Modelling Cherenkov light from irradiated nuclear fuel assemblies using GEANT4

• The Digital Cherenkov Viewing Device (DCVD) is currently used by International Atomic Energy Agency (IAEA) inspectors for gross defect verification of spent nuclear fuel assemblies in storage pools. A Cherenkov light image is obtained from the spent fuel and the verification is made by the detection of unique Cherenkov characteristics of spent fuel. To take further advantage of its quantitative capabilities, the DCVD’s ability to detect partial defects down to the 30% level is now being investigated. To evaluate the performance of the DCVD, simulations of the emitted and recorded light can be very useful. This presentation describes how the software toolkit GEANT4 is used to gain better understanding of the light contributions from the fuel and its environment by means of Monte Carlo simulations. The toolkit allows the user to access information on individual photon emission coordinates and their momentum vectors and it is also possible to take the expected rod-by-rod burnup distribution at different axial levels into account. Investigations have shown that the Cherenkov light production about the fuel is dominated by gamma radiation from the fuel material interacting with the water surrounding the fuel. A study of the range of the Cherenkov photon production from individual fuel rods, which is of relevance for partial-defect verification, is presented. In addition, emission distributions of Cherenkov light are presented for simulated PWR fuel assemblies with different configurations of replaced rods. Simulated light intensities in guide tubes are presented, showing variations depending on whether fuel rods nearby have been substituted or not.

Ämnesord

NATURVETENSKAP  -- Fysik -- Subatomär fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Subatomic Physics (hsv//eng)

Nyckelord

DCVD

Cherenkov light

GEANT4

nuclear fuel

Nuclear physics

Kärnfysik

Fysik med inriktning mot tillämpad kärnfysik

Physics with specialization in Applied Nuclear Physics

Publikations- och innehållstyp

vet (ämneskategori)

kon (ämneskategori)