS, SEPS1, VIMP), SELENOT (selenoprotein T, SELT), SELENOV (selenoprotein V, SELV) and SELENOW (selenoprotein W, SELW, SEPW1). This system, approved by the HUGO Gene Nomenclature Committee, also resolves conflicting, missing and ambiguous designations for selenoprotein genes and is applicable to selenoproteins across vertebrates