University of Pittsburgh researchers have developed a novel field inspection method to assess the internal state of dry cask storage systems (DCSS). Using a fusion of distributed fiber optics (FO) and acoustic nondestructive evaluation (NDE) this monitoring method can quantitatively characterize the internal state of DCSS. This approach could provide a viable direct inspection method for the internal components of welded storage containers allowing for safe monitoring without the need to unseal loaded DCSS.
Dry cask storage systems (DCSS) are increasingly used for the storage of spent nuclear fuel. A novel monitoring method has been developed based on fiber optics and acoustic nondestructive evaluation to detect leaks and corrosion that might impact on structural integrity.
Description
DCSS are increasingly used to store spent nuclear fuel rods before long-term storage or disposal. Once these cannisters are sealed they are stored in a vented concrete overpack for protection and shielding which allows for convective cooling. There is a great need for not only environmental, but health and national security purposes, to continuously assess the structural integrity of DCSS. This novel method could allow monitoring of a variety of conditions internal to the system including signs of corrosion or leaks.
Applications
- Nuclear waste safe storage
- Hazardous chemical storage
- Structural health monitoring
Advantages
Given the danger of radioactive material to environmental and animal health the structural integrity of storage systems needs to be guaranteed. The major risks to the structural health of canisters are corrosion and leaks. Any inspection system must withstand harsh environments, with minimum penetration of the canister surface to reduce the risk of leaks. At present there is no method to directly inspect the internal components of welded canisters once loaded and sealed.
To overcome these challenges an external canister monitoring system is needed. This method aims to use a combination of passive and active sensing techniques to monitor structural integrity. Optical fiber sensors can be arranged on the surface of the canisters to passively sense leaks and an active sensing approach that excites the structure with ultrasonic guided waves (UGW) to detect corrosion would allow for safe monitoring and meet this need.
Invention Readiness
Currently in the design phase, 3D stimulations have demonstrated UGW is a viable approach to detect corrosion defects through reflections and changes in signals detected following excitation of the entire canister surface. Passive sensing at 8 kHz could detect leaks. These approaches could use the same fiber sensor and, with time, use machine learning to predict and classify the threat of future leaks or structural failure, anticipating issues before they occur to allow for repairs.
IP Status
https://patents.google.com/patent/WO2024206395A2Related Publication(s)
Ohodnicki, P. R., Sarcinelli, E., Zhang, P., Naeem, K., Karki, D., Meyer, R., Lalam, N., & Wright, R. (2023). Nuclear canister integrity monitoring using quasi-distributed fiber acoustic sensors and physics-based modeling. In G. A. Sanders, R. A. Lieberman, & I. Udd Scheel (Eds.), Optical Waveguide and Laser Sensors II (p. 17). Optical Waveguide and Laser Sensors II. SPIE. https://doi.org/10.1117/12.2665084
