INTERNSHIP REPORT ON
C O D I N G F O R T R A N S I E N T S O LV E R AT
L ABORATORYOF COMPUTATIONAL REACTORPHYSICS & EXPERIMENTULSAN NATIONAL INSTITUTE OF SCIENCE &T E C H N O LO GY

TIAN QINNUCLEAR REACTOR ENGINEERING L AB
HOKKAIDO UNIVERSITYJ U N E 3 - AU G U S T 2 , 2 019

Acknowledgement .........................................................................................3Summary ........................................................................................................4Content ...........................................................................................................5
1. Introduction ..........................................................................................................5
2. Description of the internship ...................................................................................5
2.1 research intern activities ......................................................................................5
2.2 daily life & foods in Ulsan ....................................................................................6
3. Reflection of the internship .....................................................................................7conclusion .......................................................................................................7

AC KNOWLEDGEMENTFirst, I would like to thanks Prof. Chiba, the supervisor of mine in Hokkaido University, forproviding me the opportunity to do an internship within the institute. Also, for theacceptance from Prof. Lee in Computational Reactor Physics & Experiment (CORE), UlsanNational Institute of Science & Technology, where in last two months, the research about
coding for transient solver is conducted. Without the assistances from the professors, I
couldn’t have gain such a change and to learn more knowledge about reactor physics ares ina more comprehensive way.
Secondly, before get to Korea for the internship, thanks so much for our CEED oﬃce todeliver this oversea internship for both Japanese’s suspend and internship students. During
the internship period, the help from research colleagues can not be forgotten. It’s the Mr.
Dos who provided tremendous help for not only the standard procedures but also for thedaily life in dormitory.
Last but not least, great appreciation for their friendly hospitality from Korean students,including Mr. Kyeongwon Kim, Mr.Dongmin Yun, Mr Yunki Jo and Mr. Jinsu Park.

SUMMARYThis report details a two-month internship at CORE Lab., I worked in the Lab. Of
Computational Reactor physics and Experiment, which belongs to School of Mechanical,
Aerospace and Nuclear Engineering, UNIST. Apparently, this lab is a “nuclear engineering”
research group, which includes reactor physics, thermal hydraulics and nuclear safety forfission system, on the other hand, research about the fusion system is also conducted, andnuclear material/ fuel cycle is one the the research lab. So, for the CORE lab is an academic
laboratory dedicated to the research in nuclear reactor physics. The laboratory actively
develops theoretical methods and computer codes to tackle neutron transport and diﬀusion
theory in all its aspects: collision with medium, slowing-down, scattering, absorption,nuclear fission, chain reaction, secondary particle production and nuclide transmutation.
The laboratory manages the knowledge required for reactor core design, analysis andoperation and conducts studies in the fields of criticality, reactivity feedback and reactivity
control, reactor kinetics, nuclear fuel depletion, perturbation theory, deep-penetration
shielding, steady-state and transient simulations, reactor design and safety analysis, andmany more.
CORE lab as well as Prof. Lee preserver good reputation in the field of nuclear reactor
physics, since I am researching the application of boundary element method (BEM) into sp3
equation, essentially speaking, the purpose is to develop a steady-state solve with BEM, itwould be the great opportunity for me to learn how to solve the transport equation withtime variables. In the research group of Prof. Lee, development of RAST-K 2.0, with theaims to be used by utilities to perform in-core fuel management studies, core design
calculations, load follow simulation and transient analysis in neutronics. However, rightnow, it’s limited to PWR calculation, for the kernel part, a new spatial method name
Triangle-based Polynomial Expansion Nodal (TPEN) was introduced to discretize thehexagonal geometry for fast reactor.

CONTENT
1. INTRODUCTION
The internship program is benefit from the Oversea internship program of CEED oﬃce ofDepartment of Engineering. First, the dissuasion with the supervisor of your lab isnecessary, in which, some conclusion shall be made, such as where are you going to visit,
and what kind of research I would like to work on, but this all depends on every individual.
Secondly, with the help of professor Chiba, the CEED oﬃcer will contact you or, I will be
asked to participate an introduction meeting in our department.

2. DESCRIPTION OF THE INTERNSHIP
2 .1 R E S E A R C H I N T E R N A C T I V I T I E S
Since my internship period is limited, only 9 weeks are available for me to accomplish thetask, the first day I went to the lab, professor will conduct a meeting with other possible
mentors, based on my past research experiences about practice of neutrons diﬀusion
equation, which covers the inner iteration and outer iteration, and basic acceleration
method. The professor indicted that I could do the coding work for transient solver, which
would be of great help for my future study and work. However, for me as a first year studentof master course, I had no idea how to judge if a topic is suitable for me or not, but withfully trust of professors, which has not only experiences in research but also in mentoring
young researcher. On the other hand, they were used to a researcher in our lab did thesimilar work, but within two years, so I accept this proposal and begin my work.
After a 9- week schedule had been put up with. The first two weeks basically, I need to readthe docs about theories and prepare my first presentation. Then the next 4 weeks would bethe actually coding time for the implementation, which is not so diﬃcult since the there areexisting necessary subroutines available from PARCS code system, a another transient code
system developed by Purdue University, USA. It has been authorized by NRC for nuclear
safety evaluation. After finished the implementation, the second and third presentation wasdelivered, the major part of the solver is finished, but the most challenging session is how to
debug the finished subroutines and make it work with reasonable results. Unfortunately, inthe final 2-3 week, I stuck and no eﬀective progress had been made in this period.
In the CORE lab, research activities are active and covers wide range in nuclear reactor
physics, and all of which are closely related to the actually application/ industries, which canbe found in the website of code development, on the other hand, research about the reactor
design and nuclear data research with machine learning is one the topic as well.

2 . 2 D A I LY L I F E & F O O D S I N U L S A N
When it comes to Korean food, like when we are talking about Japanese food, the first dish I
could think about it the kimchi, which essentially you can find it in every meal either in theuniversity cafeterias or outside restaurants. And it might be little bit spicy for Japanesenormally.
In the UNIST campus, there several cafeteria you can choose, and unfortunately, you haveno option to cook in you apartment unless you’re going to rent a house around thedowntown. In each meal, the cost is around 5000 ~ 7000 won (won refers to the Koreancurrency, and it’s about 500 ~ 700 yen). As for how does it looks, it can be found in thepreviously uploaded report by Mr. Nihira at Jan, 2018(in Japanese)and Mr. Fan at Dec. 2018
(in English).
Since the campus locates in the mountain, but there are bus in the campus, by which you
can go to the downtown for shopping or buying some daily necessaries. And it would takearound 15 min or 50 min, depending which area you would like to visit.

FIG:Location of UNIST in Ulsan city

3. REFLECTION OF THE INTERNSHIPThe way how Korean students work is kind of diﬀerent from japan, however, it may be forsimilar with china, for example, for graduate school student, both China and Korea will
provide students with salary, which means, students can get paid while studying, which isgood since students can works more and the finical burden can be released, and more
students would be willing to get a degree, as a result, indeed, more students in China andKorean choose to get a PhD. Degree with combined program. While, in Japan, when
students choose to continue the master study, the work in lab is more like research at least,
for me I have the option to research, which I personally more enjoy.
Since in UNIST, the research is more closed to the actually industry application, with theexperience in such research group, It fills me with some what the nuclear field can bebenefited from my own research, however, right now, the research I’m working on is kind ofbasic, and can not contribute anything to other’s people not even the industry. But since I’mmaster students, I am not sure what I can achieve, one thing I could make sure is keep
learning and try my best at this moment and present the best of mine.

CONCLUSION
It would be a great experience for students at younger age to engage international research
activities. Most B4 students will participate the research meeting before entering the mastercourse, which should be the besting timing. So it encourage students no matter you are a
Japanese or international students to have such an experience, definitely, it will benefit you.
Try to plan you future as soon as possible and get a conversation with other people, withprofessor and CEED oﬃcer.