Teaching the algorithms that are crucial for nuclear reactor modelling

Chalmers Professor and reactor physicist Christophe Demazière is worried about the fact that nuclear engineering educational programmes are being phased out at universities throughout Europe. 
Recently he released a book on nuclear reactor modelling. It describes the methods and algorithms used for representing, with computer models, the behaviour of such systems, and their multi-physics and multi-scale aspects. 
There is a real danger that the society cannot maintain a sufficient level of knowledge and expertise for the more than 100 nuclear reactors operating in Europe and providing more than 25 percent of the electricity. One of the pillars of nuclear power safety relies on the demonstration that the system remains controllable under postulated scenarios. This demonstration heavily depends on numerical simulations. It is thus essential that the analysts and engineers using such tools are fully aware of the algorithms on which these tools are built, and their limitations,” says Christophe Demazière, who has more than 20 years of experience in nuclear reactor modelling. 

New pedagogical approaches

He describes the book as an accessible and pedagogical guide to the advanced methods used to model nuclear reactor systems. It also includes more than 70 short lectures summarizing the main concepts and related quizzes the readers can train on. 
“The video lectures and the quizzes represent a new pedagogical concept – to help the reader building a conceptual understanding of the topics. The recorded lectures are meant to extract the main features of each topic covered, the details being presented in the book. The quizzes ensure that the reader comprehends the subject and process it exercising high-order thinking skills. Feedback and additional information are also provided to the reader when answering the quizzes.”

Presenting the big picture ​

Beyond the new pedagogical approaches, the book has also some unique features content wise. 
“In my own education, I had the feeling that the knowledge provided in terms of modelling was very fragmented and scattered, focusing on some specific methods without clearly explaining the relation between those and the overall modelling of such complex systems. The main purpose of the book is to provide an overview of all important aspects of nuclear reactor modelling, during normal and abnormal situations not leading to core damage."
The book is written with a holistic approach to the subject, presenting the big picture before focusing on the details. Furthermore, since nuclear reactors are by essence multi-physics systems, several interdependent fields of physics need to be simultaneously modelled in order to properly describe the behaviour of such systems. 
"Until recently, the modelling of such systems was carried out in a mono-physics mindset by different “scientific communities”, each community having its own paradigms, the coupling with the other physics being introduced artificially or in simplistic terms. I really wanted to break this conservatism in the approach to nuclear reactor modelling, so that the students are equally knowledgeable in all fields that are important and relevant from a modelling viewpoint.” 

Built on feedback from students

Christophe Demazière has written the book with the reader’s experience in focus, capitalizing on feedback given by his students while teaching this subject at Chalmers for more than ten years. Now he hopes that master’s and PhD students as well as experts in the field will find the book, the videos and the quizzes useful and interesting. Careful attention was paid, while preparing the book and its digital resources, to enriching the reader’s experience.​

 “In addition to get the overall picture of the modelling of nuclear reactors, the algorithms detailed in the book are derived from scratch and the introduced approximations are thus clearly stated. With the increased complexity of the simulation software used these days, the analysts and engineers tend to use the modelling tools as “black boxes” without clearly knowing the underlying principles and assumptions used. I wanted to make the readers of the book fully aware of the methods and approximations, so that they can use the tools with confidence, in the range of validity the tools and methods were developed for.” 

Sharing the true marvel of nuclear reactor modelling

Christophe Demazière arranges courses and workshops in nuclear reactor modelling on a regular basis. Besides the nuclear power safety aspects, he also enjoys inspiring others by sharing his enthusiasm in modelling these complex systems. 

"The modelling of nuclear reactor systems is something that always fascinated me, and especially how to represent the behavior of neutrons (having a femto-metre size) in a strongly heterogeneous system of several meters in size. Moreover, with the interplay existing between the heat produced by fission, the cooling of the reactor, and the corresponding influence on the distribution of neutrons, being able to faithfully represent the behavior of such systems requires a lot of ingenuity. This is especially true when considering the development of modelling techniques that are affordable in computing time. Whereas the book focuses more on conceptual understanding, the workshops target hands-training exercises and more active forms of learning. More specifically, the students have to develop and implement from scratch some of the methods described in the book for modelling a nuclear reactor. With the workshops, I really want the students to understand the true marvel of the computing methods and be aware of the limitations of the codes they have been developing, using or will use in their career. In the forthcoming workshops that I will organize, I will heavily rely on the book, videos and quizzes, as a way for the students to get prepared to such workshops in an efficient manner.”

Text and photo: Mia Halleröd Palmgren, mia.hallerodpalmgren@chalmers.se



For more information, contact:  

Christophe Demazière​, Professor, Department of Physics, Chalmers, +46 31 772 30 82, demaz@chalmers.se​​

Published: Tue 17 Dec 2019.