Impact of innovative sphere-pac fuels on safety performances of sodium cooled fast reactors

319 Pages·2017·9.75 MB·English

by  Lena Andriolo

Impact of innovative sphere-pac fuels on safety
performances of sodium cooled fast reactors
Lena Andriolo
To cite this version:
Lena Andriolo. Impact of innovative sphere-pac fuels on safety performances of sodium cooled fast
reactors. Fluids mechanics [physics.class-ph]. Université Grenoble Alpes, 2015. English. ￿NNT:
2015GREAI067￿. ￿tel-01257910￿
HAL Id: tel-01257910
https://theses.hal.science/tel-01257910
Submitted on 18 Jan 2016
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THÈSE
Pour obtenir le grade de
DOCTEUR DE L’UNIVERSITÉ GRENOBLE ALPES
Spécialité : Mécanique des fluides, Énergétique, Procédés
Arrêté ministériel : 7 août 2006

Présentée par
Lena ANDRIOLO

Thèse dirigée par Elsa MERLE-LUCOTTE et
codirigée par Andrei RINEISKI

préparée au sein du Laboratoire KIT/IKET/TRANS
dans l'École Doctorale IMEP-2 : Ingénierie – Matériaux, Mécanique,
Énergétique, Environnement, Procédés, Production

Impact des combustibles
sphere-pac innovants sur les
performances de sûreté des
réacteurs à neutrons rapides
refroidis au sodium

Thèse soutenue publiquement le 19 août 2015,
devant le jury composé de :
M. Piero RAVETTO
Professeur, Polytechnic University of Turin, Rapporteur
M. Rudy KONINGS
Professeur, Delft University of Technology, Rapporteur
Mme Elsa MERLE-LUCOTTE
Professeur, Grenoble-INP PHELMA, Directrice de thèse
M. Andrei RINEISKI
Professeur, Karlsruhe Institute of Technology, Co-directeur de thèse
Mme Fabienne DELAGE
Ingénieur-chercheur, CEA de Cadarache, Co-encadrante de thèse
Mme Sandra POUMEROULY
Ingénieur-chercheur, Electricité de France, Examinatrice
M. Janne WALLENIUS
Professeur, KTH Royal Institute of Technology, Examinateur
M. Werner MASCHEK
Professeur, Karlsruhe Institute of Technology, Examinateur

ACKNOWLEDGMENTS
Acknowledgments

This work would not have been possible without the support and motivation of many people and I
would like to take the opportunity to thank them.
First of all, I would like to thank Prof. Schulenberg for giving me the opportunity to perform my
doctoral research at the Institute of Nuclear and Energy Technologies.
I thank Prof. Janne Wallenius for having agreed to be the chair of my doctoral committee as well as
Prof. Piero Ravetto and Prof. Rudy Konings for having carefully read my manuscript and for their
advice on my PhD. I thank also Dr. Sandra Poumerouly and Dr. Werner Maschek for having kindly
accepted to be part of my PhD committee.
Je tiens à remercier tout particulièrement ma directrice de thèse Prof. Elsa Merle-Lucotte pour son
soutien et sa sollicitude tout au long de ces trois années, ce qui n'était pas chose facile avec la
distance géographique.
I would like to thank my co-professor and group leader Dr. Andrei Rineiski for the trust he placed in
me to fulfill this work and for the guidance and support he continuously provided me and which
made this work a success. De même, je souhaite remercier vivement ma co-encadrante Dr. Fabienne
Delage pour toute l'aide, l'enthousiasme et les discussions que nous avons pu avoir au long de ces
trois années.
Mein besonderer Dank gilt Herrn Dr. Werner Maschek für die stets professionelle Betreuung und
wertvolle Unterstützung und die anregenden Diskussionen. Mit seinen zahlreichen konstruktiven
Ideen/Gedanken hat er maßgeblich zum Gelingen der Arbeit beigetrag. Es war und ist ein Privileg für
mich, mit ihm arbeiten zu dürfen.
Weiterhin möchte ich mich bei Frau Claudia Matzerath Boccaccini herzlich für ihre engagierte und
warmherzige Begleitung bedanken. Es hat mich immer wieder gefreut mit dir und Werner auf
PELGRIMM Dienstreise zu fahren, wo uns immer die unwahrscheinlichsten Geschichten passierten.
Diese Arbeit wäre in dieser Form nicht ohne Dr. Edgar Kiefhaber und seine glücksbringenden „4-
blättrigen Kleeblätter“ möglich gewesen: Herzlichen Dank Edgar für deine unermüdliche
Unterstützung deine große Fachkunde und äußerst hilfreichen Ratschläge zum wissenschaftlichen
Arbeiten. Ein großes Dankeschön auch für deine akribische Korrektur der Doktorarbeit.
I also would like to thank my friends and colleagues Dr. Barbara Vezzoni and Dr. Fabrizio Gabrielli, for
their unlimited support, their invaluable technical advices and the numerous laughters we had.
Whenever I felt the need to discuss some issues, you took the time to discuss them with me and gave
me precious support to go on with my work. I am very greatful for this (and for the nice coffee
breaks!).
AKCNOWLEDGMENTS
I would like to thank as well all my present and former colleagues, Xue-Nong, Rui, Michael, Mattia,
Vladimir, Simone, Marco, Dalin, Donella, Shisheng, Max, Liancheng, Eva and Aleksandra for creating
such a positive work environment and for their valuable teaching on the SIMMER code
comprehension or problem solving, let it be about step 1 or step 3 failures...
I also would like to thank my dearest friends, Simon, Lucie, Lila, Nacho, Alberto, Hiroshi, Luca,
Fidelma and all others, should they be in Karlsruhe or somewhere else around the globe, for
surrounding me during this special time. There were of course some difficult moments but I was
lucky enough to have you by my side.
Enfin, je souhaite remercier de tout coeur mes parents Stéphane et Inge ainsi que ma soeur Lisa,
pour m'avoir toujours soutenue et pour avoir pris soin de moi durant ces trois années: c'est grâce à
vous si j'ai pu aller si loin.
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CITATION

The future belongs to those
who believe in the beauty of their dreams
- E. Roosevelt

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CITATION

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ABSTRACT
Abstract

Future sodium cooled fast reactors (SFRs) have to fulfill the GEN-IV requirements of enhanced safety,
minimal waste production, increased proliferation resistance and high economical potential. This
PhD project is dedicated to the evaluation of the impact of innovative fuels (especially minor
actinides bearing oxide sphere-pac fuels) on the safety performance of advanced SFRs with
transmutation option.
The SIMMER-III code, originally tailored to mechanistically analyze later phases of core disruptive
accidents, is employed for accident simulations. During the PhD project, the code has been extended
for a better simulation of the early accident phase introducing the treatment of thermal expansion
reactivity effects and for taking into account the specifics of sphere-pac fuels (thermal conductivity
and gap conditions). The entire transients (from the initiating event to later accident phases) have
been modeled with this extended SIMMER version.
Within this PhD work, first the thermo-physical properties of sphere-pac fuel have been modeled and
casted into SIMMER-III. Then, a new computational method to account for thermal expansion
feedbacks has been developed to improve the initiation phase modeling of the code. The technique
has the potential to evaluate these reactivity feedbacks for a fixed Eulerian mesh and in a spatial
kinetics framework. At each time step, cell-wise expanded dimensions and densities are calculated
based on temperature variations. Density factors are applied to the expanded densities to get an
equivalent configuration (in reactivity) with original dimensions and modified densities. New cross
sections are calculated with these densities and the reactivity of the equivalent configuration is
computed. The developed methods show promising results for uniform and non-uniform expansions.
For non-uniform expansions, model improvement needs have been identified and neutronics
simulations have been carried out to support future SIMMER extensions. Preliminary results are
encouraging.
In the third part of the PhD, two core designs with conventional and sphere pac fuels are compared
with respect to their transient behavior. These designs were established in the former CP-ESFR
project: the working horse core and the optimized CONF2 core (with a large sodium plenum above
the core for coolant void worth reduction). The two fuel design options are compared for steady
state and transient conditions (unprotected loss of flow accident, ULOF) either at beginning of life
(BOL) or under irradiated conditions. Analyses for sphere-pac fuel reveal two main phases to
consider at BOL. At start-up, the non-restructured sphere-pac fuel shows a low thermal conductivity
compared to pellet fuel of same density. However, the fuel restructures quickly (in a few hours) due
to the high thermal gradients and its thermal conductivity recovers. The fuel then shows a behavior
close to the pellet one. The study also shows that the CONF2 core leads to a very mild transient for a
ULOF accident at BOL. The large upper sodium plenum seems to effectively prevent large positive
reactivity insertions. However, stronger reactivity and power peaks are observed under irradiated
conditions or when americium is loaded in the core and lower axial blanket.
This PhD work demonstrates, under current simulation conditions, that sphere-pac fuels do not seem
to cause specific safety issues compared to standard pellet fuels, when loaded in SFRs. The accurate
simulation of core thermal expansion reactivity feedbacks by means of the extended SIMMER version
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