Gama spektrometrik yöntem ile fosfojipsteki (226)Ra, (232)Th, (40)K aktivitelerinin ölçülmesi
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Date
2004-06
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Gazi Üniversitesi, Fen Bilimleri Enstitüsü
Abstract
Fosfatlı gübreler, doğal radyonüklitler (238)U gibi ve bunların ürünlerini ihtiva eden fosfat madeni kayalarının endüstriyel işlenmesi sonucunda üretilir. Fosforik asit ve fosfatlı gübre üretiminde oldukça büyük miktarda bir yan ürün olarak ortaya çıkan fosfojips (PG), fosforik asit endüstrisinde ciddi depolama ve çevresel problemlere sebep olmaktadır. Fosforik asit üretim işlemi sırasında kimyasal olarak kalsiyuma benzeyen (226)Ra (t(1/2)=1600 yıl), fosfojipste kalır. Fosfatlı gübre üreten fabrikaların yanındaki büyük miktarlarda biriken fosfojips yığınları oldukça ciddi çevresel radyoaktivite sorunu ortaya çıkarır. Bu çalışmada, yığın halinde (60 000 ton) bekletilen fosfojips atığından alınan 80 fosfojips örneğinin, yüksek ayırma güçlü germanyum dedektörü olan bir gama spektrometresi kullanılarak doğal radyoaktivitesi ölçülmüştür. İncelenen fosfojips örneklerinde (226)Ra aktivitesinin ortalama olarak 546 Bq.kg(-1) olduğu bulunmuştur. Fosfojips örneklerindeki (232)Th ve (40)K aktiviteleri ise ihmal edilebilecek kadar küçük gözlenmiştir. İncelenen fosfojipsin yer seviyesinden 1 m yukarıda, 1 m(2) yüzey alanına 1-1,5 kg’ı yayılması durumunda, havaya verilen fazladan gama radyasyon doz hızı ~241 nGy/h olarak hesaplanmıştır.
Phosphatic fertilizers are produced from the industrial processing of rock phosphate ores which are known to contain naturally occuring radionuclides such as (238)U and its daughter products. A high volume by-product known as phosphogypsum (PG) from the production of phosphoric acid and phosphate fertilizer causes serious storage and environmental problems in phosphoric acid industries. During the phosphoric acid production process, (226)Ra (t(1/2)=1600 y) ends up in PG which has chemical analogous to calcium periodical table. Since the stockpiles of PG near the phosphatic fertilizer plants are huge amounts, the radioactivity contained in PG has to measured in view of environmental radioactivity problem. In this work, the natural radioactivity in eighty PG samples, issued from a stock of about 60.000 tones was measured by a high resolution gamma ray spectrometer with a HPGe detector. The averaged activity of (226)Ra in PG has been found to be 546 Bq.kg(-1). However, the activities of (232)Th and (40)K measured in PG samples are negligibly small. The extra gamma radiation dose rate arising from 1 -1.5 kg of PG is estimated to be about 241 nGy/h from 1 m ground level applied in 1 m(2) surface area of field.
Phosphatic fertilizers are produced from the industrial processing of rock phosphate ores which are known to contain naturally occuring radionuclides such as (238)U and its daughter products. A high volume by-product known as phosphogypsum (PG) from the production of phosphoric acid and phosphate fertilizer causes serious storage and environmental problems in phosphoric acid industries. During the phosphoric acid production process, (226)Ra (t(1/2)=1600 y) ends up in PG which has chemical analogous to calcium periodical table. Since the stockpiles of PG near the phosphatic fertilizer plants are huge amounts, the radioactivity contained in PG has to measured in view of environmental radioactivity problem. In this work, the natural radioactivity in eighty PG samples, issued from a stock of about 60.000 tones was measured by a high resolution gamma ray spectrometer with a HPGe detector. The averaged activity of (226)Ra in PG has been found to be 546 Bq.kg(-1). However, the activities of (232)Th and (40)K measured in PG samples are negligibly small. The extra gamma radiation dose rate arising from 1 -1.5 kg of PG is estimated to be about 241 nGy/h from 1 m ground level applied in 1 m(2) surface area of field.
Description
TENMAK D.N. 10514
Keywords
Fosfojips, (226)Ra, (232)Th, (40)K, Radyonüklit, Aktivite, Gama spektrometrisi, Phosphogypsum, Radionuclide, Activity, Gamma ray spectrometry, Gama ışını spektrometresi
Citation
Parmaksız, A. (2004) Gama spektrometrik yöntem ile fosfojipsteki (226)Ra, (232)Th, (40)K aktivitelerinin ölçülmesi. (Yayımlanmamış yüksek lisans tezi). Ankara : Gazi Üniversitesi, Fen Bilimleri Enstitüsü.