Pengolahan Limbah Radioaktif Cair Sekunder Mengandung 137Cs dengan Metode Kopresipitasi Menggunakan Asam Perklorat

Wafidh Kharraz Zhillan, Dr. Ir. Widya Rosita, S.T., M.T., IPU. ; Arif Nugroho, S.T., M.Si.

2025 | Skripsi | TEKNIK NUKLIR

BAPETEN menemukan paparan radiasi cesium-137 (137Cs) melebihi batas di Perumahan Batan Indah pada tahun 2020. Proses dekontaminasi (clean up) menghasilkan ratusan drum limbah tanah terkontaminasi 137Cs dan memicu keterbatasan kapasitas penyimpanan di Interim Storage (IS). Upaya dekontaminasi dilakukan dengan soil washing, tetapi menghasilkan limbah cair radioaktif yang perlu diolah. Di antara berbagai metode, kopresipitasi dipilih karena dinilai paling praktis dan ekonomis dengan proses yang sederhana. Penelitian ini bertujuan mengkaji pengaruh zat pengotor (Fe, Si, dan Ca) dan efektivitas pengolahan awal terhadap nilai recovery 133Cs pada limbah simulasi, serta menentukan kondisi optimum suhu dan konsentrasi HClO4 untuk mengendapkan 137Cs dan keberhasilannya dalam mencapai tingkat klierens.

Penelitian dilakukan melalui tahap eksperimen awal pada limbah simulasi tanpa dan dengan pengotor, serta kopresipitasi limbah radioaktif. Variasi perlakuan meliputi tiga suhu (25?, 0?, dan -11?), tiga konsentrasi HClO4 (7,5, 15, 30) wt.%, serta dua kondisi pengolahan awal untuk menguji efek eliminasi pengotor. Analisis sampel pada limbah simulasi dilakukan menggunakan Atomic Absorption Spectroscopy (AAS) dan limbah radioaktif menggunakan Spektrometer Gamma.

Hasil penelitian menunjukkan zat pengotor tidak berpengaruh signifikan terhadap nilai recovery 133Cs. Sementara tahap pengolahan awal dengan presipitasi pengotor menggunakan NaOH dapat meningkatkan nilai recovery 133Cs secara signifikan. Kondisi optimum kopresipitasi 137Cs diperoleh pada suhu -11? dan konsentrasi HClO4 15?ngan nilai recovery 137Cs sebesar 83,79%, serta hasil akhir aktivitas jenis sebesar 0,093 Bq/g yang telah memenuhi tingkat klierens.

In 2020, BAPETEN detected radiation levels of Cesium-137 (137Cs) exceeding safety limits at the Batan Indah residential area. The clean-up process generated hundreds of drums of radioactive waste, straining the capacity of the Interim Storage (IS) facility. As a follow-up, soil washing was conducted to separate 137Cs from the soil. However, this process produced radioactive liquid waste that still required further treatment. Among various methods, co-precipitation was selected as it is considered the most practical and economical, with a simple process suitable for large-scale applications. This study aimed to evaluate the effect of impurities (Fe, Si, and Ca) and the effectiveness of pre-treatment on the recovery of 133Cs in simulated waste, as well as to determine the optimum temperature and HClO4 concentration for precipitating 137Cs and achieving clearance levels.

The experiments included preliminary tests on simulated waste with and without impurities and co-precipitation on actual waste. The process was carried out with three temperatures (25?, 0?, -11?), three HClO4 concentrations (7,5, 15, 30) wt.%, and two pre-treatment conditions to assess impurity removal. Sample analysis of simulated waste was carried out using Atomic Absorption Spectroscopy (AAS) and radioactive waste using a Gamma Spectrometer.

The results showed that impurities had only a minor effect on precipitation efficiency, while pre-treatment using NaOH significantly improved the removal of ¹³³Cs. The optimum condition for co-precipitating 137Cs was found at -11? with 15% HClO4 concentrations, achieving 137Cs recovery of 83.79% and a final activity of 0.093 Bq/g, which met the clearance level requirements.

Kata Kunci : Asam perklorat, Cesium-137, Cesium perklorat, Kopresipitasi, Konsentrasi, Recovery 137Cs, Suhu.