Karakterisasi Gelas Limbah Hasil Vitrifikasi Limbah Cair Tingkat Tinggi

KARAKTERISASI GELAS LIMBAH HASIL VITRIFIKASI LIMBAH CAIR TINGKAT TINGGI.
Limbah cair tingkat tinggi (LCTT) ditimbulkan dari ekstraksi siklus pertama proses olah ulang bahan bakar bekas reaktor nuklir. Limbah ini banyak mengandung hasil belah dan sedikit aktinida dan vitrifikasi dilakukan dengan gelas borosilikat. Komposisi limbah cair tingkat tinggi dipengaruhi antara lain oleh jenis reaktor, fraksi bakar, pengayaan uranium, daya reaktor spesifik dan lama pendinginan bahan bakar bekas sebelum divitrifikasi. Agar diperoleh karakteristik gelas limbah yang memenuhi persyaratan, bagi setiap komposisi limbah yang berbeda memerlukan komposisi bahan pembentuk gelas serta kandungan limbah yang berbeda pula. Telah dilakukan karakterisasi densitas, koefisien muai panjang dan laju pelindihan gelas limbah hasil vitrifikasi LCTT simulasi. Karakterisasi gelas limbah dilakukan dengan variabel kandungan limbah 19,84; 22,32; 25,27;
26,59 % berat, dan karakterisasi laju pelindihan dengan variabel kandungan SiO2 dan Al2O3 pada bahan pembentuk gelas masing-masing sebesar 44; 45 ; 46,8 % berat dan 1,4; 2,4; 3,4; 3,7 % berat. Sebagai acuan digunakan gelas limbah standar milik Japan Atomic Energy Agency. Hasil karakterisasi menunjukkan bahwa kandungan limbah yang semakin tinggi akan meningkatkan karakteristik densitas dan laju pelindihan gelas limbah, sedangkan karakteristik koefisien muai panjang relatif tidak berubah. Peningkatan kandungan SiO2 maupun Al2O3 akan menurunkan laju pelindihan. Jika dibandingkan dengan gelas limbah standar maka jumlah kandungan limbah dan bahan pembentuk gelas keduanya tidak signifikan mempengaruhi karakteristik densitas, koefisien muai panjang dan laju pelindihan.

Kata kunci: Gelas limbah, limbah cair tingkat tinggi, vitrifikasi, gelas borosilikat

ABSTRACT
CHARACTERIZATION of WASTE GLASS FROM PRODUCT of A HIGH LEVEL LIQUID WASTE VITRIFICATION. High level liquid waste (HLLW) is generated from the first step extraction of nuclear fuel reprocessing. This waste contains an amount of fission products and a few actinides, and such waste was vitrified with borosilicate glass. The composition of high-level liquid waste was influenced by the type of reactor, the burn up of fuel, the uranium enrichment, the specific reactor power and the cooling time of the spent fuel before vitrification. In order to obtain the characteristics of the waste glass that meets the requirements, for every composition of different of waste, require the different composition of glass frit and also the different waste loading. Characterization of density, thermal expansion coefficient and leaching rate had been carried out to the simulated waste glass of vitrified HLLW product, such characterization was carried out with a variable of the waste loading of 19.84 ; 22.32 ; 25.27 ; 26.59 wt%, and characterization of leaching rate was carried out with a variables of SiO2 and Al2O3 content of 44 ; 45 ; 46 , 8 wt% and 1.4 ; 2.4 ; 3.4 ; 3.7 wt% respectively. As a reference, the waste glass standard from Japan Atomic Energy Agency was used. The charaterization results showed that the higher the waste loading, the higher the density and leaching rate characteristics of waste glass, while the thermal expansion coefficient characteristic is relatively unchanged. The increasing content of SiO2 and Al2O3 will reduce the leaching rate. Compared to the waste glass standard, both the amount of waste loading and glass frit do not significantly affect the density, thermal expansion coefficient and leaching rate characteristics.

Keywords: Waste glass, high level liquid waste, vitrification, borosilicate glass.