Wanted: an all-rounder in chemistry and physics who has experience with research reactors, accelerators, and ion beams and who knows about industrial applications of radiation, including radiopharmaceuticals.
That’s quite the job specification. But nuclear chemist Melissa Denecke ticked all the boxes, and in March, she was appointed director of the Division of Physical and Chemical Sciences at the International Atomic Energy Agency (IAEA). Her division is involved in nuclear technology, including isotope hydrology and medical isotope production. It also curates a vast storehouse of data that underpin all the nuclear sciences.
For Denecke, nuclear technologies offer a route to a better world. The IAEA argues that nuclear power can help tackle climate change—for example, by generating electricity with low greenhouse gas emissions. But nuclear research can also play a key role in a host of other applications that advance the United Nations’ sustainable development goals, including identifying new medical treatments and managing water resources.
Mark Peplow talked with Denecke about her division’s work and the status of women in the nuclear sector.
▸ Current city: Vienna
▸ Current role: Director, Division of Physical and Chemical Sciences in the Department of Nuclear Sciences and Applications, International Atomic Energy Agency
▸ Education: BSc, chemistry and biology, Carroll University; PhD, physical chemistry, University of Hamburg
▸ Career highlight: My responsibility at the IAEA. It is an honor to be able to help countries achieve their sustainable development goals.
▸ Best professional advice you’ve received: Treat your career like a project.
▸ Best part of your job: Working with a very diverse group of people committed to helping make the world a better place
▸ Favorite isotope: Plutonium-242
▸ The book on your bedside table: There There by Tommy Orange. I’m always reading something.
▸ What’s new and exciting in your life? I just became a grandmother, which personally is a cosmos-shaking event. I couldn’t be happier and feel so incredibly blessed.
What does the IAEA do?
The IAEA’s mandate is “atoms for peace and development.” Most people think that refers only to our safeguarding work, monitoring nuclear activity to ensure it’s not being misused to secretly produce fissile material for nuclear weapons.
But peace is not just about nuclear safeguards—it’s about getting people from different parts of the world to work together on global problems. A lot of our work is focused on helping to achieve the UN’s sustainable development goals, such as clean water and sanitation for everyone, improving human health, and achieving gender equality.
My own division’s overarching goal is to coordinate the IAEA’s 171 member states to innovate in nuclear technologies that can address these global challenges. We help member states with training, technology transfer, and technology development. The division is a very colorful tapestry, woven out of many different pieces, including radiochemistry, nuclear chemistry, and nuclear physics.
Can you give me some examples of projects from your division?
We do a lot on isotope hydrology, which is an increasingly important tool for water management. The tool uses isotopes in the environment—such as 36Cl, 81Kr, and 14C—to date and track the movement of groundwater.
Countries with growing populations, particularly those with limited water resources, are looking to extract more water from deep aquifers. We’re working with countries in the Sahel region of Africa to date and map the water pathways to make sure that when people start using the water, they’re not going to be left high and dry someday.
We take an advisory role, helping them to equip their laboratories or training their people to collect and analyze samples and interpret results.
Another of our themes is medical radioisotopes, used for therapeutic and diagnostic applications. We just produced a big report on225Ac, which is an α-particle emitter being investigated for cancer therapy. It’s very important to generate enough to meet global need, but because of production costs, the supply of 225Ac is currently restricted to developed countries with a lot of money. The report outlines the need for a diverse range of production methods, including proton or electron accelerators that produce 225Ac from other isotopes, to provide a sufficient and reliable supply.
Our division also helps countries to develop their use of accelerators and research reactors, including cyclotrons, ion beam accelerators, and low- to high-flux reactors. We are collaborating with Elettra, a synchrotron in Italy, and a new ion beam accelerator in Croatia to train researchers from developing countries.
Your division also manages the IAEA’s nuclear data services—how are those used?
Nuclear data underpin everything the IAEA does, from nuclear safeguarding and nuclear power generation to nuclear applications in industry and health sciences. These data include the half-life of a radioisotope, radioactive decay pathways, the neutron absorption cross section of a nucleus, and so on.
Researchers around the world generate this experimental data, and our team works with an international network to scrutinize the data, checking that they’re properly calibrated and consistent with other data. Then it goes into our database, which is open and free for everyone to use.
The nuclear power industry is a big user of our data. The data are essential for understanding the fission reactions in nuclear power stations, for example, and for managing nuclear waste. You need to have accurate data to ensure that you don’t put too much fissile material together and set off a self-sustaining nuclear chain reaction.
You were on the executive board of Women in Nuclear Global, a network of professional women working in nuclear technologies. What’s the current status of women working in the nuclear sector?
The nuclear industry workforce tends to be older, and they’re usually male. Women in Nuclear Global is helping to change that profile. I’m still an active member. The organization does communication and outreach, and we offer prizes to help young women on their path in the nuclear sector.
In the UK, for example, the nuclear workforce is about 20% female. That’s actually pretty good in comparison to some other countries. But let’s face facts: there are more women out there that we could attract. A diverse workforce makes a better workforce. And by not tapping into that resource, we’re making a big mistake.
Across the nuclear field, we need to have policies to increase the number of women. This is not just about hiring policies but also policies on childcare, baby breaks, flexible working hours, and caring for elderly parents.
The IAEA has a policy to reach toward gender parity, and two of the six deputy directors general are female (one of them, Najat Mokhtar, is my boss). When you get some women in leadership roles, they become like crystallization sites—successful women attract more women into organizations. If you’re a young woman and you see where women have made it, it kind ofsteers your career decisions.
Mark Peplow is a freelance writer. A version of this story first appeared in ACS Central Science: cenm.ag/denecke. This interview was edited for length and clarity.