CDI Project: Experimental Studies of the Chemistry of Adsorbed Iodine Species formed in Severe Reactor Accidents

Return to Nuclear Incident Characterization Use Case

Left to right: schematic of single-particle laser ablation mass spectrometer; helium ion microscopy images of carbon soot particles; mass spectra of uncoated carbon soot particles and soot particles coated with butyl iodide; and coating of soot particles with butyl iodide as a function of time.
​​​​​Left to right: schematic of single-particle laser ablation mass spectrometer; helium ion microscopy images of carbon soot particles; mass spectra of uncoated carbon soot particles and soot particles coated with butyl iodide; and coating of soot particles with butyl iodide as a function of time.

PI: Tom Blake

Project Team: Tom Autrey, Katarzyna Grubel, Alla Zelenyuk-Imre, Robert VanGundy, Neil Henson, Yongsoon Shin, Rahul Kumar

Project Term: October 2018 to September 2021

Key Science Questions:

  • What chemical forms does iodine take when released into the environment from a severe nuclear accident?
  • How do these chemical forms change over time under different environmental conditions?
  • Are these chemical transformations accelerated on particulate surfaces?
  • What are the thermodynamics and kinetics of these surface reactions?
  • Can predictions be made about the chemistry of iodine in the environment?

Project Description: Nuclear incidents can release harmful radioactive materials into the environment, including semi-volatile organic iodides. These species are often adsorbed on different surfaces, such as dust or soot particles, or onto sorbents, designed for their efficient capture. Previous studies focused on the efficiency and stability of sorbents to trap different iodide species. However, there is much to be learned about the chemical and physical transformations of these species with time and exposure to real-world conditions, such as relative humidity, light, and oxidants.

The CDI project team is quantifying the rates of chemical transformation of semi-volatile organic iodide species adsorbed onto the surfaces of environmentally relevant particles, including soot (carbon) and dust (silica) under real-world conditions that include relative humidity, temperature, air (specifically O2 and O3), and light. The combination of experimental methods will provide molecular-level insight into the chemical dynamics of organic iodides.

The goals of this research:

  • provide information to improve modeling of the chemical kinetics of organic iodide-particulate systems
  • allow for the design of new experiments to characterize these systems
  • gain an understanding of measurement and resulting uncertainties

Moreover, the CDI project team aims to improve the design of future field campaigns to detect, identify, and quantify relevant forensics compounds, as well as to improve the design of future instrumentation for detecting those compounds. Ultimately, this work can help provide a fully vetted methodology for understanding the evolution of indicator molecules.