Development of clearance verification equipment for uranium-bearing waste

Highlights: • A model to reduce uncertainty of quantitative determination of uranium content in a drum is applied. • The 1.001 MeV gamma rays emitted by ^234mPa (a short-lived member of the ²³⁸U decay-series) and the associated scattered gamma rays were used in this model. • Relative errors between the quantitative values of uranium amounts and the true values were almost within $\pm$25%, for as little as 0.5 g. - Abstract: Dismantled materials generated from nuclear facilities are reused or directed to repository sites. If scrap metals with complicated shapes can be cleared, the amounts of radioactive waste can be reduced. A clearance verification system is constructed to determine the amount of uranium in decontaminated metals in a drum using the 1.001 MeV gamma rays of ^234mPa, produced in the decay of ²³⁸U. The experimental study with simulated waste drums demonstrated that the quantification errors of uranium fall within 25% for 0.5 g of uranium.