TRIGA fuel enrichment verification based on the measurement of short-lived fission products

Activation detection using indium foils for simultaneous monitoring neutron and photon intensities in a reactor core

“…THOR was loaded with 20% enriched TRIGA fuels (Peir et al, 1999) and utilized to produce radioisotopes and in various applications in Taiwan, since its criticality in 1961. The routine operational cycle for THOR is 20e30 h on Tuesday and Wednesday weekly at 1e2 MW.…”

“…During the first 11 months, the neutron source ( 124 Te/Be) was removed from the fuel assembly for radioactivity cooling. Indium foils were placed in the core at an irradiation position VT-A (Peir et al, 1999) to monitor levels of neutron and photon radiation and their variations over time.…”

“…Table 2 lists the long-lived (t 1/2 > 20 h) fission and activated products in the reactor cores (Reus and Westmeier, 1983;Chao and Chung, 1992), which may emit characteristic photon energies over 1.078 MeV. These nuclides are potential photon sources that can induce the photonuclear reaction 115 In (g, g 0 ) 115m In under sub-critical conditions following the time of shutdown.…”