Determination of the rod-wise fission gas release fraction in a complete fuel assembly using non-destructive gamma emission tomography

摘要: Abstract A gamma tomography instrument has been developed at the Halden Boiling Water Reactor (HBWR) in cooperation between Institute for Energy Technology, Westinghouse (Sweden) and Uppsala University. The is used to record radiation field surrounding complete fuel assemblies consists of a shielded enclosure with fixtures accurately position detector relative each other. High Purity Germanium acquiring high-resolution spectroscopic data, allowing analysis multiple gamma-ray peaks. Using data extracted from selected peaks, tomographic reconstruction algorithms are reproduce corresponding spatial source distributions within assembly. With this method, rod-wise can be deduced without need dismantle fuel. In work, device experimentally benchmarked non-destructive determination Fission Gas Release (FGR) fraction. Measurements were performed on fuel-stack gas-plenum regions assembly, quantitative reconstructions measurement order determine ratio 85 Kr gas plenum 137 Cs stack. Kr/ was, turn, calculate FGR connection measurements, rods also measured individually using scanning provide an experimental benchmark method. Fuel two donor driver placed into nine-rod HBWR assembly configuration. challenging object thus appropriate five taken burnup 51 MWd/kgUO 2 , four 26 . At time nine had cooled approximately 22 years. All operated high linear heat rates (around 70 kW/m), leading relatively fractions. Here, fraction was determined ~24% high-burnup rods, ~17% low-burnup rods. results good agreement individual rod scanning, demonstrating feasibility application. capability assess particularly valuable cases fuels that do not allow disassembly, such as fitted extensive instrumentation.