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Mr. Muhammad Subhan (NPP alumni)’s paper was selected as a best paper of the 2021 KSME Reliability Division 2021 Spring Conference.

The Abstract of the paper is:
 Currently, the seismic analysis model of APR 1400 consists of beam and lumped mass in 2D separated model in horizontal direction and vertical direction. Also in the core, fuel assemblies are aggregated and simplified into few beam and lumped masses. WEC also used beam and lumped mass elements for the AP1000 seismic analysis model, but used 3D beam and mass to represent whole core where fuel assemblies are aggregated as well. The main purpose of the lumped mass and beam modeling of fuel assembly is to simplify model and make core dynamic analysis possible without aggregating all fuels in core into few beam elements and lumped masses. This research investigates 3D dynamic analysis modeling methodology of nuclear fuel assembly reflecting performance improvement of computer technology and analysis software functionality. A 3D modeling approach of FA was proposed in which fuel rods mass was lumped, CEA guide tubes and spacer grid are represented by beam elements and lower end-fitting and upper end-fitting are represented by shell elements. The FA dynamic analysis model so developed consists of 2,740 elements and 5,148 nodes. The model was optimized for the 1st mode from the test results of FA applying modal analysis. The model was successfully represents 1st mode modal values. Also the modal analysis results exhibits similarities for 2nd, 3rd and 4th modes, hence the model can be used for further dynamic analysis of fuel assembly such as seismic analysis or time-history analysis. The corresponding mode shapes revealed additional mode of twist motion that was not shown by current FA dynamic model of APR1400 or AP1000. This research revealed there are extra modes of twist motion that could induce contact between FAs and would require further investigation of dynamic interaction between FAs.

Mr. Ahmed Mohammed Abd El-Hameed Abd EL-Samed (Department of Nuclear Power Plant Engineering, second-year student) won the KNS (Korea Nuclear Society) scholarship 2021 based on his excellent academic performance.

The awarding ceremony for KNS scholarships had been held at KNS spring conferences before the pandemic; however, this year, there was no awarding ceremony since the KNS spring conference was held online due to the COVID-19.

On behalf of KNS, Prof. Eric Yee, Head of the Department of Nuclear Power Plant Engineering, and Prof. Kim Ju-youl, Mr. Ahmed’s advisor, awarded the certificate to Mr. Ahmed on 18 May 2021 at KINGS.

(from left to right) Prof. Kim Ju-youl and Mr. Ahmed.

 

 

(from left to right) Prof. Kim Ju-youl, Mr. Ahmed, and Prof. Eric Yee

 

Mr. Mostafa Mohammed Mousa (NPP alumni)’s paper was selected as a best paper of the 2020 KOSSE (The Korean Society of Systems Engineering) Fall Conference.

The summary of the paper is:

Operators in the nuclear power plant should follow the instructions and manage information from an enormous amount of processes, procedures, and guidelines. Quick analysis for monitoring data and executing the required action on time is very important for plant safety. For this reason, a recommender or an advisory system can be developed to aid the operator so that the necessary decisions and recommended procedures are carried out. Digital Twin technology provides rapid data analysis to find good insights from this data that will lead to the necessary action. Systems engineering approach (SE) was used in developing digital twin for the reactivity control system using the control element drive mechanism system to support operator actions. The Systems engineering is introduced for identifying the requirements, operational concept and associated verification and validation steps required in development process by linking each requirement to a validation or verification test with predefined success criteria. As application for this development, the CEDM Digital Twin is able to detect control element misalignment and power escalation due to excessive CEDM withdrawal to provide the operator with the required action according to the operation limits and conditions.

Attachment: The presentation “Application of SE Approach for CEDM Digital Twin, Mr. Mostafa Mohammed Mousa, Prof. Jae-cheon Jung, The Korean Society of System Engineering fall Conference, Jeju, Korea, November 26-27, 2020”

Mr. Thomas Tsuma Kalenga (NPP second-year)’s paper was selected as a best paper of the 2020 KIEE (The Korean Institute of Electrical Engineers) Summer Conference.

This paper seeks to develop a real-time surge arrester monitoring scheme to prevent failure of surge arrester. And analyzes the VCB switching transient voltages to confirm motor surge withstand capacity and adjust the GFR pick-up and delay settings to prevent false operation.

Attachment: The paper “Countermeasures Against Surge Arrester Failure and Ground Fault Relay False Operation in Medium Voltage Distribution Systems, Mr. Thomas Tsuma Kalenga, Prof. Choong-koo Chang, The Korean Institute of Electrical Engineers, Summer Conference, Busan, Korea, July 15-17, 2020”

Ms. Amy Nkirote Gichuru (NPP second-year)’s paper was selected as a best paper of the 2020 KSME (The Korean Society of Mechanical Engineers) Spring conference.

The purpose of the paper is to estimate the equivalent Young’s modulus of the APR 1400 nuclear fuel spacer grid to obtain a reduced model of the fuel assembly. The structural strength of nuclear fuel assemblies in the reactor core throughout the core life is important due to the need to withstand lateral static and dynamic loads resulting from external forces. This requirement ensures that there is a sustained coolant flow for the fuel assembly keeping proper geometry without structural deformation. For this study, first, a three dimensional model of the nuclear fuel spacer grid was developed to provide consistent predictions of the 16 x 16 type APR 1400 spacer grid and also act as the reference for the simulation. Secondly, a 5 x 5 spacer grid beam model is designed, representative of the spacer grid. Applying the boundary conditions for the solid model maximum directional deformation is obtained. Isotropic material properties are set as this is the reference. Orthotropic material properties for the beam model and Young’s modulus and shear modulus in the respective directions, maximum directional deformation, and the modulus parameters set to optimize these values. The optimized values of Young’s modulus and shear modulus are obtained subsequently and the equivalent Young’s modulus and reduced model of the spacer grid. The conservative modeling approach is used for this analysis due to the intricate shape of the nuclear fuel assembly spacer grid.

Attachment: The paper “Estimation of APR 1400 Nuclear Fuel Spacer Grid Equivalent Young’s Modulus for a Reduced Model of Fuel Assembly, Ms. Amy Nkirote Gichuru, Prof. Ihn Namgung, The Korean Society of Mechanical Engineers, Spring Conference, Jeju, Korea, July 15-17, 2020”