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Lætitia H. Delmau, a distinguished researcher and radiochemist at 91����, has received the prestigious 2024 Glenn T. Seaborg Actinide Separations Award. 

Delmau was presented with the award May 15 at the in Petaluma, California. The annual award honors U.S. scientists and engineers who have made outstanding and lasting contributions to the development and application of actinide separations process and methodology. Actinides are the series of 15 metallic elements from 89, or actinium, to 103, lawrencium, on the periodic table. They are challenging to separate, not only because they are radioactive, but also because the heavier actinides are extremely unstable and must be created, since they do not occur in nature.

Delmau, who has worked with actinides for more than three decades, said she was honored to be chosen for the award.

“You’re nominated by your peers, and then the decision for giving the award is made by your peers,” she said. “It’s a scientific recognition, based on your accomplishments. It’s humbling to realize that I’m being given by my peers the same award that was given 40 years ago, in 1984, to Glenn T. Seaborg himself and so many highly respected actinide scientists after him.”

Jeff Delashmitt of the Chemical Sciences Division in ORNL’s Physical Science Directorate, who nominated Delmau for the Seaborg Actinide Separations Award, said that although Delmau doesn’t often promote her own work, it’s “significant and important.” 

“Behind the scenes, she is a major driver of some of ORNL’s largest and most prestigious isotope programs,” Delashmitt said. “Through her research, method development and actinide separation protocols, she is pushing the science forward in real-world isotope processing.”

Delmau’s own accomplishments in the field are many. The process she helped develop to remove cesium-137 from high-level waste at the Savannah River Site was implemented and is still used today. Delmau received the DOE Secretary’s Achievement Awards in 2013 as part of the Salt Waste Disposal Technologies Team, and she was part of the Critical Material Institute and the Fuel Cycle Research and Development Program, or STAAR, focusing on separations, solvent extraction or ion exchange. She received a second DOE Secretary’s Achievement Award in 2022, as part of the Mars 2020 Perseverance Rover Radioisotope Power Systems Team. 

Delmau joined ORNL in 1997 as a postdoctoral researcher and was hired into the Chemical Services Division of the Physical Science Directorate in 2000. In 2014, she moved to the Radioisotope Science and Technology Division of what is now the Isotope Science and Engineering Directorate.

Within the past 10 years, Delmau developed a method to recover and purify californium from ORNL’s Cf-252 production’s rework solutions, which contain tens of grams of curium. She proved it was feasible to replace the cation exchange-based solvent extraction system, or CLEANEX, with a diglycolamide-based extract system that decreased the feed adjustment time and improved the rejection of some fissions products – a process being considered for implementation in the 2025 campaign. 

Four years ago, she implemented a process in the hot cells allowing for harvesting lanthanide fission products during a plutonium campaign, then established the processes required to purify the crude lanthanide product to obtain promethium-147 – making ORNL the sole supplier of Pm-147 worldwide. She has continued to optimize these processes, ultimately producing an extremely high-purity batch of promethium that was used by her colleagues in the Chemical Sciences Division for EXAFS studies – resulting in a paper published in May 2024 in the journal Nature.

She has written 64 scientific papers published in peer-reviewed journals and holds seven patents. But Delmau said helping build the next generation of actinide scientists has been her most rewarding work. To date, she’s mentored more than 30 students.

“Actinide science is not something that the students are exposed to normally,” Delmau said. “It would be very unusual for them to get to do that kind of work in their laboratories.”

Delashmitt said Delmau’s support of her colleagues’ work across directorates is part of why he nominated her.

“Her dedication and devotion to the REDC’s missions, projects and programs, and fellow staff members is inspiring,” he said.

Delmau holds a master’s degree in chemical engineering and a post-master’s degree in radiochemistry, both from the Ecole Supérieure de Physique et de Chimie Industrielles, or ESPCI, de la ville de Paris, and a doctorate in physical chemistry from Louis Pasteur University in Strasbourg, France. 

She said her own mentors directly contributed to her successes, beginning with her very first mentor in France, the late Nicole Simon-Condamines, whose encouragement and role modeling led her to work with actinides. At ORNL, her former group leader, corporate fellow Bruce Moyer, with whom she worked for almost 20 years, was instrumental to her scientific growth. After 10 years at REDC, she continues to expand her knowledge through constant interactions with her colleague Dennis Benker, who will soon celebrate 50 years at the lab. 

Delmau said she has had the privilege to meet and collaborate with world-renowned actinide scientists. The late Renato Chiarizia and Ken Nash at Argonne National Laboratory, and Mark Jensen at Colorado School of Mines were among those who helped her build a career. 

“You need to have people who will help you all along and who will be the soundboards for your ideas,” Delmau said. “You don’t need people who will agree with you on everything; you get more out of discussion with people who disagree with you. I have been fortunate to work with very talented scientists who were generous with their time and knowledge throughout my career.”