HFIR Beryllium Reflector Replacement and Cold Guide Hall Extension

The High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) provides one of the highest steady-state neutron fluxes of any research reactor in the world. The thermal and cold neutrons produced by HFIR are used for research into the fundamental properties of condensed matter, enabling researchers to make scientific discoveries and address some of the biggest challenges facing society today.

HFIR Beryllium Reflector Replacement

HBRRORNL is preparing to replace HFIR’s permanent beryllium reflector, along with other key reactor core components, to sustain and enhance HFIR’s operational performance. The HFIR Beryllium Reflector Replacement (HBRR) process is planned to begin in 2025 and extend into 2026. See the 5 year planning schedule for up-to-date projections.

The beryllium reflector helps drive neutron production by reflecting stray neutrons back into the core as they are generated. After more than 20 years of successful operation, the reflector is approaching the end of its lifetime and will need to be replaced.

The HBRR project also presents an ideal opportunity to implement long-term infrastructure improvements and make significant upgrades to the facility’s suite of neutron instruments. Executing these changes is critical for sustaining HFIR’s capabilities into the future and expanding the scientific impact of HFIR’s key missions.

The HBRR project will feature:

  • A new design for the beryllium reflector that will optimize isotope production and irradiation experiments while sustaining HFIR’s world-leading neutron scattering instrument performance.
  • A redesigned cold guide network, used for transporting neutron beams to instruments, that will capitalize on technological improvements in neutron optics designs and materials.
  • A new turbine-expander-based helium refrigeration system for the cold source to increase HFIR’s operational reliability and reduce maintenance.
  • Upgrades to a number of thermal and cold neutron instruments, including installing new shutter controls, motor controls, goniometers, and proximity sensors.
  • Improvements to the supporting infrastructure, such as utilities and shielding, in both the beam room and cold guide hall.

Cold Guide Hall Extension

In conjunction with redesigning the cold guide network, plans are under way to extend HFIR’s cold guide hall by more than 4,000 square feet.

The cold guide hall features instruments that use cold neutrons with lower energies to unlock information about complex soft matter, such as proteins and polymers, and analyze materials with magnetic properties.

Extending this guide hall will allow for reconfiguring and optimizing the facility’s cold neutron instruments to significantly improve their performance, develop new capabilities, and provide space to build new instruments. Expanding and redesigning the instrument layout is essential for meeting emerging scientific priorities and supporting cutting-edge research.

The cold guide hall expansion will involve:

  • Relocating the existing Cold Triple Axis (CTAX) spectrometer to provide significant performance gains, including the ability to collect data faster and use smaller samples.
  • Making space to build a new Neutron Spin Echo (NSE) spectrometer, a crucial instrument for advancing research on biological materials and other forms of soft matter.   
  • Providing the IMAGING and IMAGINE instruments with new designated locations.