ASPEK KINETIKA REAKSI KERNEL U3O8 DENGAN GAS H2 TERHADAP KARAKTERISTIK ENERGI AKTIVASI, KONSTANTA LAJU REAKSI DAN RASIO O/U KERNEL UO2

Sari

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. R_o{1-(1- Xb)^1/3 } / b t C_g ] = -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 (k_s) ditentukan menggunakan persamaan kontrol reaksi kimia berorde satu dan persamaan Arrhenius, sedangkan rasio O/U ditentukan dengan metode gravimetri. Hasil analisis konstanta laju reaksi (k_s) 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 850^oC 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