Учет влияния останова реактора ВВЭР-1200 для перегрузки при расчете активностей продуктов деления

Current work is aimed at the analysis of the fission products decay influence during fuel reloading, when calculating the accumulated fission products activity for the VVER-1200 reactor fuel campaign. The Bateman problem solution based technique was used for calculations, within the framework of the two fissile nuclides approximation. The fission products producing process for the VVER-1200 reactor stationary campaign is considered, taking into account the reactor shutdown periods for refueling and without taking them into account (instant reload approximation). It was shown, that the instant reload approximation for fission products activity calculations gives the similar accurate result, as calculations with taking into account the shutdown periods. The results can be used to significantly simplify the calculations of fission product activity accumulation in nuclear power reactors.Целью исследования являлся анализ влияния распада продуктов деления во время перегрузки топлива, при определении наработанной активности продуктов деления в течение топливной кампании реактора ВВЭР-1200. Для расчетов применялась методика на основе аналитического решения задачи Бейтмана в рамках приближения двух делящихся нуклидов. Рассмотрен процесс наработки продуктов деления для стационарной кампании реактора ВВЭР-1200 с учетом периодов останова реактора для перегрузки топлива и без их учета (приближение мгновенной перегрузки). Было установлено, что расчет удельных активностей продуктов деления в моменты останова реактора для перегрузки в приближении мгновенной перегрузки по точности практически не уступает расчетам, учитывающим распад продуктов деления за период перегрузки. Полученные результаты могут быть использованы для существенного упрощения расчетов наработки активностей продуктов деления в ядерных энергетических реакторах

Определение эффективного коэффициента размножения нейтронов пoдкритической сборки «Ялiна-Тепловая»

To study the kinetics of subcritical systems and determine the optimal conditions for the transmutation of longlived radioactive waste in the neutron spectrum of ADS-systems the “Yalina” research nuclear facility was created at Joint Institute for Power and Nuclear Research – Sosny (Minsk, Belarus). The main safety indicator of a subcritical system (active zone reactivity) was measured for a “Yalina-Thermal” assembly via three independent methods: inverse multiplication, probabilistic and impulse ones. For the inverse multiplication method, the neutron flux density was monitored during assembly loading. For a fuel load of 285 EK-10 rods the neutron multiplication was M = 22.3±0.6, and the effective neutron multiplication coefficient was keff = 0.9551± 0.0016. The probabilistic method (Feynman-alpha method), based on measuring fluctuations in the neutron density level within a system with a fission chain reaction, gave the ratio of the variance to the average counting rate value D/n = 1.779±0.005, which corresponds to keff = 0.9597 ±0.0003. The pulse method is aimed at studying the neutron flux behavior of after the neutron pulse injection into the breeding system. Measurements were held with the same setup, used in the Feynman-alpha method. The measured decay constant of instantaneous neutrons is α = –670±0.7 1/s, which corresponds to keff = 0.9560±0.0001. The effective multiplication factor keff of the subcritical assembly “Yalina-Thermal”, obtained via three different independent methods, is around average value of keff = 0.9569 ± 0.0018. The methods considered can be used for subcritical level monitoring for ADS-systems and research nuclear facilities.Для изучения кинетики подкритических систем и определения оптимальных условий трансмутации долгоживущих радиоактивных продуктов деления в спектре ADS-систем (Accelerator Driven Subcritical System) в Объединенном институте энергетических и ядерных исследований – Сосны создана исследовательская ядерная установка (ИЯУ) «Ялiна», включающая генератор нейтронов и две подкритические сборки: «Яліна-Тепловая» с тепловым спектром нейтронов и «Яліна-Бустер» – с быстрым. Представлены исследования по изучению реактивности подкритической сборки «Яліна-Тепловая». Для этого были проведены измерения эффективного коэффициента размножения нейтронов (kэфф) тремя независимыми методами: обратного умножения, вероятностным и импульсным. Исследование выполнялось для топливной загрузки из 285 твэлов ЭК-10. Для метода обратного умножения измеренный коэффициент умножения составил М = 22,3 ± 0,6, что соответствует эффективному коэффициенту размножения нейтронов kэфф = 0,9551 ±0,0016. Измерения по вероятностному методу, или методу Фейнман-альфа, основанному на измерении флуктуации уровня нейтронной плотности в системе, дали значение kэфф = 0,9597± 0,0003. При изучении поведения нейтронов после введения нейтронного импульса в подкритическую среду (импульсный метод) была измерена постоянная спада мгновенных нейтронов α = –670±0,7 1/с, которая соответствует kэфф = 0,9560± 0,0001. В результате проведенных исследований получено среднее значение kэфф подкритической сборки «Ялiна-Тепловая», которое составило kэфф = 0,9569±0,0018. Рассмотренные методы могут применятся для мониторинга уровня подкритичности ADS-систем и исследовательских ядерных установок

Destruction of chemical warfare surrogates using a portable atmospheric pressure plasma jet

Today’s reality is connected with mitigation of threats from the new chemical and biological warfare agents. A novel investigation of cold plasmas in contact with liquids presented in this paper demonstrated that the chemically reactive environment produced by atmospheric pressure plasma jet (APPJ) is potentially capable of rapid destruction of chemical warfare agents in a broad spectrum. The decontamination of three different chemical warfare agent surrogates dissolved in liquid is investigated by using an easily transportable APPJ. The jet is powered by a kHz signal source connected to a low-voltage DC source and with He as working gas. The detailed investigation of electrical properties is performed for various plasmas at different distances from the sample. The measurements of plasma properties in situ are supported by the optical spectrometry measurements, whereas the high performance liquid chromatography measurements before and after the treatment of aqueous solutions of Malathion, Fenitrothion and Dimethyl Methylphosphonate. These solutions are used to evaluate destruction and its efficiency for specific neural agent simulants. The particular removal rates are found to be from 56% up to 96% during 10 min treatment. The data obtained provide basis to evaluate APPJ’s efficiency at different operating conditions. The presented results are promising and could be improved with different operating conditions and optimization of the decontamination process

Birth-death model adaptation for description of time evolution of the neutron + subcritical multiplying medium system

Section VI. Fundamental Problems of Nuclear Power Engineerin

Birth-death model adaptation for description of time evolution of the neutron + subcritical multiplying medium system

Section VI. Fundamental Problems of Nuclear Power Engineerin

The severity of respiratory disorders in different forms of amyotrophic lateral sclerosis

Sleep-disordered breathing (SDB) substantially impairs quality of life in a patient with amyotrophic lateral sclerosis (ALS) and promote the addition of serious respiratory and cardiovascular complications.Objective: to identify the early signs of SDB in patients with various onset ALS using a comprehensive sleep assessment.Patients and methods. A questionnaire survey using a comprehensive test for sleep disorders was conducted in 65 patients: 39 of them had ALS (male:female ratio, 25:14; age, 59 [51; 66] years) and 26 patients made up a control group (male:female ratio, 13:13; age, 54 [43; 59] years).The questionnaire consists of 50 questions; the results were expressed as scores.Screening portable polysomnographic study was conducted in patients with newly diagnosed ALS at the relatively early stages of the disease.A total of 61 patients (32 women and 29 men; median (Me and the 25th and 75th percentile) age was 62 [55; 67] years) were examined. The disease duration was 12 [8.9, 27.1] months after the onset of the first symptoms. The body mass index was 25.7 [23.3, 28.7] kg/m2 . In the studygroup, ALSFRSR [9] scores at study inclusion were 34.32 [32; 38]. Cervicothoracic onset ALS was present in 23 patients; 26 and 12 patients had bulbar and lumbosacral onsets, respectively.Screening diagnosis of sleep was carried out using a Polymate YH-1000C portable polysomnograph (BMC, China) that registered nasopharyngeal flow (airflow through the nasal and oral cavities); thoracoabdominal movements (movements of the thoracic and abdominal walls); hemoglobin oxygen saturation of arterial blood ( SpO2); a snore sound through the microphone; and sleeping position (actography).Results. The comprehensive screening study of breathing during sleep shows the underestimation of the complaints and symptoms of subclinical respiratory disorders in patients with ALS. Portable pulse oximetry at the early stages of the disease revealed changes in the nocturnal respiratory parameters that indicated a predisposition to the development of hypoventilation syndrome. Bulbar-onset ALS patients who had significantly higher apnea/hypopnea index (AHI) and oxygen desaturation (ODI) and lower mean SpO2 with the development of hypoventilation syndrome and, to a lesser extent, obstructive sleep apnea syndrome were most vulnerable to the development of SDB.A correlation analysis revealed the impact of minimal SpO2, ODI, and apnea duration on cardiorespiratory parameters in ALS patients and the possibility of their use as markers to analyze of SDB and cardiac arrhythmias during screening studies in these patients.Conclusion. The early detection and correction of respiratory failure symptoms can prolong patients' life and improve its quality. The screening study of nocturnal sleep and SDB in patients with ALS is a simple and informative method to evaluate a range of respiratory disorders, especially at the early stages of the disease