Description
Completed in 2004, the Neutron Radiography Facility (NRF) at the Oregon State TRIGA® Reactor (OSTR) represents a significant expansion of the reactor's capabilities. Utilizing beam port #3, the NRF takes advantage of its tangential orientation to provide a predominantly thermal neutron beam with minimal gamma contamination. The facility features a precision-engineered collimator with a bismuth filter, cadmium, boral, and lead components to ensure optimal beam quality. The emitted beam, shaped by a rectangular boral aperture, meets ASTM E545 Category 1 standards, with an L/D ratio ranging from 86 ± 4 to 117 ± 4.
The NRF blockhouse was designed for safety and operational reliability. It includes a pneumatically operated lead shutter with fail-safe interlocks, lead-lined doors, and a beam stop composed of lithium-saturated polyethylene and lead bricks to minimize residual radiation. These engineered controls, complemented by constant communication protocols, prioritize user safety and facility longevity.
This robust system supports a variety of neutron imaging applications, offering high-quality radiographs and dynamic imaging capabilities. Active imaging systems for acquisition of neutron radiographs include:
1. FUJI Neutron-Sensitive Imaging System
The FUJI Bio-Imaging Analyzer (BAS-2500) and its neutron-sensitive imaging plates remain a cornerstone of neutron radiography at the Oregon State TRIGA® Reactor (OSTR). Despite being out of production, the system offers exceptional versatility and resolution (~40 μm/pixel), making it an invaluable tool for high-resolution imaging and education.
The BAS-2500 scanner, operated via dedicated software on a legacy Windows 98 platform, exemplifies durability and reliability. Its reusable BAS-ND2025 imaging plates, featuring a Gd₂O₃ converter in their photostimulable layer, are specifically designed for neutron detection. These 20 cm x 25 cm plates can capture fine details in both wet and dry samples, enabling diverse applications in research and training.
Due to the discontinuation of these plates, usage is carefully managed to preserve them for critical applications, including external user projects requiring precision imaging. With well-documented operational procedures, the FUJI system continues to provide cutting-edge imaging capabilities while fostering the development of future nuclear scientists and radiographers.
2. ANTARES Neutron Imaging System
The ANTARES system, donated by Idaho National Laboratory (INL), has enhanced digital neutron radiography (NR) capabilities at the Oregon State University TRIGA Reactor (OSTR). Designed for compact fields of view (FOVs) and efficient neutron tomography (nCT), it supports detailed sample characterization with a square FOV of 114 mm × 114 mm, well-suited for high-resolution imaging. The system’s modular design prioritizes portability, enabling researchers to reposition it for various applications or educational purposes.
The detection scheme integrates a custom-machined 6LiF/ZnS:Ag scintillator (1:2 ratio) adhered to the camera box with optical tape to ensure minimal light leakage. Photon emissions are directed via a high-precision, first-surface mirror to an ASI178MM-Cool ZWO monochrome camera, with a 3096 × 2080-pixel resolution and peak quantum efficiency of 81%. The use of first-surface mirrors, coated with a durable dielectric layer, minimizes optical distortions and oxidation over time, critical for maintaining image fidelity. Its innovative design, operational flexibility, and adaptability for educational purposes make it a cornerstone of neutron imaging at OSTR.