SBIR-STTR Award

The solubility of airborne radionuclides is an important parameter in the assessment of inhalation hazards in the workplace and in the interpretation of routine bioassay data. Solubility is a major factor in determining the metabolism of the inhaled isotopes and dissolution rates of alpha-emitting compounds which are particularly important due to their high radiotoxicity. Current solubility testing protocols are sufficiently complex that they are normally found only in research laboratories. Much benefit could be derived from their use in operating plants. In this work we propose to investigate the feasibility of using simple lung simulant fluids for the solubility tests, and straightforward solvent extraction chemistries to transfer the radionuclides from the lung fluid simulant directly into an extractive scintillator with minimal sample preparation. Counting will be performed on a benchtop photo-electron rejecting alpha liquid scintillation (PERALS) spectrometer. This liquid scintillation counter is small yet it has a lower limit of detection of <0.03pCi under a typical alpha peak (one hour count). If successful, this work will lead to the development of a kit for the solubility testing of radionuclides on breathing zone and medium volume air sampler filters that can be used in a simple field laboratory.

Anticipated Results:
This work should produce a kit that will allow solubility testing of radionuclides on breathing zone and medium volume air sampler filters.

We propose to complete the work on development of simplified methods of solubility testing of uranium on air filters initiated in Phase I, and further to expand the work to other transuranic radionuclides. Yellowcake samples that have been characterized by the results will be compared as a test of the new method. A new technique will also be developed to rapidly dissolve and extract the insoluble uranium from the air filter at the end of the volubility test procedure. This modification to the test should eliminate the energy quenching of the spectrum observed in the Phase I work. Finally, these new techniques will then be applied to the analysis of isotopes of plutonium, curium, and uranium on air filters using sequential solvent extraction's to isolate each radionuclide.

Anticipated Results:
A simplified method for volubility testing, with some limitations, was developed in Phase I of this work. The limitations will be resolved in Phase II and the new solubility test will be offered as a service by our separations chemistry lab, and will also be made available to other facilities, perhaps as a kit. Phase II work will also develop rapid methods to analyze transuranic radionuclides on air filters in a time frame that will make them useful for radiation protection purposes. This work, if successful, will also be offered as a commercial service.