Latest Articles

volume-23-1

Distortion of the Neutron Flux Profile in Reactor Core Induced by Control Rods, V.N. Kolykhanov, I.E. Kozlov – V.I. Skalozubov

The method designed to calculation the axial profile of neutron flux in reactor core based on diffusion theory are presented. The core model describes two zones – upper part containing control rods (additional absorber) and unrodded bottom part of core. The solution of the system of diffusion equations is obtained using the criticality condition. The […]

volume-23-1

Investigation of IVMR Strategy with External Vessel Water Cooling in VVER1000 Reactor Type with ASTECv2.1.1.0 Computer Code – R. Gencheva, A. Stefanova, P. Groudev

It is investigated the applicability of In-Vessel Melt Retention (IVMR) strategy with external vessel water cooling for the VVER-1000 reactor type. The investigation concerns a calculation made with ICARE and CESAR module of ASTECv2.1.1.0 computer code. ASTEC computer code was developed by IRSN (France) and GRS (Germany) to be a European computational tool for simulation […]

volume-23-1

Investigation of Hydrogen Behaviour in the Test Facility THAI by Simulation of Severe Accident Conditions in the Containment – V. Krusteva, P. Groudev

This paper presents a discussion of the results received in a simulation of hydrogen deflagration and flame propagation during experiment HD-22 in the test facility THAI. The analysis has been performed by the integral computer code ASTEC. The assessment of severe accidents indicates that a significant load on the containment may occur, reaching or even […]

volume-23-1

Risk-Informed Maintenance Optimization for Safety Systems of NPP – V.N. Kolykhanov, I.E. Kozlov

The optimal maintenance of safety systems is one of components, which insure reliable and safe operation of nuclear power plants. The optimal service interval depends on the composition and structure of system and is unique for each safety system. So matching and determination of a common periodicity of safety systems maintenance are required. The method […]

volume-23-1

Risk Monitoring in Kozloduy NPP – E. Stefanov, L. Kandov, K. Filipov

A Risk Monitoring is one of the specific applications of PSA and is a real-time analysis tool used to determine the point-in-time risk. Risk Monitor calculates the risk for the actual plant configuration defined in terms of the Plant Operational Mode (power operation or one of the shutdown modes), the out of service components, availability […]

volume-23-1

Ex-Vessel Reactor Dosimetry for Units 5 and 6 of Kozloduy NPP – Current Status and Future Prospects – D. Dimitrov

More than 20 years the Reactor Physics Laboratory of the Institute for Nuclear Research and Nuclear Energy – Bulgarian Academy of Sciences (INRNE-BAS) provides technical support of Kozloduy NPP regarding nondestructive neutron fluence determination of the reactor pressure vessel (RPV). The activities on neutron fluence assessment and related evaluation of RPV metal degradation (embrittlement temperature […]

volume-23-1

Glasses and Ceramics for High-Level Waste Immobilization: An Overview – S. Miteva

According to their activity level, the radioactive wastes are categorized as high-, intermediate- and low-level waste. This report is mostly concentrated on high-level waste, which includes liquid waste from the first cycle of spent fuel reprocessing and solids into which such liquid waste has been converted. The disposal of the high-level radioactive waste consists of […]

volume-23-1

Human Factor as an Important NPP Safety Factor – B.G. Nenkova, E.N. Tomov

The important aspects of safety of an operating nuclear power plant addressed in a Periodic Safety Review (PSR) are termed ‘safety factors’. Fourteen safety factors are identified in the Safety Guide SSG-25, which may be used to subdivide the PSR. The review of safety factors should determine the status of each safety factor at the […]

volume-23-1

New Approach to Estimation of Thermal Broadening of Neutron Resonances – T.P. Madzharski

The thermal broadening functions in the Bethe-Placzek approximation, is possible to be present in the form of convolution of one Lorentzian and one Guaussian density. This convolution often named as Voigt-profile or Voigt-function. The computation of this profile is required in several problems arising in a variety of physicochemical subjects, such as nuclear reactors, atmospheric […]

volume-23-1

Change of the Quality of the Material Aspects of the Intrinsic Proliferation Barrier of Reactor-Grade Plutonium Produced in a PWR as a Function of Fuel Type, Cooling Time, and Burn-Up – I. Naydenov

In the recent years, non-proliferation of nuclear materials has become an important issue, regarding civilian fuel cycle’s development. In addition, future nuclear energy systems’ and nuclear fuel cycles’ advancement should comply with non-proliferation criteria. These requirements derive from the circumstance that nuclear power is considered to be a dual purpose technology. Special attention to proliferation […]

volume-23-1

Analysis of Main Areas of Interests and Key Indicators as a Base for Comparative Evaluation of Nuclear and Non-Nuclear Energy Options for Small Countries – N. Zaharieva, P. Groudev, A. Chaushevski, N. Popov

Paper presents analysis of main areas of interest and key indicators that can be used as a base for a comparative evaluation of nuclear to non-nuclear energy options in small countries. Considerations address mainly small countries without nuclear power that are interested in nuclear energy as an option for the future energy generation mix system […]

volume-23-1

Evaluation Results from the European Credit System for Vocational Education and Training Based Pilot Training Course for Radiation Protection Worker – R. Miteva, M. Ilieva, C. Pesznyak, A. Kiss, A. Klepakova

This paper presents the process of development of methodology for pilot implementation of European Credit System for Vocational Education and Training (ECVET) for Radiation Protection Worker, the development of ECVET-based training course and the results of the evaluation of the pilot training. The evaluation of the pilot training was carried out by the assessment of […]

volume-23-1

VVER Technology Knowledge Management through CORONA Academy – Activities Overview – D. Dimitrov, M. Mitev, M. Manolova, L. Pironkov, I. Tzvetkov

The purpose of this paper is to give the nuclear community an overview of the training capabilities that the CORONA Academy will bring as an added value to the European nuclear education area. Preserving and further developing nuclear competencies, skills and knowledge related to VVER technology, as a technology used in the EU is among […]

volume-23-1

Kozloduy NPP Units 5&6 Modernization and Plant Life Extension (PLEX) Programs – V. Popov

In the present material main steps and procedures for the modernization and plant lifetime extension of Kozloduy NPP Units 5&6 are discuss. The paper traces the various stages in the period 1998–2019 important for plant life extension. Keywords: Ageing, Ageing Management Program (AMP), Plant Life Extension (PLEX), Scoping & screening, Long Term Operation (LTO).

volume-23-1

Periodic Safety Review as a Key Element in the Process for Lifetime Extension and Relicence of Unit 5 at Kozloduy NPP – E. Kichev

The article presents the methods used for the Periodic Safety Review (PSR) of unit 5 at Kozloduy NPP. It is based on the Bulgarian Nuclear Regulatory Agency (BgNRA) requirements and the IAEA Specific Safety Guide SSG-25 – Periodic Safety Review for NPPs (2013). The role, requirements, objectives, scope, approach, stages and activities, and resources for […]