In the Proryv project, mixed uranium-plutonium nitride fuel is to be used in the future nuclear power with fast reactors with sodium coolant (BN-1200) and with lead coolant (BREST). At present, ...experimental fuel elements and fuel assemblies with mixed nitride fuel are fabricated by means of a technology developed at the Bochvar All-Russia Research Institute for Inorganic Materials for testing in the BN-600 reactor and the MIR and BOR-60 research reactors. The program of reactor tests of the experimental fuel assemblies and some preliminary results of these tests are presented.
The conceptual principles of a long-term strategy for the development of large-scale nuclear power in Russia based on fast reactors with natural safety and a closed NFC, conservation of the natural ...radioactivity balance for buried wastes, prevention of proliferation of weapons-grade materials, drawing uranium resources fully into energy production and ensuring that the nuclear method of electricity production is competitive are examined. The principal problems of nuclear power are characterized and ways to solve them are proposed. Mathematical models are used to examine scenarios for the development of nuclear power and the transition to a closed NFC.
For future nuclear power with fast reactors with sodium (BN-1200) and lead (BREST) as coolants, plans are being made to use mixed uranium-plutonium nitride fuel as part of the Proryv project. A ...technology for carbothermal synthesis of mixed uranium-plutonium mononitride fuel and fabrication of pellets from it has now been developed. A program of comprehensive computational and experimental research on fuel to study the initial properties and their change under irradiation in reactor experiments is being implemented. Some results of pre-reactor studies of the properties of fuel and a program for future research are presented.
This study presents a version of Water–Water Energy Reactor (WWER) type fuel elements made using inert matrix fuels (IMFs) whose oxide fissile particulates are densely placed throughout a highly ...heat-conductive metal matrix consisting of silumin (cermet fuels). In these WWER-type fuel elements with cermet fuel, the fuel is bonded to cladding in a metallurgic way. It possesses some special features allowing the fuel to be used for both steady-state and load following operation modes. The study presents the results of the analytic study of the two variants of cermet fuel based on UO
2 and UO
2
+
ThO
2. The use of burnable poisons Er
2O
3 and Gd
2O
3 was considered. Characteristics of WWER with UO
2
+
ThO
2 cermet fuel has been compared with those for conventional ceramic uranium dioxide fuel. In-pile testing of UO
2 cermet fuel elements was carried out successfully up to a burnup of ≅60 MW
d
kg
−1 of U. Results of stress calculations have shown fuel element cladding stability for operation in the load following mode.
The KDIGO (Kidney Disease: Improving Global Outcomes) 2012 clinical practice guideline for anemia management in patients with chronic kidney disease provides the structural and evidence base for the ...Canadian Society of Nephrology commentary on this guideline's relevancy and application to the Canadian health care system. While in general agreement, we provide commentary on 11 of the 61 KDIGO guideline statements. Specifically, we agreed that a therapeutic trial of iron is appropriate in cases in which a reduction in erythropoiesis-stimulating agent (ESA) dosage or avoidance of ESA and transfusion is desired, transferrin saturations are >30%, and ferritin concentrations are >500 μg/L. However, we concluded that there is insufficient evidence to support an upper target or threshold for ferritin and transferrin saturation levels. We agree with the initiation of ESA treatment when hemoglobin (Hb) level is 90-100 g/L; however, we specifically state that an acceptable range for Hb level is 95-115 g/L, with a target of 100-110 g/L, and add caution to individualization above this range due to concerns regarding the safety of ESAs. We agree that ESAs should be used with considerable caution in patients with active malignancy, history of stroke, or history of malignancy, and we suggest initiating ESA therapy at Hb level of 90 g/L and to aim for a Hb level in the range of 90-105 g/L. The reader is encouraged to note the level of evidence and review the entire KDIGO anemia guideline to interpret the guideline statements and commentary appropriately.
Background The Oxford classification of immunoglobulin A (IgA) nephropathy (IgAN) provides a histopathologic grading system that is associated with kidney disease outcomes independent of clinical ...features. We evaluated the Oxford IgAN classification in a large cohort of patients from China. Study Design Retrospective study. Setting & Participants 1,026 adults with IgAN from 18 referral centers in China. Inclusion criteria and statistical analysis were similar to the Oxford study. Predictors Histologic findings of mesangial hypercellularity score, endocapillary proliferation, segmental sclerosis or adhesion, crescents, necrosis, and tubular atrophy/interstitial fibrosis. Clinical features, blood pressure, estimated glomerular filtration rate (eGFR), proteinuria, and treatment modalities. Outcomes Time to a 50% reduction in eGFR or end-stage renal disease (the combined event); the rate of eGFR decline (slope of eGFR); proteinuria during follow-up. Results Compared with the Oxford cohort, the Chinese cohort had a lower proportion of patients with mesangial hypercellularity (43%) and endocapillary proliferation (11%), higher proportion with segmental sclerosis or adhesion (83%) and necrosis (15%), and similar proportion with crescents (48%) and tubular atrophy/interstitial fibrosis (moderate, 24%; severe, 3.3%). During a median follow-up of 53 (25th-75th percentile, 36-67) months, 159 (15.5%) patients reached the combined event. Our study showed that patients with a mesangial hypercellularity score higher than 0.5 were associated with a 2.0-fold (95% CI, 1.5-2.8; P <0.001) higher risk of the combined event than patients with a score of 0.5 or lower. Patients with tubular atrophy/interstitial fibrosis of 25%-50% and >50% versus <25% were associated with a 3.7-fold (95% CI, 2.6-5.1; P <0.001) and 15.1-fold (95% CI, 9.5-24.2; P <0.001) higher risk of the combined event, respectively. Endocapillary proliferation, glomerular crescents, and necrosis were not significant. Limitations Retrospective study; the therapeutic interventions were miscellaneous. Conclusions We confirmed the associations of mesangial hypercellularity and tubular atrophy/interstitial fibrosis with kidney disease outcomes.
Background The osmolal gap has been used for decades to screen for exposure to toxic alcohols. However, several issues may affect its reliability. We aimed to develop equations to calculate ...osmolarity with improved performance when used to screen for intoxication to toxic alcohols. Study Design Retrospective cohort study. Setting & Participants 7,525 patients undergoing simultaneous measurements of osmolality, sodium, potassium, urea, glucose, and ethanol or undergoing similar measurements performed within 30 minutes of a measurement of toxic alcohol levels at a single tertiary-care center from April 2001 to June 2016. Patients with detectable toxic alcohols were excluded. Index Test Equations to calculate osmolarity using multiple linear regression. Outcomes The performance of new equations compared with published equations developed to calculate osmolarity, and to diagnose toxic alcohol intoxications more accurately. Results We obtained 7,525 measurements, including 100 with undetectable toxic alcohols. Among them, 3,875 had undetectable and 3,650 had detectable ethanol levels. In the entire cohort, the best equation to calculate osmolarity was 2.006×Na + 1.228×Urea + 1.387×Glucose + 1.207×Ethanol (values in mmol/L, R2 = 0.96). A simplified equation, 2.0×Na + 1.2×Urea + 1.4×Glucose + 1.2×Ethanol, had a similar R2 with 95% of osmolal gap values between −10.9 and 13.8. In patients with undetectable ethanol concentrations, the range of 95% of osmolal gap values was narrower than previous published formulas, and in patients with detectable ethanol concentrations, the range was narrower or similar. We performed a subanalysis of 138 cases for which both the toxic alcohol concentration could be measured and the osmolal gap could be calculated. Our simplified equation had superior diagnostic accuracy for toxic alcohol exposure. Limitations Single center, no external validation, limited number of cases with detectable toxic alcohols. Conclusions In a large cohort, coefficients from regression analyses estimating the contribution of glucose, urea, and ethanol were higher than 1.0. Our simplified formula to precisely calculate osmolarity yielded improved diagnostic accuracy for suspected toxic alcohol exposures than previously published formulas.
The possibilities of burning americium from spent nuclear fuel of thermal reactors in the operating BN-800 are examined. It is shown that because of the small fission cross-section in the neutron ...spectrum of a fast reactor all of the americium cannot be directly converted into fission products. This can be done only by transmutation of americium into plutonium, which must be separated and directed into fuel, where it will burn. In a reactor only 15–20% of the americium is transmuted, and the remaining americium must be returned into the reactor for transmutation. The volume of the recycled americium can be significantly reduced by burning in facilities possessing a moderator (zirconium hydride) and the need for burning it can be eliminated by using plutonium with a high content of the isotope
241
Pu as the fuel of fast reactors, where this isotope fissions efficiently.
Such heavy coolants as lead and a eutectic alloy of lead with bismuth while having favorable thermophysical and technological properties are comparatively corrosive for structure materials and can be ...contaminated by solid impurities during the operation of the system. For systems with heavy coolants to operate for a long period of time, the structural materials which come into contact with the alloy must possess corrosion resistance and the coolant and inner surfaces of the equipment in the loop must have the required purity. As a result of solving these problems, a scientific basis has been developed for handling heavy coolants, new structural materials have been chosen or developed, and methods and devices have been developed for monitoring and regulating coolant quality and for removing impurities from the coolant and surfaces in the loop.PUBLICATION ABSTRACT
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