Scientific and Engineering Center for Nuclear and Radiation Safety

Moscow, Russia

Scientific and Engineering Center for Nuclear and Radiation Safety

Moscow, Russia
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Grant
Agency: European Commission | Branch: H2020 | Program: RIA | Phase: NFRP-02-2014 | Award Amount: 4.57M | Year: 2015

When dealing with emergency, two issues with fully different time requirements and operational objectives, and thus different methods and tools, have to be considered: emergency preparedness and emergency response. This project will address both issues by combining the efforts of organizations active in these two areas to make already identified deterministic reference tools and methods a decisive step toward. In particular capabilities of these methods and tools will be extended to tackle main categories of accident scenarios in main types of operating or foreseen water-cooled NPPs in Europe, including Spent Fuel Pools. A first task will be the identification of these categories of scenario, the proposition of a methodology for their description and the development of a database of scenarios. Building this database will constitute a first important step in the harmonisation goal defended in this project. Promising probabilistic approaches based on Bayesian Belief Networks (BBN) are currently developed to complement operational deterministic methodologies and tools by contributing to diagnosis accidental situations. The development of the methodologies will be pursued in this project with the extension of the existing deterministic ones to European reactors. Both approaches will be assessed against the above mentioned database of scenarios. Finally a comprehensive set of emergency exercises will be developed and proposed to be run by a large set of partners. A first series of exercises will address source term evaluations that will be compared to the reference source terms from the scenarios database. Then a second series of exercises will be proposed on the same scenarios that will be used for the first series but accounting for the main emergency objective : to protect the populations. Progresses made by the methods and tools developed within this project will be notably assessed by comparing the results obtained in these two series of exercises.


Ivanov V.,Scientific and Engineering Center for Nuclear and Radiation Safety | Bousquet J.,GRS Society for plants and Reactor Safety
Kerntechnik | Year: 2016

This work aims to assess the capabilities of reactor physics codes (initially validated for thermal reactors) to simulate fast sodium cooled reactors. The BFS-62-3A critical experiment from the BN-600 Hybrid Core Benchmark Analyses was chosen for the investigation. Monte-Carlo codes (KENO from SCALE and SERPENT 2.1.23) and the deterministic diffusion code DYN3D-MG are applied to calculate the neutronic parameters. It was found that the multiplication factor and reactivity effects calculated by KENO and SERPENT using the ENDF/B-VII.0 continuous energy library are in a good agreement with each other and with the measured benchmark values. Few-groups macroscopic cross sections, required for DYN3DMG, were prepared in applying different methods implemented in SCALE and SERPENT. The DYN3D-MG results of a simplified benchmark show reasonable agreement with results from Monte-Carlo calculations and measured values. The former results are used to justify DYN3D-MG implementation for sodium cooled fast reactors coupled deterministic analysis. © Carl Hanser Verlag, München.


Samokhin A.G.,Scientific and Engineering Center for Nuclear and Radiation Safety | Zilly M.,GRS Society for plants and Reactor Safety
Kerntechnik | Year: 2016

This work describes the application and the results of transient calculations for the RBMK-1000 with the coupled code system ATHLET 2.2A-QUABOX/CUBBOX which was developed in GRS. Within these studies the planned modernization of the graphite blocks of the RBMK-1000 reactor is taken into account. During the long-term operation of the uranium-graphite reactors RBMK-1000, a change of physical and mechanical properties of the reactor graphite blocks is observed due to the impact of radiation and temperature effects. These have led to a deformation of the reactor graphite columns and, as a result, a deformation of the control and protection system (CPS) and of fuel channels. Potentially, this deformation can lead to problems affecting the smooth movement of the control rods in the CPS channels and problems during the loading and unloading of fuel assemblies. The present paper analyzes two reactivity insertion transients, each taking into account three graphite removal scenarios. The presented work is directly connected with the modernization program of the RBMK-1000 reactors and has an important contribution to the assessment of the safety-relevant parameters after the modification of the core graphite blocks. © Carl Hanser Verlag, München.


Alpeev A.S.,Scientific and Engineering Center for Nuclear and Radiation Safety
Nuclear and Radiation Safety | Year: 2014

The paper discuses safety classification of process equipment and automation devices of nuclear power plants. It is indicated that safety classes are incorrectly transferred from safety functions to process equipment and automation devices that perform these functions. Three functional groups are proposed for equipment classification, which are the most crucial for NPP safety assurance and are the basis for developing any control system since no other control system component is characterized by such complete and unique requirements on quality indicators. A control system is just an aggregate of functional groups and their characteristics.


Lankin M.,Scientific and Engineering Center for Nuclear and Radiation Safety
11th International Probabilistic Safety Assessment and Management Conference and the Annual European Safety and Reliability Conference 2012, PSAM11 ESREL 2012 | Year: 2012

The article sets forth algorithms, created in the process of developing Russian Risk-Informed Decision Making (RIDM) Guideline for NPPs: 1) algorithm of assessment of risk acceptability in conjunction with making a decision; 2) algorithm of assessment of decision acceptability from the point of view of its influence on the defence-indepth. he first algorithm takes into account such risk metrics as Base Severe Accident Frequency (SAF) and increase of SAF as a result of making a decision, instantaneous value of SAF, as well as Large Release Frequency (LRF) and its increase as a result of making a decision. Based on the combination of values of the abovementioned metrics and according to the developed algorithm, risk falls into one of the zones: acceptable risk (green zone), unacceptable risk (red zone) or zone of conditionally acceptable risk (yellow zone). This article describes and explains those criteria, on the basis of which borderlines between the aforementioned zones are being established. A nomenclature of threats to the defence-in-depth and of possible implementation mechanisms of the indicated threats have been proposed within the framework of the second algorithm. For the decision under analysis it is necessary to evaluate for each of the nomenclature implementation mechanisms of threats to the DiD whether the decision has influence on DiD according to the mechanism under consideration. The article presents rules of assessment of level of changes in DiD vulnerability, caused by the decision under analysis, contained in the described algorithm.


Lankin M.,Scientific and Engineering Center for Nuclear and Radiation Safety
11th International Probabilistic Safety Assessment and Management Conference and the Annual European Safety and Reliability Conference 2012, PSAM11 ESREL 2012 | Year: 2012

Russian national regulatory documents require an analysis of beyond design basis accidents to be carried out for NPPs for the scope of working out control strategies for such accidents, as well as strategies of sufficiency evaluation of the NPP's technical equipment, used in mitigating the consequences of such accidents. Since sheer quantity of possible beyond design basis accidents is limitless, we face a necessity of working out selection criteria for choosing scenarios of such accidents to be taken into consideration in developing technical equipment for accident-protection, mitigation and accident control at the new NPPs, as well as in evaluation of sufficiency of such equipment at the already operational NPPs. The article presents a regulatory body's experience in developing guidelines for defining a list of beyond design basis accidents that are to be taken into account at an NPP. Developing such a list is to include examination of the following criteria: 1) representativity (from the point of view of organizing emergency response operations) of phenomenology of the processes of the scenario under analysis with reference to protection of each of the physical barriers and critical safety functions. For severe accidents, in addition to all of the above, with reference to each of the aims of accident management; 2) evaluated occurrence possibility for the scenario under analysis, taking into account uncertainty of such evaluation; 3) necessity to take into account current national and international practices of selecting scenarios of beyond design basis accidents. On their approbation the developed methods are planned to be implemented as a Regulatory Safety Guideline.


Khamaza A.,Scientific and Engineering Center for Nuclear and Radiation Safety | Lankin M.,Scientific and Engineering Center for Nuclear and Radiation Safety
PSAM 2014 - Probabilistic Safety Assessment and Management | Year: 2014

Nuclear regulatory body can exercise supervision of a considerable number of different nuclear facilities: NPPs of different capacities, generations and types, research reactors, various fuel cycle facilities, radioactive sources etc. This article presents a methodology of ranking different nuclear facilities according to the potential hazard level they represent, for the scope of optimizing controlling and supervising practices of Regulatory Body. Four criteria are proposed to be used for ranking. The first criterion is the scale of a hypothetical accident in a situation of total inefficiency of safety barriers. Depending on whether maximum hypothetical accident leads to off-site consequences and what these consequences are, as well as depending on the A/D ratio, four categories have been identified, the third of which has been further divided into four subcategories. The second and the third criteria, used for ranking, are estimated values of probabilities that operational occurrences could take place at the facility and corresponding conditional probabilities that the said occurrences would not develop into an accident of a specific level of severity. And, finally, the fourth criterion is efficiency of defence in depth of the facility. This article sets forth an algorithm of assessment of the said efficiency. It also contains a nomenclature of threats to Defence in depth and algorithm of evaluation of Defence in Depth vulnerability of the facility in respect of each of the threats and to the mechanisms of their implementation. Based on the assessment results for defence in Depth efficiency, the facility under consideration is ranked as belonging to one of the four categories. According to the rules, described in the article, after the facility under consideration has been rated according to all of the four criteria (or only according to some of them if evaluation according to the others is not possible), it is being assigned a final resulting rating of potential hazard.


Borodkin P.,Scientific and Engineering Center for Nuclear and Radiation Safety | Borodkin G.,Scientific and Engineering Center for Nuclear and Radiation Safety | Khrennikov N.,Scientific and Engineering Center for Nuclear and Radiation Safety
EPJ Web of Conferences | Year: 2016

Paper describes the new approach of fitting axial fuel burn-up patterns in peripheral fuel assemblies of VVER-1000 type reactors, on the base of ex-core neutron leakage measurements, neutron-physical calculations and in-core SPND measured data. The developed approach uses results of new ex-vessel measurements on different power units through different reactor cycles and their uncertainties to clear the influence of a fitted fuel burn-up profile to the RPV neutron fluence calculations. The new methodology may be recommended to be included in the routine fluence calculations used in RPV lifetime management and may be taken into account during VVER-1000 core burn-up pattern correction. © 2016 Owned by the authors, published by EDP Sciences.


Lankin M.,Scientific and Engineering Center for Nuclear and Radiation Safety
11th International Probabilistic Safety Assessment and Management Conference and the Annual European Safety and Reliability Conference 2012, PSAM11 ESREL 2012 | Year: 2012

Russian regulatory body, Rostechnadzor, exercises supervision of a considerable number of different nuclear facilities: NPPs of different capacities, generations and types, research reactors, various fuel cycle facilities, radioactive sources, nuclear-powered fleet etc. This article presents a developed algorithm of ranking different nuclear facilities according to the potential hazard level they represent, for the scope of optimizing controlling and supervising practices of Rostechnadzor. Four criteria are used for ranking. The first criterion is the scale of a hypothetical accident in a situation of total inefficiency of safety barriers. Depending on whether maximum hypothetical accident leads to off-site consequences and what these consequences are, as well as depending on the A/D ratio, four categories have been identified, the third of which has been further divided into four subcategories. The second and the third criteria, used for ranking, are estimated values of probabilities that operational occurrences could take place at the facility and corresponding conditional probabilities that the said occurrences would not develop into an accident of a specific level of severity. And, finally, the fourth criterion is efficiency of defence-in-depth of the facility. This article sets forth a detailed algorithm of assessment of the said efficiency. It also contains a nomenclature of threats to DiD and algorithm of evaluation of DiD vulnerability of the facility in respect of each of the threats and to the mechanisms of their implementation. Based on the assessment results for DiD efficiency, the facility under consideration is ranked as belonging to one of the four categories. According to the rules, described in the article, after the facility under consideration has been rated according to all of the four criteria (or only according to some of them if evaluation according to the others is not possible), it is being assigned a final resulting rating of potential hazard.


Lankin M.,Scientific and Engineering Center for Nuclear and Radiation Safety
International Conference on Nuclear Engineering, Proceedings, ICONE | Year: 2012

The article sets forth algorithms, created in the process of developing Russian Risk-informed Decision Making (RiDM) Guideline for Nuclear Power Plants (NPPs): 1) algorithm of assessment of risk acceptability in conjunction with making a decision; 2) algorithm of assessment of decision acceptability from the point of view of its influence on the defence-in-depth. he first algorithm takes into account such risk metrics as Base Severe Accident Frequency (SAF) and increase of SAF as a result of making a decision, instantaneous value of SAF, as well as Large Release Frequency (LRF) and its increase as a result of making a decision. Based on the combination of values of the abovementioned metrics and according to the developed algorithm, risk falls into one of the zones: acceptable risk (green zone), unacceptable risk (red zone) or zone of conditionally acceptable risk (yellow zone). This article describes and explains those criteria, on the basis of which borderlines between the aforementioned zones are being established. A nomenclature of threats to the defence-in-depth and of possible implementation mechanisms of the indicated threats have been proposed within the framework of the second algorithm. For the decision under analysis it is necessary to evaluate for each of the nomenclature implementation mechanisms of threats to the Defence-in-Depth (DiD) whether the decision has influence on DiD according to the mechanism under consideration. The article presents rules of assessment of level of changes in DiD vulnerability, caused by the decision under analysis, contained in the described algorithm. Copyright © 2012 by ASME.

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