Dr. Jiaxin Chen

Coolant Chemistry & Corrosion

Dr. Jiaxin Chen received his Ph.D degree in 1995 from the Department of Inorganic Chemistry, University of Gothenburg (Sweden). Since 1997 he has been working for Studsvik Nuclear AB in behalf of Swedish nuclear power utilities and authority as well as international customers. Currently, he holds a position as senior specialist in Studsvik Corrosion and Water Chemistry Laboratory.

What was your major in university?

I started my university education in China at the age of 16, majoring in Ceramics, and completed my Master degree in Inorganic Non-metallic Materials. I got my first job as university teacher for 3 years and later moved to Sweden to pursue PhD degree study. After that I continued to work at the High Temperature Corrosion Center, Chalmers University of Technology until I was employed by Studsvik. Breathing in the academic environment for about 19 years I had prepared myself fundamental knowledge in materials science, hand-on skills in using advanced analytical techniques and critical thinking.

What made you to start working for nuclear industry?

In 90’s a great deal of attention was paid to fuel crud and its potential impact on fuel performance and plant radiation field, and Studsvik was very active in the field. My former boss, Mr. Bo Rosborg, was keen on recruiting someone with solid chemistry background to handle the programs. After having a job interview with me, as final check he called my professor in the university asking for his opinion about me, he told me later, “On the other side of telephone line, your professor was silent for a few seconds, then recommended that I better find someone else. I knew then I have found the right person for the job.” That was how I started at Studsvik.

Describe your first job for nuclear industry

My first job was to identify what fuel crud was and how it was affected by zinc injection in a Swedish BWR. The problem was that fuel crud was so radioactive that it was hardly accepted by any non-nuclear laboratories having advanced analytical equipment. Luckily we had two high precision Guinier-Hägg focusing cameras at Studsvik site for doing X-ray powder diffraction. We first equipped the instrument with necessary ventilation systems and developed a procedure for radioactive sample preparation and safe handling. We then did a number of diffraction studies. By accurately measuring spinel crystal cell parameter, I was able to conclude that the spinel phase in fuel crud was not zinc ferrite but a solid solution with increasing zinc occupancy in the spinel structure on newer fuels. I had also made literature reviews on the subject and performed some dissolution tests using synthetic but irradiated crud in high temperature water.

After decades long studies, fuel crud is now no longer viewed as an “unidentified” matter but new crud-induced problems have just got more advanced. The question like “How many pores in a fuel crud layer are closed pores that may hamper its heat transfer property?” would need advanced analytical solutions. To answer the call, I have successfully introduced the first-of-its-kind SEM/FIB serial sectioning and 3D reconstruction for pore connectivity study on fuel crud. The results have made it possible for modellers to use the real 3D geometry of a fuel crud layer in their thermal conductivity calculations.

You seem to have worked a lot with electron microscopy. Are you an electron microscopist?

No, I am not. As material researcher micro-structural examination is an important part of my job. Electron microscopy is one of my favourite research tools and it has a special place in my heart. During my university education I had at least 4 different occasions to learn electron microscopy including advanced phase contrast theory taught by Professor Hans Nordén and practical microscope operation. Collaborating with some talented electron microscopists in universities and research institutes, I was among the early adopters of SEM/FIB to prepare high quality TEM specimens from thin oxide films, crack tips formed on various reactor materials for TEM examination, and produced a large number of high quality micro-structural images that revealed information of previously unknowns for our customers. We have confirmed, for example, the presence of lithium tetra-borate crystals being formed in fuel crud layer in simulated CIPS occurrences, bonaccordite to be a commonplace in PWR fuel crud, and several silver containing phases in fuel crud of different origins that might contribute to Ag-110m induced plant radiation field. My main research focus is about the issues occurring at the interface between reactor materials and coolant. Fuel crud, corrosion and radiation field buildup are among my top job lists.

What else do you do at Studsvik?

Studsvik Nuclear is basically a consulting company for nuclear industry. It has well-equipped laboratories that are capable of handling radioactive fuel and structural components and performing simulation of material-coolant interaction with autoclave technology. In addition to many advanced analytical facilities at Studsvik site, we also cooperate with other organizations and make use of research resources in universities and national laboratories in order to provide a broad job offering to our customers. Over years I have worked in some very different fields, such as developing scanning gamma spectroscopy for TSP crevice chemistry study and radiation field buildup examinations, infrared ellipsometry as non-descaling method for corrosion kinetics studies. I also work as supervisor and examinator for university students in their thesis works and as adjunct professor at Chalmers University of Technology, promoting knowledge exchange between nuclear industry and universities. During 2003-2005 I was sent by Swedish Research Council to European Fusion Development Agreement, a consortium based in Germany, working as Responsible Officer for International Fusion Materials Irradiation Facility.

What do you do for fun?

Although my job takes up my largest time of my daily life, I have learnt to enjoy my ordinary family life, do things like swimming and taking a long walk with my wife during weekend, outing with good friends. More recently I am learning to do some small car reparations and maintenance jobs, which are practical and actually quite fun.