在短寿命放射性医疗废物中发现长寿命杂质核素

为了确定短寿命放射性医疗废物能否清洁解控及短期的衰变贮存是否有效,本研究使用γ谱仪分析已放置了10个半衰期以上的低水平含99Tcm的放射性废物中残留的放射性核素,通过核素的全能峰定性,通过感兴趣区的净峰面积定量.经过了衰变贮存,虽然所有核素的活度浓度均低于相应的清洁解控水平,但在99Tcm废物中检出了长寿命核素137Cs、155Eu、123Tem、154Eu,其中137Cs、155Eu分析为99Tcm的母体99Mo生产过程中产生的杂质核素进入99Tcm所致,123Tem、154Eu可能为99Mo靶中杂质核素衰变而成.半衰期最长的长寿命核素137Cs的半衰期为30a,短期的衰变贮存并不能使这些长寿命核素活度显著减少,可见控制放射性药物的核纯度具有重要意义,可防止后期产生的医疗废物处置复杂化.

The Detecting of Long-lived Radionuclidic Impurities in Short-lived Radiopharmaceutical Waste

To determine if radiopharmaceutical waste can be cleared or decay-in-storage is effective for its disposal,we have evaluated the extent of this problem in low level radioactive waste involving ⁹⁹Tc^m over a 10 half-life cycle of decay-in-storage by identifying the residual radionuclides in our dry waste using a multi-channelγ-ray spectrum analyzer.Radionuclides were identified by the presence of characteristic photopeaks of each isotope in theγ-ray spectrum and quantified by region of interest analysis.Although all radionuclide activity concentrations were lower than their clearance level after the decay-in-storage cycle, long-lived radioisotopes ¹³⁷Cs,¹⁵⁵Eu,¹²³Te^m and ¹⁵⁴Eu were observed in ⁹⁹Tc^m waste.¹³⁷Cs and¹⁵⁵Eu can be the radionuclidic impurities during ⁹⁹Mo preparations.¹²³Te^m and ^l54Eu may be the decay products from the radionuclidic impurities.Short decay-in-storage cannot decrease the activity of long-lived radionuclides greatly.So to control the nuclear purity of radiopharmaceutical is important,which can prevent the disposal of the radiopharmaceutical waste from becoming complicated.