<p>To determine the total salt mass of the molten salt systems for pyroprocessing spent nuclear fuels, a <sup>22</sup>Na-based radioactive tracer dilution (RTD) technique was studied at Idaho National Laboratory in recent years. This <sup>22</sup>Na based RTD technique was deemed feasible, but due to the gamma energy peak of <sup>22</sup>Na coinciding with one of the energy peaks of <sup>154</sup>Eu, a common radioisotope in the molten salt, the uncertainty of the <sup>22</sup>Na radioactivity in the <sup>22</sup>Na-spiked salt samples was quite high. To improve the uncertainty of the <sup>22</sup>Na based RTD technique, we proposed using DGA resin to chemically remove the <sup>154</sup>Eu in the salt samples prior to gamma spectroscopy. The effectiveness of this approach in reducing uncertainty was evaluated. It was found that (1) the <sup>154</sup>Eu fission product effect on the uncertainty and detection limit can be effectively eliminated by chemically removing the <sup>154</sup>Eu during the salt sample preparation, and (2) the uncertainty of <sup>22</sup>Na radioactivity in the salt samples for electrorefining was significantly improved from 13 to 2%. This demonstrates the potential of practical engineering application of the <sup>22</sup>Na-based RTD as a safeguards method for molten salt systems for pyroprocessing spent nuclear fuels.</p>

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Uncertainty improvement of 22Na based radioactive tracer dilution for determining total mass of pyroprocessing molten salt systems by 154Eu removal

  • Guoping Cao,
  • Magen Coleman,
  • Brian Storms,
  • Shelly Li,
  • Guy Fredrickson

摘要

To determine the total salt mass of the molten salt systems for pyroprocessing spent nuclear fuels, a 22Na-based radioactive tracer dilution (RTD) technique was studied at Idaho National Laboratory in recent years. This 22Na based RTD technique was deemed feasible, but due to the gamma energy peak of 22Na coinciding with one of the energy peaks of 154Eu, a common radioisotope in the molten salt, the uncertainty of the 22Na radioactivity in the 22Na-spiked salt samples was quite high. To improve the uncertainty of the 22Na based RTD technique, we proposed using DGA resin to chemically remove the 154Eu in the salt samples prior to gamma spectroscopy. The effectiveness of this approach in reducing uncertainty was evaluated. It was found that (1) the 154Eu fission product effect on the uncertainty and detection limit can be effectively eliminated by chemically removing the 154Eu during the salt sample preparation, and (2) the uncertainty of 22Na radioactivity in the salt samples for electrorefining was significantly improved from 13 to 2%. This demonstrates the potential of practical engineering application of the 22Na-based RTD as a safeguards method for molten salt systems for pyroprocessing spent nuclear fuels.