Simulation of flow conditions in nuclear power plant reactor pressure vessel lower plenum experimental facility

master's thesis

Blaž Kamenik (Author), Jure Marn (Mentor), Ivo Kljenak (Co-mentor)

Abstract

The flow conditions during the experiment LIVE2D on reactor core melt behaviour in the lower plenum of a reactor pressure vessel, performed at the Karlsruhe Institute of Technology (Germany), were simulated with a Computational Fluid Dynamics computer code. In this hypothetical severe accident scenario in a pressurized water reactor nuclear power plant, the melt is divided into an oxidic layer and a metallic layer on top of it, and the oxidic layer is volumetrically heated due to decay heat. In the experiment, oil and salt were used as simulant materials for metallic and oxidic melt, respectively. The main goal of performed simulations was to investigate the so-called “focusing effect”, where a thin layer of the reactor vessel steel wall is exposed to high heat flux. Due to the length of experiment, which exceeds 100 hours, only intervals of the melt behaviour were simulated. Four cases were simulated. The first case investigated different boundary conditions for the oil layer behaviour for layer thickness 35 mm. The second case investigated the same conditions with added modelling of the reactor vessel steel wall and salt crust from the lower layer. The third case used similar modelling as the second case to investigate the oil layer behaviour for layer thickness 75 mm. The fourth case investigated both salt and oil layers for oil layer thickness 75 mm. Different analytical and numerical calculations were performed to determine heat losses from simulant liquids to the surroundings, which played an important part in the experiment.

Keywords

nuclear power plant;severe accident;reactor core melt;lower plenum;heat flux focusing effect;

Data

Language:	English
Year of publishing:	2019
Typology:	2.09 - Master's Thesis
Organization:	UM FS - Faculty of Mechanical Engineering
Publisher:	[B. Kamenik]
UDC:	621.318.43:621.311.25(043.2)
COBISS:	22761750
Views:	733
Downloads:	130
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	Slovenian
Secondary title:	Simulacija tokovnih razmer v eksperimentalni napravi spodnjega plenuma reaktorske posode jedrske elektrarne
Secondary abstract:	Simulirane so bile tokovne razmere tekom eksperimenta obnašanja taline v spodnjem plenumu reaktorske posode tlačnovodnega jedrskega reaktorja LIVE2D, izvedenega v Karlsruhe Institute of Technology (KIT, Nemčija).. Opisani eksperiment je bil simuliran s programom za računsko dinamiko tekočin ANSYS Fluent, ki transportne enačbe mehanike tekočin rešuje na trenutni časovni in lokalni krajevni skali. Uporabljen je bil laminaren model toka. V tem hipotetičnem scenariju težke nesreče v tlačnovodnem jedrskem reaktorju se talina v spodnjem plenumu reaktorske posode razdeli na spodnji oksidni sloj in zgornji kovinski sloj. V tem poskusu je bila za simuliranje oksidne plasti uporabljena plast evtektične taline soli, ki je bila volumetrično greta, nad katero je bila plast olja, ki simulira kovinski sloj. Glavni cilj izvedenih simulacij je bilo proučevanje efekta osredotočenja gostote toplotnega toka, kjer je tanek sloj jeklene stene reaktorske posode izpostavljen visoki gostoti toplotnega toka. Zaradi dolžine eksperimenta, ki presega 100 ur, sta bila simulirana samo dva intervala. Izvedeni so bili štirje sklopi simulacij. Prvi sklop simulacij je simuliral le oljni sloj debeline 35 mm in je bil namenjen proučevanju različnih robnih pogojev ter vplivu le-teh na rezultate. V drugem sklopu simulacij je bila za isti primer (debelina oljnega sloja 35 mm) dodana modelirana jeklena stena in predpostavljena oblika skorje soli. Tretji skop simulacij je simuliral višino oljnega sloja 75 mm, prav tako z dodano steno in predpostavljeno obliko skorje soli. Četrti sklop simulacij je simuliral oljni sloj in sloj raztaljene soli skupaj, z modelirano jekleno steno. Zaradi toplotnih izgub, ki so se pojavile tekom eksperimenta, so bili uporabljeni različni analitični in numerični izračuni za določitev toplotnih izgub v okolico.
Secondary keywords:	jedrska elektrarna;težka nesreča;talina reaktorske sredice;spodnji plenum;efekt osredotočenja gostote toplotnega toka;magistrske naloge;
Type (COBISS):	Master's thesis/paper
Thesis comment:	Mag. delo, Univ. Maribor, Fakulteta za strojništvo, Energetsko, procesno in okoljsko strojništvo
Pages:	XVI, 78 str.
ID:	11206201