Procjena neodređenosti teške nesreće u nuklearnoj elektrani s lakovodnim reaktorom

master's thesis

• Title (english): Uncertainty assessment of a severe accident in a light-water reactor nuclear power plant
• Author: Karlo Ivanjko
• Mentor: Siniša Šadek (mentor)
• Committee member: Siniša Šadek (predsjednik povjerenstva)
• Committee member: Krešimir Trontl (član povjerenstva)
• Committee member: Ninoslav Holjevac (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; Zagreb
• Defense date and country: 2022-09-21, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering

Abstract

Nuklearna sigurnost je jedan od najvažnijih zadataka prilikom analiziranja rada nuklearnih elektrana. U svrhu predviđanja ponašanja termohidrauličkih procesa unutar reaktora, koriste se računalni softveri poput programa ASYST. S obzirom na kompleksnost stvarnog nuklearnog postrojenja, ASYST pruža mnogo dodatnih značajki uključenih u program. S njima se mogu postići kvalitetniji i precizniji krajnji rezultati. Jedna od takvih značajki je analiza neodređenosti. Neodređenosti su uzrokovane slučajnim varijabilnostima parametara koji opisuju sustav te nedostatkom preciznosti računalnih fizikalnih modela. Analiza neodređenosti se provodi u svrhu određivanja kriterija prihvatljivosti, budući da ispunjenje kriterija prihvatljivosti i dobivanje licence za rad predstavlja glavnu zadaću nuklearnih postrojenja. U ovom diplomskom radu, napravljena je analiza neodređenosti na temelju modela Nuklearne elektrane Krško napisanog u obliku koda za ASYST program. U svrhu provedbe proračuna neodređenosti, odabrani su ulazni parametri neodređenosti čije vrijednosti variraju prema definiranim funkcijama gustoće vjerojatnosti. Osim toga, određeni su razina i interval pouzdanosti te broj bitnih faktora s ciljem dobivanja broja potrebnih proračuna. Nakon simulacije 22 proračuna, prikazani su grafovi svih važnijih varijabli primarnog kruga nuklearne elektrane (tlakovi, temperature, protoci, proizveden vodik, oštećenje jezgre) te su određene granice neodređenosti. Statističkom analizom izračunate su disperzije rezultata, određene su mjere važnosti kojima se utvrđuju veze između ulaznih i izlaznih veličina te je provedena analiza osjetljivosti.

Abstract (english)

Nuclear safety is one of the most important tasks when analyzing the operation of nuclear power plants. In order to predict the behavior of thermohydraulic processes inside the reactor, computer software such as the ASYST program is used. Considering the complexity of a real nuclear plant, ASYST provides many additional features included in the program. With them, better quality and more precise final results can be achieved. One such feature is uncertainty analysis. Uncertainties are caused by the random variability of the parameters that describe the system and the lack of precision of computer physical models. Uncertainty analysis is carried out for the purpose of determining the acceptance criteria, since the fulfillment of the acceptance criteria and obtaining the operating license represent the main task of nuclear facilities. In this thesis, an uncertainty analysis was made based on the Krško Nuclear Power Plant model written in the form of code for the ASYST program. In order to carry out the uncertainty calculation, input uncertainty parameters were selected whose values vary according to the defined probability density functions. In addition, the confidence level and interval and the number of important factors were determined with the aim of obtaining the number of necessary calculations. After the simulation of 22 calculations, graphs of all the most important variables of the primary system in the nuclear power plant (pressures, temperatures, flows, produced hydrogen, the core damage) are presented and uncertainty limits are determined. Statistical analysis was used to calculate the dispersion of the results, to determine the importance measures used to assess the connections between input parameters and output results and to perform a sensitivity analysis.

• Keywords: program ASYST; neodređenost; Nuklearna elektrana Krško; teška nuklearna nesreća; vodik; rastaljena jezgra; granice neodređenosti; mjere važnosti; analiza osjetljivosti
• Keywords (english): ASYST program; uncertainty; Nuclear Power Plant Krško; severe nuclear accident; hydrogen; molten core; limits of uncertainty; influence measures; sensitivity analysis
• Language: croatian
• URN:NBN: urn:nbn:hr:168:713661
• Study programme: Title: Electrical Engineering and Information Technology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka elektrotehnike i informacijske tehnologije (magistar/magistra inženjer/inženjerka elektrotehnike i informacijske tehnologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2023-01-14 08:57:02