Walking the nuclear risk tightrope

As U.S. officials strive to reduce the spread of nuclear weapons in countries such as Iran and North Korea, we need to set a global example by reducing nuclear risks here in the United States. That requires a delicate balance in one particular area. We need to maintain civilian nuclear research reactors, which are critical to our economic competitiveness and scientific enterprise, while transitioning them off fuel that can be used to build nuclear weapons.

For decades, civilian nuclear research reactors have been used to carry out research and development with neutrons, which probe matter on an atomic scale and explore the behavior of materials in extreme environments. That research has been integral to the advancement of science and industry.

{mosads}For example, neutrons have the capability of easily passing through the densest of materials like tantalum and tungsten, giving us a glimpse of what’s beyond the view of the human eye. That unique feature of neutrons has led to a range of breakthroughs — from the development of cancer therapies to paint coatings to military body armor to safer jet fuel — that have touched the health and security of every one of us.

But some research reactors that generate those neutrons are fueled by highly enriched uranium (HEU) – material that can be used to build a nuclear weapon.

While the U.S. has a strong record of carrying out the research safely and securely, HEU-fueled research facilities are located all around the world where their security may be far less assured. It has long been a goal of U.S. policy to eliminate HEU from these international sites; much progress has been made in recent decades, but the job is not finished. 

Fortunately, it’s possible to develop research reactors that operate on low enriched uranium (LEU) — fuel which substantially limits the nuclear proliferation risk while maintaining operating characteristics that enable much of the R&D being done in today’s HEU-fueled facilities. This transition, however, has to be carried out in a way that maintains critical U.S. neutron R&D capability that supports industrial innovation and the scientific enterprise. 

Complicating the transition from HEU to LEU is the fact that the U.S. has seen a decline in global leadership relative to Western Europe and, increasingly, China, in neutron R&D capabilities during the last decade as a number of important neutron facilities have closed. The construction of the state-of-the-art Spallation Neutron Source, which does not rely on HEU, has not compensated fully for the decommissioned facilities. Meanwhile, other nations have developed new neutron-producing capabilities, including a number that don’t require HEU fuel.

So, the drive to remain globally competitive economically and scientifically is pushing the U.S. to remain reliant on HEU-fueled neutron sources, while the risks of nuclear proliferation are pushing the U.S. to disinvest from these capabilities. To successfully walk this tightrope, we need to tread carefully and deliberately.

First, we need to steady our position. We need to get more out of the reactor and spallation devices that we currently have. We can only transition successfully if we start from a position of balance. The United States should sharply increase its investments in neutron instrumentation development and deployment to partially compensate for the country’s dramatic decrease in neutron R&D capacity and capability in recent decades. 

Second, we need to commit to our path. The United States should reaffirm its commitment to the timely development and deployment of high-density LEU fuels for use in existing high-performance research reactors, both in the U.S. and around the world. Any transition from HEU to LEU reactor fuel must not compromise neutron research and engineering capabilities, especially those that cannot be duplicated using spallation sources.

And finally, we need to take a bold step that sends a global message. The United States should initiate an effort to competitively design and build a new generation of LEU-fueled high-performance research reactors that would satisfy all needs presently met by current HEU-fueled high-performance research reactors as well as provide new capabilities.

Taken together, these steps would strengthen our nation’s role as a global leader in neutron science and engineering while also meeting its goals to reduce the risk of spreading nuclear weapons and setting an example for the world. 

Julia Phillips and James Wells are co-chairs of the recent study “Neutrons for the Nation. “ Phillips is the former chief technology officer at Sandia National Laboratories and current member of the National Science Board. Wells is a professor of physics at the University of Michigan.