Mentor: Peter Burns, assistant Jie Qiu

Location of Research: Stinson-Remick Hall, Notre Dame

Category of Research: Actinide nanoclusters

Working Title: Synthesis of Uranyl peroxide nanoclusters

Topic/problem: ā€¨Control the properties/structure of Uranium nanoclusters

Research Plan:

The management of nuclear waste is not just a major economic issue, but also a critical environmental issue. Annually, the nuclear industry produces 2,000 - 2,300 metric tons of used nuclear fuel. In the past four decades, 74,258 metric tons of used nuclear fuel has been produced. Due to the long half-lives of some radioactive elements, the dangers of much of this waste will not be negated for hundreds, thousands, or even millions of years.
The messes we make with radioactive waste have the potential to last for long stretches of time, possibly even longer than we will last. Having the opportunity to be under the mentorship of some of the leading experts in nuclear waste management is not only thrilling to me from an experience point of view, but also from a moral perspective. Being able to contribute at all to a project that's impact could be felt by people for generations to come motivated me to choose this project.
The goal of this research project is to synthesize new actinide (specifically Uranium peroxide) nanoclusters. While no clear use for actinide nanoclusters has been definitively determined, they are currently a leading prospect for the future of radioactive waste storage. Uranium peroxide nanoclusters are cage-clusters composed of uranium, peroxide, bases, and iron. The structure of these cage-clusters consists of uranyl polyhedra (uranium atoms bonded to many oxygen atoms in a three dimensional shape), and iron polyhedra (iron atoms bonded to many oxygen atoms in a three dimensional shape) bonded together in rings connected by peroxide. Uranyl peroxide nanoclusters are formed via self-assembly in aqueous solutions, and crystallize through the evaporation of the solution. Through variation in uranium, peroxide, base, and iron in solution, new uranium peroxide nanoclusters will be synthesized in this research.
To make solutions of varied uranium, peroxide, base, and iron, ultra pure water will be mixed to form solutions of 0.5 M Uranyl nitrate hexahydrate, 2.38 M Lithium hydroxide monohydrate, and 0.1 M Iron nitrate nonahydrate. These solutions will be mixed according to a matrix laid out to vary the amounts of uranium, peroxide, base, and iron per experiment. Many syntheses will occur in order to determine solutions that would precipitate new nanoclusters. After mixing, the solutions will be covered with parafilm and small holes will be poked in the top to allow for slow evaporation of the solutions. Crystals will precipitate through solution evaporation, and they then will be examined using single crystal X-ray diffraction to determine their structure.

Other experiments will explore the optimum conditions for repeating the synthesis of known clusters. Once conditions are found that give the purest crystals, these syntheses will be repeated in order to grow enough crystals for other analysis such as Raman spectroscopy, Infrared spectroscopy, and small angle X-ray scattering.
Work on this experiment will involve the use of many potentially hazardous materials. Radioactive materials and dangerous chemicals can be found in the solutions of Uranyl nitrate hexahydrate, Lithium hydroxide monohydrate, and Iron nitrate nonahydrate. To mitigate these risks, proper safety clothing (such as lab coats, gloves, goggles, and badges to detect radiation) will be worn, proper training on working in a lab with potentially dangerous materials will be given, and time spent directly working with dangerous substances will be minimized.
The data gathered from this experimentation will better help researchers understand how to control the formation of Uranium peroxide nanoclusters with specific properties.

Research Updates:
11/17/15: Research topic further defined
-focus: new mineral discovered with cage-cluster formation that uniquely lack peroxide bonds, we want to find out how it forms
+Step 1: precisely analyse similar forming structures

11/20/15: Lab orientation completed and initial experimentation outlined