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Nosovsky A.,State Scientific and Technical Center for Nuclear and Radiation Safety
Nuclear and Radiation Safety | Year: 2016

Many organizations and institutions participated in the elimination of ChNPP-4 accident. However, the main efforts on conservation of the damaged unit and ChNPP- 3 commissioning were performed in 1986-1987 by experts of the enterprises and organizations of the Ministry of Medium Machine Building of the Soviet Union, who have been sent to the staff of the specially created Construction Administration US- 605. The paper presents the activity of US-605 experts, describes administrative and technical measures of radiation safety during construction of the Shelter in difficult radiation conditions. Such efforts enabled accumulation of significant and unique experience in mitigation of severe accident consequences, which shall be used to prevent any nuclear accidents and eliminate their consequences. © A. Nosovsky, 2016.


Khalimonchuk V.,State Scientific and Technical Center for Nuclear and Radiation Safety | Kuchin A.,State Scientific and Technical Center for Nuclear and Radiation Safety | Tokarevsky V.,Institute for Chornobyl Problems
Nuclear and Radiation Safety | Year: 2016

The paper analyzes physical peculiarities of RBMK leading to catastrophic progression of the accident at ChNPP-4 on 26 April 1986. The modeled transient, which preceded the accident, and modeling of its first phase showed that introduction of absorbing rods into the core played a decisive role in the accident progression. © V. Khalimonchuk, A. Kuchin, V. Tokarevsky, 2016.


Snisar I.B.,State Scientific and Technical Center for Nuclear and Radiation Safety
Nuclear and Radiation Safety | Year: 2014

This paper analyzes a mathematical model of ionizing radiation fields generated near material surfaces by the sources distributed over them. It is shown that there is an objective limit of their spatial heterogeneity, and this limit does not depend on the distribution of sources on surfaces. Some possible applications of the obtained result in radiation protection and dosimetry have been identified.


Shevchenko I.A.,State Scientific and Technical Center for Nuclear and Radiation Safety | Vorobyov Y.Y.,State Scientific and Technical Center for Nuclear and Radiation Safety
Nuclear and Radiation Safety | Year: 2015

The thermal-hydraulic aspects of modeling the mixed core (several types of nuclear fuel) with TVSA, TVS-W and TVS-WR fuel are analyzed. The safety criteria for the maximal fuel cladding temperature are evaluated for representative events of design basis accident (DBA) analysis for WWER-1000 reactors using RELAP5/MOD3.2 computer code. It is shown that the maximal cladding temperature increases with introduction of new TVS-WR or TVS-W fuel as compared to TVSA. Preliminary analyses have shown that the maximal cladding temperature does not exceed its limit of 1200°C in the events involving seizure of the main coolant pump (MCP) and double-ended cold leg break of the main coolant piping. The results confirm the need for further thermal-hydraulic analysis of WWER-1000 mixed cores. DBA analysis has to be complemented with calculations for mixed cores.


Bilodid I.,State Scientific and Technical Center for Nuclear and Radiation Safety | Duspiva J.,State Scientific and Technical Center for Nuclear and Radiation Safety
Nuclear and Radiation Safety | Year: 2015

Interest in the analysis of beyond design basis accidents, involving a combination of several failures with fuel damage, has increased throughout the world after the Fukushima accident. Stress tests were performed at NPPs, and development of severe accident management guidelines was started. These activities necessitated calculations to analyze the probability of beyond design basis accidents and assess their initiating events and consequences. One of the aspects in analysis of beyond design basis accidents is to determine the potential for re-criticality during such accidents. The paper provides results of some criticality safety calculations for VVER reactors performed, in particular, by ÚJV Řež and SSTC NRS experts. It is shown how criticality can occur in different severe accident phases. © I. Bilodid, J. Duspiva, 2015.


Snisar I.,State Scientific and Technical Center for Nuclear and Radiation Safety
Nuclear and Radiation Safety | Year: 2015

The paper presents original procedures for zoning, survey optimization and verification of surface radiation fields dosimetry data. These procedures give an opportunity to find unambiguous solutions for the problems of zoning and survey routing of the above fields at any scope of input data, as well as an opportunity to verify field measurements data acquired at any measurement grid and using any methods.


Bilodid Y.,State Scientific and Technical Center for Nuclear and Radiation Safety | Kovbasenko Y.,State Scientific and Technical Center for Nuclear and Radiation Safety
Nuclear and Radiation Safety | Year: 2015

The paper presents parameters calculated with SCALE-4.4 code to assess impact of fabrication tolerances and uncertainty of input data on geometrical and material composition of VVER-1000 fuel assembly (FA) elements on results of nuclear fuel criticality analysis. The most conservative set of parameters within the process error has been identified in terms of effect on fuel multiplication properties. The dependence of multiplication properties on FA material temperature has been analyzed.


Vorobyov Y.,State Scientific and Technical Center for Nuclear and Radiation Safety | Zhabin O.,State Scientific and Technical Center for Nuclear and Radiation Safety
Nuclear and Radiation Safety | Year: 2015

Applicability of cladding deformation model in RELAP5/MOD3.2 code is analyzed for VVER-1000 fuel cladding from Zr+1%Nb alloy. Experimental data and calculation model of fuel assembly channel of the core are used for this purpose. The model applicability is tested for the cladding temperature range from 600 to 1200 °C and pressure range from 1 to 12 MPa. Evaluation results demonstrate limited applicability of built-in RELAP5/MOD3.2 cladding deformation model to the estimation of Zr+1%Nb cladding rupture conditions. The limitations found shall be considered in application of RELAP5/MOD3.2 cladding deformation model in the design-basis accident analysis of VVER reactors.


Dybach O.,State Scientific and Technical Center for Nuclear and Radiation Safety | Nosovsky A.,State Scientific and Technical Center for Nuclear and Radiation Safety
Nuclear and Radiation Safety | Year: 2015

The paper considers the general task on checking compliance of probabilistic safety indicators with regulatory criteria. It presents correlations to assess probable exceeding of safety criterion for different laws of distribution of the numerical results of the probabilistic safety analysis (PSA). The paper presents the scale for rationing probability of safety criteria exceeding.


Klevtsov A.,State Scientific and Technical Center for Nuclear and Radiation Safety
Nuclear and Radiation Safety | Year: 2013

The approaches and methods accepted in Ukraine for reliability assessment of NPP instrumentation and control systems are presented in the paper. The software for reliability calculation which was developed by SSTC NRS and results of its verification are described as well.

Loading State Scientific and Technical Center for Nuclear and Radiation Safety collaborators
Loading State Scientific and Technical Center for Nuclear and Radiation Safety collaborators