Nondestructive Assay Techniques for Recycled 233u Fuel for High-Temperature Gas-Cooled Reactors

ABSTRACT Nondestructive fissile material assay techniques are reviewed for application to the refabrication of recycled fuel for High Temperature Gas-Cooled Reactors (HTGR). The refabrication processes and fuel characteristics are identified and explained, and nondestructive assay techniques are evaluated in light of these characteristics and assay requirements. The study concludes that currently developed and implemented gamma-ray assay techniques for 235TJ of its high radioactivity. Calorimetry has potential for fuel assay if appropriate corrections for isotopic composition can be applied. For most nondestructive assay requirements, active interrogation methods must be employed. Neutron interrogation systems using either Be neutron sources and delayed or prompt fission neutron detection offer the greatest potential for assay of HTGR recycled the fuel forms during processing and the particulate nature of the HTGR fuel complicate the direct application of these neutron interrogation techinques. Photofission techniques, which offer enhanced penetrability for the assay of bulk fuel quantities or fuel elements, cannot be evaluated for this application because of a lack of basic data. 233Uancj 239pu are not applicable to 233U fuel because233U252Cf or 124Sb-233U fuel. The presence of hydrogen in some of