Source: EM Update | Vol. 14, Issue 4; Contributor: Shannon Potter | February 1, 2022
The improvements to the Molten Salt Reactor Experiment (MSRE) are needed for safe continued operations and will also support the facility’s eventual transfer from maintenance to deactivation, which will save approximately $5 million in annual operating costs.
“This reactor facility was shut down nearly 50 years ago, and we have the important responsibility of keeping it safe until major cleanup operations begin,” said Nathan Felosi, EM’s Oak Ridge National Laboratory (ORNL) portfolio federal project director. “The latest round of projects is making sure that’s the case and achieving considerable cost savings to taxpayers.”
MSRE, located at ORNL, is one of more than 200 facilities in Oak Ridge that no longer support ongoing missions. The Oak Ridge Office of Environmental Management and its contractor UCOR are tasked with keeping many of these facilities in a safe, stable condition, and together they examine ways to reduce costs without compromising safety as these facilities await deactivation and demolition.
Since MSRE is still classified as an active nuclear facility with a deactivated nuclear reactor, numerous upgrades are needed to keep critical systems safe until the facility is torn down. UCOR is making upgrades and modifications that minimize maintenance costs, reduce risks of injury and exposure to personnel, provide reliable electric service to key systems, and eventually eliminate the need for personnel to work at the facility.
Tank headspace-gas pressure builds up from fluorine gases in tanks inside the facility. A new continuous purge system, scheduled to begin operation next year, will provide safe continuous off-gassing instead of allowing the pressure to build up. This project is also reducing risks by replacing an old reactive gas removal system, which has exceeded its operational life expectancy.
Workers are also installing a new roof over a portion of the facility to protect key systems such as the reactor and containment ventilation systems. UCOR is also relocating employees stationed in MSRE to nearby offices to further reduce the possibility of hazards.
Construction of MSRE began in 1962. Test runs began in 1965 using uranium-235 as fuel. The reactor reached full power in 1966. Two years later, scientists added uranium-233 to demonstrate the design’s flexibility, making it the first reactor in the world to operate with uranium-233. Famed scientist Glenn Seaborg, discoverer of plutonium and creator of uranium-233, came to ORNL to start the reactor.
The facility was inspired by a short-lived effort to develop a nuclear-powered aircraft in the 1950s. After that initiative was cancelled, focus shifted to using MSRE technology to generate electricity. Concerns about long-term uranium supplies made this concept more attractive because of its ability to function as a “breeder,” producing more fuel than it consumed.
MSRE was shut down in 1973 in favor of a sodium-cooled fast breeder reactor that was planned for construction — but never built — in Oak Ridge.