Journal Issue: Nuclear Energy and Technology
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Volume
10
Number
3
Issue Date
Journal Title
Journal ISSN
2452-3038
Том журнала
Том журнала
Статьи
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Particle emission from irradiated VVER-1200 fuel with Am burnable absorber
(2024) Veretennikov, D. G.; Ali, A. H.; Bedenko, S. V.
For long-term and safe operation of the reactor, nuclear fuel is modified by doping with various homogeneous compounds and heterogeneous inclusions. Such modified fuel has demonstrated satisfactory performance when irradiated at elevated temperatures and high burnup. However, the issues of radiation safety when handling modified fuel remain less studied. Elements of low and medium atomic mass are often targets for (α, n) reactions, so their use as alloying additives, as well as the use of α-emitting additives, can complicate the radiation situation at the stages of the nuclear fuel cycle. In this work, the neutron components of the radiation characteristics of UO2 with Gd2O3 and AmO2 additives were analyzed. Americium has been investigated as a possible alternative to gadolinium. In fuel containing AmO2, the neutron yield is higher compared to Am-free fuel and is formed mainly by (α, n) reactions in AmO2 in fresh fuel and spontaneous fission of 244Cm nuclides in spent fuel. The research was carried out with the aim of developing procedures and regulations for handling new fuel during its manufacture and after irradiation in the reactor. This work contributes to the study of the neutronic and radiation characteristics of Am-containing fuel, which has the potential for use in modern reactors. Calculations were performed using verified computational codes SOURCES-4C and WIMS-D5B.
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Neutronic evaluation of VVER fuel assembly with chemical spectral shift regulation
(2024) Ashraf, O.; El-Kholy, A. H.; Elzayat, T.; Abdalla, A. M.; Ashry, A. H.
he performance of the spectral shift control (SSC) method is evaluated and compared to the conventional poison method in the VVER-1000 fuel assembly design. The SSC method can be implemented by gradually adjusting the ratio of heavy water to light water moderator (D2O/H2O) during the fuel cycle. In this study, the efficiency of using the SSC design with or without a thermal absorber (gadolinium) is investigated. We apply the SSC with both 12 burnable absorber rods containing 4.0 wt.% Gd2O3 (Case 1) and without Gd2O3 (Case 2). The neutronic calculations indicate that the discharge burnup is enhanced by 60% and the conversion ratio (CR) is increased by 64.4% at the beginning of the cycle (BOC) compared to the benchmark data. The breeding of Pu239 and Pu241 is extended to 33.7% and 29.5%, respectively, for the SSC design case (2), and better utilization of U-235 and U-238 has been achieved compared to BM.
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Conducting in-reactor studies of objects the length of which exceeds the height of the IVV-2M reactor core
(2024) Russkikh, I. M.; Seleznev, E. N.; Zyryanova, A. A.; Kotelnikov, N. A.; Tashlykov, O. L.
When solving several research problems, the need arises for reactor testing of non-standard objects. The IVV-2M reactor is a pool, heterogeneous, light-water reactor. The 500 mm-high reactor core comprises six sections of six fuel assemblies (FA) with central water traps and a water trap in the center of the core. The personnel of INM JSC were tasked with testing an object whose length exceeded the height of the IVV-2M reactor core. A non-standard core layout was developed with six sections of seven fuel assemblies to accomplish this task.. The test object is located in the center of the core, surrounded by special aluminum blocks. Several fuel assemblies are installed on special supports, which allow the fuel assemblies to be installed 200 mm higher. Shim rods have been moved to the center of the sections. The safety of the developed arrangement was confirmed by neutron-physical calculations using the certified MCU-PTR software tool. Calculations have shown that the maximum maximum power in the fuel assembly is 236 kW, which is 50% less than the permissible value. To confirm the safety of the layout and ensure the required test conditions, tests of a mock-up of the object were carried out. The efficiency of the control members was experimentally determined. The overall efficiency of the control members was 4.85% ∆k/k, the physical weight of the object was 1.46% ∆k/k. Based on the requirements of the Nuclear Safety Rules for Research Reactors, the test duration is no more than three days. The distribution of neutron flux density over the height of the core was determined using indium neutron activation detectors. The developed design solutions made it possible to form a unique IVV-2M reactor core layout for testing objects exceeding its height.. Neutron-physical calculations and tests of the irradiated device mock-up confirmed the safety and performance of this core arrangement.
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Analyzing (Th-233U-235U)O2 fuel performance in various assembly configurations: A comparative neutronic study
(2024) Banni, F. E.; Gogon, B. L.; Kabach, O.; Chakir, E. M.
This article investigates alternate fuel options for Pressurized Water Reactors (PWRs), focusing on thorium use to address safety, efficiency, and waste issues associated with standard UO2 fuel. Challenges in thorium utilization, such as the lack of a fissile isotope, are handled using approaches such as homogeneous mixtures and heterogeneous arrangements, promoting the exploration of (Th-233U-235U)O2 fuel in various assembly configurations. According to recent research, the annular dual-cooled assembly design has promising results in terms of fuel efficiency and safety while lowering the requirement for higher fissile enrichment levels. Studies additionally demonstrate that annular dual-cooled duplex fuel configurations can produce higher discharge burnup and lower power peaking factors than traditional UO2 fuel. The purpose of this work is to analyze and compare the performance of (Th-233U-235U)O2 fuel in various configurations against conventional UO2 fuel, focusing on key characteristics such as reactivity change, criticality, discharge burnups, and reactivity feedback coefficients.
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Monitoring of the radioactivity in the marine environment: a White Paper - Part I
(2024) Lagaki, V.; Siltzovalis, G.; Madesis, I.; Vasileiou, P.; Mertzimekis, T. J.
Radioactivity in the marine environment, although present since the Earth’s formation, is comparatively understudied in contrast to aerial and terrestrial environments. A thorough examination of the radioactivity levels in aquatic environments can establish a robust foundation for comprehending various geochemical processes and phenomena within the water column and near the seabed, and as a result estimate the impact of radioactivity on local ecosystems. To achieve this objective, in-situ, long-term, and continuous monitoring is required. The present part I of the white paper highlights the fundamentals of marine radioactivity, describes the main objectives of an ambitious EU-funded project (RAMONES: Radioactivity Monitoring in Ocean Ecosystems) and introduces the innovative aspects of the technology developed as novel solutions to open problems.