ASPEK KINETIKA REAKSI KERNEL U3O8 DENGAN GAS H2 TERHADAP KARAKTERISTIK ENERGI AKTIVASI, KONSTANTA LAJU REAKSI DAN RASIO O/U KERNEL UO2 - Damunir . (Jurnal Teknologi Bahan Nuklir, 2007)
ABSTRAK ASPEK KINETIKA REAKSI KERNEL U3O8 DENGAN GAS H2 TERHADAP KARAKTERISTIK ENERGI AKTIVASI, KONSTANTA LAJU REAKSI DAN RASIO O/U KERNEL UO2. Aspek kinetika reaksi kernel U3O8 dengan gas H2 terhadap karakteristik energi aktivasi, konstanta laju reaksi dan rasio O/U kernel UO2 telah dipelajari. Kernel U3O8 direaksikan dengan gas H2 di dalam reduktor dengan variasi suhu dan waktu reaksi. Suhu reaksi divariasi pada suhu 600, 700, 750, 800 dan 850 °C dengan tekanan 50 mmHg selama 3 jam dalam media gas N2. Waktu reaksi divariasi selama 1, 2, 3 dan 4 jam pada suhu 750 °C dengan kondisi yang sama. Hasil reaksinya adalah kernel UO2. Aspek kinetika reaksi antara kernel U3O8 dengan gas H2 di atas meliputi karakterisasi energi aktivasi minimum (AE), konstanta laju reaksi dan rasio O/U kernel UO2. Energi aktivasi minimum ditentukan dari koefisien arah garis lurus dari persamaan ln [{Db. Ro{1-(1- Xb)1/3 } / b t Cg ] = -3,9406x103 / T + 4,044 yang diperoleh. Dengan mengalikan koefisien arah sebesar -3,9406x103, tetapan gas ideal (R) sebesar 1,985 kal/mol dan perbedaan molaritas koefisien reaksi sebesar 2, diperoleh energi aktivasi minimum (AE) sebesar 15,644 kkal/mol. Konstanta laju reaksi (ks) ditentukan menggunakan persamaan kontrol reaksi kimia berorde satu dan persamaan Arrhenius, sedangkan rasio O/U ditentukan dengan metode gravimetri. Hasil analisis konstanta laju reaksi (ks) dengan persamaan kontrol reaksi kimia adalah 0,775 - 1,671 det-1 dan persamaan Arrhenius pada suhu 650 - 850 °C sebesar 0,674 - 2,914 det-1. Rasio O/U pada setiap perubahan konstanta laju reaksi tersebut sebesar 2,03 - 2,014 dan rasio O/U pada perubahan waktu reaksi 1 - 4 jam sebesar 2,04 - 2,014. Hasil percobaan menunjukkan bahwa energi aktivasi minimum berpengaruh pada konstanta laju reaksi berorde satu dan rasio O/U kernel UO2. Kondisi optimum adalah pada konstanta laju reaksi 1,43 det-1, rasio O/U kernel UO2 2,01 pada suhu 750 °C dan waktu reaksi 3 jam. Kernel UO2 yang dihasilkan berbentuk bulat, tidak retak dan memiliki mikrostruktur yang halus. KATA KUNCI: Kinetika reaksi, Energi aktivasi minimum, Konstanta laju reaksi, Persamaan kontrol reaksi kimia, Kernel U3O8, Kernel UO2 ABSTRACT REACTION KINETICS ASPECT OF U 3 O 8 KERNEL WITH GAS H 2 ON THE CHARACTERISTICS OF ACTIVATION ENERGY, REACTION RATE CONSTANT AND O/U RATIO OF UO2 KERNEL. The reaction kinetics aspect of U3 O8 kernel with gas H2 on the characteristics of activation energy, reaction rate constant and O/U ratio of UO2 kernel had been studied. U3O8 kernel was reacted with gas H2 in a reduction furnaceat varied reaction time and temperature. The reaction temperature was varied at 600, 700,750 and 850 oC with a pressure of 50 mmHg for 3 hours in gas N2 atmosphere. Thereation time was varied at 1,2,3 and 4 hours at a temperature of 750 oC using similarconditions. The reaction product was UO2 kernel. The reaction kinetic aspect betweenU3 O8 and gas H2 comprised the minimum activation energy (ΔE), the reaction rateconstant and the O/U ratio of UO2 kernel. The minimum activation energy wasdetermined from a straight line slope of equation ln [{D b. R o {(1(1X b )1/3} / (b.t.C g )] =-3.9406 x 103/ T + 4.044. By multiplying withthe straight line slope -3.9406 x 103, the ideal gas constant (R) 1.985 cal/mol and the molarity difference of reaction coefficient 2, aminimum activation energy of 15.644 kcal/mol was obtained. The reaction rate constantwas determined from first-order chemical reaction control and Arrhenius equation. The O/U ratio of UO2 kernel was obtained using gravimetric method. The analysis result ofreaction rate constant with chemical reaction control equation yielded reaction rateconstants of 0.745 1.671 s-1 and the Arrhenius equation at temperatures of 650 850oC yielded reaction rate constants of 0.637 2.914 s-1. The O/U ratios of UO 2 kernelat the respective reaction rate constants were 2.013 2.014 and the O/U ratios at reaction time 1 4 hours were 2.04 2.011. The experiment results indicated that the minimum activation energy influenced the rate constant of first-order reaction and the O/U ratio of UO2 kernel. The optimum condition was obtained at reaction rate constant of 1,43 s-1, O/U ratio of UO2 kernel of 2,01 at temperature of 750 oC and reaction time of 3 hours. The UO2 kernel produced was spherical, did not crack and had fine microstructure. FREE TERMS: Reaction kinetics, Minimum activation energy, Reaction rate constant, Chemical reaction control equation,U3O8 kernel, UO2 kernel