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The Thermal Column experimental facility is designed to provide several variations of thermal energy neutron beams. The facility consists of a 4-foot (ft.) x 4-ft. square column embedded within the biological shield wall, encasing a series of graphite blocks that moderate and collimate neutrons within the space.

Within the pool on the reactor side of the Thermal Column is an end box made of aluminum that encases a layer of graphite blocks and a layer of lead. The graphite in this end box significantly moderates the neutrons entering the thermal column, and the lead reduces most of the gamma rays from the reactor.

Within the Thermal Column are a series of removable graphite stringers that assist with collimating the beam and may be arranged to provide specific geometries for experiments. An internal collimator composed of a large graphite stringer with a sealed center bore hole can be placed in the centerline of the thermal column and evacuated of air to provide a clean geometry of thermal neutrons to the face of the thermal column door.

Three access ports are also available for instrumentation lines or sample insertion to the interior of the Thermal Column. These access ports consist of two 3-inch (in) ports on either side of the Thermal Column door, and one 4-in vertical port that extends through the biological shield to an endpoint on the Intermediate Level of the facility.

The Thermal Column door is a 5-ft x 5-ft heavy steel door with four access ports that are 7-in diameter at the exterior face of the door, 6-in diameter on the interior face, and horizontally centered to the core. Each access port is fitted with a steel plug that may be removed for beam use. One of these ports has been fitted with a pneumatically activated borated aluminum plate door, which may be opened and closed to allow sample insertion in the beam path.

This facility also contains an experiment station for neutron radiography. An exterior collimator made of aluminum, lined with cadmium, and evacuated of air, is placed between the Thermal Column door access port and the radiography camera. The radiography camera system consists of a Lithium Flouride (LiF) neutron converter screen and a 2-Megapixel Charge-Coupled Device (CCD) camera system. Specimens are radiographed on a precision turning table, which can be rotated 360 degrees, translated across the face of the imaging detector, and raised or lowered by approximately 12-inches.

Total Neutron Flux at 1 Megawatt (MW):

• 1.44E+07 neutrons per centimeter squared per second (n/(cm^2 sec)) at the face of the door port.

Typical Uses:

• Neutron Activation Analysis
• Neutron Radiography
• Non-destructive testing of materials and components
• Tomography of low-Z materials