Methodology for a simplified sipping test in the IPR-R1 TRIGA reactor of CDTN

The Brazilian Nuclear Energy Commission (CNEN) which is the inspection agency of nuclear facilities in Brazil, has granted permanent operating authorization (OAP) to the IPR-R1 TRIGA nuclear reactor at Nuclear Technology Development Center (CDTN). However, subject to the presentation of results of safety fuel elements inspections to the reactor, related to its structural integrity. One of the tests then planned for this purpose is the sipping test, which aims to verify the integrity of the fuel cladding with respect to leakage of fission products. Sipping is the most common technique used to locate fuel failures in water cooled reactors. Identification of fuel rod failure is based on detecting the activity of fission products released through defects during sipping. The measured radioisotopes include krypton, xenon, cesium, and iodine. Various versions of sipping have been used to detect leaking fuel assemblies. A sipping test method was developed by CDTN. However, the application of this method involves the movement of fuel elements from the core. To prevent the fuel elements movement, a simplified method for the sipping test is presented in this document. This method detects leakage in core regions, although not specifying which element or elements are responsible for the defect. In this circumstance, if the cesium-137 isotope detected by the gamma spectrometry system, suspect fuel elements must pass the complete sipping test, developed by the authors of this article. (author)