Monitoring nuclear reactors is essential for safety. Existing methods are effective but frequently require invasive procedures that can disrupt reactor operations or pose security risks.
Furthermore, new difficulties for nuclear monitoring arise as nuclear technology advances continuously. Because small modular reactors (SMRs) are tiny and frequently located in remote places, conventional monitoring techniques may need to be more sensitive and sufficiently adaptive to their workings, as they are primarily built for larger facilities.
Researchers at the Paul Scherrer Institut (PSI) and EPFL have now developed a non-invasive and more effective method for monitoring reactors using gamma noise. In a new study, they demonstrate that, without actual physical intrusion into the reactor vessel, gamma radiation can offer precise and timely data on reactor criticality and composition, in contrast to the neutron signals utilized by typical monitoring methods.
Researchers used two bismuth germanate scintillators in this monitoring method. These scintillators were placed outside EPFL’s CROCUS research nuclear reactor, allowing them to noninvasively monitor gamma radiation emitted from its operation.
Additionally, the novel method uses statistical analysis of the variability of gamma-ray detection across time. Gamma noise analysis, in contrast to traditional techniques that mostly rely on neutrons, is concerned with the variations in gamma ray counts associated with the fission chain reactions taking place inside the reactor. The level of correlation sheds light on the reactor’s operational state.
Finally, the method may provide critical data in minutes, significantly improving over traditional approaches that typically call for longer measurement intervals and closer proximity to the reactor core. Alternatively, the gamma-radiation method uses computer tools to analyze recorded gamma rays’ temporal and spatial variation, providing rapid and accurate assessments of the reactor’s condition.
Through extensive testing, the researchers proved the effectiveness of their approach at distances up to several meters from the reactor core. Gamma-radiation monitoring reduces the requirement for direct contact with the reactor core while improving the speed and precision of data collecting by accurately detecting prompt decay constants.
The new method offers reliable, non-invasive monitoring of various nuclear reactors, including SMRs. It could upgrade nuclear safety protocols, facilitate easier compliance with international treaties, and be used in other industries where radiation monitoring without direct sensor contact is necessary.
Journal Reference:
- Oskari Pakari, Tom Mager, Pavel Frajtag, Andreas Pautz, Vincent Lamirand. Gamma noise to non-invasively monitor nuclear research reactors. Scientific Reports 14, 8409, 10 April 2024). DOI: 10.1038/s41598-024-59127-y