Communication Dans Un Congrès Année : 2023

Enrichment diagnostic by molecular spectroscopy

Résumé

Detection of U main isotopes in UF6 is achieved by absorption spectroscopy with the help of a jet-cooled cavity. Measurement conditions are chosen to obtain non overlapping spectra of the two isotopes. This is the case in the v3 band where the isotopic gap is the largest and it is also one of the most intense band. Although lead-salt laser diodes made it possible to achieve some limited high-resolution v3 spectra in the 1980s-90s, high-resolution spectroscopy at 16μm is now possible with quantum cascade laser diodes (QCL) at 16μm (625cm-1) thanks to QCL produced by Montpellier university/IES. These components are able to scan a domain of 9 cm-1 by changing the operating temperature, or of a fraction of 1 cm-1 by varying the injected current. We show that the wavelength can be modulated by the injected current up to a frequency of nearly one MHz, allowing us to implement a synchronous signal detection during the 10ms time window of the pulsed jet. Reducing noise is necessary to obtain reliable isotope ratios because the isotopic ratio of natural Uranium is high (~140). Current modulation amplitude is limited to 0.1cm-1 and only the R5 and R6 rotational bands of the main isotope 238UF6 are accessible on either sides of the Q band of 235UF6. This paper compares experimental results with natural U to the HTDS simulation of the whole measurement process in either direct or modulated absorption. The obtained rotational temperature of 20K is deduced from the model parameters. Once the temperature is known, the comparison of the Q-bands of the two isotopes (measured and simulated) allows the calculation of the relative abundance or isotopic ratio.
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Dates et versions

cea-04654499 , version 1 (19-07-2024)

Identifiants

  • HAL Id : cea-04654499 , version 1

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Laurent Bruel, Pierre-Anne Bausson, Pascal Lemaire, Agnes Pailloux. Enrichment diagnostic by molecular spectroscopy. SPLG 2023 - Fenómenos de Separación en Líquidos y Gases, Jun 2023, Buenos Aires, Argentina. ⟨cea-04654499⟩
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