Projects / Programmes
Simulation of selected design extension conditions without core melt
| Code |
Science |
Field |
Subfield |
| 2.03.02 |
Engineering sciences and technologies |
Energy engineering |
Fuels and energy conversion technology |
| Code |
Science |
Field |
| T140 |
Technological sciences |
Energy research |
| Code |
Science |
Field |
| 2.03 |
Engineering and Technology |
Mechanical engineering |
extended design accidents, realistic simulations, pressurized water reactor model, separate experiments, integral experiments
Researchers (11)
Organisations (1)
| no. |
Code |
Research organisation |
City |
Registration number |
No. of publicationsNo. of publications |
| 1. |
0106 |
Jožef Stefan Institute |
Ljubljana |
5051606000 |
90,664 |
Abstract
After the Fukushima Dai-ichi accident in 2011, a need for further improvement of nuclear safety was identified in the world. This comprises also of application of the 2014 revised European directive on nuclear safety with reinforced safety objectives, i.e. prevention and mitigation of severe accidents in existing operating reactors (for advanced reactors severe accident prevention and mitigation is part of design basis). The European directive was implemented also in Slovenian regulation. Nuclear safety of nuclear power plant is demonstrated by safety analyses. Before the Fukushima Dai-ichi accident, the safety analyses of existing reactors have been performed for design basis accidents only, where a single equipment failure or human error is considered. Accident conditions with multiple failures or human errors, also named design extension conditions, that may lead to severe accidents have not been considered in those analyses. Therefore, new computer simulations are needed to study the robustness of existing NPPs to design extension conditions.
The purpose of the proposed project is an independent analysis of selected design extension conditions without core melt aiming to independently assess the licensing calculations and by this to improve the understanding of the reactor response on multiple equipment failures and human errors. The project is organised in four (4) work packages (WPs).
The main objective of the first work package WP1 is to analyse the physical phenomena and processes which are expected to occur in design extension conditions selected for the simulation. The study will focus on safety of nuclear reactors. As the modern nuclear reactor system operates at a level of sophistication whereby the human reasoning and simple theoretical models are simply not capable of bringing to light a full understanding of system's response to the imposed perturbation, the predictions with computer codes are needed.
The main objective of the WP2 is to evaluate the adequacy of TRACE (TRAC/RELAP Advanced Computational Engine) computer code for simulation of design extension conditions. State-of-the-art TRACE code has been developed for safety analyses of loss-of-coolant accidents and operational transients, and other accident scenarios in pressurized light-water reactors and boiling light-water reactors. It can also model the phenomena occurring in experimental facilities designed to simulate transients in reactor systems.
Work package WP3 focuses on development of a validated TRACE input model for Krško nuclear power plant (NPP) – a two-loop pressurized water reactor (PWR). For preparation and validation of the TRACE input model, a SNAP (Symbolic Nuclear Analysis Package) tool will be used to develop input models, run the calculations, post-process the results and to visualize and animate the phenomena and processes. Validation of advanced thermalhydraulic TRACE computer code requires detailed data for the Krško nuclear power plant, experimental data and detailed information on the considered transients and accident conditions.
In the work package WP4 the selected TRACE simulation results will be compared with the results of the RELAP5 computer code. Additional RELAP5 calculations will be performed for the purpose of code-to-code comparison and thorough validation of TRACE results. The final goal of the proposed analyses is to show if there is a need for additional equipment to mitigate the selected design extension conditions.
Significance for science
The simulation results of the project will contribute to better understanding of the phenomena and processes during design extension conditions. The simulations and development of the TRACE input model for the new accident scenarios will have a significant impact on the development and validation of thermal-hydraulic system codes.
The results will also allow active cooperation, required by the international organisations like the Nuclear Energy Agency (NEA) at OECD or the International Atomic Energy Agency (IAEA) or the U.S. NRC CAMP programme. Such cooperation will enable the access to the state-of-the-art knowledge in the field of nuclear safety.
Significance for the country
In Slovenia, the RELAP5 computer code is currently used as an analysis tool for licensing of design extension conditions. In this context, the newly developed TRACE input model will present the independent evaluation tool for licensing of safety analyses of design extension conditions.
The project will provide a basis for future more accurate analyses of the existing and potential new nuclear power plant Krško.
The expected results and gained knowledge will be also used for education and training in the area of nuclear safety. The relevant results will be disseminated through the lectures to nuclear industry and regulatory bodies, in the undergraduate and postgraduate education in the nuclear engineering field.
Most important scientific results
Interim report
Most important socioeconomically and culturally relevant results
Interim report
