Nuclear Options

Behind a security gate in the southeast corner of the University Park campus sits the Breazeale Nuclear Reactor, one of Penn State’s oldest and most renowned research facilities.

“This was one of the first licensed research reactors in the nation,” says Kenan Ünlü, who has been director of the University’s Radiation Science and Engineering Center since 2008.

The impetus to build a reactor here sprang from President Dwight Eisenhower’s push to develop peacetime uses of nuclear technology. In a speech before the United Nations in 1953, Eisenhower proposed diverting much of the world’s stockpile of fissionable material away from the production of weapons and toward more productive ends. Penn State’s reactor went into service a year and a half later.

“For the first time, neutrons and gamma rays were available for civilian scientists,” says Ünlü. “A vast expansion of fundamental research started at that time.”

Hot cells and cool tools

One of just a dozen active research reactors at U.S. universities, the Breazeale Reactor gives scientists the ability to conduct experiments using neutrons or gamma rays emitted from fission reactions. Neutron-based research begins in the main reaction pool, where 72,000 gallons of water cool the reactor core and act as a barrier to prevent radiation from escaping into the air. The fission reaction in the core is powered by fuel rods of uranium zirconium hydride and is moderated by neutron-absorbing rods of boron carbide. Human operators control the reaction from a console in a nearby room.

For some research, neutrons generated at the reactor core travel through pipes, called neutron beam ports, into an experimental bay. Irradiated samples can be moved to one of two heavily-shielded chambers called “hot cells” that allow researchers to use mechanical hands to safely handle highly radioactive samples. The manipulator hands are so deft they can pick a needle up off the floor, says Ünlü.

In a smaller pool in another building, cobalt-60 serves as the source of gamma rays. They have been used to generate mutations in seeds, which are then screened for useful properties, and to sterilize items that would not survive treatment by heat or chemicals: pollen and royal jelly for research on honey bee colony collapse, culture chambers used to study breast cancer cells, and materials that will be used in orthopedic implants.

Far-ranging research

The facility serves both academic and commercial researchers. It produces isotopes for industrial use and medical research. Neutron imaging has been used to look for flaws inside enclosed metal components and to check the integrity of NASA space suits. Commercial clients use the reactor’s neutron beam to test how susceptible memory chips and microprocessors are to “soft errors” that occur due to environmental radiation. These transient faults do no permanent damage to hardware, but can cause glitches in a device’s operation; minimizing them is critical for production of dependable electronics.

A technique called neutron activation analysis (NAA) can detect trace elements in a sample without destroying the sample in the process. This is especially valuable to archaeologists and others working with irreplaceable specimens. Knowing the trace elements within a clay, wooden, or metal artifact can help pinpoint where the material originated, providing clues about trade routes in ancient times.

Trace elements can also tell us about the global impacts of local events. Doing NAA on dated wood samples from Cornell scientist Peter Kuniholm, Ünlü found that individual growth rings contain gold spewed out by volcanoes. Their analysis pinpointed the eruptions of the Indonesian volcanoes Tambora (1815) and Krakatoa (1883). That’s amazing, Ünlü says, because the wood was from trees growing in Turkey — which means the gold from those eruptions had traveled through the atmosphere almost all the way around the world before ending up in the air and soil the trees were growing in.

The Breazeale Reactor has been upgraded several times during its 63-year history, and this year, with funding from the U.S. Department of Energy, it underwent a major renovation that increases the number of neutron beam ports and gives researchers the ability to do additional techniques for materials characterization.

Through its role in research and as an essential resource for more than 20 Penn State courses, such as radiation detection, reactor physics, and nuclear security, says Ünlü, the Breazeale Reactor continues to fulfill the vision Dwight Eisenhower presented in his “Atoms for Peace” speech at the U.N.

Ike came to campus to see the reactor in 1955 — his brother Milton was president of the University at the time — and repeated the speech at commencement.

Nuclear power, Eisenhower said, “must be put into the hands of those who will know how to…adapt it to the arts of peace…If the fearful trend of atomic military build-up can be reversed, this greatest of destructive forces can be developed into a great boon, for the benefit of all mankind.”

Kenan Ünlü is professor of nuclear engineering and director of the Radiation Science and Engineering Center.

This story first appeared in the Fall 2018 issue of Research/Penn State magazine.