Elemental and Radiological Characterization of Residue on the Surface of PRR-1 TRIGA Fuel Cluster Assembly

Abstract

The Philippine Research Reactor-1 (PRR-1) of the Philippine Nuclear Research Institute (PNRI) has slightly irradiated Training Research Isotope General Atomics (TRIGA) nuclear fuel rods that have been stored in a wet storage tank for three decades. In support of the re-operation of PRR-1 as a subcritical assembly, which will reuse the TRIGA fuel rods, residues collected from the fuel cluster shrouds were characterized to ascertain the integrity of the fuel. The elemental composition of the residue samples was determined via wavelength dispersive X-ray fluorescence spectroscopy (WDXRF), while radiological characterization of potential alpha, beta, and gamma contamination was performed using a radiation counter. Gamma spectrometry was also carried out for water samples obtained from the fuel storage tank to determine if the water contains any radioactive materials that are beyond normal levels. Results indicated that residues collected on the fuel cluster shrouds were aluminum oxide while radiological contaminations were found to be below the values for surface and water contamination based on the Code of PNRI Regulations Part 3. These results demonstrated that although the fuel cluster shroud had some level of oxidation, there is no evidence that the integrity of the TRIGA fuel cladding has been compromised, thus confirming its suitability for repurposing.