The detection equipment for measuring the burnup depth in
spent fuel rods is a vital component of the spent fuel management
system. which can determine the burnup depth of spent fuel board and
plays a crucial role in safeguarding the safety, economic
efficiency, and structural integrity of the fuel assembly. This
study introduces an innovative technical approach for assessing the
burnup depth of spent fuel veneers, utilizing transmitted thermal
neutron imaging technology. We have significantly enhanced the
design of a thermal neutron moderator collimator, leading to
remarkable improvements in the quality of the thermal neutron
beam. Following moderation by the collimator, the ultimate thermal
neutron injection rate at the designated sample location exceeds
103 n/cm2, with thermal neutrons comprising over 74% of the
collimated neutron beam. This advanced measurement system enables us
to obtain a detailed two-dimensional distribution map of thermal
neutrons transmitted through spent fuel boards with varying burnup
depths. By analyzing the grayscale intensity patterns in these maps,
we can accurately evaluate the burnup degree within the simulated
spent fuel plate. Furthermore, we establish a correlation between
the transmitted thermal neutron count in the imaging field and the
burnup depth of the spent fuel veneer. This allows for precise
determination of burnup depth through the analysis of the
two-dimensional distribution of transmission thermal neutron
intensity. Our findings demonstrate the feasibility of a scheme for
detecting the burnup depth in spent fuel boards based on
transmission thermal neutron imaging technology, and obtained a
linear relationship between the neutron transmission count and the
burnup depth of the spent fuel plate, laying a solid theoretical
foundation for future research and development of testing equipment
to assess burnup in spent fuel veneers.
