Design of an irradiation facility with a real-time radiation effects monitoring capability

An in-core irradiation facility for radiation effects testing with a real-time monitoring capability has been designed for the 1.1 MW TRIGA Mark II research reactor at The University of Texas at Austin. The facility is larger than any currently available non-central location in a TRIGA, supporting testing of larger electronic components as well as other in-core irradiation applications requiring significant volume such as isotope production or neutron transmutation doping of silicon. This article presents the layout and characterization of the large in-core irradiation facility and the real-time electronics performance monitoring capability it is designed to support. To demonstrate this capability, an experimental campaign was conducted where the real-time current transfer ratio for 4N25 general-purpose optocouplers was obtained from in-situ voltage measurements. The resultant radiation effects data – current transfer ratio as a function of neutron and gamma dose – was seen to be repeatable and exceptionally finely resolved. Therefore, the real-time capability at UT TRIGA appears competitive with other effects characterization facilities in terms of number and size of testable samples while additionally offering a novel real-time, in-core monitoring capability.