Quantitative Imaging Evaluation of Corrosion in Oak Ridge Research Reactor POOL

The Oak Ridge Research Reactor (ORRR) was operated as an isotope production and irradiation facility from March 1958 until March 1987. The US Department of Energy permanently shut down and removed the fuel from the ORRR in 1987. The water level must be maintained in the ORRR pool as shielding for radioactive components still located in the pool. The U.S. Department of Energy’s Environmental Management (DOE EM) needs to decontaminate and demolish the ORRR as part of the Oak Ridge cleanup program. In February 2004, increased pit corrosion was noted in the pool’s 6-mm (¼”)-thick aluminum liner in the section nearest where the radioactive components are stored. If pit corrosion has significantly penetrated the aluminum liner, then DOE EM must accelerate its decontamination and demolition (D&D) efforts. The goal of Mississippi State University’s Diagnostic Instrumentation & Analysis Laboratory (DIAL) is to provide a determination of the extent and depth of corrosion. Results from the work will facilitate ORNL in making reliable disposition decisions. DIAL’s inspection approach is to quantitatively estimate the amount of corrosion by using Fourier-transform profilometry (FTP). FTP is a non-contact 3-D shape measurement technique. By projecting a fringe pattern onto a target surface and observing its deformation due to surface irregularities from a different view angle, FTP is capable of determining the height (depth) distribution of the target surface, thus reproducing the profile of the target accurately. DIAL has previously demonstrated that its FTP system can quantitatively estimate the volume and depth of removed and residual material to high accuracy.