PENGARUH SUHU, WAKTU DAN PROSES RE-OKSIDASI PELET BAHAN BAHAN BAKAR BEKAS PWR SIMULASI

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ABSTRAK

PENGARUH SUHU, WAKTU DAN PROSES RE-OKSIDASI PELET BAHAN BAHAN BAKAR BEKAS PWR SIMULASI. Telah dilakukan pembuatan pelet bahan bakar bekas PWR simulasi dengan cara kompaksi terhadap campuran serbuk UO₂ yang ditambah dengan serbuk Sr, Y, Zr, Mo, Ru, Rh, Pd, Te, Ba, La, Ce, Pr, Nd, Sm, Cd, Eu, Gd, dan Sb  oksida sebagai unsur hasil fisi simulasi hingga menjadi pelet (UO₂+hasil fisi) mentah. Pelet mentah tersebut kemudian disinter pada suhu 1700 ^oC selama 4 jam hingga menjadi pelet (UO₂+hasil fisi) sinter. Terhadap pelet mentah dan pelet sinter dilakukan pengukuran dimensi, volume dan berat untuk menentukan densitas pelet, sedangkan untuk serbuk diukur apparent density, tap density dan true density. Pelet (UO₂+hasil fisi) sinter tersebut kemudian dioksidasi pada suhu dan waktu yang bervariasi hingga diperoleh serbuk (U₃O₈+hasil fisi). Proses tersebut adalah oksidasi ke-1. Serbuk (U₃O₈+hasil fisi) direduksi menjadi serbuk (UO₂+hasil fisi) lalu dikenai proses oksidasi ke-2 menjadi (U₃O₈+hasil fisi). Proses oksidasi dan reduksi diulangi sampai empat kali. Densitas serbuk hasil oksidasi diukur dan diamati struktur mikronya, serta ditentukan efisiensi proses oksidasi. Pengulangan proses oksidasi tersebut bertujuan untuk memperoleh serbuk dengan densitas tinggi sebagai bahan baku untuk proses reduksi. Hasil percobaan menunjukkan bahwa tekanan kompaksi berpengaruh pada densitas pelet yang diperoleh. Makin tinggi tekanan kompaksi, makin tinggi pula densitas baik pelet (UO₂+hasil fisi) mentah maupun sinter. Pada tekanan kompaksi 6,3168 ton/cm² diperoleh densitas pelet (UO₂+hasil fisi) mentah dan sinter masing-masing 6,13 g/cm³ dan 9,9726 g/cm³ (90,91 %TD/Theoritical Density). Proses oksidasi selama 1 jam dan suhu 500 ^oC dan re-oksidasi ke-3 memberikan densitas hasil serbuk (U₃O₈+hasil fisi) yang relatif baik yaitu apparent, tap dan true density masing-masing 1,9996, 2,8123 dan 7,8057 g/cm³ dan efisiensi proses oksidasi 100%.

Kata kunci: Proses oksidasi, pelet bahan bakar bekas PWR simulasi, hasil fisi, densitas nyata, ketuk, dan sejati

ABSTRACT

EFFECT OF TEMPERATURE, TIME AND RE-OXIDATION PROCESS OF SIMULATION PWR SPENT FUEL PELLETS. Manufacture of simulation PWR spent fuel pellets has been done by compacting mixture of UO₂ powder with Sr, Y, Zr, Mo, Ru, Rh, Pd, Te, Ba, La, Ce, Pr, Nd, Sm, Cd , Eu, Gd, and Sb oxides as simulation element to produce (UO₂ + fission products) green pellets. Green pellets are then sintered at a temperature of 1700 ° C for 4 hours until obtained (UO₂+fission products) sintering pellets. The green pellets and sintered pellets were measured dimensions, volume and weight to determine the density of the pellets, whereas for the powders were measured apparent density, tap density and true density. The (UO₂+fission products) sintering pellets were then oxidized at various temperatures and times to obtain (U₃O₈ + fission products) powder. The process is called first oxidation process. The (U₃O₈ + fission products) powder then were reduced to powder (UO₂+fission products) and subjected to second oxidation process to produce (U₃O₈+fission products) powder. Oxidation and reduction process was repeated four times. Powder density, microstructure and oxidation efficiensy were determined. Repetition of the oxidation process aims to obtain a powder with high density as green material for the reduction process. The experimental results showed that the compacting pressure affects the density of the pellets obtained. The higher the compacting pressure, the higher the density of both pellets (UO₂+fission products) green or sintered. For compacting pressure 6.3168 ton/cm³, the (UO₂+fission product) green and sintered pellet density obtained were 6,13 and 9.9726 g/cm³ (90.91% TD/Theoritical Density) respectively. Oxidation process for 1 hour, the temperature of 500 ° C and third oxidation provides the results of (U₃O₈+fission products) powder density were relatively good, that is apparent, tap and true density of 1.9996, 2.8123 and 7.8057 g/cm³ respectively and 100% oxidation processes efficiency.

Keywords: Oxidation process, PWR simulation spent fuel pelet, fission products, apparent, tap  and true density