Neutron Radiography of Irradiated Nuclear Fuel at Idaho National Laboratory

Abstract

Neutron radiography of irradiated nuclear fuel provides more comprehensive information about the internal condition of irradiated nuclear fuel than any other non-destructive technique to date. Idaho National Laboratory (INL) has multiple nuclear fuels research and development programs that routinely evaluate irradiated fuels using neutron radiography. The Neutron Radiography reactor (NRAD) sits beneath a shielded hot cell facility where neutron radiography and other evaluation techniques are performed on these highly radioactive objects. The NRAD currently uses the foil-film transfer technique for imaging fuel that is time consuming but provides high spatial resolution. This paper describes the NRAD and hot cell facilities, the current neutron radiography capabilities available at INL, planned upgrades to the neutron imaging systems, and new facilities being brought online at INL related to neutron imaging.

Epithermal Neutron Radiography and Tomography on Large and Strongly Scattering Samples

“…The 250 kW NRAD reactor at INL is optimized for radiography on highly radioactive samples (spent fuel) using the transfer method with dysprosium and cadmium-filtered indium foils, which are sensitive in the thermal and epithermal ranges, respectively [2]. For this, the beam tubes are mounted close to the cladding of the core ( Fig.2) with only a few millimeters of water between the fuel and beginning of the beam tube, so the epithermal flux is maximized because only minimal neutron moderation happens on the way into the beam tubes.…”

Reactivation of the Transient Reactor Test (TREAT) Facility Neutron Radiography Program

“…The TREAT radiography system is used to perform neutron radiography of fuels, experiments, and other specimens before and after irradiation at the TREAT reactor [2]. Neutron radiographs are acquired using transfer method with dysprosium conversion foils and image plates [3], similar to the process used at INL's Neutron Radiography (NRAD) Reactor [4]. The system includes the radiography facility where radiography cassettes are exposed to the neutron beam and a Radiography Room where radiographs are subsequently processed.…”

Quantitative Crack Analysis using Indirect Neutron Radiography and Neutron Activation Analysis with Contrast Enhancement Agents

“…Phase One of this project investigated the ability of a gadolinium-based infiltrant to enhance the contrast of indirect neutron radiography images at the Neutron RADiography (NRAD) reactor at the Idaho National Laboratory. This reactor is a 250 kW TRIGA (Training, Research, Isotopes, General Atomics) reactor, and provides neutrons for two beamlines [3]. Two radiography stations at the NRAD allow for indirect neutron imaging using a cassette containing activation foils.…”