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By substituting Eq. (28) into Eq. (26), one can obtain:

106 Uranium - Safety, Resources, Separation and Thermodynamic Calculation

The minimum attainable spectral resolution is given by:

resolving power for the optical system degrades.

ΔλFSR = λ/m.

5. Conclusion

BP <sup>¼</sup> <sup>W</sup>:<sup>d</sup>

For instance, considering G = 1200 gr/mm, W = 0.05 mm, f = 500 mm, and m = 1, the obtained bandpass is 0.083 nm. For selecting grating, one should consider that the grating equation reveals only the spectral orders for which |mλ/d| < 2 exist. This restriction prevents light of wavelength λ from being diffracted in more than a finite number of order m. Once angle of incidence has been determined, the choice must be made whether a small width grating should be used in a low order, or a large width grating such as an echelle grating should be used in a high order; though, the small width grating will provide a larger free spectral range,

Δλ <sup>¼</sup> <sup>λ</sup><sup>2</sup>

regardless of the order m or number of grooves N under illumination. Here D = Nd is the rules width of the grating. This minimum condition corresponds to the grazing Littrow configuration. Noticeably when the grating is incorporated in a spectrometer or monochromator, however, aberrations and imperfections in other elements (e.g., lenses and mirrors) rather than grating and factors related to the size of the slits and detector elements may result in even wider spectral resolution. This means that the minimum wavelength difference Δλ that can be resolved will be larger that for the grating only defined by Eq. (30), and, in general, the

A sudden release of UF6 into the atmosphere can conceivably cause undesirable health effects to the workers and the public in general associated with high level of toxicity of the hydrolysis products HF and UO2F2. Although the hydrolyze reaction of UF6 is fast, however, after escaping of UF6 into the atmosphere, besides HF and UO2F2, UF6 may also be found in the atmosphere. Therefore, the combination of DIAL and Raman lidar for simultaneously detection of UF6 and HF can be a reliable technique for remotely detection and monitoring UF6 leaks and further improving the safety and economically operation of a uranium-enrichment plant. The DIAL provides information on UF6 concentration using the off- and on-wavelength at 266 and 245 nm, respectively, while Raman scattering of HF at 297.3 nm can identify and quantify HF as a probe for real-time detection and localization of toxic UF6 leaks. This system might be mounted on a helicopter for quickly and remotely surveying the leaks from the large facilities. Since the system is working in the solar blind ultraviolet (200–310 nm), the Raman signal may simply be enhanced by

increasing FOV or increasing the integration time (or number of shots).

<sup>f</sup> :<sup>m</sup> (29)

=2D (30)

Gholamreza Shayeganrad

Address all correspondence to: gholamreza.shayeganrad@unibas.ch; shayeganrad@yahoo.com

Department of Biomedical Engineering, University of Basel, Gewerbestr, Allschwil, Switzerland
