Spectral emissions and dosimetry of metal tritide particulates.
Spectral emissions and dosimetry of metal tritide particulates.
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DOI：
10.1093/oxfordjournals.rpd.a006729
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发表时间：
2002-04
影响因子：
1
通讯作者：
D. J. Strom;R. Stewart;J. McDonald
中科院分区：
文献类型：
--
作者：
D. J. Strom;R. Stewart;J. McDonald
由于美国能源部设施的退役和去污，对吸入金属氚粒子的摄入量和剂量的推断受到了审查。由于辐射的自吸收对于较大的粒子是非常重要的，通过液体闪烁对金属氚粒子的计数结果的解释需要关于发射光谱的信息。同样，剂量的推断需要带电粒子和光子光谱的知识。PENELOPE Monte Carlo辐射输运计算机代码用于计算Sc、Ti、Zr、Er和Hf的氚粒子的光谱发射和其他剂量测定量。发射分数，径向吸收剂量分布，比能量分布和相关的频率平均比能量和线性能量，以及电子和韧致辐射光子的发射光谱的直径范围从约0.01微米至25微米的选定颗粒。结果表征与氚的组成和密度的不确定性的影响。发射光谱用于说明表观活性和观察到的活性之间关系的趋势，作为颗粒类型和尺寸的函数。从金属氚粒子的发射是弱穿透，和电子发射光谱往往“硬化”的颗粒尺寸的增加。微剂量学的考虑表明，金属氚化物发射的辐射可以归类为低线性能量转移辐射源。对于距离金属氚化物表面小于7微米的细胞，主要剂量成分是由于电子。然而，韧致辐射可能会将某些能量存款在离氚粒子表面几十、几百甚至几千微米的地方。本报告所提供的数据和分析将有助于提高五种金属氚化物微粒剂量测定的准确性。未来关于金属氚粒子的光谱发射和剂量测定的工作需要考虑所谓的内部韧致辐射的贡献，内部韧致辐射是在β衰变期间发射的另一种形式的韧致辐射。
Inference of intakes and doses from inhalation of metal tritide particles has come under scrutiny because of decommissioning and decontamination of US Department of Energy facilities. Since self-absorption of radiation is very significant for larger particles, interpretation of counting results of metal tritide particles by liquid scintillation requires information about emission spectra. Similarly, inference of dose requires knowledge of charged particle and photon spectra. The PENELOPE Monte Carlo radiation transport computer code was used to compute spectral emissions and other dosimetric quantities for tritide particulates of Sc, Ti, Zr, Er, and Hf. Emission fractions, radial absorbed dose distributions, specific energy distributions and related frequency-mean specific energies and lineal energies, and the emitted spectra of electrons and bremsstrahlung photons are presented for selected particulates with diameters ranging from about 0.01 microm to 25 microm. Results characterising the effects of uncertainties associated with the composition and density of the tritides are also presented. Emission spectra are used to illustrate trends in the relationship between apparent and observed activity as a function of particle type and size. Emissions from metal tritide particles are weakly penetrating, and electron emission spectra tend to 'harden' as particle size increases. Microdosimetric considerations suggest that the radiation emitted by metal tritides can be classified as a low linear energy transfer radiation source. For cells less than about 7 microm away from the surface of a metal tritide, the primary dose component is due to electrons. However, bremsstrahlung radiation may deposit some energy tens, hundreds or even thousands of micrometres away from the surface of a tritide particle. The data and analyses presented in this report will help improve the accuracy of dose determinations for particulates of five metal tritides. Future work on the spectral emissions and dosimetry of metal tritide particulates needs to consider the contributions of so-called internal bremsstrahlung, an additional form of bremsstrahlung radiation emitted during beta decay.