Modernization of the Target Design for Molybdenum Production

The following work is a comparative analysis of two target designs for Molybdenum-99 production. Important parameters for their usage are their thermal-hydraulic properties. The considered target designs can be used in a research reactor of basin type. The research channel, where the target is being installed, does not possess high static pressure; therefore, the target should not cause the coolant boiling during operation. The more fissile material in the target, the higher the expected isotope producing and at the same time the energy release. The main task of construction modernization of the target is to increase the production of the necessary radioisotope in the normal removal of heat from the walls of the target sleeve. Comparative analysis is carried out for targets of the cylindrical type

Investigation of Check Valve Aerodynamic Characteristics in Different Operating Modes

The paper presents a computational study of the NPP ventilation system check valve aerodynamics, namely, a numerical simulation of the air flowing through the open valve with the subsequent determination of the relationship between the reactive torque acting on the valve closure axles and the input air velocity.This numerical simulation of the air flowing through the check valve was performed using the ANSYS CFX program. In the computation, different operating modes of the check valve were considered when the air flow was passing through it. The valve operating modes were set depending on changes in the input air velocity. As a result of aerodynamic computation, the values of pressure and velocity components were obtained over the entire valve volume.Reactive forces were calculated in the ANSYS Mechanical program. The reactive forces acting on the valve body form a torque at the gate axles. When adjusting the check valve to the actual flow rate, it is necessary to know this torque value and compensate for it. As a result of a series of computations of reactive forces, a relationship was found between the torque value of the valve’s working element axles and the input air velocity.

Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

Genetic algorithms for nuclear reactor fuel load and reload optimization problems

Approaches are examined in the present paper to the application of genetic algorithms for optimization of initial reactor load and subsequent reloading and reshuffling of fuel assemblies in the nuclear reactor core. The issues associated with selection of the optimization criterion, which was chosen to be the nuclear fuel burnup depth, are discussed. The burnup depth is estimated after the fuel assembly is unloaded from the core, i.e. after residence in the reactor core during 3 fuel irradiation campaigns. An important aspect determining the efficiency of the use of the genetic algorithm in the problem under examination is that the neutronics calculation of the reactor core is to be performed in sufficient details allowing "feeling" the change in the location of the fuel assemblies relative to each other. The use of low-precision instrument results in the uselessness of the proposed approach to the optimization of reactor core loading. The opposite extreme, i.e. the excessive degree of details, is associated with significant increase of expended computer CPU time. In the presented paper, the TRIGEX [1,2] application software package was used in the analysis of neutronics characteristics of the reactor core providing acceptable degree of details and capable to demonstrate sensitivity of the results to the changes in the reactor load arrangement. The genetic algorithm incorporates the use of at least two basic procedures—selection and mutation. One of the most important issues in the application of the genetic algorithm is the definition of the basic concepts, namely the concepts of mutation, crossing, and specimen. The answers to these questions as applicable to the problem under discussion are provided in the present paper. In addition, the main recommendations for the organization of crossing and mutation procedures are also given. The efficiency of use of the developed model of the genetic algorithm is demonstrated by the test example of a BN type reactor. The results of the test run demonstrated that the use of the proposed approach allows searching for optimal reactor load mapping for each separate core reshuffling operation. The main objective of the performed study was to demonstrate the applicability and efficiency of the new up-to-date approach to solving the problem of fuel loading into a nuclear reactor

Permian Bivalves of the Pronchishchev Ridge (North Siberia): New Data on Taxonomic Composition, Biostratigraphy, and Biogeographic Relationships

Abstract—: Permian marine bivalves of the Pronchishchev Ridge (North Siberia) were systematically studied for the first time. The presence of the Middle and Upper Permian with five biostratigraphic levels was established based on fossil findings. In the Middle Permian, these are the bivalve Kolymia inoceramiformis–K. plicata (undivided) and Kolymia multiformis zones, and in the Upper Permian—the Maitaia bella Zone (Beds with Phestia ex gr. ovata), Maitaia belliformis Zone, and Intomodesma costatum Zone. The bivalve assemblages from the Middle and the lower Upper Permian (up to the Intomodesma costatum Zone) are similar in their taxonomic composition to those from the Western and Northern Verkhoyansk regions. The uppermost Permian fossil assemblages (Intomodesma costatum Zone) are different. They are represented almost exclusively by monotaxonic aggregations of the large pectinoid Streblopteria rotunda (Lutkevich et Lobanova) and rather rare representatives of the genus Intomodesma. The marine basin of the present-day Pronchishchev Ridge had stable links with the Verkhoyansk basin throughout almost the entire Permian. This basin was very shallow and may have experienced episodes of desalination. In the end of the Permian, the paleogeographic situation changed, and the connection between the Pronchishchev Ridge and the East Taimyr basins became more pronounced. Most characteristic bivalve species are illustrated, and a new species Kolymia rutskovi Biakov, sp. nov. is described