Association Vinçotte Nuclear

Статья посвящена презентации нового информационного ресурса в сети Internet-базы знаний по диссипативным и дисперсионным свойствам разностных схем для простейшего линейного уравнения переноса, охватывающей 2113 схем от первого порядка аппроксимации до десятого, которые могут быть получены на вычислительном шаблоне из четырех расчетных узлов на трех слоях по времени. Информационный массив, содержащий паспорта всех этих схем, размещен на сайте Лаборатории индустриальной математики ВМК МГУ им. М.В. Ломоносова по адресу http://lim.cmc.msu.ru/index.php?id=86. Паспорт разностной схемы содержит коэффициенты характеристических уравнений, область устойчивости и диссипативные и дисперсионные поверхности. Дружественный графический интерфейс пользователя позволяет в интерактивном режиме осуществлять поиск паспортов по вычислительным шаблонам. В качестве примера приведены диссипативные и дисперсионные поверхности некоторых схем, имеющих различные порядки аппроксимации.

Purpose: The assess the contribution of modern activity of Research Institute of Atomic Reactors (JSC «SSC RIAR») in the formation of man-made risks for the population of Dimitrovgrad, Ulyanovsk region.
 Material and methods: The results of monitoring of the state of the environment, meteorological features of the area of JSC «SSC RIAR» location, data on the radiation and sanitary-epidemiological situation in Dimitrovgrad were studied and analyzed. The materials of the state reports, annual reports and analytical references of the Rospotrebnadzor, the Volga UGMS, Ulyanovskstat, the Ministry of Ecology and Nature Management of the Ulyanovsk Region and the Interregional Department № 172 of the FMBA of Russia, as well as the results of industrial and environmental monitoring provided directly by JSC “SSC RIAR” were used as the sources of the initial data.
 The work was carried out dispersion modeling of current annual gas and aerosol emissions to estimate the contribution of JSC « RIAR » in the formation of ambient city air pollution. The calculation of risks was carried out in accordance with the UNSCEAR methodology for the assessment of radiation risk and the Guidelines for the assessment of the effects of toxic and carcinogenic chemicals approved by the Ministry of Health of the Russian Federation.
 Results: The average annual dose rate for the population of Dimitrovgrad caused by current emissions of JSC «SSC RIAR» according to the results of conservative calculations is 0.9 µSv/year. The value of radiation risk for the population of the residential zone is at the level of 2.9∙10–8, while for the entire territory of Dimitrovgrad it is 5.4∙10–8. The resulting value of the radiation risk to the health of people living in a residential area of the city is more than 30 times lower than the level of acceptable risk (1∙10–6). 
 The total value of chemical risk from all sources of air pollution in Dimitrovgrad is 1.3∙10–3. This risk level is in the range of unacceptable risk neither for the population nor for professional groups. Assessment of a carcinogenic risk from pollutants suggests the occurrence of malignant neoplasms as a negative effect. The total value of carcinogenic risk is 1.3∙10–4, which slightly exceeds the upper limit of the acceptable risk level for the population.
 Conclusion: The contribution of anthropogenic radiation factor to the overall risk structure is less than 0.003 %. The role of JSC “SSC RIAR” in the air pollution of the residential zone of the city is negligible and does not create toxic risks for the population of Dimitrovgrad. Thus the current activity of JSC “SSC RIAR” leads to negligible values of carcinogenic risks for the population of the area of the nuclear facility location.

It has been shown that simple mixture theory models are inadequate to describe low-frequency sound propagation through seagrass meadows and further understanding of the acoustic properties of seagrass tissue is necessary. To that end, we present two ultrasonic sound speed measurements on the Mediterranean seagrass Posidonia oceanica. First, a transit time measurement through a stack of 120 leaf blades at 2.25 MHz are compared to similar measurements made on macroalgae Ecklonia radiata. Sound speed differences are related to the gas content within the aerenchyma of seagrass and other tissue characteristics. Second, ultrasonic sound speed measurements through a suspension of finely divided P. oceanica leaf blades at frequencies between 1 and 4 MHz are compared to low-frequency (1-8 kHz) sound speed obtained on the same blade suspension by means of a resonance chamber.

This paper reports on a comparative study between the well-established test patterns for daily quality assurance (QA) of monitors of the American Association of Medical Physicists, Task Group 18 (AAPMtg18) and the Deutsches Institut für Normung e.V (DIN), and a newly proposed variable test pattern. A characteristic of the test patterns currently used for the QA of monitors is their static nature: The same test pattern is always used. This enables a learning effect that may bias the results over time. To address this problem we have developed a variable pattern for the quality assurance of monitors (MoniQA) that allows an evaluation of contrast visibility, geometric distortion, resolution, global image quality including uniformity, and artifacts. The test pattern includes randomly generated elements intended to prevent the observer from learning the test. Examples are random characters that have to be discriminated from the background to evaluate the threshold luminance difference and variable positions of different features in the test pattern. The newly proposed test patterns were generated and visualized on different viewing stations with a software tool developed in JAVA. In this study, we validated these patterns against the well-known AAPMtg18 and DIN test patterns on 22 monitors. The results showed that the MoniQA test can indicate the same monitor problems as the other well-known patterns and is significantly quicker to evaluate than the AAPMtg18 test patterns. The MoniQA pattern is a promising alternative for daily quality control of medical viewing stations.

UT probes to be used for the examination of coarse‐grain structure must allow to detect and size cracks, with a high reliability level. The combination of TRL probes, with phased array and piezocomposite technologies allows to improve probes performances and inspection speed. Single element crystals are replaced by matrix arrays, allowing to deflect and skew the beams, to change the inspection depth. This paper describes the designing, the manufacturing and the characterisation of several probes.

When considering beyond design-basis accidents in Transportation Casks (TC) for temporary storage of Spent Fuel Assemblies (SFA) of Nuclear Submarines (NS), the most hazardous radiological consequences occur if a Spontaneous Chain Reaction (SCR) is initiated. Despite a considerable safety margin for TCs against mechanical and other external impacts, an investigation to assess the type of destruction and the scale of external impact under which a SCR can be initiated is advisable.

This paper presents MCNP criticality calculations for both UOX and MOX disrupted fuel assemblies canisters systems in the reference Belgian disposal concept and one of its variant. We examine the influence of different parameters (water moderation and geometry alteration) on the neutron multiplication factor, keff. In all the studied cases, the reference concept does not present criticality risks. The variant concept sometimes presents criticality risks. The present results only concern fresh UOX and MOX fuel assemblies. Further developments of this work will include irradiated (UOX and MOX) fuels.