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Accident Tolerant Fuels (ATF) have emerged as a promising solution to improve safety during reactor accidents by enhancing fuel performance in light water reactors (LWRs). This paper investigates the performance of different ATF concepts, including Chromium-coated Zircaloy (CrZry), advanced steel (FeCrAl), and Silicon Carbide (SiC) as cladding materials, paired with Uranium Dioxide (UO 2 ), Uranium Silicide (U 3 Si 2 ), and Uranium Nitride (UN) fuels, under spectrum shift regulation conditions in a VVER-S reactor. Using the GETERA program, a series of calculations were conducted to compare multiplying factors and isotopic concentrations under spectrum-shifted conditions. The results demonstrate significant differences in fuel cycle characteristics and isotopic behavior, with SiC emerging as the optimal cladding material for maximizing neutron economy and minimizing parasitic absorption.

A solution for the nuclear waste problem is the key challenge for an extensive use of nuclear reactors as a major carbon free, sustainable, and applied highly reliable energy source. Partitioning and Transmutation (P&T) promises a solution for improved waste management. Current strategies rely on systems designed in the 60's for the massive production of plutonium. We propose an innovative strategic development plan based on invention and innovation described with the concept of developments in s-curves identifying the current boundary conditions, and the evolvable objectives. This leads to the ultimate, universal vision for energy production characterized by minimal use of resources and production of waste, while being economically affordable and safe, secure and reliable in operation. This vision is transformed into a mission for a disruptive development of the future nuclear energy system operated by burning of existing spent nuclear fuel (SNF) without prior reprocessing. This highly innovative approach fulfils the sustainability goals and creates new options for P&T. A proof on the feasibility from neutronic point of view is given demonstrating sufficient breeding of fissile material from the inserted SNF. The system does neither require new resources nor produce additional waste, thus it provides a highly sustainable option for a future nuclear system fulfilling the requests of P&T as side effect. In addition, this nuclear system provides enhanced resistance against misuse of Pu and a significantly reduced fuel cycle. However, the new system requires a demand driven rethinking of the separation process to be efficient.

Fast reactors can be used to adjust the isotopic composition of plutonium from spent mixed uranium-plutonium fuel from PWR and make it recyclable. The efficacy of such an adjustment is directly related to the scope for breeding in fast reactors. This can be done in the operating BN-800 reactor by multiple recycling of plutonium in the fuel of the fast reactor as well as by using 235U or in specialized (target) fuel assemblies with reduced plutonium content. The international project with the use of BN-800 will make it possible to experimentally demonstrate this possibility on representative batches of plutonium (up to 100 kg/yr) as well as to work out the particularities of international and national laws in the field of accounting and moving of nuclear materials. A commercially significant project (with a turnover of 1 t or more of plutonium per year) to adjust the plutonium composition can be planned when a series of commercial high-power fast reactors with a heightened breeding ratio is put into operation.

Studies of health effects in animals after exposure to internally deposited radionuclides were intended to supplement observational studies in humans. Both nuclear workers and Beagle dogs have exhibited plutonium-associated lung fibrosis; however, the dogs' smaller gene pool may limit the applicability of findings to humans. Data on Beagles that inhaled either plutonium-238 dioxide (238PuO2) or plutonium-239 dioxide (239PuO2) were analyzed. Wright's Coefficient of Inbreeding was used to measure genetic or familial susceptibility and was assessed as an explanatory variable when modeling the association between lung fibrosis incidence and plutonium exposure. Lung fibrosis was diagnosed in approximately 80% of the exposed dogs compared with 23.7% of the control dogs. The maximum degree of inbreeding was 9.4%. Regardless of isotope, the addition of inbreeding significantly improved the model in female dogs but not in males. In female dogs, an increased inbreeding coefficient predicted decreased hazard of a lung fibrosis diagnosis. Lung fibrosis was common in these dogs with inbreeding affecting models of lung fibrosis incidence in females but not in males. The apparent protective effect in females predicted by these models of lung fibrosis incidence is likely to be minimal given the small degree of inbreeding in these groups.

The early life history of girellid fishes in Japanese waters is unclear, and little is known about their species-specific reproductive strategies. We examined seasonal changes of distribution patterns for settlement-stage juveniles of Girella punctata and Girella leonina on the rocky shore in the regions of Kanto and Izu, Japan, to infer the influence of the Kuroshio Current on their reproduction. We collected 813 settlement-stage juveniles mainly in Sagami Bay and genetically identified the species. The juveniles of G. punctata were collected on the rocky shore in Sagami Bay during April to August, with the abundant catch in May and June. Thus, we infer that juvenile G. punctata ubiquitously inhabit the rocky shore in the area in spring and summer. By contrast, juveniles of G. leonina were rarely collected in Sagami Bay, with a total catch of only 66. Notably, no juveniles were collected during the wintertime in Sagami Bay, although an abundant catch of G. leonina had been previously reported for Sagami Nada off Sagami Bay during January to March. This clear-cut difference between the areas likely reflects the difference in proximity to the path of the Kuroshio Current. We expect that the Kuroshio Current strongly influences the reproductive success of G. leonina.

In the present investigation, a fusion–fission hybrid reactor system was designed by using 9Cr2WVTa ferritic steel structural material and 99–95 % Li 20 Sn 80 -1–5 % SFG-Pu, 99–95 % Li 20 Sn 80 -1–5 % SFG-PuF 4 , 99–95 % Li 20 Sn 80 -1–5 % SFG-PuO 2 the molten salt-heavy metal mixtures, as fluids. The fluids were used in the liquid first wall, blanket and shield zones of a fusion–fission hybrid reactor system. Beryllium zone with the width of 3 cm was used for the neutron multiplicity between liquid first wall and blanket. The contributions of each isotope in fluids on the nuclear parameters of a fusion–fission hybrid reactor such as tritium breeding ratio, energy multiplication factor, heat deposition rate were computed in liquid first wall, blanket and shield zones. Three-dimensional analyses were performed by using Monte Carlo code MCNPX-2.7.0 and nuclear data library ENDF/B-VII.0.

In this study, the improvement of neutronic performance of a dual purpose modified PACER concept has been investigated. Flibe as the main constituent are fixed as 92% coolant. ThF 4 is mixed with increased mole-fractions of RG-PuF 4 starting by 0 mol % up to 1 mol %. TBR variations for all the investigated salts with respect to the RG-PuF 4 contents are computed. Tritium self-sufficiency is provided with the ThF 4 when the adding RG-PuF 4 content is higher than 0.75%. The energy multiplication of the blanket is increased as 70% with adding RG-PuF 4 contents to ThF 4 . High quality fissile isotope 233 U are produced with increasing RG-PuF 4 . DPA and helium production increases with increased RG-PuF 4 content in molten salt. Radiation damage with dpa <1.7 and He <3.3 ppm after a plant operation period of 30 years will be well below the damage limit values.

The paper brings out the advantages of fast breeder reactor and importance of developing closed nuclear fuel cycle for the large scale energy production, which is followed by its salient safety features. Further, the current status and future strategy of the fast reactor programme since the inception through 40 MWt/13 MWe Fast Breeder Test Reactor (FBTR), is highlighted. The challenges and achievements in science and technology of FBRs focusing on safety are described with the particular reference to 500 MWe capacity Prototype Fast Breeder Reactor (PFBR), being commissioned at Kalpakkam. Roadmap with comprehensive R&D for the large scale deployment of Sodium Cooled Fast Reactor (SFRs) and timely introduction of metallic fuel reactors with emphasis on breeding gain and enhanced safety are being brought out in this paper.

In the context of India's three-stage nuclear power programme, there have been a number of recent submissions emphasizing the disadvantages of using thorium in fast breeder reactors (FBRs), and implying that thorium utilization should be through thermal reactors in the third stage. In this article, it is pointed out that the advantages of using thorium in fast reactors far outweigh the perceived disadvantages, which are anyway common for the thermal reactors also. Therefore, we advocate a strategy that ensures both growth and sustainability in nuclear electricity generation through a symbiotic combination of Pu/²³⁸U FBRs and Pu/²³⁸U FBRs with thorium radial blankets early enough in the second stage, and using the ²³³U so produced to set up ²³³U/Th FBRs along with thermal reactors (breeders or advanced converters), which will then become the mainstay of the third stage. The key concept is to avoid a sequential mind-set and have proper blend and gradual merging of the stages.

In recent years, a great deal has been written and discussed about the need for the US to develop sustainable sources of energy that do not pollute the air or water. Although the concept of sustainable energy is a hot-button issue today, attempts to develop such technologies are not new. In 1943, physicist Leo Szilard suggested it might be possible to construct a nuclear reactor that would create or breed fuel, producing an inexhaustible supply of energy. The concept became so compelling that the federal government would vigorously pursue it for the next forty years, with the ultimate goal of having the nation's electricity generated largely by breeder reactors. The purpose of this article is to briefly chronicle major developments in the history of the breeder reactor in the US. It is a history of peaks and valleys, where the federal government attempted to rapidly develop a technology based on what turned out to be a set of erroneous assumptions.