In the design of a spent-fuel (SF) storage, the consideration of burnup credit brings the benefits in safety and economic views. According to it, various SF burnup measurement systems have been developed to estimate high fidelity burnup credit, such as FORK and SMOPY. Recently, there are a few attempts to localize the SF burnup measurement system in South Korea. For the localization of SF burnup measurement systems, it is very important to build the isotope inventory data base (DB) of various kinds of SFs. In this study, we performed DeCART2D/MASTER core follow calculations and McCARD single fuel assembly (FA) burnup analyses for Hanbit unit 3 and confirmed the characteristic of the isotope inventory over burnup. Firstly, the core follow calculations for Cycles 1~7 were performed using DeCART2D/MASTER code system. The core follow calculation is very realistic and practical because it considers the design conditions from its nuclear design report (NDR). Secondly, the Monte Carlo burnup analyses for single FAs were conducted by the McCARD Monte Carlo (MC) transport code. The McCARD code can utilize continuous energy cross section library and treat complex geometric information for particle transport simulation. Accordingly, the McCARD code can provide accurate solutions for burnup analyses without approximations, but it needs huge computing resources and time burden to perform whole-core follow calculations. Therefore, we will confirm the effectiveness of the single McCARD FA burnup analyses by comparing the DeCART2D/MASTER core follow results with the McCARD solution. From the results, the use of single FA burnup analyses for the establishment of the DBs will be justified. Various FAs, that have different 235U enrichments and loading pattern of fuel rods and burnable absorbers, were considered for the burnup analyses. In addition, the results of the sensitivity analyses for power density, initial enrichment, and cooling time will be presented.

The effect of Li2O addition on precipitation behavior of uranium in LiCl-KCl-UCl3 has been investigated in this study. 99.99% LiCl-KCl eutectic salt is mixed with 10wt% UCl3 chips at 550°C in the Pyrex tube in argon atmosphere glove box, with 10 ppm O2 and 1 ppm H2O. Then, Li2O chunks are added in mixed LiCl-KCl-UCl3 and the system has been cooled down to room temperature for 10 hours to form enough UO2 particles in the salt. The solid salt has been taken out from the glove box, and cut into three sections (top, middle and bottom) by low-speed saw for further microscopic analysis. Three pieces of solid salt are dissolved in deionized water at room temperature and the solution is filtered by a filter paper to collect non-dissolved particles. The filter paper with particles is baked in vacuum oven at 120°C for 6 hours to evaporate remaining moisture from the filter paper. Further analysis was performed for the powder remaining on the filter paper, and periphery of the powder (cake) on the filter paper. Scanning electron microscopy (SEM), electron diffraction spectroscopy (EDS), and X-ray powder diffraction (XRD) are adopted to analysis the characteristic of the particles. From SEM analysis, the powders are consisted of small particles which have 5 to 10 m diameter, and EDS analysis shows they are likely UO2 with 23 at. % of uranium and 77 at. % oxygen. Cake is also analyzed by SEM and EDS, and needle like structures are widely observed on the particle. The length of needle is distributed from 5 to 20 m, and it has 6 to 10 at. % of chlorine, which are not fully dissolved into deionized water at room temperature. From XRD analysis, the particles show the peak position of UO2, and the result is well matched with the SEM-EDS results. We are planning to add more Li2O in the system for fully reacting uranium in UCl3, and compare the results to find the effect of Li2O concentration on UO2 precipitation.

Minuartia laricina (L.) Mattf. is a Korean native plant with high potential as a commercial flowering potted plant due to its compactness and long flowering duration. However, because this plant is a groundcover, it is susceptible to lodging and leggy growth. Therefore, this study investigated the effects of plant growth retardants (PGRs) on the inhibition of stem elongation and flowering characteristics of M. laricina. Commercial products, Trimmit, Cycocel, and B-Nine, were used for the exogenous PGR application of paclobutrazol (PBZ), chlormequat chloride (CCC), and daminozide (DMZ), respectively. Application concentrations were 50 and 100 mg·L-1 for PBZ; 100, 500, and 1,000 mg･L-1 for CCC; and 500, 1,000, and 2,000 mg·L-1 for DMZ. Paclobutrazol was the only PGR that inhibited stem elongation. The stem lengths of the plants treated with 50 or 100 mg·L-1 PBZ were 2.2 cm (13%) or 9.8 cm (57%) shorter, respectively, than those of the control. 50 mg·L-1 PBZ retarded stem growth effectively without negatively affecting flowering or other growth parameters, whereas 100 mg·L-1 PBZ caused excessive dwarfing and significantly reduced flowering by 59%. CCC and DMZ applications were ineffective for growth control. Flowering time was accelerated with most PGRs, except for 2,000 mg·L-1 DMZ, reducing the time to flowering by 2–8 days. These results indicate that the stem growth of M. laricina was successfully inhibited with PBZ but not with CCC or DMZ. Thus, we concluded that a single application of 50 mg·L-1 PBZ or similar treatment is effective in miniaturizing M. laricina without causing harm to its growth or aesthetic value, such as the flower number. Additionally, because CCC and DMZ are not persistent in the growing medium, testing multiple application times for these PGRs is crucial.

Sustainable capacity building of the rice value chain in Africa is essential in achieving the rice self-sufficiency and poverty alleviation. The breeding capacity enhancement has also been at the heart of AfricaRice’s mandate. Therefore, the Korea-Africa Food and Agriculture Cooperation Initiative (KAFACI) has concentrated breeding capacity enhancement for young breeders or breeding technicians of national research institutes in the KAFACI member countries. Four-month trainings have been conducted at the Regional Training Center located in Saint Louis, Senegal. The actual practice training is as follows; First is to learn practical skills and techniques of key aspects of rice breeding which are field preparation and layout, sowing, transplanting, fertilizer application, weed control, water management, hybridization/crossing, selection, yield and yield components determination, and rice palatability testing. Second is to learn some theoretical aspects of plant breeding through lectures including basic principles of breeding, evaluation for biotic and abiotic stresses, and statistical analysis. Third is to learn about the accurate use of field and lab equipment for rice breeding. Forth is to learn about proper scientific reporting and presentation. The courses were organized twice per year following two rice cultivation seasons in Senegal. From 2019, a total of 24 trainees participated in the 4 month courses. We believe they have acquired the basic knowledge and skills to implement rice breeding activities indpendently in their countries.

The Korea-Africa Food and Agriculture Cooperation Initiative (KAFACI) has been cooperating with AfricaRice since 2014 for the eradication of hunger and poverty in Africa through sustainable agriculture and its industrialization. At first, rice breeding activities for staple food production started with KAFACI member countries by sharing high-yielding Tongil-type rice breeding lines and varieties. The Africa Rice Development Partnership project entitled “Enhancement of high-yielding rice germplasm and breeding capacity of rice producing countries in Africa” is implemented for the period from 2016 to 2025 with three phases. The actual rice breeding activities have been conducted by applying anther culture haploid breeding technology in the laboratory and field of AfricaRice Saint-Louis center. The 1,547 elite lines selected through participatory variety selection were distributed to 21 national breeders of KAFACI member countries. These lines derived from the 1,181 cross combination and 34,616 breeding lines on Korea and AfricaRice germplasm crossed. Among them 11 new Tongil-type rice varieties have been selected and registered in the national variety catalogue of Senegal, Mali, Rwanda, Malawi, and Tanzania.

Iris laevigata, which belongs to the Iridaceae, is now designated as an “endangered” (EN) grade by Korea Forest Service because it does not have many natural sites known for its reckless development and damage to its natural habitats. This study was carried out to establish the propagation protocol from seed to restore the native habitat of the I. laevigata and to utilize it for ornamental purposes. Basically, the appearance and internal structure of seeds were observed and imbibition experiments were conducted. Germination rate was measured by cold stratification experiment, after warm followed by cold stratification experiment, and GA3 treatment experiment. The seeds had underdeveloped embryos, which had grown to about 25% of those of fully matured seed before germination. In the controlled laboratory experiment, after cold stratification at 5°C for 0, 4, 8, or 12 weeks, the seeds germinated to 0, 11.7, 43.4, or 51.7%, respectively, after 4 weeks of incubation at 25°C. After warm stratification (25°C, 8 weeks) followed by cold stratification for 0, 4, 8, or 12 weeks, the seeds germinated to 0, 51.7, 85.0, or 88.3%, respectively, after 4 weeks of incubation at 25°C. GA3 treatment did not overcome the dormancy. Our study determined the dormancy type of I. laevigata seed. Imbibition experiments showed that there was no physical dormancy, and it was also found that there was an underdeveloped embryo when it was observed that the embryo was growing according to the period of incubation. A nd t he e m bryo grew a t relatively w arm temperatures. It is concluded that the seeds of I. laevigata have morphophysiological dormancy (deep simple MPD). This is the first report to determine the dormancy type in seeds of this valuable ornamental plant.

The lattice thermal expansion of zirconium-based samples containing tin, niobium, and iron elements at a temperature range of 30–870°C with intervals of 40°C was studied by in situ hightemperature X-ray diffraction (HT-XRD). The a- and c-axes lattice constants of the hexagonal Zr crystal structure for the zirconium-based samples were calculated by Pawley refinement using the in situ HT-XRD spectra. The a-axis lattice parameters for the zirconium-based samples with tin element overall decreased, whereas those for the samples containing niobium or iron elements are not declined, as compared to those for a pure zirconium sample. It suggests that the lattice thermal expansion along the a-axis direction of the hexagonal Zr crystal structure for zirconium-based samples was suppressed by the tin element. This effect is the greatest when the content of tin element added in zirconiumbased sample is 3wt%. On the other hand, the c-axis lattice parameters for all the zirconium-based samples overall increase as compared to the pure zirconium, indicating no suppression effect by tin, niobium, and iron elements, in contrast to the a-axis lattice constants.