Process Distribution in the Network Systems

Performing risk analysis of systems, evaluating reliability of technological objects, hazard of technological processes, we usually have to systems of network type and distribution of various processes in such systems. A well-known mathematical apparatus of diffusive processes example is dispersion in continuum medium (air, water, etc.). Process distribution in network systems is simpler, however, it much depends on network features. In this article theory of Markov chains is selected, distributions of different processes in transitional regimes are analysed as well as issues of their stability. Created models may be used in many different ways, for example, for the analysis or viruses in computer networks, hazard distribution in transport systems regarding transportation of hazardous materials, etc

Analysis of ASTEC-Na capabilities for simulating a loss of flow CABRI experiment

Abstract This paper presents simulation results of the CABRI BI1 test using the code ASTEC-Na, currently under development, as well as a comparison of the results with available experimental data. The EU-JASMIN project (7th FP of EURATOM) centres on the development and validation of the new severe accident analysis code ASTEC-Na (Accident Source Term Evaluation Code) for sodium-cooled fast reactors whose owner and developer is IRSN. A series of experiments performed in the past (CABRI/SCARABEE experiments) and new experiments to be conducted in the new experimental sodium facility KASOLA have been chosen to validate the developed ASTEC-Na code. One of the in-pile experiments considered for the validation of ASTEC-Na thermal–hydraulic models is the CABRI BI1 test, a pure loss-of-flow transient using a low burnup MOX fuel pin. The experiment resulted in a channel voiding as a result of the flow coast-down leading to clad melting. Only some fuel melting took place. Results from the analysis of this test using SIMMER and SAS-SFR codes are also presented in this work to check their suitability for further code benchmarking purposes

Extension of ASTEC-Na capabilities for simulating reactivity effects in Sodium Cooled Fast Reactor

The EU-JASMIN project (7th FP of EURATOM) has been centred on the development and validation of the new severe accident analysis code ASTEC-Na (Accident Source Term Evaluation Code) for Sodium-cooled Fast Reactors (SFR). The development of such computational tool being able to assist safety analysis of innovative reactor concepts is of crucial importance. One of the challenging issues when modelling SFRs is the neutronic reactivity feedbacks. This paper presents the model implemented in ASTEC-Na for representing the reactivity effects in SFR as well as the benchmarking results of a ULOF transient against SAS-SFR code results. It has been verified that the models are correctly implemented and that ASTEC-Na is now able to calculate reactivity feedbacks not only in the sodium single phase, but also after boiling onset and fuel in-pin relocation

Accident risk assessment and reduction of petrol transportation on Lithuania roads

Transportation safety is a term related to avoidance of risk from bodily harm and property damage associated with the operation of transport system. However, there is a paradox in the conventional usage of the term in that most safety statements instead discuss the amount of risk present. Low levels of risk are thus equated with safe conditions/systems. Petrol transportation on the public roads raises significant risk that often are underestimated and possible large consequences of road accidents mostly are not considered. The purpose of this work is to identify and manage risks presented by transportation of hazardous materials on public roads and to identify the most dangerous (with highest probability of accidents that involves petrol transportation vehicles) road segmentsLietuvos energetikos institutasVytauto Didžiojo universiteta

ASTEC-Na code Thermal-hydraulic model validation and benchmarking with other codes

International audienceThis paper describes the work performed within the WP2.1 of the JASMIN project to validate the thermal-hydraulic models of ASTEC-Na code. The experiments used for validation purposes have been BI1, E8 and EFM1, carried out in the CABRI reactor; BE + 3, APL1 and APL3, carried out in the SCARABEE reactor and N02, conducted in the KNS facility. ASTEC-Na has been also successfully applied (pretest calculations) to assess the performances of the KASOLA sodium loop and to verify its response under different operating conditions. Finally, a PHENIX natural circulation test has also been performed with ASTEC-Na. Besides, these experimental tests have been used as a code benchmarking exercise where thermal-hydraulic codes (CATHARE, RELAP5-Na and RELAP5-3D) and severe accident codes (SIMMER-III and SAS-SFR) have been compared with ASTEC-Na. © 2017 Elsevier Lt

Development and assessment of ASTEC-Na fuel pin thermo-mechanical models performed in the European JASMIN project

International audienceASTEC-Na is a computer code system which evaluates protected and unprotected accidents in Sodium-cooled Fast Reactors throughout the Initiation Phase. The fuel pin behavior models implemented in ASTEC-Na simulate the essential aspects of the thermal and mechanical behavior of SFR fuel pins in nominal and accidental conditions. Besides the improvement of existing ASTEC-Na models, a specific cladding mechanical model and an in-pin fuel relocation model have been developed during the JASMIN project, where the latter has been already implemented in the code. ASTEC-Na fuel pin behavior models are described in this paper and their transient predictions for four CABRI transient tests are compared to available experimental data as well as to SAS-SFR and SIMMER-III code calculations. Conclusions on the overall performance of ASTEC-Na fuel pin models are also presented. © 2017 Elsevier Lt