Uranium mining industry in Bulgaria started operation in 1945, followed by in situ leaching technology in the beginning of 1970-ties. Two decades later (1990) all uranium mining sites in the country are closed. However the radioactive discharges from these sites continue cause various environmental problems and after the closing phase. Sborishte (Southern Bulgaria, Sliven region) […]
volume-22-1
The Role of NCRRP in Education and Training on Radiation Protection – N. Chobanova
Radiological protection is in constant motion, raised by new developments and research in the medical and industrial sectors. Radiation protection and safety associated with the application of ionizing radiation depends strongly on the skills and expertise of the professionals. The International Basic Safety Standard places great emphasis on education and training for all persons engaged […]
Factors Influencing the Nuclear Knowledge Loss Risk in Republic of Bulgaria: External Factors Overview – I. Naydenov, K. Filipov, L. Pironkov
In the recent years, personnel ageing, loss of critical knowledge and gaps in education and training are observed worldwide. Nuclear knowledge preservation, transfer, and expansion are critical for sustaining viable nuclear power sector and increasing nuclear applications’ usage in non-energy fields. Moreover, efficient knowledge management is paramount for ensuring safe, reliable, and effective operation of […]
Possibilities for High Level Waste Reduction through Transmutation of Minor Actinides – K. Zashev
For many years there has been a sustained international interest in partitioning and transmutation of the actinides, and particularly americium, neptunium and curium, mainly because of the major contribution to the decay heat and radiotoxicity of spent nuclear fuel. Therefore in the current report are examined the possibilities for high level waste reduction through transmutation […]
Scoping and Screening of Systems & Components and Plant Programs Relevant to Long Term Operation of Kozloduy NPP Units 5&6 – V. Popov
In the present material main steps and procedures for the plant lifetime extension of Kozloduy NPP Units 5&6 are discuss. The paper traces the various stages in the period 2007–2015 important for plant life extension. Keywords: Ageing, Ageing Management Program (AMP), Plant Life Extension (PLEX), Scoping & screening, Long Term Operation (LTO).
Comparison of Innovative and Evolutionary NPPs in a Country-Specific Context for Bulgaria (Based on IAEA INPRO KIND – ET Methodology) – P.P. Groudev, N.N. Zaharieva, C.A. Margeanu, M. Constantin
A comparison of two hypothetical Nuclear Energy Systems (NES) has been performed: NES-1 – GEN III/III + evolutionary design (LWR) and NES-2 – GEN IV – so called innovative design: LFR technology /SFR technology Two cases for GEN IV NES have been considered: NES-2 (at present time) and NES-3 (in 10–15 years); for example, ALFRED […]
Content of Sr-90 and Cs-137 in Sediments and Soils from the Vicinity of the NPP Kozloduy during the Period 2008-2010 – R. Kotova, R. Kamenova-Totzeva, V. Badulin
The systemic radiation monitoring of the environment in the vicinity of the Kozloduy NPP is exceptionally significant part of the radiation protection. For monitoring purposes and in accordance with the control program annually samples are being analyzed to determine the content of anthropogenic long-lived radionuclides of a biological significance such as 90Sr and 137Cs. The […]
Rn Intensity Variation in the Vicinity of Moussala BEO, Moussala Peak – I. Penev, C. Angelov, S. Georgiev, N. Arhangelova
Using a scintillation gamma-spectrometer with a NaI detector, the 222Rn intensity variations were registered at the Moussala Basic Ecological Observatory (BEO) located at Moussala Peak at an altitude of 2925 m above sea level. The gamma-spectrometer works in a “non-stop” mode, except for a few time periods when the weather conditions or other causes interrupt […]
Indoor Radon Measurements in Plovdiv City – M. Cenova, B. Kunovska, K. Ivanova, A. Angelova
Radon is a radioactive gas that is formed naturally by the breakdown of uranium in soil, rock and water. Recent epidemiological findings from residential studies demonstrate a statistically significant increase of lung cancer risk from prolonged exposure to indoor radon. The new requirements of ICRP and WHO include the control of indoor exposure due radon […]
Calibration of the Alpha-Spectrometry System for Radiological Evaluation of Systems and Equipment Subject to Decommissioning at Units 1-4 of Kozloduy NPP – E. Stoyanova, G. Neshovska, Tz. Nonova
During the radiological inventory evaluation of systems and equipment subject to decommissioning at units 1-4 of Kozloduy NPP, and for the purpose of radioactive waste characterization, it is necessary to determine the activity of a number of difficult-to-measure alpha-emitting radio nuclides (isotopes of uranium, plutonium, americium and curium). Their determination requires destructive analysis involving radiochemical […]
Investigation of an Innovative Material for Neutron Shielding – M. Mitev, D. Dimitrov, Z. Zahariev, A. Naydenov
The effectiveness in neutron attenuation of an innovative composite material for neutron shielding has been investigated in comparison with a conventional neutron shielding material – paraffin. For this purpose a set of calculations were performed and validated with adequate measurements. The Monte Carlo N-Particle (MCNP) computer code was used for these calculations. The measurements were […]
Prevention of Early Containment Melt-Through during Severe Accident on WWER-1000, B-320 Light Water Reactor – D. Popov, V. Yurukov
An analysis was performed within PHARE Project BG 01.10.01 in 2003-2004 that has discovered a vulnerability of LWR WWER-1000, V-320 design consisting in early (up to one hour) containment melt-through via ionization chambers channels during severe accident. Based on this analysis, a separate project was started to find out the possibilities to retain the melt […]
Improving the Results of QUENCH-16 Experiment by Using New Models of MELCOR 2.1 – P. Vryashkova, P. Groudev
The air ingress experiment Quench-16 was analysed with MELCOR 2.1. The code version of MELCOR 2.1 included oxidation model for air at low and high temperatures. This study explores the influence of oxygen concentration on the hydrogen generation and temperature escalation. The influence of the oxygen concentration on the kinetics behaviour was observed from the […]
Fuel Performance Modelling under LOCA Conditions by TRANSURANUS Code – N. Mihaylov, S. Kalburov, S. Boneva, M. Manolova
The ability to calculate accurately the performance of light water reactor (LWR) fuel rods under long-term irradiation conditions and various operational transients and hypothetical accidents is an important objective of the reactor safety investigations. The IAEA Coordinated Research Project(CRP) FUMAC (Fuel Modelling in Accident Conditions), focuses on the accident conditions and supports the improvement and […]
Application of ASTEC Computer Code for Validation of SAMG Based on LB LOCA Scenario for VVER 1000 – P. Groudev, A. Stefanova, R. Gencheva
In case of unsuccessful application of VVER1000 Emergency Operating Procedures (EOPs) for different reasons during the accident in Nuclear Power Plant (NPP), the operators have to leave the EOPs and to start applying Severe Accident Management Guidance (SAMGs). This paper presents calculation results using computer code for validation of operator actions during severe accident conditions […]