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Telah dilakukan ekstraksi konsentrat thorium oksalat hasil olah monasit memakai ekstraktan Tri – n - Oktil Posfin Oksida (TOPO).  Pengotor  yang paling banyak  terkandung dalam konsentrat thorium oksalat adalah cerium (Ce) dan lantanum (La).  Tujuan penelitian ini adalah untuk memurnikan thorium (Th) dengan memisahkan Ce dan La dengan cara ekstraksi. Ekstraksi dilakukan secara batch dan bertingkat.  Larutan umpan atau fase air adalah 10 gram konsentrat Th oksalat yang dilarutkan dalam 10,08 M HNO3 sehingga volume menjadi 100 mL dan fase organik adalah TOPO dalam kerosen.  Stripping setiap tingkat ekstraksi dilakukan tiga kali, yaitu stripping pertama memakai air, stripping kedua memakai asam oksalat 5%, dan stripping ketiga memakai air. Waktu ekstraksi setiap tingkat 15 menit dan waktu stripping setiap tingkat  5 menit dengan perbandingan fase air dengan fase organik adalah 1 berbanding 1.  Parameter yang diteliti  adalah persentase TOPO dalam kerosen dan jumlah tingkat ekstraksi. Pemakaian TOPO dalam kerosen yang optimum 5% dan jumah tingkat ekstraksi 3.  Pada ekstraksi I diperoleh konsentrat Ce dan pada tingkat ekstraksi II dan III diperoleh Th.  Efisiensi ekstraksi Th  tingkat II sebesar 39,76% dan efisiensi ekstraksi Th tingkat III 26,33%. Koefisien distribusi (Kd) Th tingkat ekstraksi II adalah 0,7587 dan Kd Th tingkat ekstraksi III  1,0096. Efisiensi ekstraksi Th total adalah  80,08 %, efisiensi ekstraksi Ce total  56,12%,  efisiensi ekstraksi La total  1,54.  Faktor pisah (FP) Th – Ce pada ekstraksi I adalah 1,00, FP Th – La pada ekstraksi I  92,07, FP Th – Ce pada ekstraksi II adalah 250,24 dan FP Th – La  pada ekstraksi II adalah ∞,  FP Th – Ce pada ekstraksi III 124,22 dan FP Th – La pada ekstraksi III adalah ∞. Faktor pisah total Th – Ce sebesar 1,4270 dan Faktor pisah total Th – La  47,0459. Kadar Th oksalat pada ekstraksi II sebesar 97,06%, kadar Th oksalat pada ekstraksi III  98,00 %. The extraction of thorium oxalate concentrate as processing product  of monazite using  Tri  Octyl Posfine Oxide  (TOPO) has been done.  The most impurities contained in thorium oxalate concentrate are Ce (cerium) and La (lanthanum). The purpose of this study is to purify Th by separating Ce and La using extraction process. The extraction is done by bacth and multistage. The solution of  feed or water phase is 10 grams of Th oxalate concentrate dissolved in 10.08 M HNO3 so that the volume becomes 100 mL and the organic phase is TOPO in kerosene. Stripping in each stage conducted three times, first stripping use water, second stripping use 5 % oxalic acid and the third stripping use water. Extraction time at every stage is 15 minutes and stripping time at every stage is 5 minutes with  ratio of aqueous phase to organic phase = 1 : 1 . The parameters were studied % TOPO - kerosene and number of extraction stage. The optimum usage of TOPO in kerosene is 5 %.  On extraction I obtained Ce concentrate and on extraction II and III obtained Th concentrates. The extraction II efficiency of Th is 39.76 % and extraction III efficiency of Th is 26.33 % . Coefficient of distribution (Kd) of Th in stage II is 0.7587 and Kd of Th in stage III is 1.0096.  Total extraction efficiency of Th is  80.08 %, total extraction efficiency of Ce is 56.12 %,  and total extraction efficiency of La is 1.54 %. The separation factor of  Th – Ce in extraction I  is 1.00 and separation factor of  Th – La in extraction I  is 92.0,  separation factor of  Th – Ce in extraction II  is 250.24, and separation  factor of  Th – La in extraction II  is ∞.  Separation factor of  Th – Ce in extraction III  is 124.22 and separation factor of  Th – La in extraction III  is  ∞.  Total  separation  factor of  Th – Ce  is 1.4270 and total separation factor of  Th – La is 4.0459.  The content of Th oxalate in stripping product from the extraction II is 97.06 % and in stripping product from  the extraction III is 98.00%.

The leaching kinetics of sodium zirconate in hydrochloric acid has been studied. Sodium zirconate was the result of melting zircon sand after separation from sodium silicate. The variables studied were temperature, contact time and the mole ratio of solvent to feed (R). These study aims are to determine the optimum conditions, the reaction rate controller and the reaction rate constant (k) and activation energy (Ea) for the leaching process of sodium zirconate (Na2ZrO3).This experiment performed by leaching the sodium zirconate in hydrochloric acid with various temperatures of 50 °C, 70 °C and 90 °C, the mole ratio of solvent to feed of 5, 7 and 9, and various contact time of 10 minutes to 50 minutes. The experimental data were analyzed according to the kinetic models for heterogeneous reaction processes by using shrinking core models. It was found that the leaching of sodium zirconate in hydrochloric acid solution is controlled by chemical reaction with the activation energy was-62.974 kJ/mol. The optimum conditions for the performed experiment in the leaching step were achieved at a temperature of 50 °C, the mol ratio of solvent to feed of 5 and contact time of 50 minutes with the conversion of sodium zirconate was 43.43% and the value of reaction rate constant was 0.0027 min−1.

Sintering process is the final stage of fuel kernel manufacturing prior to the coating process. This stage is very important part of the whole process, because it will determine the feasibility of UO2 kernel to comply with the specifications of HTR reactor fuel. The objective of this research was to obtain UO2 kernel with the density of ≥ 95% TD. The results showed that the highest density reached 92.56% TD or about 10.1441 g/cm3. This condition of sintering was gained at the temperature of 1400 °C with sintering time of 2 hours. The sintering product diameter gained was around 919 μm the specific surface area 4.4213 m2/g, and a total pore volume 4,751 x 10−3 cm3/g. The density of UO2 kernel produced from this research is the best compared to previous finding because of its density already approaches the HTR fuel specification requirements.

Cerium oxide (CeO2) and Neodymium oxide (Nd2O3) nanoparticles using local content have been synthesized by precipitation method. The CeO2 and Nd2O3 nanoparticles were characterized by X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) to analyze the material phase and structure. The XRD spectrum shows that CeO2 and Nd2O3 nanoparticles have face-centered cubic and hexagonal, and cubic, respectively. The anti-microbial activity of CeO2 and Nd2O3 nanoparticles was analyzed by diffusion method using gram-negative bacteria (E.coli, S.aeureus, P. aeruginosa), and gram-positive bacteria (S. entericatyphi, L. monocyogenes), and fungus (C. albicans). The result confirms that CeO2 and Nd2O3 nanoparticles have the capability of patogen microbia inhibition. The CeO2 nanoparticles have the effective activities of inhibition for the microbia of S. aereus and S. entericatyphi, whereas Nd2O3 nanoparticles can inhibit the microbia of P. aeruginosa, S. entericatyphi, and  L. monocyogenes.