TY - CHAP AU - Hajas, Tamás Zoltán AU - Tolnai, Gábor AU - Pázmán, Előd AU - Légrády, Dávid ED - Eva, Davidson ED - Luka, Snoj TI - Optimization of the Forced Fission Coefficient via Stochastic Calculus T2 - Proceedings of the International Conference on Physics of Reactors PHYSOR 2024 PB - American Nuclear Society CY - Westmont (IL) SN - 9780894487972 PY - 2024 SP - 1591 EP - 1599 PG - 9 DO - 10.13182/PHYSOR24-43571 UR - https://m2.mtmt.hu/api/publication/35294285 ID - 35294285 N1 - Conference code: 201724 Export Date: 16 September 2024 Correspondence Address: Hajas, T.Z.; Institute of Nuclear Techniques, Hungary; email: hajas@reak.bme.hu AB - This paper uses Stochastic Differential E quations (SDEs) t o m odel t he v ariance o f t he Dynamic Monte Carlo (DMC) method.The Non-Analog Monte Carlo (NAMC) model was applied to the Stochastic Point-Kinetics equations (SPKe).The focus of this paper is modelling forced fission as a variance reduction technique with a general analytic representation for the variance.As a result, this paper shows an analytic derivation for the optimal fission biasing verifying that similar end result is obtained with time-dependent calculations. © 2024 AMERICAN NUCLEAR SOCIETY. All rights reserved. LA - English DB - MTMT ER - TY - GEN AU - Orosz, Róbert AU - Varju, Tamás AU - Aranyosy, Ádám AU - Holl, Viktor AU - Hajas, Tamás Zoltán AU - Aszódi, Attila TI - RELAP5, TRACE and APROS Model Benchmark for the IAEA SPE-2 Experiment PY - 2024 PG - 62 UR - https://m2.mtmt.hu/api/publication/34865770 ID - 34865770 LA - English DB - MTMT ER - TY - JOUR AU - Hajas, Tamás Zoltán AU - Tolnai, Gábor AU - Margóczi, Márk AU - Légrády, Dávid TI - Noise term modeling of dynamic Monte Carlo using stochastic differential equations JF - ANNALS OF NUCLEAR ENERGY J2 - ANN NUCL ENERGY VL - 195 PY - 2024 PG - 19 SN - 0306-4549 DO - 10.1016/j.anucene.2023.110061 UR - https://m2.mtmt.hu/api/publication/34231211 ID - 34231211 N1 - Funding Agency and Grant Number: Ministry of Innovation and Technology of Hungary from the National Research, De-velopment and Innovation Fund [TKP2021] Funding text: This paper was supported by the UNKP-21-3 New National Excellence Program of the Ministry of Human Capacities.The research reported in this paper is part of project no. BME-EGA-02, implemented with the support provided by the Ministry of Innovation and Technology of Hungary from the National Research, Development and Innovation Fund, financed under the TKP2021 funding scheme. Authors acknowledge the support and the computational resources of the Wigner Scientific Computational Laboratory (WSCLAB) (the former Wigner GPU Laboratory) .r The research reported in this paper is part of project no. BME-EGA-02, implemented with the support provided by the Ministry of Innovation and Technology of Hungary from the National Research, De-velopment and Innovation Fund, financed under the TKP2021 funding scheme. Authors acknowledge the support and the computational resources of the Wigner Scientific Computational Laboratory (WSCLAB) (the former Wigner GPU Laboratory) . AB - Dynamic Monte Carlo (DMC) method recently became a relevant tool to perform kinetic calculations even on the scale of power plants and further to simulate coupled neutronics - thermal-hydraulics problems. DMC offers time-dependent, high fidelity calculations in very detailed and complex geometries in return for the high computational need. DMC provides stochastic results which is an indescribable property by the mathematics of the deterministic neutron transport. The stochasticity of the results also rises the unsolved problem of stability and convergence during the nonlinear, coupled DMC and thermal-hydraulics simulation. This paper aims to introduce the Stochastic Differential Equations (SDEs) in the field of Monte Carlo neutron transport for connecting the DMC method and differential equation formalism. The derivation of a Non-Analog Monte Carlo (NAMC) model is shown for the Stochastic Point-Kinetics equation (SPKe) to determine a noise model capable to approximate one trajectory of DMC. The theoretical framework allows the reader to observe analytic solutions for a random variate, the expectation and the variance of the reactor power. Also, analytic formulas are given for a simple system of coupled reactor physics and thermal-hydraulics without feedback. The analytic variance of the Monte Carlo simulated reactor power were compared to the calculations of GUARDYAN (GpU Assisted Reactor DYnamic ANalysis) code in a subcritical, a critical and a supercritical reactor models. LA - English DB - MTMT ER - TY - CHAP AU - Hajas, Tamás Zoltán AU - Tolnai, G. AU - Legrady, D. ED - Motta, AM ED - Olander, DR TI - Variance Analysis of the Coupling of Thermal-hydraulics and Point Kinetics with Stochastic Noise Term Modeling Dynamic Monte Carlo Behavior for later use in GUARDYAN T2 - 2022 International Conference on Physics of Reactors, PHYSOR 2022, Proceedings of TopFuel 2022 Light Water Reactor Fuel Performance Conference PB - American Nuclear Society (ANS) CY - La Grange Park (IL) SN - 9780894487873 PY - 2022 SP - 2502 EP - 2511 PG - 10 DO - 10.13182/PHYSOR22-37834 UR - https://m2.mtmt.hu/api/publication/34886488 ID - 34886488 N1 - Conference code: 196271 Cited By :1 Export Date: 29 May 2024 AB - This paper demonstrates that the mathematical tool of stochastic analysis is capable to create a mathematical base for the analysis of coupled dynamic Monte Carlo (MC) and thermal-hydraulics (TH) systems. Dynamic Monte Carlo (DMC) is evolving into a well-established method for neutron transport calculations, still, little has been analyzed the convergence properties of coupled DMC and thermal-hydraulics. Inspired by the GPU-based GUARDYAN DMC code, this research attempts to analyze the stochastic interaction between high fidelity stochastic neutronics and thermal-hydraulics codes thereby establishing the fidelity of the coupled results. One way for describing a stochastic system with the definitions of analysis is using stochastic analysis where the solution contains randomness. The goal of this paper is to introduce a heuristically created time-dependent noise model that is capable of reproducing the most important stochastic properties of DMC and to insert this noise term into point kinetics - thermal-hydraulics coupled system as confirmed by the obtained analytical solutions. Results were analyzed using stochastic analysis regarding convergence to steady-state values. In simulations we have found variance amplitude evolutions dependent on the heat removal boundary condition types, these results were supported by analytical solutions as well. © 2022 Proceedings of the International Conference on Physics of Reactors, PHYSOR 2022. All Rights Reserved. LA - English DB - MTMT ER - TY - GEN AU - Orosz, Róbert AU - Varju, Tamás AU - Aranyosy, Ádám AU - V., Holl AU - Hajas, Tamás Zoltán AU - Aszódi, Attila TI - RELAP5, TRACE and APROS Model Benchmark for the IAEA SPE-4 Experiment PY - 2022 PG - 188 UR - https://m2.mtmt.hu/api/publication/33141001 ID - 33141001 LA - English DB - MTMT ER - TY - JOUR AU - Légrády, Dávid AU - Tolnai, Gábor AU - Hajas, Tamás Zoltán AU - Pázmán, Előd AU - Parko, T. AU - Pos, I. TI - Full Core Pin-Level VVER-440 Simulation of a Rod Drop Experiment with the GPU-Based Monte Carlo Code GUARDYAN JF - ENERGIES J2 - ENERGIES VL - 15 PY - 2022 IS - 8 PG - 17 SN - 1996-1073 DO - 10.3390/en15082712 UR - https://m2.mtmt.hu/api/publication/32836401 ID - 32836401 N1 - Department of Nuclear Techniques, Institute of Nuclear Techniques, Budapest University of Technology and Economics, Budapest, H-1111, Hungary Wigner Research Center for Physics, Budapest, H-1121, Hungary MVM Paks NPP Ltd, Paks, H-7030, Hungary Cited By :2 Export Date: 29 May 2024 Correspondence Address: Legrady, D.; Department of Nuclear Techniques, Hungary; email: legrady@reak.bme.hu LA - English DB - MTMT ER - TY - JOUR AU - Varju, Tamás AU - Orosz, Róbert AU - Aranyosy, Ádám AU - Holl, Viktor AU - Hajas, Tamás Zoltán AU - Aszódi, Attila TI - Sensitivity analysis of the IAEA SPE-2 small-break LOCA experiment with RELAP5, TRACE and APROS system codes JF - NUCLEAR ENGINEERING AND DESIGN J2 - NUCL ENG DES VL - 388 PY - 2022 PG - 21 SN - 0029-5493 DO - 10.1016/j.nucengdes.2021.111630 UR - https://m2.mtmt.hu/api/publication/32683975 ID - 32683975 N1 - Funding Agency and Grant Number: Ministry of Innovation and Technology of Hungary from the National Research, Development and Innovation Fund; Paks II; [BME-NVA-02] Funding text: The research reported in this paper is part of project no. BME-NVA-02, implemented with the support provided by the Ministry of Innovation and Technology of Hungary from the National Research, Development and Innovation Fund, financed under the TKP2021 funding scheme. Furthermore, the first part of the previous SPE-4 model development was carried out in the framework of a research project supported by Paks II. Nuclear Power Plant Ltd. and MVM ERBE. The authors want to thank J ' ozsef B ' an ' ati and R ' obert D ' aniel R ' adi for their valuable comments and proposals made during the development of the RELAP5 model. AB - The Hungarian PMK-2 test facility is a scaled-down model of the VVER-440/213 type pressurized water reactors of Paks NPP, on which several measurement series have been carried out since the 80s. One of these series include four Standard Problem Exercises (SPE), primarily small-break loss-of coolant accident (SBLOCA) transients, performed in cooperation with IAEA. New RELAP5, TRACE and APROS models have already been developed and a comparative analysis of the results has been published recently for the PMK SPE-4 experiment. In that SBLOCA scenario, no high-pressure injection system (HPIS) was available, but a secondary side bleed and feed operation has been performed during the transient. This paper is a continuation of the previous one and presents the required model modifications and the analysis of the second SPE. The initiating event, similarly to the SPE-4 experiment, is a 7.4% break located at the top of the downcomer, while the main differences are that one line of the HPIS is available and no secondary side feed and bleed operation is performed in this case. One of the main objectives of the experiment was to verify that these safety measures are enough to prevent core dry-out. In addition to the investigation of this question, a sensitivity study was also carried out with respect to selected parameters that might have a significant impact on the characteristic of the simulated processes. The assessment of the results has also been performed with two quantitative methods, namely the Fast Fourier Transform Based Method with Signal Mirroring (FFTBM-SM) and Stochastic Approximation Ratio Based Method (SARBM). LA - English DB - MTMT ER - TY - JOUR AU - Varju, Tamás AU - Aranyosy, Ádám AU - Orosz, Róbert AU - Holl, Viktor AU - Hajas, Tamás Zoltán AU - Aszódi, Attila TI - Analysis of the IAEA SPE-4 small-break LOCA experiment with RELAP5, TRACE and APROS system codes JF - NUCLEAR ENGINEERING AND DESIGN J2 - NUCL ENG DES VL - 377 PY - 2021 SN - 0029-5493 DO - 10.1016/j.nucengdes.2021.111109 UR - https://m2.mtmt.hu/api/publication/31936687 ID - 31936687 LA - English DB - MTMT ER - TY - JOUR AU - Babcsány, Boglárka AU - Hajas, Tamás Zoltán AU - Mészáros, Péter TI - Tranziens reaktorfizikai folyamatok végeselem-módszeren alapuló diffúziós modellezése JF - NUKLEON J2 - NUKLEON VL - 13 PY - 2020 IS - 2 SN - 1789-9613 UR - https://m2.mtmt.hu/api/publication/31598097 ID - 31598097 LA - Hungarian DB - MTMT ER - TY - JOUR AU - Cséfalvay, Edit AU - Hajas, Tamás Zoltán AU - Mika, László Tamás TI - Environmental sustainability assessment of a biomass-based chemical industry in the Visegrad countries: Czech Republic, Hungary, Poland, and Slovakia JF - CHEMICAL PAPERS / CHEMICKÉ ZVESTI J2 - CHEM PAP VL - 74 PY - 2020 SP - 3067 EP - 3076 PG - 10 SN - 0366-6352 DO - 10.1007/s11696-020-01172-8 UR - https://m2.mtmt.hu/api/publication/31311023 ID - 31311023 N1 - Funding Agency and Grant Number: Budapest University of Technology and Economics (BME); Janos Bolyai Research Scholarship of the Hungarian Academy of SciencesHungarian Academy of Sciences [UNKP-18-4-BME-192]; National Research, Development and Innovation Fund [TUDFO/51757/2019ITM]; Thematic Excellence Program; National Research, Development and Innovation Office [KH 129508]; Higher Education Excellence Program of the Ministry of Human Capacities in the frame of Biotechnology research area of Budapest University of Technology and Economics (BME FIKP-BIO) Funding text: Open access funding provided by Budapest University of Technology and Economics (BME). Edit Csefalvay is grateful to the support of Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences, and UNKP-18-4-BME-192 Project. The research reported in this paper has been supported by the National Research, Development and Innovation Fund (TUDFO/51757/2019ITM), Thematic Excellence Program. This work was funded by National Research, Development and Innovation Office under projects KH 129508 as well as Higher Education Excellence Program of the Ministry of Human Capacities in the frame of Biotechnology research area of Budapest University of Technology and Economics (BME FIKP-BIO). Department of Energy Engineering, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, Műegyetem rkp. 3., Budapest, 1111, Hungary Department of Chemical and Environmental Process Engineering, Budapest University of Technology and Economics, Műegyetem rkp. 3., Budapest, 1111, Hungary Export Date: 24 May 2021 CODEN: CHPAE Correspondence Address: Cséfalvay, E.; Department of Energy Engineering, Műegyetem rkp. 3., Hungary; email: csefalvay@mail.bme.hu Funding details: Budapesti Műszaki és Gazdaságtudományi Egyetem, BME Funding details: Magyar Tudományos Akadémia, MTA, ÚNKP-18-4-BME-192 Funding details: Emberi Eroforrások Minisztériuma, EMMI Funding details: Nemzeti Kutatási, Fejlesztési és Innovaciós Alap, NKFIA, TUDFO/51757/2019-ITM Funding details: National Research, Development and Innovation Office, KH 129508 Funding text 1: Open access funding provided by Budapest University of Technology and Economics (BME). Edit Cs?falvay is grateful to the support of J?nos Bolyai Research Scholarship of the Hungarian Academy of Sciences, and ?NKP-18-4-BME-192 Project. The research reported in this paper has been supported by the National Research, Development and Innovation Fund (TUDFO/51757/2019-ITM), Thematic Excellence Program. This work was funded by National Research, Development and Innovation Office under projects KH 129508 as well as Higher Education Excellence Program of the Ministry of Human Capacities in the frame of Biotechnology research area of Budapest University of Technology and Economics (BME FIKP-BIO). Funding text 2: Open access funding provided by Budapest University of Technology and Economics (BME). Edit Cséfalvay is grateful to the support of János Bolyai Research Scholarship of the Hungarian Academy of Sciences, and ÚNKP-18-4-BME-192 Project. The research reported in this paper has been supported by the National Research, Development and Innovation Fund (TUDFO/51757/2019-ITM), Thematic Excellence Program. This work was funded by National Research, Development and Innovation Office under projects KH 129508 as well as Higher Education Excellence Program of the Ministry of Human Capacities in the frame of Biotechnology research area of Budapest University of Technology and Economics (BME FIKP-BIO). LA - English DB - MTMT ER -