PERHITUNGAN PEMBUATAN IRIDIUM-192 UNTUK RADIOGRAFI MENGGUNAKAN REAKTOR G.A. SIWABESSY

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ABSTRAK

PERHITUNGAN PEMBUATAN IRIDIUM-I92 UNTUK RADIOGRAFI MENGGUNAKANREAKTOR G.A.

SIWABESSY. Iridium-In merupakan salah satu radioisotop yang digunakan untukradiografi gamma. Telah dilakukan perhitungan pembuatan radioisotop iridium-In menggunakan fasilitasiradiasi neutron yang ada di reaktor nuklir G.A. Siwabessy BA TAN. Sasaran berupa disk logam iridiumdengan diameter 2,7 mm dan tebal 0,15 mm. Fluks neutron digunakan nilai fluks neutron di centralirradiation position sebesar 1,3 x 10'4 n.s".cm·2• Hasil perhitungan menunjukkan bahwa iradiasi neutronterhadap iridium selama 12 hari diperoleh iridium-192 sebesar 96,8 GBq pada saat akhir iradiasi. Jikairadiasi dilanjutkan setelah jeda operasi selama 16 hari maka diperoleh sebesar 171,2 GBq. Jika iradiasidilakukan secara terus menerus tanpa jeda operasi selama 40 hari, maka diperoleh sebesar 284,5 GBq.Pengotor radionuklida yang dihasilkan hanya iridium-194 dengan waktu paruh 19,15 jam, sehingga meluruhdengan cepat. Untuk radiografi diperlukan sumber radiasi radioaktivitas sebesar 3700 GBq untuk tiapsumber radiasi. Jika iradiasi dilakukan dengan jeda, disk sebanyak 24 buah diperlukan untuk tiap sumberradiasi. Jika reaktor dapat beroperasi kontinyu selama 40 hari, disk diperlukan sebanyak 14 buah untuk tiapsumber radiasi.

Kata kunci: iridium-In, radiografi, iradiasi neutron.

ABSTRACT

CALCULATION OF IRIDIUM-192 PRODUCTION FOR RADIOGRAPHY USING G.A.SIW ABESSY REACTOR.

Iridium-In is one of the radioisotopes used in gamma radiography. Calculationfor producing iridium-In using G.A. Siwabessy nuclear reactor has been carried out. The targets were discswith 2.7 mm in diameter and 0.15 mm in thickness. The neutron flux was the value at the central irradiationposition as high as 1.3 x 1014 n.s".cm-2. Calculation results showed that iridium metal irradiation for 12 daysresulted in iridium-l92 with radioactivity of 96.8 GBq per disc at the end of irradiation. If the irradiation wascontinued to the next irradiation period after 16 days of shut down, the irradiation resulted in 171.2 GBq ofiridium-In. If the target was irradiated continuously for 40 days, the irradiation resulted in 284.5 GBq ofiridium-192. The resulted radionuclide impurity was iridium-194 which decayed rapidly with half life of19.15 hours. The initial radioactivity required for effective radiation source for gamma radiography was3700 GBq in a radiation source. If the target was irradiated with shut down, the discs required in a radiationsources were 24 discs. If the target was irradiated continuously, the required discs were 14 discs in aradiation source.

Keywords: iridium-192, radiography, neutron irradiation.