Experiments on making a plastic scintillator with polystyrene as a base material mixed with fluorescent compounds (primary and secondary dopants) have been performed. Primary dopants (PTP) used to produce emission at wavelengths of visible light and secondary dopants (POPOP) to shift the visible wavelengths to wavelengths that could be detected by Photomultiplier Tube (PMT) ) were carried out. Experiments were performed on the melting points condition of these materials, which had previously been subjected to a thermo-mechanical analysis using a Thermogravimetric Analysis-Differential Scanning Calorimetry (TGA-DSC) machine, where the melting point was in the range of 200-240°C. Furthermore, the fabrication was carried out using the extrusion technique, where polystyrene pellets mixed with PTP (1.5% by weight) and POPOP (0.05% by weight) were fed into an extrusion machine which has four hot areas to obtain a thin plate plastic scintillator. The plates were then analyzed with a UV-Vis Spectrophotometer to determine the absorption spectrum and Fluorescence Spectrophotometer to determine the emission spectrum. From the results of the analysis, it was found that the samples that went through scintillation pellets and without the addition of antioxidants had absorption spectrum data of 330 nm and emission spectrum of 421 nm. These values are in accordance with the characteristics of plastic scintillators on the market.

ABSTRAK Monasit (Ce, La, Nd, Th,)PO4 dengan kandungan torium (Th) antara 3-4% cukup signifikan untuk diproses menghasilkan Th. Pengolahan awal dilakukan dengan pelindian monasit menggunakan reagen basa karbonat (Na2CO3) untuk mengambil uraniumnya. Sisa tailing dilarutkan dengan asam sulfat untuk menghasilkan larutan Th(SO4)2 yang kemudian dimurnikan dari unsur-unsur pengotornya. Pengolahan dilakukan secara kontinyu menggunakan mixer settler dengan tahapan proses meliputi proses ekstraksi Th, stripping Th dan regenerasi pelarut organik. Ekstraksi Th menggunakan pelarut organik Primene JM-T (RNH2) yang merupakan campuran dari 0,15M Primene JM; 5% Tridecanol; dan 95% Kerosin. Sementara itu, proses stripping Th menggunakan larutan 2M HCl. Untuk efisiensi maka regenerasi pelarut organik menggunakan 1% H2SO4. Untuk mendapatkan recovery dan kemurnian yang tinggi dari Th, penghitungan jumlah stage mixer settler diperlukan dengan menggunakan metode McCabe Thiele. Dari hasil perhitungan diperoleh jumlah stage dalam proses ekstraksi Th adalah 3, proses stripping Th adalah 3 dan regenerasi pelarut organik adalah 2. Recovery total Th sebesar 84,90% diperoleh dengan kemurnian produk mencapai 99,02%. ABSTRACT Monazite (Ce, La, Nd, Th)PO4 with thorium (Th) content between 3-4 % is significant enough to be processed to produce Th. The initial treatments conducted by using carbonate base reagents (Na2CO3) for monazite leaching to fetch the uranium. The remaining tailings were dissolved with sulfuric acid to produce Th(SO4)2 solution which is then purified from its impurities. The processing is carried out continuously using a mixer settler with the process steps include Th extraction, Th stripping, and organic solvents regeneration. Thorium extraction uses a primene JM-T (RNH2) organic solvent which is a mixture of 0.15M Primene JM; 5% Tridecanol and 95% Kerosine. Meanwhile, the Th stripping process uses 2M HCl solution. For efficiency, regeneration of organic solvents uses 1% H2SO4. To obtain a high recovery and purity from Th, it is necessary to calculate the number of stage mixer settlers using the McCabe Thiele method. Based on the calculation, the number of stage for extraction process, Th stripping, and organic solvents regeneration are 3, 3, and 2 respectively. The total recovery of Th is obtained at 84.90 % where product purity reaches 99.02 %.

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