Analiza primjenjivosti vezanog programa RELAP5-GOTHIC na proračun akcidenta puknuća parovoda u nuklearnoj elektrani

scientific master's theses

• Title (english): Applicability analysis of coupled RELAP5-GOTHIC program for calculation of main steam line break accident in nuclear power plant
• Author: Mario Keco
• Mentor: Nenad Debrecin (mentor)
• Committee member: Davor Grgić (predsjednik povjerenstva)
• Committee member: Nenad Debrecin (član povjerenstva)
• Committee member: Željko Bogdan (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; (Department of Energy and Power Systems); Zagreb
• Defense date and country: 2005-11-29, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering; Power Engineering
• Universal decimal classification (UDC): 621.3 - Electrical engineering

Abstract

U slučaju loma glavnog parovoda dolazi do povećanog odvođenja mase i energije iz parogeneratora. To dovodi do povećanog odvođenja topline iz primarnog kruga što rezultira smanjivanjem temperature i tlaka primarnog rashladnog sredstva. Budući da primarno rashladno sredstvo ima negativni temperaturni koeficijent reaktivnosti, smanjivanje temperature u primarnom krugu dovodi do povećanja reaktivnosti i nivoa snage reaktora. U ovom akcidentu važnu ulogu ima kontejnment reaktora budući da on postaje ponor topline, tj. energije. Količina energije koju primi kontejnment direktno je povezana s odzivom primarnog kruga.
Uobičajeni način proračuna odziva primarnog kruga na akcident loma glavnog parovoda je korištenje sistemskog programa s fiksnim rubnim uvjetom ili vrlo pojednostavljenim modelom kontejnmenta. S druge strane, uobičajeni način proračuna odziva kontejnmenta na akcident loma glavnog parovoda je korištenje kontejnmentskog programa s rubnim uvjetom oslobađanja mase i energije modeliranim rezultatima iz sistemskog programa. Glavni nedostaci tog pristupa su nužnost konzervativnih pretpostavki za rubne uvjete koje nije moguće modelirati na odgovarajući način u pripadajućem programu i nužnost manipulacije velikim količinama podataka prilikom pripremanja ulaznih podataka za rubne uvjete u programima.
U radu je izvršena kvalitativna i kvantitativna analiza primjenjivosti eksplicitnog povezivanja modela primarnog kruga (program RELAP5) i modela kontejnmenta (program GOTHIC) vezanim programom R5G na proračun odziva primarnog kruga i kontejnmenta tijekom akcidenta puknuća glavnog parovoda na punoj snazi. Potvrđena je mogućnost primjene vezanog programa R5G na akcidente u sadašnjim lakovodnim reaktorima koji su tradicionalno analizirani pomoću odvojenih proračuna sistemskim i kontejnmentskim programima. Posebna vrijednost vezanog proračuna je mogućnost korištenja točnih vrijednosti tlaka u kontejnmentu za potrebe reaktorskog zaštitnog sustava. Pored toga, otvoren je i put za analizu čitavog niza kvarova u NEK-u u kojima je veza između primarnog ili sekundarnog sustava i kontejnmenta izraženija nego što je to slučaj kod HFP MSLB-a. Takvi su kvarovi karakteristični za vrijeme obustave i tijekom izmjene goriva kada je reaktorska posuda otvorena.

Abstract (english)

Main steam line break leads to increased mass and energy release from steam generator. This leads to increased energy removal from the Reactor Coolant System (RCS) which causes a reduction of coolant temperature and pressure. In the presence of a negative moderator temperature coefficient, the cooldown results in increased reactivity and power level. Reactor containment has an important role in this accident since it becomes a heat sink. The amount of energy received by containment is in direct relation with the primary circuit response.
Primary circuit response to main steam line break accident has usually been analysed with a system code with a fixed containment boundary condition or a very simplified model of containment. Containment response to main steam line break accident has usually been analysed with a containment code and a mass and energy release boundary condition modelled with data retrieved from the system code. Main setbacks of this approach are necessity of conservative boundary condition assumptions and a manipulation with large data sets in boundary condition input data preparation.
A qualitative and quantitative analysis of applicability of explicit coupling for primary system model (RELAP5) and containment model (GOTHIC) with coupled R5G program for calculation of hot full power main steam line break accident has been conducted. Applicability of R5G coupled code for accident analysis in current light water reactors, which were traditionally analysed with separate system and containment codes, has been confirmed. An exceptional feature of coupled code is an opportunity to calculate reactor protection system conditions with correct values of pressure in containment. Besides that, a broad spectrum of accidents with stronger connection between primary or secondary system and containment can now be analysed for NEK. Typical examples of these accidents are those that take place during shutdown and refuelling when reactor vessel is opened.

• Keywords: Vezani program; lom glavnog parovoda; RELAP5; GOTHIC; R5G
• Keywords (english): Coupled code; main steam line break; RELAP5; GOTHIC; R5G
• Language: croatian
• URN:NBN: urn:nbn:hr:168:905826
• Study programme: Title: Postgraduate master programme in electrical engineering; Study programme type: university; Study level: postgraduate; Academic / professional title: Magistar znanosti elektrotehnike (Magistar znanosti elektrotehnike)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2019-07-16 13:31:09